CN114172170A - Phase modulator equipment with expandable energy storage and inertia, control method and system - Google Patents

Phase modulator equipment with expandable energy storage and inertia, control method and system Download PDF

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Publication number
CN114172170A
CN114172170A CN202111510495.9A CN202111510495A CN114172170A CN 114172170 A CN114172170 A CN 114172170A CN 202111510495 A CN202111510495 A CN 202111510495A CN 114172170 A CN114172170 A CN 114172170A
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China
Prior art keywords
frequency
flywheel
doubly
motor
fed
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CN202111510495.9A
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Chinese (zh)
Inventor
孙华东
李志强
郭强
李文锋
王东阳
张健
魏巍
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China Electric Power Research Institute Co Ltd CEPRI
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China Electric Power Research Institute Co Ltd CEPRI
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J15/00—Systems for storing electric energy
    • H02J15/007—Systems for storing electric energy involving storage in the form of mechanical energy, e.g. fly-wheels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/30—Arrangements for balancing of the load in a network by storage of energy using dynamo-electric machines coupled to flywheels
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/40—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation wherein a plurality of decentralised, dispersed or local energy generation technologies are operated simultaneously
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/16—Mechanical energy storage, e.g. flywheels or pressurised fluids

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses phase modulator equipment with expandable energy storage and inertia, and a control method and a system. The apparatus comprises: the synchronous phase modulator is arranged at a grid-connected point of the new energy plant; the rotor of the double-fed motor is connected with the rotor of the synchronous phase modifier; at least one group of flywheel devices, wherein each group of flywheel devices comprises a flywheel motor and a flywheel driven by the flywheel motor; when each flywheel motor is connected with the stator of the double-fed motor, the corresponding flywheel releases inertia through the flywheel motor and the synchronous phase modulator; when each flywheel motor is connected with the stator of the double-fed motor and the power-on frequency of the flywheel motor is changed, the rotating speed of the corresponding flywheel is changed, and the energy storage state of the corresponding flywheel is changed; the energy storage capacity and inertia of the phase modifier apparatus are extended as the number of flywheel units connected to the stator of the doubly fed machine is extended. The phase modulator equipment can conveniently expand the energy storage capacity and inertia through a flywheel device, has primary frequency modulation capability and provides inertia support for a new energy plant station.

Description

Phase modulator equipment with expandable energy storage and inertia, control method and system
Technical Field
The invention relates to the technical field of motors and electric appliances, in particular to phase modulator equipment with expandable energy storage and inertia, and a control method and a system.
Background
The new energy occupation ratio will be continuously and greatly improved in the future. Compared with a traditional generator set, the new energy power supply has the main defects that the equivalent moment of inertia is small, the voltage supporting capacity and the frequency adjusting capacity are insufficient, and effective support cannot be provided for a power grid when the power grid is in serious failure. And the fault ride-through capability of the new energy power supply is poor, and the stable operation of the power system can be seriously threatened.
Different from a large phase modulator which is traditionally built on the main network side, the main technical direction for solving the problems is to realize voltage support and inertia support on the spot of a new energy plant station, distributed energy and the like by using a small distributed phase modulator and configure a proper energy storage device.
However, the rotational inertia of the traditional phase modulator is only 30% -50% of that of a generator set with the same capacity, and the maximum matching capacity is usually less than 25% of that of a new energy plant or a distributed energy source, so that the inertia supporting capacity of the traditional phase modulator to the system is relatively deficient, and the traditional phase modulator also has no primary frequency modulation function.
Therefore, it is a very urgent task to increase the capacity and the moment of inertia of the distributed phase modulator system, thereby providing effective support to the grid.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides phase modulator equipment with expandable energy storage and inertia, a control method and a system, which are arranged in a new energy plant station and aim to solve the problems that the traditional synchronous phase modulator has smaller rotational inertia and can not participate in primary frequency modulation of the system.
This application first aspect provides an energy storage and inertia extensible phase modulation machine equipment, includes:
the synchronous phase modulator is arranged at a grid-connected point of the new energy plant;
the rotor of the double-fed motor is connected with the rotor of the synchronous phase modifier;
at least one group of flywheel devices, wherein each group of flywheel devices comprises a flywheel motor and a flywheel driven by the flywheel motor;
when each flywheel motor is connected with the stator of the double-fed motor, the corresponding flywheel releases inertia through the flywheel motor and the synchronous phase modulator;
when each flywheel motor is connected with the stator of the double-fed motor and the energizing frequency of the flywheel motor is changed, the rotating speed of the corresponding flywheel is changed, and the energy storage state of the corresponding flywheel is changed;
when the number of flywheel devices connected to the stator of the doubly-fed machine is extended, the energy storage capacity and the inertia of the phase modifier apparatus are extended.
In some embodiments, the doubly-fed machine is provided with a converter for adjusting the energisation frequency of the rotor of the doubly-fed machine; when the power-on frequency provided by the converter to the rotor of the doubly-fed motor is kept unchanged, the rotating speed and the energy storage state of the flywheel are kept unchanged;
when the energizing frequency provided by the converter to the rotor of the doubly-fed motor is changed, the rotating speed of the flywheel is increased or reduced, and the energy storage state of the flywheel is increased or reduced.
A second aspect of the present application provides a method for controlling a phase modulation apparatus having an expandable energy storage and inertia, the method being applied to the phase modulation apparatus described in the first aspect, the method including:
when the frequency of a power grid is detected to be larger than a preset forward safety frequency, generating a first-class primary frequency modulation instruction for reducing the frequency of the power grid;
generating instructions for controlling a frequency variation of an operating current of a converter of a doubly-fed machine of said phase modifier apparatus in response to said first class of primary frequency modulation instructions,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is increased, and the energy storage state of the flywheel is increased.
In some embodiments, further comprising:
when the frequency of the power grid is detected to be smaller than a preset reverse safety frequency, generating a second type of primary frequency modulation instruction for increasing the frequency of the power grid;
generating instructions for controlling a frequency variation of an operating current of a converter of a doubly-fed machine of said phase modulation apparatus in response to said primary frequency modulation instructions of the second type,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is reduced, and the energy storage state of the flywheel is reduced.
In some embodiments, further comprising:
when the frequency of the power grid is detected to be larger than a preset reverse safety frequency or smaller than a preset forward safety frequency, generating an inertia response instruction;
generating a command for controlling the frequency of the operating current of the converter of the doubly-fed machine of the phase modifier apparatus to remain constant in response to the inertia response command,
so that the current transformer of the doubly-fed machine maintains the energizing frequency supplied to the rotor of the doubly-fed machine constant in response to a command that the frequency of the operating current remains constant, so that the energizing frequency supplied to the flywheel motor of the phase modifier apparatus remains constant, so that the flywheel of the phase modifier apparatus enters an inertia response state.
In some embodiments, further comprising:
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of the phase modifier apparatus in response to a received system start instruction,
adjusting the energizing frequency provided to the rotor of the doubly-fed machine so that the rotating speed of the rotor of the doubly-fed machine is increased from zero to the rated rotating speed thereof in response to the instruction of the frequency change of the working current by the converter of the doubly-fed machine;
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of said phase modifier apparatus in response to a received detection result that a synchronization of a synchronous phase modifier of said phase modifier apparatus is completed,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so as to increase the rotation speed of the flywheel of the phase modifier apparatus to its nominal rotation speed.
A third aspect of the present application provides a control device for a phase modulation apparatus with scalable energy storage and inertia, the control device being used for the phase modulation apparatus described in the first aspect, the control device including:
the primary frequency modulation instruction generating unit is used for generating a first type of primary frequency modulation instruction for reducing the frequency of the power grid when the frequency of the power grid is detected to be greater than a preset forward safety frequency;
an operating current adjusting unit of the converter, which is used for responding to the first class primary frequency modulation instruction and generating an instruction for controlling the frequency change of the operating current of the converter of the doubly-fed motor of the phase modifier equipment,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is increased, and the energy storage state of the flywheel is increased.
In some embodiments, the primary frequency modulation instruction generation unit is further configured to generate a second type of primary frequency modulation instruction for increasing the frequency of the power grid when it is detected that the frequency of the power grid is smaller than a preset reverse safety frequency;
the working current adjusting unit of the converter is also used for responding to the second type primary frequency modulation instruction and generating an instruction for controlling the frequency change of the working current of the converter of the double-fed motor of the phase modifier equipment,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is reduced, and the energy storage state of the flywheel is reduced.
In some embodiments, the system further comprises an inertia response instruction generation unit, configured to generate an inertia response instruction when it is detected that the frequency of the power grid is greater than a preset reverse safety frequency or less than a preset forward safety frequency;
the working current adjusting unit of the converter is also used for responding to the inertia response instruction and generating an instruction for controlling the frequency of the working current of the converter of the doubly-fed motor of the phase modifier equipment to be kept unchanged,
so that the current transformer of the doubly-fed machine maintains the energizing frequency supplied to the rotor of the doubly-fed machine constant in response to a command that the frequency of the operating current remains constant, so that the energizing frequency supplied to the flywheel motor of the phase modifier apparatus remains constant, so that the flywheel of the phase modifier apparatus enters an inertia response state.
In some embodiments, the operating current adjusting unit of the converter is further configured to:
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of the phase modifier apparatus in response to a received system start instruction,
adjusting the energizing frequency provided to the rotor of the doubly-fed machine so that the rotating speed of the rotor of the doubly-fed machine is increased from zero to the rated rotating speed thereof in response to the instruction of the frequency change of the working current by the converter of the doubly-fed machine;
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of said phase modifier apparatus in response to a received detection result that a synchronization of a synchronous phase modifier of said phase modifier apparatus is completed,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so as to increase the rotation speed of the flywheel of the phase modifier apparatus to its nominal rotation speed.
A fourth aspect of the present application provides a computer storage medium having stored thereon a computer program for implementing the method as explained in the second aspect.
A fifth aspect of the present application provides a phase modulation system, which is provided in a new energy plant, and is provided with the phase modulation apparatus as described in the first aspect; a control device as explained in the third aspect is provided.
The phase modifier is arranged in the phase modifier equipment of a new energy plant station, the synchronous phase modifier is electrically coupled with the flywheel device through the double-fed motor, and the reliability is high. The flywheel device can realize modularization, and is convenient for expanding energy storage capacity. The phase modulator equipment not only has primary frequency modulation capability, can provide primary frequency modulation support for a new energy plant station, but also can greatly improve the equivalent inertia time constant of the phase modulator equipment. The added rotary inertia of the phase modifier is irrelevant to a primary frequency modulation control unit or an excitation control unit which is externally connected with the phase modifier, and is the inherent characteristic of the phase modifier. The converter of the double-fed motor is used for rotor alternating current excitation control and starting of the whole phase modulator system, and therefore starting and excitation are integrated.
The control method and the control device provided by the invention are used for controlling the phase modifier equipment to execute primary frequency modulation, inertia support or system starting.
The phase modulator system provided by the invention is provided with the synchronous phase modulator, the double-fed motor and the plurality of groups of flywheel devices, and can provide expandable rotational inertia and energy storage capacity, so that the problem that the rotational inertia of the synchronous phase modulator is small is solved, active power can be provided for a power grid, and the primary frequency modulation capability is realized. The phase modulator system can better meet the inertia support requirement of a power grid, greatly improve the primary frequency modulation performance of the new energy plant station, is beneficial to improving the consumption capacity and the stability level of the new energy, and can improve the efficiency of the new energy plant station in the power grid.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
FIG. 1 is a schematic diagram of the composition of a phase modulation apparatus in accordance with a preferred embodiment of the present invention;
fig. 2 is a schematic electrical wiring diagram of a phase modifier apparatus in accordance with a preferred embodiment of the present invention;
FIG. 3 is a schematic flow chart of a control method according to a preferred embodiment of the present invention;
FIG. 4 is a schematic diagram of the components of the control device according to the preferred embodiment of the present invention;
fig. 5 is a schematic diagram of the composition of a phase modulator system in accordance with a preferred embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Annual average new energy installation will exceed 1 hundred million kilowatts (kW). The large increase in the new energy ratio poses serious challenges to the voltage support, inertia support and frequency modulation capability of the power system.
According to the grid-connected standard of the new energy power supply, the new energy plant station is required to provide a certain short-circuit capacity and inertia support for the system; meanwhile, the new energy plant is required to improve the active regulation capacity and the reactive regulation capacity, and active regulation resources such as a gas power station, a pumped storage power station and an energy storage power station and dynamic reactive regulation equipment such as a phase modulator, a static synchronous compensator and a static reactive compensator are configured as necessary.
However, the conventional synchronous phase modulator has a small rotational inertia, and relatively limited inertia supporting capability for a power grid. In addition, the conventional synchronous phase modulator does not have a primary frequency modulation capability. Moreover, compared with other dynamic reactive power compensation equipment, the cost of the phase modifier is relatively high. For the above reasons, the conventional synchronous phase modulator is not widely used in new energy plants at present.
In a power system operating safely and stably, the change (which is 50Hz away from the basic frequency and can be increased or reduced) of the power grid frequency is usually less than 0.25Hz (namely, 0.5%), so that during the dynamic adjustment of the power grid frequency, the inertia power provided by the synchronous phase modulator to the system is very small (belonging to the damping power in nature), and the primary frequency modulation performance of the system cannot be improved remarkably.
An example of a conventional synchronous phase modulator participating in system primary modulation is provided below. Taking a new energy plant with the capacity of 50MW Megawatts (MW) as an example, according to the capacity ratio of 20%, the new energy plant is provided with a new energy plant with the capacity of 10MVar megafunctions (M) at the grid-connected pointvar), time constant of inertia Tj10s synchronous phase modulator. When the frequency of the power grid changes by 0.25Hz within 1s, the maximum inertial power provided to the system is 10s 10MW (1-0.995)2) And/2/1 s is approximately equal to 0.5 MW. According to the relevant specifications of the primary frequency modulation of the power grid, when the frequency of the system changes by 0.25Hz, the new energy plant station can provide the primary frequency modulation power of 10% of the current operating power of the new energy plant station. For a new energy plant with a capacity of 50MW, a maximum of 5MW primary frequency modulation power is required. As mentioned before, the maximum inertial power that the synchronous condenser provides to the system is only 0.5MW, which is only one tenth of the demand. Therefore, it is generally considered that the conventional synchronous phase modulator has substantially no primary modulation capability.
The small distributed phase modulators are used for carrying out local voltage and inertia support on new energy plants, distributed energy sources and the like, and the small distributed phase modulators become main means for improving the safety and stability of a power grid and the consumption level of new energy sources in the future.
A flywheel is a mechanical component that is driven in rotation by a prime mover. The flywheel rotating at high speed has larger kinetic energy, and the kinetic energy of the rotation can be controlled to increase or decrease by controlling the rotating speed of the flywheel, so that the aim of increasing the stored energy or releasing the stored energy is fulfilled. The flywheel is used for an energy storage scene, has the advantages of high power density, long cycle life, quick response and environmental friendliness, and is suitable for occasions with low primary frequency modulation power but frequent adjustment. If the primary frequency modulation power is larger, an electrochemical energy storage device can be adopted. In order to increase the service life of an electrochemical energy storage device, electrochemical energy storage devices are generally suitable for frequent unregulated applications.
As shown in fig. 1 and fig. 2, a phase modulation apparatus 100 according to an embodiment of the present invention includes a synchronous phase modulator 10, a doubly-fed motor 20, and a multi-group flywheel device 30. Each set of flywheel devices comprises a flywheel motor 31 and a flywheel 32 driven by the flywheel motor 31, wherein the rotor of the flywheel motor 31 and the flywheel 32 rotate coaxially, and the stator of the flywheel motor 31 is electrically connected with the stator of the doubly-fed motor 20.
The stator of the synchronous phase modifier 10 is electrically connected to a grid-connected point of a new energy plant station, and the rotor of the synchronous phase modifier 10 is coaxially connected with the rotor of the double-fed motor 20 and rotates at the same speed. The flywheel motors 31 are each independently powered by the doubly fed motor 20. Wherein, the stator of the flywheel motor 31 is electrically connected with the stator of the doubly-fed motor 20, for example, connected by a large-capacity copper bar.
The rotor of the doubly fed motor 20 is excited by its converter 21, and the rotor of the synchronous phase modifier 10 is excited by its excitation system 11 provided with an Automatic Voltage Regulator (AVR). The exciting current of the double-fed motor can be direct current, positive sequence alternating current and negative sequence alternating current; the rotating magnetic field generated by the positive sequence alternating current is the same as the rotation direction of the rotor, and the rotating magnetic field generated by the negative sequence alternating current is opposite to the rotation direction of the rotor.
As above, when each flywheel motor is connected to the stator of the doubly-fed motor, the corresponding flywheel releases its inertia through the flywheel motor and the synchronous phase modulator; when each flywheel motor is connected with the stator of the double-fed motor and the energizing frequency of the flywheel motor is changed, the rotating speed of the corresponding flywheel is changed, and the energy storage state of the corresponding flywheel is changed; when the number of flywheel devices connected to the stator of the doubly-fed machine is extended, the energy storage capacity and the inertia of the phase modifier apparatus are extended.
As above, the flywheel means is controllably connected to the stator of the doubly-fed machine. For example, when the circuit switch is closed, the rotor of the flywheel motor is communicated with the stator of the double-fed motor. When the circuit switch is disconnected, the connection between the rotor of the flywheel motor and the stator of the double-fed motor is disconnected. And the flywheel devices are connected to the stator of the double-fed motor in parallel, have the same energizing frequency and have the same rotating speed of each flywheel.
As shown in fig. 3, a control method according to an embodiment of the present invention is applied to the foregoing phase modulation apparatus, and the method includes:
step S101: when the frequency of a power grid is detected to be larger than a preset forward safety frequency, generating a first-class primary frequency modulation instruction for reducing the frequency of the power grid;
generating instructions for controlling a frequency variation of an operating current of a converter of a doubly-fed machine of said phase modifier apparatus in response to said first class of primary frequency modulation instructions,
step S102: so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is increased, and the energy storage state of the flywheel is increased.
The frequency of the power grid is greater than the preset forward direction safety frequency, and the frequency of the power grid is obtained from a grid-connected point by connecting a synchronous phase modulator at the grid-connected point. The predetermined forward safety frequency may be a frequency outside the primary frequency modulation dead zone (e.g., -0.025Hz to-0.025 Hz) that is greater than 50Hz, such as 50.03Hz, of the nominal frequency of the ac power grid.
Generating, in response to the first type of primary frequency modulation command, a command for controlling a frequency variation of an operating current of a converter of a doubly-fed electric machine of the phase modifier apparatus, comprising: and the command of increasing the frequency of the working current of the converter of the double-fed motor or the command of reducing the frequency of the working current of the converter of the double-fed motor. In this case, the flywheel is stably operated at a speed around its rated speed as an initial state of the primary frequency modulation. At this time, according to the value of the power frequency provided by the converter to the rotor of the doubly-fed motor and the working current, which are positive sequence or reverse sequence, the command for generating the frequency increase or decrease of the working current of the converter of the doubly-fed motor for controlling the phase modifier equipment is determined, so that the rotating speed of the flywheel is increased finally.
And the speed of the frequency increase or decrease of the working current can be constant speed or variable speed and can be flexibly set according to the requirement.
In some embodiments, further comprising:
step S103: when the frequency of the power grid is detected to be smaller than a preset reverse safety frequency, generating a second type of primary frequency modulation instruction for increasing the frequency of the power grid;
step S104: generating instructions for controlling a frequency variation of an operating current of a converter of a doubly-fed machine of said phase modulation apparatus in response to said primary frequency modulation instructions of the second type,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is reduced, and the energy storage state of the flywheel is reduced.
The reverse safety frequency may be a frequency outside the dead zone of the primary frequency modulation action (e.g., -0.025Hz and-0.025 Hz) that is less than 50Hz, such as 49.97Hz, of the nominal frequency of the ac power grid.
Generating, in response to the primary frequency modulation command of the second type, a command for controlling a frequency variation of an operating current of a converter of a doubly-fed electric machine of the phase modulation apparatus, comprising: and the command of increasing the frequency of the working current of the converter of the double-fed motor or the command of reducing the frequency of the working current of the converter of the double-fed motor. In this case, the flywheel is stably operated at a speed around its rated speed as an initial state of the primary frequency modulation. At this time, according to the value of the power-on frequency provided by the converter to the rotor of the doubly-fed motor and the working current being in a positive sequence or a negative sequence, determining a command for generating a frequency increase or decrease of the working current of the converter of the doubly-fed motor for controlling the phase modifier equipment so as to finally reduce the rotating speed of the flywheel.
And the speed of the frequency increase or decrease of the working current can be constant speed or variable speed and can be flexibly set according to the requirement.
It can be considered that the primary frequency modulation is based on the control of the exciting current of the converter of the double-fed motor, and is participated by the double-fed motor, the flywheel motor and the flywheel, and a certain response time and duration are required for the useful power conversion process between the phase modulator equipment and the power grid.
In some embodiments, further comprising:
step S105: when the frequency of the power grid is detected to be larger than a preset reverse safety frequency or smaller than a preset forward safety frequency, generating an inertia response instruction;
step S106: generating a command for controlling the frequency of the operating current of the converter of the doubly-fed machine of the phase modifier apparatus to remain constant in response to the inertia response command,
so that the current transformer of the doubly-fed machine maintains the energizing frequency supplied to the rotor of the doubly-fed machine constant in response to a command that the frequency of the operating current remains constant, so that the energizing frequency supplied to the flywheel motor of the phase modifier apparatus remains constant, so that the flywheel of the phase modifier apparatus enters an inertia response state.
The frequency of the power grid is greater than a preset reverse safety frequency or less than a preset forward safety frequency, for example, within a primary frequency modulation action dead zone. At this point, the phase modulator device does not initiate primary frequency modulation. But the synchronous phase modifier, the double-fed motor or the flywheel device passively enters an inertia response state along with the power grid fluctuation to provide inertia power. The inertia response can be considered to be a spontaneous response based on the physical characteristics of the flywheel. Naturally occurring at the instant the grid frequency changes and decaying over time.
In some embodiments, further comprising:
step S107: generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of the phase modifier apparatus in response to a received system start instruction,
adjusting the energizing frequency provided to the rotor of the doubly-fed machine so that the rotating speed of the rotor of the doubly-fed machine is increased from zero to the rated rotating speed thereof in response to the instruction of the frequency change of the working current by the converter of the doubly-fed machine;
step S108: generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of said phase modifier apparatus in response to a received detection result that a synchronization of a synchronous phase modifier of said phase modifier apparatus is completed,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so as to increase the rotation speed of the flywheel of the phase modifier apparatus to its nominal rotation speed.
In the starting process, the working current frequency of the stator of the double-fed motor (namely the working current in the flywheel motor) is close to direct current, the rotating speed of the rotor of the double-fed motor and the rotating speed of the alternating-current excitation rotating magnetic field are opposite in rotating direction, the rotating speed is close to zero, and the rotating speed of the air gap magnetic field is close to zero. When the rotor of the double-fed motor approaches the synchronous speed, the frequency of alternating current exciting current introduced into the rotor of the double-fed motor approaches 50Hz, the energizing frequency in the flywheel motor is still very low, and the rotating speed of the flywheel approaches 0. After the synchronous phase modulator is connected to the grid, the rotating speed of the rotor of the double-fed motor is always kept at the synchronous speed, the alternating current frequency of the rotor of the double-fed motor is gradually reduced, the rotating speed of an air gap magnetic field of the double-fed motor is gradually increased, the working current frequency of the stator of the double-fed motor is gradually increased, and the rotating speed of a flywheel is increased. When the rotor current frequency of the double-fed motor is reduced to 0, namely direct current is introduced, the rotating speed of the flywheel reaches the rated rotating speed, and the starting process of the whole system is finished.
After the double-fed motor enters a steady state, when the double-fed motor is introduced with positive rotating alternating current, the rotating speed of the air gap magnetic field is higher than the synchronous speed, and the rotating speed of the flywheel is increased; when the alternating current rotating in the opposite direction is introduced, the air gap magnetic field is lower than the synchronous speed, and the rotating speed of the flywheel is reduced.
When the frequency of the reverse alternating current is 50Hz, the rotating speed of the flywheel is close to 0, and the state before grid connection is approximate. At the moment, the reverse alternating current frequency is reduced to enable the rotating speed of the flywheel to gradually recover the rated rotating speed, and the starting process of the rotating speed of the flywheel after the synchronous phase modulator is connected to the power grid is similar.
As shown in fig. 4, a control device 200 according to an embodiment of the present invention is applied to the aforementioned phase modulation apparatus 100, and includes:
the primary frequency modulation instruction generating unit 201 is configured to generate a first type of primary frequency modulation instruction for reducing the frequency of the power grid when it is detected that the frequency of the power grid is greater than a preset forward safety frequency;
an operating current adjusting unit 202 of the converter for generating an instruction for controlling a frequency variation of an operating current of the converter of the doubly-fed machine of the phase modifier apparatus in response to the first class primary modulation instruction,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is increased, and the energy storage state of the flywheel is increased.
In some embodiments, the primary frequency modulation instruction generating unit 201 is further configured to generate a secondary frequency modulation instruction for increasing the frequency of the power grid when detecting that the frequency of the power grid is smaller than a preset reverse safety frequency;
the converter operating current adjusting unit 202 is further configured to generate, in response to the second type primary frequency modulation command, a command for controlling a frequency variation of an operating current of a converter of a doubly-fed machine of the phase modulation apparatus,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is reduced, and the energy storage state of the flywheel is reduced.
In some embodiments, the system further includes an inertia response instruction generating unit 203, configured to generate an inertia response instruction when it is detected that the frequency of the power grid is greater than a preset reverse safety frequency or less than a preset forward safety frequency;
the converter operating current adjusting unit 202 is further configured to generate, in response to the inertia response command, a command for controlling the frequency of the converter operating current of the doubly-fed machine of the phase modulation apparatus to remain unchanged,
so that the current transformer of the doubly-fed machine maintains the energizing frequency supplied to the rotor of the doubly-fed machine constant in response to a command that the frequency of the operating current remains constant, so that the energizing frequency supplied to the flywheel motor of the phase modifier apparatus remains constant, so that the flywheel of the phase modifier apparatus enters an inertia response state.
In some embodiments, the operating current adjusting unit 202 of the converter is further configured to:
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of the phase modifier apparatus in response to a received system start instruction,
adjusting the energizing frequency provided to the rotor of the doubly-fed machine so that the rotating speed of the rotor of the doubly-fed machine is increased from zero to the rated rotating speed thereof in response to the instruction of the frequency change of the working current by the converter of the doubly-fed machine;
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of said phase modifier apparatus in response to a received detection result that a synchronization of a synchronous phase modifier of said phase modifier apparatus is completed,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so as to increase the rotation speed of the flywheel of the phase modifier apparatus to its nominal rotation speed.
As shown in fig. 5, a phase modulation system 1000 according to an embodiment of the present application is provided in a new energy plant, and is provided with the phase modulation apparatus 100 as described in the first aspect; a control device 200 as explained in the third aspect is provided.
The following describes a phase modulation apparatus, a control method, a control device, and a phase modulation system according to various embodiments of the present invention with reference to fig. 1 to 5.
The voltage and inertia supporting characteristics of the phase modifier device 100 are the same as those of the traditional phase modifier, and the double-fed motor 20 in the system is not directly connected with a power grid, so that compared with a full-capacity variable-frequency speed-regulating double-fed energy storage phase modifier (refer to ZL200420075971.4), the double-fed motor has no fault ride-through problem and is stable and reliable in operation.
In the above way, the phase modulator 10 realizes electrical coupling and electromagnetic coupling with the flywheel device 30 through the double-fed motor 20, and has mature technology and high reliability.
In the phase modifier apparatus 100, the doubly-fed machine 20 acts as a continuously variable transmission in response to a primary frequency modulation of the power grid. The converter 21 of the doubly-fed machine 20 adjusts the energizing frequency of the alternating excitation current of the rotor of the doubly-fed machine, such as the direct excitation, or the alternating excitation from 0.01 to 20Hz, in response to the primary frequency modulation command.
Specifically, the power-on frequency of the flywheel motor is changed by adjusting the frequency of the alternating-current exciting current led into the stator of the doubly-fed motor, so that the speed of the flywheel is increased and reduced, and energy exchange is performed with a power grid through the synchronous phase modulator 10 by changing the rotational kinetic energy of the flywheel, such as electric energy absorption or electric energy feed-in.
The power-on frequency of the flywheel motor is changed by adjusting the power-on frequency of the alternating current exciting current of the rotor of the double-fed motor, so that the rotating speed of the flywheel is changed, the mutual conversion of the mechanical energy of the flywheel and the electric energy in a power grid is realized, and the double-fed motor has strong primary frequency modulation capability.
In an electric power system, the time constant of inertia TjThe method is an important index for measuring the system inertia supporting capability of rotating equipment such as a generator set, a phase modifier and the like.
Note that the moment of inertia of synchronous phase modulator 10 is J1Omega rotation speed and S apparent powernThen its equivalent inertia time constant Tj＝Jω2/(2Sn). For a flywheel 32 having a circular cylindrical structure with a uniform mass distribution and a radius R in cross section, the moment of inertia J is2＝(mR2)/2. The moment of inertia of the flywheel can be converted to the equivalent inertia time constant T at the rated capacity of phase modulator 10 (i.e. the aforementioned apparent power) according toj2：
Tj2＝2*J2ω2/Sn＝mR2ω2/Sn＝mVm 2/SnWherein m represents the flywheel mass, VmRepresenting the linear velocity of the outer edge of the flywheel, having Vm＝Rω。
From the above equation, it can be seen that, while keeping the equivalent inertia time constant on the left side of the equation unchanged, if the linear velocity of the flywheel outer edge is increased to 4 times the original linear velocity on the right side of the equation, the mass of the flywheel can be reduced to one sixteenth of the original mass.
That is, if the linear velocity of the outer edge of the flywheel is increased to 4 times the original linear velocity while keeping the mass of the flywheel unchanged at the right side of the equation, the equivalent inertia time constant at the left side of the equation can be increased to 16 times the original linear velocity.
From the above equation, if the mass of the flywheel is kept constant and the linear velocity of the outer edge of the flywheel is increased, the moment of inertia of the flywheel can be increased to be converted into the equivalent inertia time constant T of the phase modulator 10j2。
To increase the linear speed of the flywheel outer edge, the speed is increased by VmAs can be seen from R ω, increasing the radius of the flywheel (for a cylindrical flywheel having a circular cross section with radius R, the radius R of the circular cross section) or the angular velocity ω of the flywheel increases the linear velocity of the flywheel outer edge. Accordingly, if the radius of the flywheel is increased and the mass of the flywheel is kept constant, a higher strength material having a lower density can be selected to fabricate the flywheel.
Starting from increasing the angular speed of the flywheel, i.e. the rotational speed of the flywheel, the phase modifier apparatus 100 employs a doubly-fed motor 20 with a plurality of pairs of poles, and employs a synchronous phase modifier 10 with a small number of pole pairs and a flywheel motor 31 with 1 pair of poles. When the rotor of the synchronous phase modifier 10 rotates at 3000 revolutions per minute (rpm) and the number of pole pairs of the doubly-fed motor is p, the stator of the doubly-fed motor supplies a power supply frequency to the flywheel motor of 50p when the rotor of the doubly-fed motor 20 is supplied with direct current, and at this time, the phase modifier apparatus 100 operates in a steady state, and the flywheel rotation speed is maintained at p × 3000 rpm. If p is 3 antipodes, the flywheel rotation speed is kept at 9000 rpm.
For simple system design, the flywheel motor can adopt a permanent magnet motor, and a rotor made of a permanent magnet completes subsequent excitation work after being magnetized without arranging additional excitation equipment.
As shown in fig. 2, an excitation system 11 of the synchronous phase modulator 10 may be connected to a high-voltage bus of a power grid via an excitation transformer 12 and a boost transformer 13. The converter 21 of the doubly-fed machine 20 is connected with the service power through the doubly-fed machine excitation transformer 22.
In the above, after the doubly-fed motor 20 is accelerated, the rotation speed of the flywheel apparatus 30 is high, and in order to reduce the blowing loss and the mechanical friction loss of the flywheel motor or the flywheel, the flywheel apparatus 30 is disposed in a vacuum environment, and a magnetic suspension bearing is used to support the flywheel motor and/or the flywheel.
As described above, in the phase modulation apparatus 100, the synchronous phase modulator and the flywheel device are electrically and electromagnetically coupled by using the double-fed motor. The rotor of the doubly fed machine 20 is always rotating synchronously with the rotor of the synchronous phase modifier 10. After the speed of the doubly-fed motor 20 is increased, the flywheel device 30 is kept at a higher rotating speed.
When a power grid fails, the synchronous phase modulator, the double-fed motor and the flywheel device provide inertia support for the system together, and the flywheel device rotating at a high speed can greatly improve the equivalent inertia time constant of the synchronous phase modulator device 100.
In the phase modulation apparatus 100, as mentioned above, each flywheel device rotating at a high speed can be regarded as a plurality of groups of energy storage modules which are respectively independent and respectively provide energy storage capacity, so that the number of the energy storage modules can be selected, or the number of the energy storage modules can be increased or decreased according to the actual needs of the system. For example, one or more sets of flywheel devices may be added or one or more sets of flywheel devices may be reduced to adapt to the capacity of the new energy plant station to which the phase modulation apparatus 100 is connected, the capacity of the synchronous phase modulation machine, or the capacity of the doubly-fed motor or the requirement of the power grid on the equivalent inertia time constant of the phase modulation apparatus 100. That is, in the phase modulation apparatus, the number of flywheel devices can be expanded.
In the phase modifier apparatus 100, the capacity of the doubly-fed machine is typically determined according to the relevant specifications for the primary frequency modulation of the power grid. For example, according to the relevant specifications of the primary frequency modulation of the power grid, when the frequency of the system changes by 0.25Hz, the new energy plant station should provide the primary frequency modulation power with 10% of the current operating power. For a new energy plant with a capacity of 50MW, a maximum of 5MW primary frequency modulation power is required. Therefore, the capacity of a doubly-fed machine is determined to be approximately 5MW.
In the phase modulator apparatus 100, the capacity of the synchronous phase modulator is determined according to a 20% reactive compensation capacity ratio. For example, a new energy plant with 50MW Megawatts (MW) is installed with a synchronous phase modulator with 10MVar megavars (MVar) capacity at its grid-connected point. When the voltage of the power grid drops, the synchronous phase modulator 10 and the excitation system 11 of the phase modulator apparatus 100 provide reactive power to the power grid in response to the voltage drop, which is not described in detail.
In the phase modulation apparatus 100, the step of increasing the equivalent inertia time constant by the flywheel device is described below.
Taking a 10Mvar small-sized distributed phase modulator as an example, the equivalent inertia time constant is recorded as 5s, and is about half of the equivalent inertia time constant of 10s of a conventional generator set. If the small distributed phase modulator is used with a photovoltaic station with a capacity of 50MW, calculated according to a reactive compensation rate of 20%, reference is made to the aforementioned formula (T)j＝Jω2/ (2Sn) The equivalent inertia time constant of the whole photovoltaic plant station is about 1s, which is equal to 1/10 of the equivalent inertia time constant of the conventional generator set, and the equivalent inertia time constant of the whole photovoltaic plant station cannot provide enough inertia support capacity for the power grid.
In order to raise the inertia support level of the photovoltaic station to 40% of that of a conventional generator set, i.e. 4s, calculated according to the reactive compensation rate of 20%, the equivalent inertia time constant T of a phase modulator device 100 consisting of a synchronous phase modulator 10, a doubly-fed motor 20 and at least one set of flywheel devices 30 is calculatedjIt needs to be increased from 5s when a small distributed phase modulator is separately provided to 20s, that is, 4 times, that is, 3 times.
Energy storage capacity of synchronous phase modulator is Sn*Tj10 × 5/2 × 25 mw.s. Increasing the equivalent inertia time constant by a factor of 3 requires the flywheel to store 3 times more kinetic energy than the phase modulator, so that the flywheel arrangement stores at least 75 mw.s.
As previously mentioned, the moment of inertia of the flywheel translates into the equivalent inertia time constant T at the rated capacity of phase modulator 10 (i.e., the apparent power previously mentioned)j2The following relationship is provided with the energy storage capacity E of the flywheel device:
E＝Tj2Sn/2。
according to the requirement of the power grid on the equivalent inertia time constant of the phase modulation apparatus 100 and the energy storage capacity E of the single set of flywheel devices, the energy storage capacity E of the single set of flywheel devices or the number of sets of flywheel devices to be set in the phase modulation apparatus 100 can be determined.
In the above, to realize phase modulationEquivalent inertia time constant T of machine 100jFrom 5s to 20s, the energy storage capacity E of the flywheel device needs to reach 3 times of the mechanical energy storage of the synchronous phase modulator at the rated rotating speed of the synchronous phase modulator, namely 75mw.s is approximately equal to 20.83 kw.h.
With reference to the design and manufacturing level of the current flywheel device, the energy storage capacity of 20.83kW.h can be conveniently realized. However, considering that the phase modulator apparatus 100 mainly meets the requirement of primary frequency modulation in a short time, the discharge power requirement is high, and the frequency modulation power of 10% of the current operating power of the new energy plant station, that is, 5MW, needs to be achieved. Accordingly, flywheel devices require more powerful designs.
In the phase modifier apparatus 100, the capacity of the doubly-fed machine also needs to reach 5MW in order to meet the maximum primary modulation power. Assuming that 4 pairs of poles are selected for the number of pole pairs of the doubly-fed motor, the rated rotating speed of the flywheel is 12000rpm, and +/-25% rotating speed adjustment can be performed, and the rated capacity of the rotor-side converter of the doubly-fed motor is not lower than 1/4, namely 1.25MW, of the maximum power of the stator of the doubly-fed motor according to the working condition under the maximum slip and the maximum frequency modulation power. When the frequency converter works under the maximum slip, the frequency of the frequency converter is p multiplied by 50Hz multiplied by 25 percent to 50 Hz. In addition, in consideration of the need for starting the phase modulation apparatus 100, the frequency of the maximum operating current of the inverter/rotor-side converter is p × 50Hz — 200 Hz.
As above, the phase modulation apparatus 10 not only has a primary frequency modulation capability, and can provide a primary frequency modulation support for a new energy plant, but also can greatly improve the inertia time constant of the phase modulation apparatus. The phase modulator is electrically coupled with the flywheel device through the double-fed motor, and the reliability is high. The flywheel device can realize modularization, and is convenient for expanding energy storage capacity. The added rotary inertia of the system is irrelevant to a primary frequency modulation control unit or an excitation control unit which is externally connected with the system, and is the inherent characteristic of phase modulator equipment. The converter of the double-fed motor is used for rotor alternating current excitation control and starting of the whole phase modulator equipment, and therefore starting and excitation are integrated.
The phase modulator device 100 can increase inertia support, and can change the rotating speed of the flywheel by adjusting the power-on frequency of the alternating current exciting current at the rotor side of the double-fed motor in response to a primary frequency modulation instruction, so that the mechanical energy of the flywheel is converted into electric energy exchanged with a power grid, and primary frequency modulation power is provided for the power grid.
On the whole, when the power-on frequency of the alternating current exciting current at the rotor side of the double-fed motor is not actively adjusted to change the rotating speed of the flywheel, the synchronous phase modulator, the double-fed motor and the flywheel do not participate in primary frequency modulation and only participate in inertia support. When the power-on frequency of alternating current exciting current at the rotor side of the double-fed motor is actively adjusted to change the rotating speed of the flywheel, the synchronous phase modulator, the double-fed motor and the flywheel jointly participate in primary frequency modulation, and primary frequency modulation power is provided for a system.
Referring to fig. 1, 2 and 3, the process of providing inertial support to a power grid by a phase modulation apparatus 100 of an embodiment of the present invention is generally as follows:
in normal operation, the doubly-fed machine 20 and the synchronous phase modifier 10 rotate coaxially at the same rotational speed. Synchronous phase modulator 10 operates in a motoring mode, drawing a small portion of power from the grid to compensate for windage and mechanical friction losses throughout the system. The doubly-fed machine 20 operates in a generator mode, and direct current is introduced into a three-phase rotor winding of the doubly-fed machine to carry out alternating current excitation. In this case, the doubly-fed machine acts as a synchronous generator, supplying power to the flywheel machine via the stator. Because the doubly-fed motor is p-pole, the power-on frequency of the doubly-fed motor is p multiplied by 50Hz, wherein 50Hz is the frequency of commercial power alternating current of the service power. The flywheel motor is a permanent magnet motor with 1 pair of poles, the stator of the flywheel motor receives power supply of the doubly-fed motor, and the rotor of the flywheel motor drives the flywheel to rotate at a high speed of p multiplied by 3000 rpm.
When the frequency of the power grid is reduced, the phase angle of the excitation induced electromotive force of the synchronous phase modulator lagging behind the system voltage can be reduced or even changed into a leading system voltage. At this point, the active power absorbed by the synchronous phase modulator from the system is reduced and even changed to generator mode. In the process, the electromagnetic torque of the synchronous phase modulator decreases or becomes negative. When the electromagnetic torque thereof is negative, the electromagnetic torque acts as a braking torque. At this time, the synchronous phase modulator decelerates, and converts its own rotational kinetic energy, i.e., mechanical energy, into electrical energy, providing inertial power to the system. However, because the rotational inertia of the rotor is small, the reduction amplitude of the rotating speed of the rotor is relatively small, and the inertia power which can be provided by the synchronous phase modulator to a system is usually small, and the synchronous phase modulator only plays a role in delaying the reduction of the frequency of a power grid.
Meanwhile, as the rotation speed of the synchronous phase modulator is reduced, the excitation magnetic field of the rotor of the doubly-fed motor rotating coaxially with the synchronous phase modulator is changed from an advance armature magnetic field to a retard armature magnetic field, the electromagnetic torque of the rotor of the doubly-fed motor is changed from a braking torque to a driving torque, the doubly-fed motor enters a motor mode, and the rotation speed of the flywheel device is reduced. The flywheel device converts the self rotational kinetic energy, namely mechanical energy into electric energy, provides inertial power for a system, and reversely provides driving torque for the synchronous phase modulator through the double-fed motor.
Thus, for a synchronous phase modulator, there is an input torque from the outside that continues to maintain its supply of more inertial power to the system, thus, equivalently increasing the equivalent inertial time constant of the synchronous phase modulator. At this time, that is, when the frequency of the power grid is reduced, the synchronous phase modulator, the doubly-fed motor and each group of flywheel devices respectively convert the mechanical energy of the synchronous phase modulator, the doubly-fed motor and each group of flywheel devices into electric energy, and active power is released to the power grid.
When the frequency of the power grid is increased, the dynamic response process of the self-synchronizing phase modulator, the double-fed motor and each group of flywheel devices is just opposite to that of the power grid when the frequency of the power grid is reduced. At this time, the whole phase modulator device absorbs a certain active power from the power grid and converts the active power into its own mechanical energy, which is not described in detail.
In the above, direct current is introduced into the three-phase rotor winding of the doubly-fed motor to perform alternating current excitation, and the energization frequency of the alternating current excitation current at the rotor side of the doubly-fed motor is not actively adjusted to change the rotating speed of the flywheel, so that the synchronous phase modulator, the doubly-fed motor and the flywheel do not participate in primary frequency modulation, and only participate in inertia support.
Referring to fig. 2 and 3, the process of participating in the primary frequency modulation of the power grid by phase modulation apparatus 100 of the embodiment of the present invention is roughly as follows:
when the grid frequency drops to exceed the dead zone of the primary frequency modulation action (such as-0.025 Hz, namely 0.05%), alternating current opposite to the rotation direction of the rotor is introduced into the rotor winding of the doubly-fed motor. At this time, the rotating speed of the synchronous magnetic field in the double-fed motor is reduced, the flywheel motor powered by the double-fed motor operates in a generator mode, the rotating speed of the flywheel is reduced, and the mechanical energy of the flywheel motor is converted into electric energy through the flywheel motor. If the energizing frequency of the alternating current which is introduced into the rotor winding of the doubly-fed motor and is opposite to the rotor rotation direction (the magnetic field rotation direction of the alternating current is opposite to the rotor rotation direction) is continuously increased from 0.01Hz to 10Hz, the rotating speed of the flywheel is further reduced, and the mechanical energy is continuously released. The mechanical energy released by the flywheel is continuously converted into electric energy through the flywheel motor until the primary frequency modulation of the wheel is finished. In the process, the electromagnetic torque of the stator of the doubly-fed machine is driving torque, and the driving phase modulator maintains the operation in a generator mode and continuously provides primary frequency modulation power to a power grid.
When the frequency of the power grid rises and exceeds a primary frequency modulation action dead zone (for example, +0.025Hz, namely 0.05 percent), alternating current which is the same as the rotation direction of the rotor is introduced into the rotor winding of the doubly-fed motor. At this time, the rotating speed of the synchronous magnetic field in the dual-feeder rises, the flywheel motor operates in a motor mode, the flywheel continuously rises, primary frequency modulation power is absorbed from the system through the synchronous motor, and the primary frequency modulation power is converted into self mechanical energy to be stored. The energizing frequency of alternating current which is introduced into a rotor winding of the doubly-fed motor and has the same rotor rotation direction (the magnetic field rotation direction of the alternating current is the same as the rotor rotation direction) is continuously increased, for example, the energizing frequency is increased from 0.01Hz to 10Hz, and the flywheel continuously increases the speed. The flywheel is continuously converted into electric energy through mechanical energy absorbed by the flywheel motor until the primary frequency modulation of the flywheel is finished. In the process, the electromagnetic torque of the stator of the doubly-fed machine is braking torque, the phase modulator is driven to maintain the operation in the motor mode, and primary frequency modulation power is continuously supplied to a power grid.
The rotating speed of the flywheel is greatly changed by adjusting the energizing frequency of the alternating current exciting current of the rotor of the double-fed motor, so that enough primary frequency modulation power is provided for the system.
It should be understood that the entire phase modifier apparatus provides primary modulated power to the grid only when the energization frequency of the rotor-side ac excitation current of the doubly-fed machine is changing. When the electrified frequency of the rotor is stable, the double-fed motor and the phase modifier rotate at a stable speed as a whole, and primary frequency modulation power is not provided for a power grid.
And the primary frequency modulation power comprises two parts of power at the rotor side of the doubly-fed motor and power output to or input from a power grid by the synchronous phase modulator. When the loss is not considered, the primary frequency modulation power provided by the rotor side of the doubly-fed motor is equal to the armature power (i.e. the power output or absorbed by the flywheel device or the electric energy) of the doubly-fed motor.
Referring to fig. 1, fig. 2 and fig. 3, in the phase modulation apparatus 100 according to the embodiment of the present invention, the doubly-fed motor can also be used as a starting motor of the entire phase modulation apparatus, and the specific process is roughly as follows:
firstly, a switch of the flywheel motor is closed, and low-frequency alternating current rotating reversely is led into a rotor of the double-fed motor. Due to the low frequency, e.g. 0.01Hz or 0.5Hz, the stator windings of the doubly-fed machine are equivalently short-circuited by the flywheel machine. Subsequently, the magnitude of the dc excitation current and the frequency of the ac excitation current of the doubly-fed motor 20 are controlled, so that the rotor of the synchronous phase modifier and the rotor of the doubly-fed motor are slowly accelerated (the rotor rotates in the forward direction, that is, the direction of the rotation speed of the phase modifier in normal operation is consistent). By gradually increasing the energizing frequency of the alternating excitation current of the doubly-fed machine, the rotor will be further accelerated. When the rotating speed is increased to be close to the rated rotating speed of the synchronous phase modulator, the synchronous phase modulator 10 enters an automatic quasi-synchronous grid connection process to complete grid connection.
After the synchronous phase modulator 10 is successfully connected to the grid, the energizing frequency of the alternating current exciting current of the rotor of the doubly-fed motor is slowly reduced, and at the moment, the flywheel is converted from a low-speed reverse state to a forward speed-up state. And continuously reducing the electrifying frequency of the rotor until the electrifying frequency is changed into direct current power supply, and further accelerating the flywheel to the rated rotating speed. The entire start-up procedure is now complete.
As described above, when the phase modulation apparatus 100 is started, the synchronous phase modulator is first started and connected to the grid by controlling the energizing frequency and direction of the ac exciting current of the rotor of the doubly-fed motor, and then the flywheel device is started to its rated rotational speed.
As described above, the converter of the doubly-fed motor in the phase modulation apparatus 100 can be used for starting the whole phase modulation apparatus, so that the integration of starting and excitation is realized, and the investment cost can be effectively controlled.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The invention has been described above by reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a// the [ device, component, etc ]" are to be interpreted openly as at least one instance of a device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (12)

1. A phase modulation apparatus with scalable energy storage and inertia, comprising:
the synchronous phase modulator is arranged at a grid-connected point of the new energy plant;
the rotor of the double-fed motor is connected with the rotor of the synchronous phase modifier;
at least one group of flywheel devices, wherein each group of flywheel devices comprises a flywheel motor and a flywheel driven by the flywheel motor;
when each flywheel motor is connected with the stator of the double-fed motor, the corresponding flywheel releases inertia through the flywheel motor and the synchronous phase modulator;
when each flywheel motor is connected with the stator of the double-fed motor and the energizing frequency of the flywheel motor is changed, the rotating speed of the corresponding flywheel is changed, and the energy storage state of the corresponding flywheel is changed;
when the number of flywheel devices connected to the stator of the doubly-fed machine is extended, the energy storage capacity and the inertia of the phase modifier apparatus are extended.
2. Phase modulation apparatus according to claim 1,
the double-fed motor is provided with a converter for adjusting the power-on frequency of a rotor of the double-fed motor; when the power-on frequency provided by the converter to the rotor of the doubly-fed motor is kept unchanged, the rotating speed and the energy storage state of the flywheel are kept unchanged;
when the energizing frequency provided by the converter to the rotor of the doubly-fed motor is changed, the rotating speed of the flywheel is increased or reduced, and the energy storage state of the flywheel is increased or reduced.
3. A method of controlling a phase modulation apparatus with scalable energy storage and inertia, for use in a phase modulation apparatus according to any one of claims 1 to 2, the method comprising:
when the frequency of a power grid is detected to be larger than a preset forward safety frequency, generating a first-class primary frequency modulation instruction for reducing the frequency of the power grid;
generating instructions for controlling a frequency variation of an operating current of a converter of a doubly-fed machine of said phase modifier apparatus in response to said first class of primary frequency modulation instructions,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is increased, and the energy storage state of the flywheel is increased.
4. The control method according to claim 3, characterized by further comprising:
when the frequency of the power grid is detected to be smaller than a preset reverse safety frequency, generating a second type of primary frequency modulation instruction for increasing the frequency of the power grid;
generating instructions for controlling a frequency variation of an operating current of a converter of a doubly-fed machine of said phase modulation apparatus in response to said primary frequency modulation instructions of the second type,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is reduced, and the energy storage state of the flywheel is reduced.
5. The control method according to claim 3, characterized by further comprising:
when the frequency of the power grid is detected to be larger than a preset reverse safety frequency or smaller than a preset forward safety frequency, generating an inertia response instruction;
generating a command for controlling the frequency of the operating current of the converter of the doubly-fed machine of the phase modifier apparatus to remain constant in response to the inertia response command,
so that the current transformer of the doubly-fed machine maintains the energizing frequency supplied to the rotor of the doubly-fed machine constant in response to a command that the frequency of the operating current remains constant, so that the energizing frequency supplied to the flywheel motor of the phase modifier apparatus remains constant, so that the flywheel of the phase modifier apparatus enters an inertia response state.
6. The control method according to claim 3, characterized by further comprising:
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of the phase modifier apparatus in response to a received system start instruction,
adjusting the energizing frequency provided to the rotor of the doubly-fed machine so that the rotating speed of the rotor of the doubly-fed machine is increased from zero to the rated rotating speed thereof in response to the instruction of the frequency change of the working current by the converter of the doubly-fed machine;
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of said phase modifier apparatus in response to a received detection result that a synchronization of a synchronous phase modifier of said phase modifier apparatus is completed,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so as to increase the rotation speed of the flywheel of the phase modifier apparatus to its nominal rotation speed.
7. A control device for a phase modulation apparatus with scalable energy storage and inertia, characterized in that it is used in a phase modulation apparatus according to any one of claims 1 to 2,
the control device includes:
the primary frequency modulation instruction generating unit is used for generating a first type of primary frequency modulation instruction for reducing the frequency of the power grid when the frequency of the power grid is detected to be greater than a preset forward safety frequency;
an operating current adjusting unit of the converter, which is used for responding to the first class primary frequency modulation instruction and generating an instruction for controlling the frequency change of the operating current of the converter of the doubly-fed motor of the phase modifier equipment,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is increased, and the energy storage state of the flywheel is increased.
8. The control device according to claim 7,
the primary frequency modulation instruction generating unit is further used for generating a second type of primary frequency modulation instruction for increasing the frequency of the power grid when the frequency of the power grid is detected to be smaller than a preset reverse safety frequency;
the working current adjusting unit of the converter is also used for responding to the second type primary frequency modulation instruction and generating an instruction for controlling the frequency change of the working current of the converter of the double-fed motor of the phase modifier equipment,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so that the energizing frequency provided to the flywheel motor of the phase modifier apparatus is changed, so that the rotation speed of the flywheel of the phase modifier apparatus is reduced, and the energy storage state of the flywheel is reduced.
9. The control device according to claim 7,
the system further comprises an inertia response instruction generating unit, wherein the inertia response instruction generating unit is used for generating an inertia response instruction when the frequency of the power grid is detected to be greater than a preset reverse safety frequency or less than a preset forward safety frequency;
the working current adjusting unit of the converter is also used for responding to the inertia response instruction and generating an instruction for controlling the frequency of the working current of the converter of the doubly-fed motor of the phase modifier equipment to be kept unchanged,
so that the current transformer of the doubly-fed machine maintains the energizing frequency supplied to the rotor of the doubly-fed machine constant in response to a command that the frequency of the operating current remains constant, so that the energizing frequency supplied to the flywheel motor of the phase modifier apparatus remains constant, so that the flywheel of the phase modifier apparatus enters an inertia response state.
10. The control device according to claim 7,
the working current adjusting unit of the converter is further configured to:
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of the phase modifier apparatus in response to a received system start instruction,
adjusting the energizing frequency provided to the rotor of the doubly-fed machine so that the rotating speed of the rotor of the doubly-fed machine is increased from zero to the rated rotating speed thereof in response to the instruction of the frequency change of the working current by the converter of the doubly-fed machine;
generating an instruction for controlling a frequency variation of an operating current of a converter of a doubly-fed motor of said phase modifier apparatus in response to a received detection result that a synchronization of a synchronous phase modifier of said phase modifier apparatus is completed,
so that the converter of the doubly-fed machine adjusts the energizing frequency provided to the rotor of the doubly-fed machine in response to the command of the frequency variation of the operating current, so as to increase the rotation speed of the flywheel of the phase modifier apparatus to its nominal rotation speed.
11. A computer storage medium comprising, in combination,
stored thereon a computer program for implementing the method according to any of claims 3 to 6.
12. A phase modifier system is characterized in that the phase modifier system is arranged at a new energy plant station,
providing a phase modulation apparatus according to any one of claims 3 to 6;
a control device according to any one of claims 7 to 10 is provided.
CN202111510495.9A 2021-12-11 2021-12-11 Phase modulator equipment with expandable energy storage and inertia, control method and system Pending CN114172170A (en)

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