CN112994019B - Flexible interconnected power distribution network system - Google Patents
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Abstract
The invention relates to the technical field of power distribution networks, particularly provides a flexible internet power distribution system, and aims to solve the technical problem of improving the power supply reliability of a power distribution network. For this purpose, the system according to an embodiment of the present invention includes a plurality of power grid units that are connected to each other to form a cellular networking structure, each multi-station fusion unit in the power grid unit includes a management and control device and/or a multi-port flexible multi-state switch that is constructed based on a virtual power plant technology, and a feeder line connected to each port of the multi-port flexible multi-state switch is connected to a plurality of function stations. Based on above-mentioned management and control device not only can carry out unified coordinated control to all function stations in the distribution network system, improve the power supply reliability of system, can also carry out the power supply with the electric power market and coordinate, improve the economic nature of system. Meanwhile, based on the honeycomb networking structure, each multi-station fusion unit can not only operate independently, but also can be used for realizing power flow, and the power supply reliability of the system is further improved.
Description
Technical Field
The invention relates to the technical field of power distribution networks, in particular to a flexible internet power distribution system.
Background
Distributed power sources (such as distributed photovoltaic power generation and distributed wind power generation) and electric vehicles and the like have large uncertainty in time and space distribution, and if a large number of distributed power sources and electric vehicles are connected into a power distribution network system, the stability of power flow in the power distribution network system can be seriously influenced, so that the power supply reliability of the power distribution network system is reduced. At present, a conventional power distribution network system mainly constructs a plurality of Micro-grids (Micro-grids) by using distributed power sources, loads and energy storage devices (electric vehicles can be used as special carriers of the energy storage devices), and each Micro-Grid is respectively used as a controlled unit of the power distribution network system, wherein each Micro-Grid is an independent power generation and distribution system, so that the influence of a large number of distributed power sources, electric vehicles and the like which are connected into the power distribution network system on the power flow stability in the system is reduced. However, in a conventional power distribution network system, each microgrid is connected with other power grids mainly in a series-parallel connection mode, and a power loop formed in the series-parallel connection mode cannot be flexibly switched, so that the microgrid cannot fully play its own resources (power supply, load and the like) to participate in power flow adjustment of the whole power distribution network system, and the stability of power flow in the power distribution network system cannot be effectively improved. Therefore, there is a need in the art for a new power distribution network solution to solve the above problems.
Disclosure of Invention
In order to overcome the above-mentioned drawbacks, the present invention is proposed to provide a flexible interconnected power distribution network system that solves or at least partially solves the technical problem of how to improve the power supply reliability of a power distribution network, the system comprising a plurality of power grid units, each of which comprises a plurality of multi-station fusion units, respectively; each multi-station fusion unit comprises a management and control device and/or a multi-port flexible multi-state switch which are constructed based on a virtual power plant technology; each management and control device is respectively configured to perform function management and control on a function station preset in each multi-station fusion unit; a plurality of preset function stations are respectively connected to a feeder line connected with each port of the multi-port flexible multi-state switch; for each power grid unit, each multi-port flexible multi-state switch in the power grid unit is sequentially connected with each other, and each multi-port flexible multi-state switch is also respectively connected with multi-port flexible multi-state switches in other power grid units, so that each power grid unit is connected with each other to form a honeycomb-shaped networking structure.
In one technical solution of the above flexible interconnected power distribution network system, the preset function station includes a power supply function station and/or a power grid function station and/or a load function station and/or an energy storage function station; the power supply function stations comprise a new energy power generation power supply function station and a hydrogen energy power generation power supply function station, the load function stations comprise an electrical energy load function station and a hydrogen energy load function station, and each hydrogen energy power generation power supply function station and each hydrogen energy load function station are respectively connected with each other to form a hydrogen energy interconnection network;
the management and control device is further configured to respectively perform power management and/or hydrogen energy management and control on the preset function stations.
In one embodiment of the flexible power distribution grid system, the multi-port flexible multi-state switch includes a plurality of voltage source converters, each of the voltage source converters includes a first bidirectional input/output side and a second bidirectional input/output side;
the first bidirectional input/output sides of each voltage source converter are respectively connected in parallel;
a second bidirectional input/output side of each said voltage source converter forms each port of said multi-port flexible multi-state switch respectively.
In an embodiment of the above flexible interconnected power distribution system, the management and control device is further configured to control the operating mode of the voltage source type converter corresponding to each port in the multi-port flexible multi-state switch according to the operating state of the feeder line connected to each port in the multi-port flexible multi-state switch by:
when each feeder line is in a normal operation state, controlling one voltage source type converter to adopt U dc The Q control mode is operated, and other voltage source type converters are controlled to operate in a P _ Q control mode;
when a feeder line is detected to have a fault and lose power, acquiring a voltage source type converter corresponding to the feeder line access port before the fault occurs, taking the voltage source type converter as a fault side voltage source type converter, and taking other voltage source type converters as non-fault side voltage source type converters;
if the fault-side voltage source type converter adopts a P _ Q control mode before the fault occurs, controlling the fault-side voltage source type converter to be switched to a U ac The F control mode is operated, and the fault side voltage source type converter is controlled to be switched to the P _ Q control mode again to operate after the fault is recovered;
if the failure occurs before the failure occursThe side voltage source type converter adopts U dc A Q control mode, the fault side voltage source type current converter is controlled to be switched to U ac F control mode operation and control of a non-fault side voltage source inverter to switch to U dc A Q control mode is operated, and the fault side voltage source type converter is controlled to be switched to the U again after the fault is recovered dc And controlling the one non-fault side voltage source type converter to switch to the P _ Q control mode again.
In an aspect of the above flexible internet power distribution system, the management and control apparatus is further configured to perform the following operations:
the voltage source type converter is switched to U at the fault side ac Before the f control mode, U is respectively acquired by using a secondary control strategy applied to droop control ac A voltage reference value and a frequency reference value of the f control mode, so that the fault side voltage source type converter adopts U according to the voltage reference value and the frequency reference value ac When the f control mode is operated, the amplitude and the frequency of the voltage at the alternating current side of the converter per se and the amplitude and the frequency of the alternating voltage at the feeder line connecting side in each functional station connected to the feeder line connected with the corresponding port of the fault side voltage source type converter can be respectively kept consistent.
In one technical solution of the above flexible internet power distribution network system, the power grid unit further includes a public connection point, and the multi-port flexible multi-state switch in each multi-station fusion unit in the power grid unit is respectively connected to the public connection point so as to be connected to an external power grid through the public connection point.
One or more technical schemes of the invention at least have one or more of the following beneficial effects:
in the technical scheme of the invention, the flexible interconnected power distribution network system can comprise a plurality of power grid units, and each power grid unit can respectively comprise a plurality of multi-station fusion units; each multi-station fusion unit can respectively comprise a management and control device and/or a multi-port flexible multi-state switch which are constructed based on the virtual power plant technology; each management and control device can be respectively configured to perform function management and control on preset function stations (including but not limited to a power supply function station, a power grid function station, a load function station and an energy storage function station) in each multi-station fusion unit. And a plurality of preset function stations are respectively connected to a feeder line connected with each port in the multi-port flexible multi-state switch. Based on the control device, all the function stations in the flexible interconnected power distribution network system can be subjected to unified coordination control, aggregation and coordination optimization of the function stations such as a distributed power supply, an energy storage system, a controllable load and an electric automobile in the system are achieved, and meanwhile power supply coordination can be carried out through the control device and an electric power market so as to improve the economy of the flexible interconnected power distribution network system. In addition, for each grid unit, each multi-port flexible multi-state switch in the grid unit is sequentially connected with each other, and each multi-port flexible multi-state switch is also respectively connected with one multi-port flexible multi-state switch in other grid units, so that each grid unit is connected with each other to form a honeycomb-shaped networking structure. Based on the honeycomb networking structure, under the condition that the flexible internet power distribution system normally operates, each multi-station fusion unit can operate independently, and redundant electric energy generated by a distributed power supply in a power supply function station in each multi-station fusion unit can be transmitted to an adjacent multi-station fusion unit; under the condition of failure, the adjacent multi-station fusion units can realize tidal current mutual aid, so that the economy, reliability and flexibility of the whole flexible interconnected power distribution network system are improved.
Drawings
Embodiments of the invention are described below with reference to the accompanying drawings, in which:
fig. 1 is a main structural block diagram of a flexible internet power distribution system according to an embodiment of the present invention;
FIG. 2 is a block diagram of the main structure of a multi-station fusion unit according to one embodiment of the present invention;
fig. 3 is a schematic diagram of the signal/energy flow between components within a multi-station fusion unit, according to one embodiment of the present invention.
Detailed Description
Some embodiments of the invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.
In the description of the present invention, "module", "unit" may include hardware, software, or a combination of both. A module/unit may comprise hardware circuitry, various suitable sensors, communication ports, memory, may comprise software components such as program code, and may be a combination of software and hardware. The term "a and/or B" denotes all possible combinations of a and B, such as a alone, B alone or a and B.
Some terms to which the present invention relates will be explained first.
A Flexible Multi-State Switch (FMSS) refers to a power electronic device constructed based on power electronic devices and having functions of power flow coordination, voltage support, and the like. Depending on the type of power conversion architecture employed, flexible multi-state switches include, but are not limited to: flexible multi-state switches based on an alternating current-direct current-alternating current power conversion structure (AC/DC/AC), flexible multi-state switches based on an alternating current-alternating current power conversion structure (AC/AC), flexible multi-state switches based on an alternating current-direct current power conversion structure (AC/DC), flexible multi-state switches based on a direct current-direct current power conversion structure (DC/DC), and the like. The multi-port flexible multi-state switch refers to a flexible multi-state switch with a plurality of power input/output ports.
A functional station refers to a system, device, equipment, etc. associated with a power source, grid, load, and energy storage in an energy system, such as an electric power system. The functional stations may comprise power functional stations and/or grid functional stations and/or load functional stations and/or energy storage functional stations. The power functional station comprises, but is not limited to, a hydrogen energy power generation power functional station and a new energy power generation power functional station such as a photovoltaic power functional station. The load function station includes, but is not limited to, a hydrogen load function station and an electric energy load function station such as an electric vehicle charging station. It should be noted that, a person skilled in the art may flexibly set a functional station in the flexible internet power distribution system according to actual requirements, as long as the functional station can perform communication interaction with an external system, and has functions of sending an operation state to the external system and receiving an operation instruction sent by the external system. For example: besides the functional stations, a heat supply station, an environment monitoring station and the like can be arranged in the flexible interconnected power distribution system. On the premise of not deviating from the technical principle of the invention, the technical scheme of changing the number and/or the type of the functional stations in the flexible interconnected power distribution network system falls into the protection scope of the invention.
The flexible internet power distribution system according to the embodiment of the present invention will be specifically described below.
In the embodiment of the present invention, the flexible interconnected power distribution network system may include a plurality of power grid units, and each power grid unit may include a plurality of multi-station convergence units. Each multi-station fusion unit can respectively comprise a management and control device constructed based on virtual power plant technology and/or a multi-port flexible multi-state switch. In addition, a plurality of preset function stations are further respectively arranged in each multi-station fusion unit, and each control device can be respectively configured to perform function control on the preset function stations in each multi-station fusion unit. The multi-station fusion unit provided with the management and control device and the multi-port flexible multi-state switch is taken as an example, and the management and control device, the multi-port flexible multi-state switch and the function station in the multi-station fusion unit are specifically explained below.
1. Function station
In an embodiment of the invention the functional stations may comprise power functional stations and/or grid functional stations and/or load functional stations and/or energy storage functional stations. Further, in one implementation manner of the embodiment of the present invention, the power supply function stations may include a new energy power generation power supply function station and a hydrogen energy power generation power supply function station, and the load function stations may include an electric energy load function station and a hydrogen energy load function station, wherein each hydrogen energy power generation power supply function station and each hydrogen energy load function station are respectively connected to each other to form a hydrogen energy interconnection network. Accordingly, the management and control device may be further configured to perform power management and/or power management and control on the functional stations within the multi-station fusion unit. For example, the management and control device may perform electric power management and control on the new energy power generation power supply function station and/or the electric energy load function station and/or the power grid function station and/or the energy storage function station, and may also perform hydrogen energy management and control on the hydrogen energy power generation power supply function station and the hydrogen energy load function station, that is, the management and control device not only has a function of performing electric power management and control on the function stations, but also has a function of performing hydrogen energy management and control on the function stations. It should be noted that, a person skilled in the art may flexibly set the specific control manner of the power management and control and the specific control manner of the hydrogen energy management and control in the management and control device according to actual needs, and on the premise of not departing from the technical principle of the present invention, the technical solutions obtained by changing/replacing the specific control manners of the power management and control and the hydrogen energy management and control in the management and control device all fall within the protection scope of the present invention.
2. Multi-port flexible multi-state switch
In the embodiment of the invention, for each power grid unit, each multi-port flexible multi-state switch in the power grid unit is sequentially connected with each other, and each multi-port flexible multi-state switch is also respectively connected with one multi-port flexible multi-state switch in other power grid units, so that each power grid unit is connected with each other to form a honeycomb-shaped networking structure. In addition, in the embodiment, a plurality of preset function stations are respectively connected to the feeder line connected to each port in each multi-port flexible multi-state switch.
Referring to fig. 1, fig. 1 is a main structural block diagram of a flexible internet power distribution system according to an embodiment of the present invention. The flexible internet power distribution network system comprises a plurality of power grid units, and each power grid unit can comprise a plurality of multi-station fusion units. The following is a detailed description of a power grid unit composed of the multi-station fusion units 1 to 6 shown on the right side of fig. 1 as an example. As shown in fig. 1, the multi-station convergence units 1 to 6 respectively include 3-port FMSS, 4-port FMSS, 3-port FMSS, and 3-port FMSS, 4-port FMSS, and the several FMSSs are sequentially connected to each other. In addition, each FMSS may also be connected to FMSSs within other grid units, respectively. For example, the 3-port FMSS in the multi-station fusion unit 1 may be connected to the 3-port FMSS in another grid unit adjacent to the upper side of the "current grid unit" (the grid unit constituted by the multi-station fusion units 1 to 6), the 3-port FMSS in the multi-station fusion unit 5 is connected to the 3-port FMSS in another grid unit adjacent to the left side of the "current grid unit", and the 4-port FMSS in the multi-station fusion unit 6 is connected to the 3-port FMSS in another grid unit adjacent to the left side of the "current grid unit", where the connection structure of the FMSSs in the multi-station fusion units 2 to 4 to the FMSSs of the other grid units is not shown in fig. 1. By the above connection, the multi-station fusion units 1-6 can form a basic unit (grid unit) in a honeycomb (honeycomb) networking structure, and the basic units are connected with each other to form the honeycomb networking structure.
It should be noted that, those skilled in the art can flexibly select the flexible multi-state switch based on different power conversion structures according to actual needs, for example, the flexible multi-state switch based on an ac-dc power conversion structure or a dc-dc power conversion structure may be selected, and such specific adjustment and change to the flexible multi-state switch are not departing from the principle and scope of the present invention, and should be limited within the protection scope of the present invention. In addition, the number of the multi-station merging units can be flexibly set by those skilled in the art according to actual needs, for example, the number of the multi-station merging units can be 7, 8, 9 or other values, and such specific adjustment and change of the number of the multi-station merging units are not departing from the principle and scope of the present invention and should be limited within the protection scope of the present invention.
Further, in an implementation manner of the embodiment of the present invention, a Voltage Source Converter (VSC) may be used to construct the multi-port flexible multi-state switch. In particular, the multi-port flexible multi-state switch in this embodiment may comprise a plurality of voltage source converters, and each voltage source converter may comprise a first bidirectional input/output side and a second bidirectional input/output side, respectively. For each multi-port flexible multi-state switch, the first bidirectional input/output sides of each voltage source converter in the multi-port flexible multi-state switch are respectively connected in parallel, and the second bidirectional input/output sides of each voltage source converter respectively form each port of the multi-port flexible multi-state switch. Referring to fig. 2, fig. 2 illustrates a multi-station convergence unit constructed based on a 4-port FMSS according to an embodiment of the present invention. As shown in fig. 2, four voltage source converters (VSC 1, VSC2, VSC3, and VSC 4) form four ports of the 4-port FMSS, respectively, and each port is connected to the feeders Bus1 to Bus4, respectively. The functional stations accessed on the feeder Bus1 comprise a Data Center (IDC), a conventional load (including but not limited to electric equipment of enterprises, residents, factories and the like), an energy storage power station 1, a hydrogen generation station 1 and a gas engine (hydrogen generator), the functional stations accessed on the feeder Bus2 comprise a conventional load, a 5G base station, a hydrogen generation station 2, an energy storage power station 2 and a photovoltaic power station, the functional stations accessed on the feeder Bus3 comprise a conventional load and a hydrogen fuel electric automobile, and the functional stations accessed on the feeder Bus4 comprise a conventional load and a pure electric automobile. In addition, the feeder lines Bus1 to Bus4 are also respectively connected with the adjacent multi-station fusion units 1 to 4 so as to respectively perform energy interaction of electric energy/hydrogen energy with the adjacent multi-station fusion units 1 to 4.
3. Management and control device
The management and control device constructed based on the virtual power plant technology in the embodiment of the invention can be configured to respectively perform electric power management and/or hydrogen energy management and control on the functional stations preset in the multi-station fusion unit.
Virtual Power Plant (VPP) refers to a conventional Power supply coordination management system that can realize aggregation and coordination optimization of a distributed Power supply, an energy storage system, a controllable load, an electric vehicle, and the like through an advanced information communication technology and a software system in the field of Power technologies, so as to participate in Power market and Power grid operation as a special Power Plant. The management and control device constructed based on the virtual power plant technology refers to a device constructed by utilizing a virtual power plant and having management and control functions of performing electric power management and control, hydrogen energy management and control and the like on a functional station.
The management and control device in the multi-station convergence unit will be described below by taking the multi-station convergence unit constructed based on the 4-port FMSS shown in fig. 2 as an example. Referring to fig. 3, fig. 3 exemplarily shows a signal flow/energy flow between a policing device and a functional station within the multi-station fusion unit shown in fig. 2. The regional autonomous subsystem 1 refers to an electric energy subsystem formed by an energy storage power station 2, a photovoltaic power station, a conventional load and a 5G base station (not shown in fig. 3) which are connected to a feeder Bus2, the regional autonomous subsystem 2 refers to an electric energy subsystem formed by the energy storage power station 1, the conventional load and an IDC (not shown in fig. 3) which are connected to the feeder Bus1, the regional autonomous subsystem 3 refers to an electric energy subsystem formed by the conventional load connected to the feeder Bus3, and the regional autonomous subsystem 4 refers to an electric energy subsystem formed by the conventional load and a pure electric vehicle which are connected to a feeder Bus 4. In addition, the hydrogen generation station 1, the hydrogen generation station 2, the gas engine and the hydrogen-fueled electric vehicle in the multi-station fusion unit can form a single hydrogen energy subsystem. As shown in fig. 3, the management and control device may be respectively in communication connection with the 4-port FMSS, the regional autonomous subsystem 1, the regional autonomous subsystem 2, the regional autonomous subsystem 3, the regional autonomous subsystem 4, and the hydrogen energy subsystem, so as to perform power management and control on the 4-port FMSS, the regional autonomous subsystem 1, the regional autonomous subsystem 2, the regional autonomous subsystem 3, and the regional autonomous subsystem 4, and perform hydrogen energy management and control on the hydrogen energy subsystem. In addition, the management and control device can also communicate with an external management center/power market so as to receive an electric energy/hydrogen energy control instruction issued by the management center to perform corresponding electric energy/hydrogen energy control, or participate in power supply coordination management of the power market to improve the economy of the system. Further, in the multi-station fusion unit shown in fig. 2, electric energy and hydrogen energy are respectively kept in power balance (power conservation). The calculation formulas of the power balance between the electric energy and the hydrogen energy can be respectively shown as the following formulas (1) and (2).
The meaning of each parameter in formula (1) is as follows:
P IDC (t) represents the electrical energy input power of the data center station at time t, P 5G (t) represents the power input power of the base station at time t 5G,
represents the electrical energy input power of the jth conventional load at time t,
representing power of jth conventional loadThe coefficients of which are such that,
representing the electrical energy input power of the jth energy storage plant at time t,
representing the power coefficient of the j-th energy storage plant,
the electric energy input power of the pure electric vehicle at the moment t is shown,
the power coefficient of the pure electric vehicle is shown,
represents the electric energy input power of the jth hydrogen generation station at the time t,
represents the power coefficient, P, of the jth hydrogen generation station PV (t) represents the electrical energy output power of the photovoltaic plant at time t, λ PV Represents the power coefficient of the photovoltaic power plant,
represents the electric energy power output to the current multi-station fusion unit by the j-th other multi-station fusion unit at the time t,
representing the power coefficient, P, of the jth other multi-station fusion unit GT (t) represents the electrical output power of the gas engine at time t, λ GT Representing the power coefficient of the gas engine.
The meaning of each parameter in the formula (2) is as follows:
η 1 representing the efficiency, eta, of conversion of electrical energy into hydrogen energy 2 Indicating the efficiency of conversion of hydrogen energy into electrical energy,
represents the hydrogen energy power output by other multi-station fusion units to the current multi-station fusion unit at the time t,
represents the hydrogen energy input power of the jth hydrogen-fueled electric vehicle at the time t,
the power coefficient of the jth hydrogen fuel electric automobile is shown, and alpha is a preset constant coefficient.
Further, in an implementation manner of the embodiment of the present invention, the management and control device may be further configured to respectively adjust the operation mode of the voltage source type inverter corresponding to each port in the multi-port flexible multi-state switch according to the operation state of the feeder line connected to each port in the multi-port flexible multi-state switch by performing the following operations:
(1) When each feeder line is in a normal operation state, one voltage source type converter can be controlled to adopt a U dc And the Q control mode is operated, and other voltage source type converters are controlled to operate in the P-Q control mode.
(2) When a fault and power loss of a certain feeder line are detected, the working mode of each voltage source type converter can be determined according to the type of the control mode adopted by the voltage source type converter (fault side voltage source type converter) connected with the feeder line before the fault occurs:
when a feeder line is detected to have a fault and lose power, a voltage source type converter corresponding to the feeder line access port (the port of the multi-port flexible multi-state switch) before the fault occurs is obtained, the voltage source type converter is used as a fault side voltage source type converter, and other voltage source type converters are used as non-fault side voltage source type converters. For example: referring to fig. 2, if it is detected that the feeder Bus1 has a fault and loses power, the VSC1 may be used as a fault side voltage source type converter, and the VSCs 2 to VSC4 may be used as non-fault side voltage source type converters.
If the fault side voltage source type converter adopts the P _ Q control mode before the fault occurs, controlling the fault side voltage source type converter to be switched to the U ac And (4) operating in a f control mode, and controlling the fault side voltage source type converter to be switched to the P _ Q control mode again after the fault is recovered.
If the fault side voltage source type converter adopts U before the fault occurs dc Q control mode, the voltage source converter at the fault side is controlled to switch to U ac F control mode operation and control of a non-fault side voltage source inverter to switch to U dc Q control mode operation, and controlling the fault side voltage source type converter to switch to U again after fault recovery dc And controlling the one non-fault side voltage source type converter to switch to the P _ Q control mode again.
With continued reference to fig. 2, the control mode of each VSC in the 4-port FMSS when the feeder Bus1 to the feeder Bus4 are in different states, respectively, may be as shown in table 1 below.
TABLE 1
Note that U is dc Q control mode, P Q control mode and U ac The _ f control modes are all control modes conventional in the power technology field. Wherein, U ac The f control mode belongs to droop control, and mainly utilizes droop characteristics to respectively obtain stable alternating voltage amplitude and frequency. Specifically, U dc The Q control mode refers to a constant direct current voltage and reactive power control mode, and U in the embodiment of the invention dc The Q control mode mainly comprises the direct current bus voltage U of the fault side voltage source type converter dc And the output reactive power Q is constantly controlled. The P _ Q control mode refers to a constant power control mode, and in the embodiment of the invention, the P _ Q control mode mainly comprises a mode of respectively controlling the power of the power converter and the power converterAnd performing constant control on active power P and reactive power Q output by the fault side voltage source type converter. U shape ac The f control mode refers to a constant voltage and constant frequency control mode, U in the embodiment of the invention ac The f control mode mainly comprises constant control of the amplitude and the frequency of the alternating-current side voltage of the fault side voltage source type converter. For simplicity of description, U is not repeated here dc Q control mode, P Q control mode and U ac The specific control principle of the _ f control mode is described in detail.
In practical application, one or more functional stations are connected to a feeder line connected to each port of the multi-port flexible state switch, and when a fault-side voltage source type converter is switched to a U state ac When the f control mode is operated, the U is controlled ac The droop control characteristic of the _ f control mode may cause the AC voltage amplitude/frequency of the feeder connection side of the functional stations (for example, a functional station is an energy storage station which includes an energy storage station body and an AC/DC device, the DC side of the AC/DC device is connected to the energy storage station body, the AC side of the AC/DC device is connected to the feeder, and the AC/DC device converts the AC power transmitted in the feeder into DC power and outputs the DC power to the energy storage station body for power storage. For example, when Bus2 fails, VSC2 switches to U ac After the f control mode, the voltage amplitude/frequency of the alternating current side of the VSC2, the alternating voltage amplitude/frequency of the feeder connection side in the energy storage power station 2, and the alternating voltage amplitude/frequency of the feeder connection side in the photovoltaic power station are inconsistent. In this regard, the voltage amplitude/frequency deviation may be compensated using a secondary control strategy applied to droop control to ensure that the ac voltage amplitude/frequency of the fault-side voltage source converter and the functional station connected to the corresponding feeder are consistent. In one embodiment, the regulating device may be further configured to supply the voltage source at the fault sideThe type converter is switched to U ac Before the f control mode, U is respectively acquired by using a secondary control strategy applied to droop control ac Voltage reference value and frequency reference value of _Fcontrol mode, so that the fault side voltage source type converter adopts U according to the voltage reference value and the frequency reference value ac When the F control mode is operated, the amplitude and the frequency of the voltage on the alternating current side of the controller can be kept consistent with those of the alternating voltage on the feeder line connecting side of each functional station connected to the feeder line connected with the fault side voltage source type converter. Further, in the present embodiment, the U-shaped sections can be obtained by a method "Secondary control of Microdiodes based on distributed cooperative control of Multi-agent systems" disclosed in the engineering society of engineering technology (IET) 2013 ac The voltage reference value and the frequency reference value of the f control mode can be obtained by the method shown in the following formula (3) ac Voltage reference and frequency reference for the _ f control mode:
the meaning of each parameter in formula (3) is as follows:
U refi the output voltage reference value of a port corresponding to the ith fault side voltage source type current converter in the multi-port flexible multi-state switch is represented; u. of vi The voltage source type converter for indicating and controlling the ith fault side adopts U ac Auxiliary control variables for voltage droop control during operation in the _ f control mode; n is i The voltage source type converter representing the ith fault side adopts U ac A droop control coefficient for voltage droop control when operating in the f control mode,
the differential of the reactive power measurement value of the port corresponding to the ith fault side voltage source type converter is shown. Omega ni Indicating a frequency reference value u of a port corresponding to the ith fault-side voltage source converter ωi The voltage source type converter for indicating and controlling the ith fault side adopts U ac Auxiliary control variable m for frequency droop control during operation in the _ f control mode i The voltage source type converter representing the ith fault side adopts U ac Droop control coefficients for frequency droop control when operating in the _ f control mode,
and the differential of the active power measured value of the port corresponding to the ith fault side voltage source type converter is shown. The specific methods for acquiring the parameters can be obtained according to the method described in "self control of microorganisms based on distributed cooperative control of Multi-agent systems", and are not described herein again.
With continued reference to fig. 1, in another embodiment according to the present invention, the grid units within the flexible, commutated power distribution system may not only include the functional structures of the previous embodiments, but each may also include a point of common connection. For each power grid unit, the multi-port flexible multi-state switch in each multi-station fusion unit in the power grid unit can be respectively connected with the public connection point so as to be connected with an external power grid through the public connection point. That is to say, if the flexible internet power distribution network system is regarded as a network layer as a whole, the network unit can be connected with other network units in the network layer, and the network unit can also be connected with other network layers outside the network layer through the public connection point, that is, connected with an external network outside the flexible internet power distribution network system, so as to realize power flow interaction between different network layers.
So far, the technical solution of the present invention has been described in conjunction with one embodiment shown in the accompanying drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
Claims (6)
1. The flexible interconnected power distribution network system is characterized by comprising a plurality of power grid units, wherein each power grid unit comprises a plurality of multi-station fusion units; each multi-station fusion unit comprises a management and control device and/or a multi-port flexible multi-state switch which are constructed based on the virtual power plant technology; the system comprises a multi-station fusion unit based on a 2-port flexible multi-state switch, a 3-port flexible multi-state switch and a 4-port flexible multi-state switch;
each management and control device is respectively configured to perform function management and control on a function station preset in each multi-station fusion unit;
a plurality of preset function stations are respectively connected to a feeder line connected with each port of the multi-port flexible multi-state switch; for each power grid unit, sequentially connecting each multi-port flexible multi-state switch in the power grid unit with each other, and respectively connecting each multi-port flexible multi-state switch with multi-port flexible multi-state switches in other power grid units, so that each power grid unit is connected with each other to form a honeycomb-shaped networking structure;
in a multi-station fusion unit based on a 4-port flexible multi-state switch, each port is respectively connected with feeder lines Bus1 to Bus4, functional stations accessed on the feeder lines Bus1 comprise an energy storage power station, a hydrogen generation station, a gas engine, a conventional load and a data center station, functional stations accessed on the feeder lines Bus2 comprise a hydrogen generation station, an energy storage power station, a photovoltaic power station, a conventional load and a 5G base station, functional stations accessed on the feeder lines Bus3 comprise a hydrogen fuel electric automobile and a conventional load, and functional stations accessed on the feeder lines Bus4 comprise a pure electric automobile and a conventional load;
in the multi-station fusion unit based on the 4-port flexible multi-state switch, a calculation formula of power balance of electric energy is shown as follows:
wherein, P IDC (t) represents the electrical energy input power of the data center station at time t,P 5G (t) represents the power input power of the base station at time t 5G,
representing the electrical energy input power of the jth conventional load at time t,
represents the power coefficient of the jth conventional load,
representing the electrical energy input power of the first energy storage plant at time t,
representing the power coefficient of the jth energy storage plant,
the electric energy input power of the pure electric vehicle at the moment t is shown,
the power coefficient of the pure electric vehicle is shown,
represents the electric energy input power of the jth hydrogen generation station at the time t,
represents the power coefficient, P, of the jth hydrogen generation station PV (t) represents the electrical energy output power of the photovoltaic plant at time t, λ PV Represents the power coefficient of the photovoltaic power plant,
represents the electric energy power output by the j-th other multi-station fusion unit to the current multi-station fusion unit at the time t,
representing the power coefficient, P, of the jth other multi-station fusion unit GT (t) represents the electrical output power of the gas engine at time t, λ GT Representing the power coefficient of the gas engine;
in the multi-station fusion unit based on the 4-port flexible multi-state switch, a calculation formula of the power balance of hydrogen energy is shown as follows:
wherein eta is 1 Representing the efficiency, eta, of conversion of electrical energy into hydrogen energy 2 Indicating the efficiency of conversion of hydrogen energy into electrical energy,
represents the hydrogen energy power output by other multi-station fusion units to the current multi-station fusion unit at the time t,
represents the hydrogen energy input power of the jth hydrogen-fueled electric vehicle at the time t,
the power coefficient of the jth hydrogen fuel electric automobile is shown, and alpha is a preset constant coefficient.
2. The flexible internet power distribution system according to claim 1, wherein the preset function stations comprise a power supply function station and/or a power grid function station and/or a load function station and/or an energy storage function station, the power supply function station comprises a new energy power generation power supply function station and a hydrogen energy power generation power supply function station, and the load function station comprises an electrical energy load function station and a hydrogen energy load function station;
each hydrogen energy power generation power supply functional station and each hydrogen energy load functional station are respectively connected with each other to form a hydrogen energy interconnection network;
the management and control device is further configured to respectively perform power management and/or hydrogen energy management and control on the preset function stations.
3. The flexible interconnected power distribution system as set forth in claim 1, wherein said multi-port flexible multi-state switch comprises a plurality of voltage source converters, each of said voltage source converters comprising a first bidirectional input/output side and a second bidirectional input/output side, respectively;
the first bidirectional input/output sides of each voltage source type converter are respectively connected in parallel;
the second bidirectional input/output side of each of the voltage source converters forms each port of the multi-port flexible multi-state switch, respectively.
4. The flexible interconnected power distribution system according to claim 3, wherein the management and control device is further configured to control the operation mode of the voltage source type converter corresponding to each port in the multi-port flexible multi-state switch respectively according to the operation state of the feeder connected to each port in the multi-port flexible multi-state switch and through the following operations:
when each feeder line is in a normal operation state, controlling one voltage source type converter to adopt U dc The Q control mode is operated, and other voltage source type converters are controlled to operate in a P-Q control mode;
when a feeder line is detected to have a fault and lose power, acquiring a voltage source type converter corresponding to the feeder line access port before the fault occurs, taking the voltage source type converter as a fault side voltage source type converter, and taking other voltage source type converters as non-fault side voltage source type converters;
controlling the fault side voltage source type converter to be switched to a U if the fault side voltage source type converter adopts a P _ Q control mode before the fault occurs ac -f control mode operation and controlling the fault side voltage source converter to switch again to P-Q control mode operation after fault recovery；
If the fault side voltage source type converter adopts U before the fault occurs dc A Q control mode is adopted, the fault side voltage source type converter is controlled to be switched to U ac F control mode operation and control of a non-fault side voltage source inverter to switch to U dc A Q control mode is operated, and the fault side voltage source type converter is controlled to be switched to the U again after the fault is recovered dc -Q control mode and controlling said one non-fault side voltage source converter to switch to P-Q control mode again.
5. The flexible internet power distribution system of claim 4, wherein the policing apparatus is further configured to:
at the fault side the voltage source converter is switched to U ac Before the f control mode, U is respectively acquired by using a secondary control strategy applied to droop control ac -f controlling the voltage reference and the frequency reference of the mode so that the fault side voltage source converter adopts U according to the voltage reference and the frequency reference ac The control mode operation can make the amplitude and the frequency of the alternating-current side voltage of the control mode operation and the amplitude and the frequency of the alternating-current voltage of the feeder connection side of each functional station connected to the feeder connected to the corresponding port of the fault side voltage source type converter respectively consistent.
6. The flexible interconnected power distribution system according to any one of claims 1-5, wherein the grid unit further comprises a common connection point to which the multi-port flexible multi-state switches in each multi-station fusion unit within the grid unit are respectively connected to connect with an external grid through the common connection point.
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