CN117674174B - Control method and system of network-structured STATCOM - Google Patents
Control method and system of network-structured STATCOM Download PDFInfo
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Abstract
The invention discloses a control method and a system of a network-structured STATCOM, wherein the method comprises the following steps: generating a phase angle control signal; generating an internal potential amplitude signal; generating self-adaptive virtual impedance according to the network-structured STATCOM output current measured value and the maximum allowable overload multiple; setting current limiting impedance; calculating virtual impedance voltage drop according to the self-adaptive virtual impedance, combining an internal potential amplitude signal, adjusting the voltage output value of the equipment in real time, combining a phase angle control signal, and inversely transforming the voltage output value of the equipment into an ABC three-phase sinusoidal modulation signal; and the sinusoidal modulation signals of the ABC three phases are input into the PWM module to drive the power element to output, so that the reactive response function of the grid-structured STATCOM is realized. The network construction technology is combined with the STATCOM, so that the network construction technology has the characteristics of a voltage source, can respond to reactive power shortage of a system instantaneously, does not influence the short-circuit capacity and the rotational inertia supporting performance of network construction equipment, and therefore low-cost network construction under a reactive power supporting scene is realized.
Description
Technical Field
The invention belongs to the technical field of reactive power compensation, and relates to a control method and a system of a grid-built STATCOM.
Background
The dynamic reactive power compensation technology can be mainly divided into rotary type equipment and static compensation equipment. The former mainly includes rotating electric machines such as synchronous regulators and synchronous generators, and has been used in electric power systems at the earliest. The static compensation device mainly comprises SVC (static var compensator), STATCOM (static var generator, also called SVG), controllable high reactance and the like. The SVC and the STATCOM are mainly connected into a lower voltage class, and the controllable high-voltage resistor is directly connected into a high voltage class.
As a third generation dynamic reactive compensation technology, the STATCOM can realize reactive voltage closed-loop control based on a voltage source type converter, and is widely applied to voltage support of new energy stations, load centers and power grid sides. The existing STATCOM mostly adopts a technical route based on phase-locked loop control, is essentially a grid-following type current source control scheme, has obvious influence on dynamic reactive power supporting effect when being connected to the power grid, and particularly can cause voltage stability when being connected to a weak alternating current power grid. Therefore, in order to solve the problem of insufficient strength of the alternating current power grid and simultaneously consider the requirement of dynamic reactive power support, the existing solution often adopts a synchronous tuning machine, but the problems of large initial investment, high loss, high maintenance cost and the like exist, and the requirement of improving the economy of the solution exists.
At present, the network construction technology is used as a voltage source control technology route, does not need to rely on a phase-locked loop, can improve the strength of an access power grid, makes up the problems of insufficient rotational inertia, short-circuit capacity, reactive support and the like of a local power system, and is valued internationally. Combining the web-based technology with the STATCOM solution provides a tuning function similar to a tuning camera and has significant advantages over tuning camera solutions in terms of equipment cost, wear rate, operational maintenance costs.
The conventional network construction technology can maintain faults or disturbance moments, the internal potential amplitude and the phase angle are unchanged in a certain time, emergency active and reactive support is provided based on the internal and external pressure difference moments, and the problems of insufficient peak regulation capacity, rotational inertia, short-circuit capacity and reactive support of a local power system can be solved. However, in some application scenarios, the local power system has strong active power regulation capability, requires the network construction equipment to provide reactive power support, realizes the function similar to a camera, and has high requirements on equipment economy in the reactive power support scenario. In addition, the conventional STATCOM externally presents a current source characteristic, reactive compensation of the power grid is required to be subjected to measurement calculation and control links, the existence of a measurement time window inevitably leads to the risk of incapability of instantaneous response and even counteradjustment, and the conventional STATCOM is especially incapable of adapting to power grid faults caused by power electronic devices such as direct current commutation failure and the like.
Therefore, how to obtain better economy and adaptability on the basis of retaining the reactive power supporting capability, the moment of inertia and the short-circuit capacity of the network construction equipment, and research on the combination of the network construction technology and the STATCOM so that the network construction equipment has the voltage source characteristic and can respond to the reactive power shortage of the system instantaneously is a key for realizing low-cost network construction under the reactive power supporting scene.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a control method and a control system for a grid-structured STATCOM, which combine a grid-structured technology with the STATCOM to enable the grid-structured STATCOM to have voltage source characteristics, can respond to reactive power shortage of a system instantaneously, and does not influence the short-circuit capacity and the rotational inertia supporting performance of grid-structured equipment, thereby realizing low-cost grid construction under a reactive power supporting scene.
In order to achieve the above object, the present invention adopts the following technical scheme:
A method of controlling a web-formed STATCOM, the method comprising:
S1, generating a frequency deviation dω, integrating the frequency deviation dω, and then superposing an angle signal theta ref0 output by a phase-locked loop to generate a phase angle control signal theta ref;
s2, generating an internal potential amplitude signal E ref according to the voltage deviation and the reactive power deviation;
S3, setting current limiting impedance Z limit according to the network-structured STATCOM output current measured value and the maximum allowable overload multiple, and generating self-adaptive virtual impedance Z vir;
S4, calculating virtual impedance voltage drop according to input impedance, combining E ref, adjusting the voltage output value to be modulated of the grid-formed STATCOM in real time, and combining theta ref, and inversely transforming the voltage output value into a three-phase sinusoidal modulation signal;
and S5, inputting a three-phase sinusoidal modulation signal to the PWM module to drive the inverter of the grid-type STATCOM.
The invention further comprises the following preferable schemes:
preferably, the grid-structured STATCOM comprises a direct-current side power supply, an inverter module and an LC filter module;
wherein the direct current side power supply provides a steady energy source;
The inverter module inverts direct current into alternating current waves meeting the network control requirement according to the sinusoidal modulation signals of ABC three phases output by the PWM module, and the alternating current waves are directly connected into an alternating current power grid after passing through the LC filter module;
The AC grid access point provides required measured values for the control method, including an active power measured value P mea, a frequency measured value F mea, voltage and reactive power measured values U mea and Q mea, and a grid-formed STATCOM output current measured value I mea.
Preferably, in S1, the phase angle control signal θ ref＝θref0+dθref＝θref0 ++.dω
Where, dω refers to the integral of dω with respect to time;
dθ ref denotes the deviation value of the phase angle.
Preferably, in S2, the voltage control module generates the internal potential amplitude signal E ref by:
The voltage deviation is PI controlled and then superimposed with a voltage reference value, and then subtracted in combination with the Q-V droop control, the droop control gain K Q is multiplied by the reactive deviation.
Preferably, the internal potential amplitude signal E ref is calculated as follows:
Wherein, U set and Q set are respectively reference values of voltage and reactive power;
u mea and Q mea are respectively measured values of voltage and reactive power;
K is proportional link gain in PI control;
T is the time constant of the integration link in PI control;
K Q is the Q-V droop control gain.
Preferably, in S3, the current limiting impedance Z limit is set in the following manner:
wherein r vir and x vir are virtual resistance and virtual reactance, respectively;
K r_limit and K x_limit are the proportionality coefficients of the virtual resistor and the virtual reactance, respectively;
I mea and I max are respectively the net-type STATCOM output current measurement value and the maximum allowable overload multiple.
Preferably, the current limiting impedance Z limit is dynamically enabled when needed to limit short circuit current during a fault, and the virtual impedance is enabled during normal operation.
Preferably, the net-structured STATCOM output current measurement may be selected from single-phase current, three-phase current, positive sequence, negative sequence current, or any combination thereof.
Preferably, in S4, the voltage drop of the virtual impedance on the d axis and the q axis is calculated according to the input impedance, the voltage output value to be modulated of the net-structured STATCOM on the d axis and the q axis under the dq coordinate system is adjusted in real time by combining with the internal potential amplitude signal E ref, and the voltage output value is inversely transformed into an ABC three-phase sinusoidal modulation signal by Clark and Park by combining with the phase angle control signal θ ref, specifically:
The internal potential amplitude signal E ref is used as a d-axis voltage reference value, 0 is used as a q-axis voltage reference value, the net-structured STATCOM voltage output values U d、Uq on the d-axis and the q-axis are regulated in real time, and the calculation formula is as follows:
Where U vir_d and U vir_q are the voltage drops of the virtual impedance on the d-axis and q-axis, respectively.
Preferably U vir_d＝Rvir*Id-Xvir*Iq
Uvir_q＝Rvir*Iq+Xvir*Id
Wherein R vir、Xvir is the real and imaginary parts of the impedance;
I d、Iq is the current component of the d-axis q-axis in the dq coordinate system.
Preferably, in S4, the voltage output value is inversely transformed into a sinusoidal modulation signal of ABC three phases by Clark and Park by:
Wherein U A、UB、UC is a sinusoidal modulation signal of ABC three phases;
u 0 is the 0-axis component of the voltage.
A control system of a web-formed STATCOM, the control system comprising:
The phase angle control signal generating unit is used for generating a frequency deviation dω, integrating the frequency deviation dω, and then superposing an angle signal theta ref0 output by the phase-locked loop to generate a phase angle control signal theta ref;
An internal potential amplitude signal generating unit for generating an internal potential amplitude signal E ref according to the voltage deviation and the reactive power deviation;
The impedance generation module is used for setting current limiting impedance Z limit according to the network-structured STATCOM output current measured value and the maximum allowable overload multiple, and generating self-adaptive virtual impedance Z vir;
The sinusoidal modulation signal generation unit is used for calculating virtual impedance voltage drop according to input impedance, regulating the voltage output value to be modulated of the network-structured STATCOM in real time in combination with E ref, and inversely transforming the voltage output value into a three-phase sinusoidal modulation signal in combination with theta ref;
And the reactive power response unit is used for inputting three-phase sine modulation signals to the PWM module to drive the inverter of the grid-structured STATCOM.
A terminal comprising a processor and a storage medium; the storage medium is used for storing instructions;
The processor is configured to operate in accordance with the instructions to perform the steps of the method.
A computer readable storage medium having stored thereon a computer program which when executed by a processor realizes the steps of the method.
The invention has the beneficial effects that compared with the prior art:
The current source characteristic of the conventional STATCOM causes unavoidable measurement and calculation delay, the emergency reactive power support of the power grid under the power electronic device faults such as direct current commutation failure is difficult to meet, the current networking technology is only used for equipment such as energy storage, wind power and photovoltaic, the networking technology is creatively combined with the conventional STATCOM topology, the voltage source characteristic is displayed externally, the reactive power response capacity during transient is fully utilized, the STATCOM has transient reactive power performance similar to that of a regulator, and meanwhile the advantages of obvious low cost and low loss are achieved. The innovation point is that firstly, the networking technology is combined with the STATCOM, so that the widely-regarded idea that the STATCOM cannot adapt to power grid faults caused by power electronic devices is changed, and secondly, the implementation details of networking control comprise implementation modes of phase angle reference values, internal potential reference values, virtual impedance, current limiting impedance and the like.
1. According to the control method, the internal potential amplitude E ref and the phase angle theta ref are controlled to be stable, after a main network side fails, as the voltage of the access PCC point of the grid-built STATCOM is changed instantaneously, the grid-built STATCOM can output active power and reactive power instantaneously after the voltage difference is changed, so that the grid-built STATCOM has the voltage source characteristic and can respond to reactive power shortage of a system instantaneously;
And can realize the low-cost network construction under the reactive support scene, compare in the scheme of adjusting the camera, have obvious cost advantage, specifically: the STATCOM is only reactive compensation equipment, reactive power is only provided in the normal condition, the low cost is realized on the one hand in comparison with a commonly adopted scheme of a camera for transient reactive power compensation, the network-built STATCOM has the advantages of low manufacturing cost of primary equipment, low operation and maintenance cost of static equipment and low overall loss, and on the other hand, the network-built energy storage scheme commonly used for network-built control is lower than the network-built energy storage because an energy storage battery is not adopted although active transient response cannot be provided;
2. The invention can realize the moment of inertia characteristic by constructing the virtual moment of inertia of df/dt; short-circuit current can be externally output during faults to maintain the amplitude of the internal potential at a higher level, the short-circuit current depends on the overload multiple of equipment, and the short-circuit capacity supporting characteristic can be realized by limiting amplitude through I max; thereby retaining the characteristics of reactive support, moment of inertia, short-circuit capacity and the like of the network-structured STATCOM and obtaining better economy and adaptability;
3. The overload capacity determines the maximum transient current which can be output by the network STATCOM during the transient period, the stronger the overload capacity is, the stronger the capacity of maintaining the terminal voltage under the condition of large transient faults is, the response characteristics after the faults and the like can be adjusted through each control parameter in the network control logic so as to realize the control effects of smaller overshoot and faster oscillation attenuation.
Drawings
FIG. 1 is a device body topology of a mesh-type STATCOM;
FIG. 2 is a schematic diagram of a control method of the networked STATCOM of the present invention;
The reference numerals in fig. 1 are: 1. a direct-current side power supply; 2. an inverter; 3. a filtering reactance; 4. a filter capacitor; 5. equivalent line reactance.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. The described embodiments of the application are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art without inventive faculty, are within the scope of the application, based on the spirit of the application.
In a preferred but non-limiting embodiment of the present invention, fig. 1 is a device body topology of a mesh-type STATCOM, and fig. 2 is a control method topology of a mesh-type STATCOM according to the present invention.
The input voltage, current, active, reactive measurements of fig. 2 are all measurements of the device of fig. 1 at the point of access to the grid PCC (equivalent line reactance 5 in fig. 1); the output three-phase sinusoidal modulation signal U A、UB、UC in fig. 2 is modulated by the PWM module and drives the inverter in fig. 1, so as to implement the reactive response function of the grid-structured STATCOM.
The invention acquires the voltage current active and reactive signals of the outlet side (equivalent line reactance 5 and right side in fig. 1) of the body device, and forms an ABC three-phase sinusoidal modulation signal to be input into a PWM module to drive a power element (inverter 2 in fig. 1) by the control method of the invention, thereby realizing the reactive response function of the grid-structured STATCOM.
The grid-formed STATCOM comprises a direct-current side power supply, an inverter module and an LC filter module;
wherein the direct current side power supply 1 provides a steady energy source;
the inverter module (inverter 2 in fig. 1) inverts direct current into alternating current waves meeting the network control requirement according to the PWM modulation signal, and the alternating current waves are directly connected into an alternating current power grid (corresponding to equivalent line reactance 5 in fig. 1) after passing through the LC filter module (corresponding to filter reactance 3 and filter capacitor 4 in fig. 1).
The network-structured STATCOM can maintain the internal potential amplitude not to change greatly within a certain period of time when a fault occurs, the DC power supply side needs to be supported by stable energy, and the DC side power supply can be an energy storage element, a capacitor element, a super capacitor element and the like;
The grid-structured STATCOM can provide rotational inertia, and the direct-current side power supply needs to use an energy storage or super capacitor;
The voltage level of the grid-structured STATCOM access point (i.e. the voltage of the access point of the grid-structured STATCOM to the rightmost ac power grid in fig. 1) includes, but is not limited to, 400 v, 10 kv, 35 kv, 66 kv, etc., which can meet the low-voltage and high-voltage connection needs.
Specifically, the control method comprises the following steps of S1-5:
S1, a power control module generates a frequency deviation dω, and then the frequency deviation dω is integrated and then an angle signal theta ref0 output by a phase-locked loop is superimposed to generate a phase angle control signal theta ref;
Further preferably, the phase angle control signal θ ref is: θ ref＝θref0+dθref＝θref0 ++dω
Where, dω refers to the integral of dω with respect to time;
dθ ref refers to the deviation value of the phase angle, which is generated by integrating the angular frequency deviation dω, and the phase of the superimposed phase-locked loop is the final phase angle control signal θ ref.
In specific implementation, the mode of generating the frequency deviation signal dω is not unique, and can be generated through an integration link by the deviation of an active measured value and a reference value, or can be generated through PI control by combining the frequency deviation of a network side system.
The most general way is depicted in fig. 2, namely, the way in which dω can be generated together from the active power measurement value P mea, the system angular frequency measurement value ω mea, the frequency measurement value F mea, the active power reference value P ref generated by PI control of the physical quantities such as the dc side voltage C dc, and the like.
The following gives a calculation formula for dω, but it should be noted that other embodiments, which use physical quantities such as the active power measurement value P mea, the system angular frequency measurement value ω mea, the frequency measurement value F mea, and the dc side voltage C dc to form dω, are all within the scope of protection of the present patent:
wherein dω is the frequency deviation;
P mea、Fmea is the active measurement and the frequency measurement, respectively;
P ref、Fref is an active reference value and a frequency reference value respectively;
K p、Kf、Kc is the proportionality coefficient of the active power, frequency and DC side voltage item respectively;
T p、Tf、Tc is the integral time constant of the active power, frequency and DC side voltage item respectively;
C dc、Cset is the dc side voltage and dc side voltage set point, respectively.
S2, the voltage control module generates an internal potential amplitude signal E ref according to the voltage deviation and the reactive power deviation;
Further preferably, the voltage control module generates the internal potential amplitude signal E ref by:
And (3) superposing a voltage reference value after PI control is carried out on the voltage deviation, and then combining Q-V droop control, and subtracting the value obtained by multiplying the reactive deviation by the droop control gain KQ.
The internal potential amplitude signal E ref has the following calculation formula:
Wherein, U set and Q set are respectively reference values of voltage and reactive power;
u mea and Q mea are respectively measured values of voltage and reactive power;
K is proportional link gain in PI control;
T is the time constant of the integration link in PI control;
k O is the Q-V droop control gain.
S3, setting a current-limiting impedance Z limit according to the net-structured STATCOM output current measured value and the maximum allowable overload multiple by the current-limiting impedance module so as to be used for dynamic current limiting, and generating a self-adaptive virtual impedance Z vir by the virtual impedance module so as to solve the problem of multi-machine parallel stability and avoid system oscillation;
Further preferably, the virtual impedance Z vir needs to be set according to the network configuration STATCOM access power grid parameters, and specifically, the virtual impedance Z vir can be set automatically by a worker according to requirements, so as to realize multi-machine parallel connection with other voltage source devices (network configuration devices or synchronous machines and the like) and ensure an active and reactive response distribution relationship with the other voltage source devices;
the net-structured STATCOM output current measurement value can be selected from single-phase current, three-phase current, positive sequence current, negative sequence current or any combination of the above.
Further preferably, a current limiting link is designed, and if the measured value of the output current of the grid-formed STATCOM exceeds the set maximum allowable current overload multiple, the current limiting impedance Z limit is input;
The current limiting impedance Z limit is set as follows:
wherein r vir and x vir are virtual resistance and virtual reactance, respectively;
K r_limit and K x_limit are the proportionality coefficients of the virtual resistor and the virtual reactance, respectively;
I mea and I max are respectively the net-type STATCOM output current measurement value and the maximum allowable overload multiple.
S4, calculating the voltage drop of the virtual impedance on the d axis and the q axis according to the input impedance, combining an internal potential amplitude signal E ref, adjusting the voltage output value to be modulated of the net-structured STATCOM on the d axis and the q axis under the dq coordinate system in real time, combining a phase angle control signal theta ref, and inversely transforming the voltage output value into an ABC three-phase sinusoidal modulation signal through Clark and Park;
Further preferably, the current limiting impedance Z limit is only dynamically put into use when it is required to limit the short-circuit current during a fault, while the virtual impedance may remain in use during normal operation.
The internal potential amplitude signal E ref is taken as a d-axis voltage reference value, 0 is taken as a q-axis voltage reference value, the voltage output value U d、Uq of equipment (a network-structured STATCOM) on the d-axis and the q-axis is regulated in real time, and the calculation formula is as follows:
Where U vir_d and U vir_q are the voltage drops of the virtual impedance on the d-axis and q-axis, respectively.
Uvir_d＝Rvir*Id-Xvir*Iq
Uvir_q＝Rvir*Iq+Xvir*Id
Wherein R vir、Xvir is the real and imaginary parts of the impedance, Z vir＝Rvir+jXvir;
I d、Iq is the current component of the d-axis q-axis in the dq coordinate system.
The voltage output value is further inversely transformed into an ABC three-phase sinusoidal modulation signal by Clark and Park by the following transformation:
U A、UB、UC is a sinusoidal modulation signal of ABC three phases;
U 0 is the 0-axis component of the voltage, U 0＝1/3(UA+UB+UC).
The d-axis q-axis in the invention has no actual physical meaning, but is the result of equivalent transformation, in particular, the result of transformation of a rotating ABC three-phase sine wave into an orthogonal two-phase dq coordinate system by applying dq transformation (park transformation), which is used for decoupling and reducing control complexity, and then can be restored into a three-phase sine wave through park inverse transformation.
S5, inputting the sinusoidal modulation signals of the ABC three phases into the PWM module to drive the power element to output, and realizing the reactive response function of the grid-structured STATCOM.
Further preferably, the power element includes power electronic switching devices such as IGBTs and IGET, and in the embodiment of the present invention, the inverter of fig. 1 is referred to.
Embodiment 2 of the present invention provides a control system of a mesh-type STATCOM, the system including:
The phase angle control signal generating unit is used for generating frequency deviation dω by the power control module, and generating a phase angle control signal theta ref by superposing an angle signal theta ref0 output by the phase-locked loop after integrating the frequency deviation dω;
the internal potential amplitude signal generating unit is used for generating an internal potential amplitude signal E ref according to the voltage deviation and the reactive power deviation by the voltage control module;
The impedance generation module is used for setting current-limiting impedance Z limit according to the network-structured STATCOM output current measured value and the maximum allowable overload multiple, and the virtual impedance module generates self-adaptive virtual impedance Z vir;
the sine modulation signal generation unit is used for calculating the voltage drop of the virtual impedance on the d axis and the q axis according to the input impedance, combining the internal potential amplitude signal E ref, adjusting the voltage output value to be modulated of the net-structured STATCOM on the d axis and the q axis under the dq coordinate system in real time, combining the phase angle control signal theta ref, and inversely converting the voltage output value into an ABC three-phase sine modulation signal through Clark and Park;
and the reactive power response unit is used for inputting the sinusoidal modulation signals of the ABC three phases to the PWM module to drive the inverter of the grid-structured STATCOM so as to realize the reactive power response function of the grid-structured STATCOM.
Embodiment 3 of the present invention provides a terminal, including a processor and a storage medium; the storage medium is used for storing instructions;
the processor is configured to operate in accordance with the instructions to perform the steps of the method described above.
Embodiment 4 of the present invention provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the control method described above.
The invention has the beneficial effects that compared with the prior art:
The current source characteristic of the conventional STATCOM causes unavoidable measurement and calculation delay, the emergency reactive power support of the power grid under the power electronic device faults such as direct current commutation failure is difficult to meet, the current networking technology is only used for equipment such as energy storage, wind power and photovoltaic, the networking technology is creatively combined with the conventional STATCOM topology, the voltage source characteristic is displayed externally, the reactive power response capacity during transient is fully utilized, the STATCOM has transient reactive power performance similar to that of a regulator, and meanwhile the advantages of obvious low cost and low loss are achieved. The innovation point is that firstly, the networking technology is combined with the STATCOM, so that the widely-regarded idea that the STATCOM cannot adapt to power grid faults caused by power electronic devices is changed, and secondly, the implementation details of networking control comprise implementation modes of phase angle reference values, internal potential reference values, virtual impedance, current limiting impedance and the like.
1. According to the control method, the internal potential amplitude E ref and the phase angle theta ref are controlled to be stable, after a main network side fails, as the voltage of the access PCC point of the grid-built STATCOM is changed instantaneously, the grid-built STATCOM can output active power and reactive power instantaneously after the voltage difference is changed, so that the grid-built STATCOM has the voltage source characteristic and can respond to reactive power shortage of a system instantaneously;
And can realize the low-cost network construction under the reactive support scene, compare in the scheme of adjusting the camera, have obvious cost advantage, specifically: the STATCOM is only reactive compensation equipment, reactive power is only provided in the normal condition, the low cost is realized on the one hand in comparison with a commonly adopted scheme of a camera for transient reactive power compensation, the network-built STATCOM has the advantages of low manufacturing cost of primary equipment, low operation and maintenance cost of static equipment and low overall loss, and on the other hand, the network-built energy storage scheme commonly used for network-built control is lower than the network-built energy storage because an energy storage battery is not adopted although active transient response cannot be provided;
2. The invention can realize the moment of inertia characteristic by constructing the virtual moment of inertia of df/dt; short-circuit current can be externally output during faults to maintain the amplitude of the internal potential at a higher level, the short-circuit current depends on the overload multiple of equipment, and the short-circuit capacity supporting characteristic can be realized by limiting amplitude through I max; thereby retaining the characteristics of reactive support, moment of inertia, short-circuit capacity and the like of the network-structured STATCOM and obtaining better economy and adaptability;
3. The overload capacity determines the maximum transient current which can be output by the network STATCOM during the transient period, the stronger the overload capacity is, the stronger the capacity of maintaining the terminal voltage under the condition of large transient faults is, the response characteristics after the faults and the like can be adjusted through each control parameter in the network control logic so as to realize the control effects of smaller overshoot and faster oscillation attenuation.
The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.
The computer readable storage medium may be a tangible device that can hold and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: portable computer disks, hard disks, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static Random Access Memory (SRAM), portable compact disk read-only memory (CD-ROM), digital Versatile Disks (DVD), memory sticks, floppy disks, mechanical coding devices, punch cards or in-groove structures such as punch cards or grooves having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media, as used herein, are not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., optical pulses through fiber optic cables), or electrical signals transmitted through wires.
The computer readable program instructions described herein may be downloaded from a computer readable storage medium to a respective computing/processing device or to an external computer or external storage device over a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers and/or edge servers. The network interface card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium in the respective computing/processing device.
The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as SMALLTALK, C ++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions may be executed entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, aspects of the present disclosure are implemented by personalizing electronic circuitry, such as programmable logic circuitry, field Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), with state information of computer readable program instructions, which can execute the computer readable program instructions.
Various aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.
These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, 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/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable medium having the instructions stored therein includes an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.
The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer, other programmable apparatus or other devices implement the functions/acts specified in the flowchart and/or block diagram block or blocks.
The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (5)
1. The control method of the grid-structured STATCOM comprises a direct-current side power supply, an inverter module and an LC filter module; wherein the direct current side power supply provides a steady energy source; the inverter module inverts direct current into alternating current waves meeting the network control requirement according to the sinusoidal modulation signals of ABC three phases output by the PWM module, and the alternating current waves are directly connected into an alternating current power grid after passing through the LC filter module; an ac grid access point provides the control method with required measurements, including active power measurementsFrequency measurement/>Measured value of voltage, reactive power/>And/>Net-structured STATCOM output current measurement valueThe method is characterized in that: the method comprises the following steps:
S1, generating frequency deviation For frequency deviation/>Superimposed phase-locked loop output angle signal/>, after integrationGenerating phase angle control signal/>；
Phase angle control signalWherein/>Finger/>Integration over time; /(I)Indicating the deviation value of the phase angle;
S2, generating an internal potential amplitude signal according to the voltage deviation and the reactive power deviation ；
Generating an internal potential amplitude signalThe method comprises the following steps:
PI control of the voltage deviation is followed by superposition of the voltage reference value, then the combination of Q-V droop control is subtracted, and the droop control gain is multiplied by the reactive deviation Is a value of (2);
The internal potential amplitude signal The calculation formula of (2) is as follows:
Wherein, And/>Respectively the reference values of voltage and reactive power; /(I)And/>Respectively measuring voltage and reactive power; /(I)The proportional link gain in PI control; /(I)The time constant of an integration link in PI control; /(I)Controlling gain for Q-V droop;
S3, setting current limiting impedance according to the network-structured STATCOM output current measured value and the maximum allowable overload multiple Generating an adaptive virtual impedance/>; Current limiting impedance/>The setting mode is as follows:
Wherein, And/>Virtual resistance and virtual reactance respectively; /(I)And/>The ratio coefficients of the virtual resistor and the virtual reactance are respectively; /(I)And/>Respectively outputting a current measured value and a maximum allowable overload multiple for the grid-formed STATCOM;
current limiting impedance Dynamic switching in use when short-circuit current needs to be limited during a fault period, and virtual impedance switching in use during normal operation;
S4, calculating virtual impedance voltage drop according to the input impedance, combining Real-time adjusting the output value of the voltage to be modulated of the network-structured STATCOM, and combining/>Inversely transforming the voltage output value into a three-phase sinusoidal modulation signal:
calculating virtual impedance from input impedance Axis,/>Voltage drop on axis combined with internal potential amplitude signal/>Real-time adjustment of/>, under dq coordinate systemAxis,/>On-axis network-structured STATCOM (static synchronous compensator) to-be-modulated voltage output value and combined with phase angle control signalInversely transforming the voltage output value into an ABC three-phase sine modulation signal through Clark and Park, and specifically:
internal potential amplitude signal For/>Shaft voltage reference value, 0/>Shaft voltage reference value, real-time adjustment/>Axis,/>On-axis grid-structured STATCOM voltage output value/>、/>The calculation formula is as follows:
Wherein, And/>Virtual impedance at/>, respectivelyAxis,/>Pressure drop over the shaft;
Wherein, 、/>Is the real and imaginary parts of the impedance; /(I)、/>A current component of a d-axis q-axis in a dq coordinate system;
The voltage output value is inversely transformed into an ABC three-phase sinusoidal modulation signal by Clark and Park by the following transformation:
Wherein, 、/>、/>Sinusoidal modulation signals of ABC three phases; /(I)Is the 0-axis component of the voltage;
and S5, inputting a three-phase sinusoidal modulation signal to the PWM module to drive the inverter of the grid-type STATCOM.
2. A method for controlling a web-structured STATCOM according to claim 1, characterized in that:
the net-structured STATCOM output current measurement value can be selected from single-phase current, three-phase current, positive sequence current, negative sequence current or any combination of the above.
3. A control system for a web-formed STATCOM, using the method according to claim 1 or 2, characterized in that: the control system includes:
Phase angle control signal generating unit for generating frequency deviation For frequency deviation/>Superimposed phase-locked loop output angle signal/>, after integrationGenerating phase angle control signal/>；
An internal potential amplitude signal generating unit for generating an internal potential amplitude signal from the voltage deviation and the reactive power deviation；
An impedance generation module for setting current limiting impedance according to the net-structured STATCOM output current measurement value and the maximum allowable overload multipleGenerating an adaptive virtual impedance/>；
A sinusoidal modulation signal generation unit for calculating virtual impedance voltage drop based on input impedance, combined withReal-time adjusting the output value of the voltage to be modulated of the network-structured STATCOM, and combining/>Inversely transforming the voltage output value into a three-phase sinusoidal modulation signal;
And the reactive power response unit is used for inputting three-phase sine modulation signals to the PWM module to drive the inverter of the grid-structured STATCOM.
4. A terminal comprising a processor and a storage medium; the method is characterized in that:
the storage medium is used for storing instructions;
the processor is operative according to the instructions to perform the steps of the method according to claim 1 or 2.
5. Computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the steps of the method according to claim 1 or 2.
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