Method and device for suppressing temporary overvoltage of grid-following type static var compensator

Abstract

The invention provides a method and a device for suppressing temporary overvoltage of a grid-following type static var compensator. The method comprises the following steps: establishing a transient impedance model of the grid-following type static var compensator; obtaining related parameters and network topology parameters of the power electronic equipment; calculating the output current required by the static var compensator under the overvoltage constraint; obtaining a transient optimal parameter according to the output current and the stability constraint; the required transient over-current capacity is obtained based on the output current; when the transient over-current capacity is smaller than the maximum over-current capacity, switching to a transient optimal parameter during a fault period, and switching to a steady state control parameter after the fault is recovered; and when the transient over-current capacity is greater than or equal to the maximum over-current capacity, reducing the output for operation under the transient optimal parameter. According to the method, the safety risk caused by temporary overvoltage can be effectively avoided only by performing control parameter optimization on the static var compensator, and theoretical guidance can be provided for capacity and output planning of a new energy station.

Description

Technical Field

[0001] The present invention relates to the technical field of reactive power compensators, and in particular to a method and device for suppressing temporary overvoltage of a grid-following static reactive power compensator. Background Art

[0002] With the increasing demand for energy and environmental pressure, building a clean, low-carbon, safe and efficient energy system and vigorously developing new energy represented by wind power and photovoltaics have become an inevitable trend in energy transformation. The large-scale grid connection of new energy units has led to a decrease in the proportion of synchronous machines in new power systems, thereby increasing the reactive-voltage sensitivity of the system and deteriorating the transient response performance. When a ground fault occurs near a new energy station, the equipment enters the low voltage ride-through process under the requirements of the grid connection guidelines, and begins to generate reactive power. At the moment of fault recovery, the reactive current may not be withdrawn in time under the influence of control delay, causing temporary overvoltage problems. Overvoltages that exceed the tolerance of the equipment will cause equipment damage, and even large-scale disconnection of new energy and stability problems of the power system. SVG (Static Var Generator) is a new generation of reactive compensation device. It is connected to the grid through a converter, has the characteristics of high controllability and high flexibility, and can effectively improve the transient response performance of the system. Therefore, it is very important to study temporary overvoltage suppression measures for new power systems starting from SVG.

[0003] At present, the design principles of SVG have taken into account the voltage support, resonance, harmonic control and asymmetric faults during faults, and added auxiliary control links such as fault ride-through to solve them. However, due to the overcurrent capacity limitation of SVG, the voltage support capacity during faults is still insufficient, and during the fault recovery period, overshoot will occur due to control system delay, and surplus reactive power will be generated, causing overvoltage problems in the system, which may cause equipment to be disconnected from the grid. Therefore, it is necessary to study the enhancement of SVG voltage support capacity through control optimization. Summary of the invention

[0004] In view of this, the present invention provides a method and device for suppressing temporary overvoltage of a grid-connected static VAR compensator to solve at least one of the above-mentioned problems.

[0005] In order to achieve the above object, the present invention adopts the following scheme:

[0006] According to a first aspect of the present invention, there is provided a method for suppressing temporary overvoltage of a grid-following static VAR compensator, the method comprising: establishing a transient impedance model of the grid-following static VAR compensator; obtaining relevant parameters of power electronic equipment and network topology parameters in the transient impedance model; calculating the output current required by the static VAR compensator under overvoltage constraints based on the relevant parameters of the power electronic equipment and the network topology parameters; obtaining transient optimal parameters according to the output current and stability constraints; obtaining the transient overcurrent capacity required by the static VAR compensator based on the output current; judging whether the transient overcurrent capacity is less than the maximum overcurrent capacity; in response to the transient overcurrent capacity being less than the maximum overcurrent capacity, switching to the transient optimal parameters during the fault period, and switching back to the steady-state control parameters after the fault is recovered; in response to the transient overcurrent capacity being greater than or equal to the maximum overcurrent capacity, reducing the output operation under the transient optimal parameters.

[0007] As an embodiment of the present invention, the relevant parameters of the above-mentioned power electronic equipment include: phase-locked loop, inner loop, outer loop PI parameters and filter parameters, and the network topology parameters include transmission line structure and line impedance.

[0008] As an embodiment of the present invention, in the above method, based on the relevant parameters of the power electronic equipment and the network topology parameters, calculating the output current required by the static VAR compensator under the overvoltage constraint includes: based on the relevant parameters of the power electronic equipment and the network topology parameters, giving the overvoltage limit value V that the static VAR compensator can withstand l and q-axis output current I q0 Then, the output current required by the static VAR compensator is calculated using the following formula:

[0009]

[0010] Among them, I dm is the output current required by the static VAR compensator; I q0 =k l (0.9-U p0 ), k l is the reactive voltage coefficient during low-voltage wear, U p0 is the voltage in the steady-state stage of the fault; R and X are the line resistance and line reactance respectively; E is the infinite grid-side voltage.

[0011] As an embodiment of the present invention, obtaining the transient optimal parameters according to the output current and the stability constraint in the above method includes:

[0012] to I dm The d-axis component I of the converter output current is obtained by performing an inverse Laplace transform on the expression d The expression is:

[0013] I d (t) = L -1 [I dref -Y vsc (s)U d (s)]

[0014] Get I d With proportional gain k ip With the feedforward time constant T ff ;

[0015] Determine the overvoltage constraint k according to the change trend diagram ip 、T ff Parameter set;

[0016] The stability constraint is introduced as the lower limit of the parameter to obtain the transient optimal parameters.

[0017] As an embodiment of the present invention, in the above method, obtaining the transient overcurrent capacity required by the static VAR compensator based on the output current includes:

[0018] The transient overcurrent capacity required by the static VAR compensator is obtained using the following formula:

[0019]

[0020] Among them, I max is the converter current limit; I dm is the output current required by the static VAR compensator; I q is the q-axis component of the converter output current.

[0021] According to a second aspect of the present invention, there is provided a device for suppressing temporary overvoltage of a grid-following static VAR compensator, the device comprising: a model building unit, for building a transient impedance model of the grid-following static VAR compensator; a parameter acquisition unit, for acquiring relevant parameters of power electronic equipment and network topology parameters in the transient impedance model; an output current calculation unit, for calculating the output current required by the static VAR compensator under overvoltage constraints based on the relevant parameters of the power electronic equipment and the network topology parameters; an optimal parameter acquisition unit, for obtaining transient optimal parameters according to the output current and stability constraints; a transient overcurrent capacity acquisition unit, for obtaining the transient overcurrent capacity required by the static VAR compensator based on the output current; a judgment unit, for judging whether the transient overcurrent capacity is less than the maximum overcurrent capacity; a control unit, for switching to the transient optimal parameters during a fault when the transient overcurrent capacity is less than the maximum overcurrent capacity, and switching back to the steady-state control parameters after the fault is recovered; and for reducing the output operation under the transient optimal parameters when the transient overcurrent capacity is greater than or equal to the maximum overcurrent capacity.

[0022] As an embodiment of the present invention, the relevant parameters of the above-mentioned power electronic equipment include: phase-locked loop, inner loop, outer loop PI parameters and filter parameters, and the network topology parameters include transmission line structure and line impedance.

[0023] As an embodiment of the present invention, the output current calculation unit is specifically used for:

[0024] Based on the relevant parameters of the power electronic equipment and the network topology parameters, the overvoltage limit value V that the static VAR compensator can withstand is given l and q-axis output current I q0 Then, the output current required by the static VAR compensator is calculated using the following formula:

[0025]

[0026] Among them, I dm is the output current required by the static VAR compensator; I q0 =k l (0.9-U p0 ), k l is the reactive voltage coefficient during low-voltage wear, U p0 is the voltage in the steady-state stage of the fault; R and X are the line resistance and line reactance respectively; E is the infinite grid-side voltage.

[0027] As an embodiment of the present invention, the above-mentioned optimal parameter acquisition unit is specifically used for:

[0028] to I dm The d-axis component I of the converter output current is obtained by performing an inverse Laplace transform on the expression d The expression is:

[0029] I d (t) = L -1 [I dref -Y vsc (s)U d (s)]

[0030] Get I d With proportional gain k ip With the feedforward time constant T ff ;

[0031] Determine the overvoltage constraint k according to the change trend diagram ip 、T ff Parameter set;

[0032] The stability constraint is introduced as the lower limit of the parameter to obtain the transient optimal parameters.

[0033] As an embodiment of the present invention, the above-mentioned transient overcurrent capacity acquisition unit is specifically used for:

[0034] The transient overcurrent capacity required by the static VAR compensator is obtained using the following formula:

[0035]

[0036] Among them, I max is the converter current limit; I dm is the output current required by the static VAR compensator; I q is the q-axis component of the converter output current.

[0037] According to a third aspect of the present invention, there is provided an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0038] According to a fourth aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0039] The method and device for suppressing temporary overvoltage of a grid-following static VAR compensator proposed in the present invention can effectively suppress the temporary overvoltage problem caused by the delayed exit of the low-through control after fault recovery by optimizing the control parameters of the grid-following static VAR compensator. By optimizing the control parameters, the voltage support capacity of the static VAR compensator is enhanced, and the problems of equipment disconnection and system instability caused by overvoltage are avoided. In addition, this method only needs to optimize the control parameters of the static VAR compensator to effectively avoid the safety risks caused by temporary overvoltage, and can provide theoretical guidance for the capacity and output planning of new energy sites, and support the safe and stable operation of a high-proportion new energy power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0041] Figure 1 It is a flow chart of a method for suppressing temporary overvoltage of a grid-type static VAR compensator provided by an embodiment of the present invention;

[0042] Figure 2 is a transient equivalent circuit diagram provided by an embodiment of the present invention;

[0043] Figure 3 is a schematic diagram of a process for obtaining transient optimal parameters provided by an embodiment of the present invention;

[0044] Figure 4 is a graph showing the relationship between output current and control parameters provided by an embodiment of the present invention;

[0045] Figure 5 is a block diagram of the relationship between a phase-locked loop and an inner loop provided by an embodiment of the present invention;

[0046] Figure 6 is an inner loop Nyquist diagram provided by an embodiment of the present invention;

[0047] Figure 7 It is a structural schematic diagram of a device for suppressing temporary overvoltage of a grid-type static VAR compensator provided by an embodiment of the present invention;

[0048] Figure 8 It is a structural schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0050] like Figure 1 FIG. 1 is a flow chart of a method for suppressing temporary overvoltage of a grid-connected static VAR compensator provided by an embodiment of the present invention. The method comprises the following steps:

[0051] Step S101: establishing a transient impedance model of a grid-connected static VAR compensator.

[0052] The transient impedance modeling process of the grid-connected static VAR compensator in this embodiment is as follows:

[0053] Under the effect of the inner loop cross decoupling term, the inner loop dynamics can be expressed as:

[0054]

[0055] Among them, U c is the output voltage vector of the converter bridge arm, U p is the PCC voltage vector, I g is the converter output current vector, I ref is the output current command vector; s is the Lagrangian operator, L f is the filter inductor; PI cc (s) is the proportional integral transfer function, and its specific form is k ip +kii / s,k ip is the proportional gain, k ii is the integral gain; G ff (s) is the feedforward transfer function, which is in the form of 1 / (1+sT ff ), T ff is the feedforward time constant.

[0056] For ease of analysis, the integral constant is considered to be 0 when establishing the equivalent impedance model, and the device equivalent impedance is simplified to Z vsc (s)=(k ip +sL f ) / [1-G ff (s)], whose structure is Figure 2 As shown, Figure 2 In the above equation, R1 = k ip , R2=L f / T ff , R eq =R1+R2,L eq =L f , C eq =T ff / k ip .

[0057] Step S102: Obtain relevant parameters of power electronic equipment and network topology parameters in the transient impedance model.

[0058] Preferably, the relevant parameters of the power electronic equipment here include: phase-locked loop, inner loop, outer loop PI parameters and filter parameters, while the network topology parameters include transmission line structure, line resistance and line impedance. Among them: the phase-locked loop parameters are used to synchronize the parameters of the power electronic equipment with the grid phase to ensure that the equipment can accurately track the frequency and phase of the grid. The inner loop PI parameters are used to control the proportional integral (PI) controller parameters of the current, affecting the dynamic response and stability of the equipment. The outer loop PI parameters are used to control the PI controller parameters of the voltage and adjust the output voltage of the equipment to maintain system stability. The filter parameters involve the design parameters of the filter, which are used to reduce harmonics and noise and improve the quality of current and voltage waveforms. The transmission line structure describes the configuration and connection method of the transmission lines in the power grid, which affects the path and efficiency of power transmission. The line resistance is the resistance value of the transmission line, which affects the energy loss in power transmission. The line impedance includes the resistance and reactance of the line, which affects the voltage drop and current distribution of power transmission.

[0059] Step S103: Based on the relevant parameters of the power electronic device and the network topology parameters, the output current required by the static VAR compensator under the overvoltage constraint is calculated.

[0060] First, the circuit equation of the dq synchronous coordinate system under the steady state of the transmission line is written as follows:

[0061]

[0062] Among them, R and X are line resistance and line reactance respectively, E d , E q are the dq axis components of the infinite grid voltage, U pd , U pq are the dq axis components of the common coupling point voltage, I d , I q are the dq axis components of the converter output current respectively. Since the phase-locked loop accurately tracks the grid phase in steady state, U pq =0, the equation can be obtained as follows:

[0063]

[0064] During the fault, the static VAR compensator generates reactive power to support the voltage in the low-voltage mode, thus I q <0.

[0065] The calculation formula of the dq axis component of the converter output current can be derived from the above formula (1):

[0066] I g =I ref -Y vsc U p (4)

[0067] Where Y vsc is the device equivalent admittance matrix. When the phase-locked loop error is ignored, the q-axis output current is determined by the command value, i.e., I q =I qref When the overvoltage limit value V that the static VAR compensator can withstand is given l and q-axis output current I q0 After that, the output current I required by the static VAR compensator to meet the overvoltage constraint can be calculated. dm As shown in formula (5):

[0068]

[0069] Among them, I q0 =k l (0.9-U p0 ), k l is the reactive voltage coefficient during low-voltage wear, U p0 is the voltage in the steady-state stage of the fault, and E is the infinite grid-side voltage.

[0070] Step S104: Obtaining transient optimal parameters according to the output current and stability constraints.

[0071] Preferably, Figure 3 As shown, this step may further include the following sub-steps:

[0072] Step S1041: dm The d-axis component I of the converter output current is obtained by performing an inverse Laplace transform on the expression d The expression is:

[0073] I d (t) = L -1 [I dref -Y vsc (s)U d (s)] (6)

[0074] In the above formula, I dref is the d-axis current command value; Y vsc is the device equivalent admittance matrix, U d (s) is the d-axis voltage at the device port.

[0075] Step S1042: Obtain I d With proportional gain k ip With the feedforward time constant T ff 's changing trend chart.

[0076] Step S1043: Determine the k of the overvoltage constraint according to the change trend diagram ip 、T ff Parameter set.

[0077] I d Follow k ip With T ff The changing trend is Figure 4 As shown in Figure 2, the curve (red dashed line) where the surface intersects the plane is the k that satisfies the overvoltage constraint. ip 、T ff Parameter set.

[0078] Step S1044: Introduce stability constraints as parameter lower limits to obtain transient optimal parameters.

[0079] The stability constraint is mainly discussed around the interaction coupling between the phase-locked loop and the inner loop. pq The control output phase θ is used to achieve grid-connected point voltage phase tracking. The proportional gain and integral gain of the phase-locked loop are k ppll and k ipll Its closed-loop transfer function G cpll (s), as shown in formula (7).

[0080]

[0081] Where U pd0 is the d-axis voltage of the common coupling point in the steady-state stage of the fault, Gpll (s) is the transfer function of the PI link of the phase-locked loop.

[0082] The influence of the phase-locked loop on the potential inside the converter, the output current and the PCC voltage can be represented by the following matrix:

[0083]

[0084] Where V pll is the internal potential under the influence of the phase-locked loop. pll is the output current under the influence of the phase-locked loop. V fpll is the PCC voltage under the influence of the phase-locked loop. upll G is the influence matrix of the phase-locked loop on the internal potential. ipll is the influence matrix of the phase-locked loop on the output current. fpll It is the influence matrix of phase-locked loop on PCC voltage.

[0085] The equivalent block diagram of the inverter grid-connected system taking into account the influence of the phase-locked loop is as follows: Figure 5 shown.

[0086] Depend on Figure 5 The inner closed-loop transfer function can be derived as:

[0087] G c (s) = [I + Y fg PI cc (s)-Y fg G ff (s)Z g ] -1 Y fg PI cc (s) (9)

[0088] Among them, Y fg is the filter admittance and network admittance matrix, Z g Considering the open-loop transfer function of the phase-locked loop and voltage feedforward, it is:

[0089]

[0090] In the formula, G c (1,1) is an element of the inner closed-loop transfer function matrix. The stability constraint can be expressed as a Bode diagram obtained according to equation (10). The parameter boundary obtained according to the stability constraint is k ipmin ,like Figure 6 As shown. According to k ipmin and Figure 4 The curve in can be used to obtain the optimal parameters of the inner loop based on temporary overvoltage and stability constraints. Specifically, Figure 4 The horizontal and vertical coordinates of the curve (red dashed line) are k ip With T ff, when k ip After determining (i.e. k ipmin ) to get the only T ff , this group k ip With T ff is the optimal parameter.

[0091] Step S105: Obtaining the transient overcurrent capacity required by the static VAR compensator based on the output current.

[0092] Preferably, in this step, the transient overcurrent capacity required by the static VAR compensator can be obtained using the following formula:

[0093]

[0094] Among them, I max is the converter current limit; I dm is the output current required by the static VAR compensator; I q is the q-axis component of the converter output current.

[0095] Step S106: Determine whether the transient overcurrent capacity is less than the maximum overcurrent capacity, if so, proceed to step S107, otherwise proceed to step S108.

[0096] Step S107: switching to the transient optimal parameters during the fault period, and switching back to the steady-state control parameters after the fault is recovered.

[0097] Step S108: operating at reduced output under the transient optimal parameters.

[0098] If it is greater than or equal to the maximum overcurrent capacity, it means that the device cannot solve the temporary overvoltage problem through parameter optimization, and it is necessary to expand the capacity of the equipment or reduce the operating output under the transient optimal parameters.

[0099] From the above, it can be seen that the method for suppressing temporary overvoltage of the grid-following static VAR compensator proposed in the present invention can effectively suppress the temporary overvoltage problem caused by the delayed exit of the low-through control after fault recovery by optimizing the control parameters of the grid-following static VAR compensator. By optimizing the control parameters, the voltage support capacity of the static VAR compensator is enhanced, and the problems of equipment disconnection and system instability caused by overvoltage are avoided. In addition, this method only needs to optimize the control parameters of the static VAR compensator to effectively avoid the safety risks caused by temporary overvoltage, and can provide theoretical guidance for the capacity and output planning of new energy sites, and support the safe and stable operation of high-proportion new energy power systems.

[0100] like Figure 7The structure diagram of a device for suppressing temporary overvoltage of a grid-type static VAR compensator provided by an embodiment of the present application is shown. The device includes: a model building unit 710, a parameter acquisition unit 720, an output current calculation unit 730, an optimal parameter acquisition unit 740, a transient overcurrent capacity acquisition unit 750, a judgment unit 760 and a control unit 770, which are connected in sequence, wherein:

[0101] The model building unit 710 is used to build a transient impedance model of the grid-following static VAR compensator.

[0102] The parameter acquisition unit 720 is used to acquire relevant parameters of the power electronic equipment and network topology parameters in the transient impedance model.

[0103] The output current calculation unit 730 is used to calculate the output current required by the static VAR compensator under overvoltage constraints based on relevant parameters of the power electronic equipment and the network topology parameters.

[0104] The optimal parameter acquisition unit 740 is used to obtain the transient optimal parameter according to the output current and the stability constraint.

[0105] The transient overcurrent capacity acquisition unit 750 is used to obtain the transient overcurrent capacity required by the static VAR compensator based on the output current.

[0106] The judging unit 760 is used to judge whether the transient overcurrent capacity is less than the maximum overcurrent capacity.

[0107] The control unit 770 is used to switch to the transient optimal parameters during a fault period when the transient overcurrent capacity is less than the maximum overcurrent capacity, and switch back to the steady-state control parameters after the fault is recovered; and when the transient overcurrent capacity is greater than or equal to the maximum overcurrent capacity, reduce the output operation under the transient optimal parameters.

[0108] Preferably, the relevant parameters of the above-mentioned power electronic equipment include: phase-locked loop, inner loop, outer loop PI parameters and filter parameters, and the network topology parameters include transmission line structure and line impedance.

[0109] Preferably, the output current calculation unit 730 is specifically used to: based on the relevant parameters of the power electronic equipment and the network topology parameters, determine the overvoltage limit value V that the static VAR compensator can withstand. l and q-axis output current I q0 Then, the output current required by the static VAR compensator is calculated using the following formula:

[0110]

[0111] Among them, I dmis the output current required by the static VAR compensator; I q0 =k l (0.9-U p0 ), k l is the reactive voltage coefficient during low-voltage wear, U p0 is the voltage in the steady-state stage of the fault; R and X are the line resistance and line reactance respectively; E is the infinite grid-side voltage.

[0112] Preferably, the above-mentioned optimal parameter acquisition unit 740 is specifically used for:

[0113] to I dm The d-axis component I of the converter output current is obtained by performing an inverse Laplace transform on the expression d The expression is:

[0114] I d (t) = L -1 [I dref -Y vsc (s)U d (s)]

[0115] Get I d With proportional gain k ip With the feedforward time constant T ff ;

[0116] Determine the overvoltage constraint k according to the change trend diagram ip 、T ff Parameter set;

[0117] The stability constraint is introduced as the lower limit of the parameter to obtain the transient optimal parameters.

[0118] Preferably, the transient overcurrent capacity acquisition unit 750 is specifically used for:

[0119] The transient overcurrent capacity required by the static VAR compensator is obtained using the following formula:

[0120]

[0121] Among them, I max is the converter current limit; I dm is the output current required by the static VAR compensator; I q is the q-axis component of the converter output current.

[0122] From the above, it can be seen that the temporary overvoltage suppression device for the grid-following static VAR compensator proposed in the present invention can effectively suppress the temporary overvoltage problem caused by the delayed exit of the low-through control after fault recovery by optimizing the control parameters of the grid-following static VAR compensator. By optimizing the control parameters, the voltage support capacity of the static VAR compensator is enhanced, and the problems of equipment disconnection and system instability caused by overvoltage are avoided. In addition, this method only needs to optimize the control parameters of the static VAR compensator to effectively avoid the safety risks caused by temporary overvoltage, and can provide theoretical guidance for the capacity and output planning of new energy sites, and support the safe and stable operation of high-proportion new energy power systems.

[0123] Figure 8 is a schematic diagram of an electronic device provided by an embodiment of the present invention. Figure 8 The electronic device shown is a general data processing device, which includes a general computer hardware structure, which at least includes a processor 801 and a memory 802. The processor 801 and the memory 802 are connected via a bus 803. The memory 802 is suitable for storing one or more instructions or programs executable by the processor 801. The one or more instructions or programs are executed by the processor 801 to implement the steps in the above-mentioned method for suppressing temporary overvoltage of a grid-connected static VAR compensator.

[0124] The processor 801 may be an independent microprocessor or a collection of one or more microprocessors. Thus, the processor 801 executes the commands stored in the memory 802 to execute the method flow of the embodiment of the present invention as described above to realize the processing of data and the control of other devices. The bus 803 connects the above-mentioned multiple components together, and at the same time connects the above-mentioned components to the display controller 804 and the display device and the input / output (I / O) device 805. The input / output (I / O) device 805 may be a mouse, a keyboard, a modem, a network interface, a touch input device, a somatosensory input device, a printer, and other devices known in the art. Typically, the input / output (I / O) device 805 is connected to the system via an input / output (I / O) controller 806.

[0125] The memory 802 may store software components such as an operating system, a communication module, an interaction module, and an application program. Each of the modules and applications described above corresponds to a set of executable program instructions that implement one or more functions and methods described in the embodiments of the invention.

[0126] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the above-mentioned method for suppressing temporary overvoltage of a grid-connected static VAR compensator are implemented.

[0127] An embodiment of the present invention further provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the above-mentioned method for suppressing temporary overvoltage of a grid-connected static VAR compensator.

[0128] From the above, it can be seen that the method and device for suppressing temporary overvoltage of a grid-following static VAR compensator proposed in the present invention can effectively suppress the temporary overvoltage problem caused by the delayed exit of the low-through control after fault recovery by optimizing the control parameters of the grid-following static VAR compensator. By optimizing the control parameters, the voltage support capacity of the static VAR compensator is enhanced, and the problems of equipment disconnection and system instability caused by overvoltage are avoided. In addition, this method only needs to optimize the control parameters of the static VAR compensator to effectively avoid the safety risks caused by temporary overvoltage, and can provide theoretical guidance for the capacity and output planning of new energy sites, and support the safe and stable operation of a high-proportion new energy power system.

[0129] The preferred embodiments of the present invention are described above with reference to the accompanying drawings. Many features and advantages of these embodiments are clear from this detailed description, and therefore the claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. In addition, since many modifications and changes are easily conceivable to those skilled in the art, it is not intended to limit the embodiments of the present invention to the precise structure and operation illustrated and described, but all suitable modifications and equivalents falling within its scope may be covered.

[0130] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0131] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0132] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0133] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0134] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for suppressing temporary overvoltage of a grid-connected static VAR compensator, characterized in that: The method comprises: Establish the transient impedance model of grid-following static VAR compensator; Obtaining relevant parameters of power electronic equipment and network topology parameters in the transient impedance model; Based on the relevant parameters of the power electronic equipment and the network topology parameters, calculating the output current required by the static VAR compensator under overvoltage constraints; Obtaining transient optimal parameters according to the output current and stability constraints; Obtaining a transient overcurrent capacity required by the static VAR compensator based on the output current; Determining whether the transient overcurrent capacity is less than the maximum overcurrent capacity; In response to the transient overcurrent capacity being less than the maximum overcurrent capacity, switching to the transient optimal parameters is performed during the fault period, and switching back to the steady-state control parameters after the fault is recovered; in response to the transient overcurrent capacity being greater than or equal to the maximum overcurrent capacity, the output is reduced under the transient optimal parameters.

2. The method for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 1, characterized in that: The relevant parameters of the power electronic equipment include: phase-locked loop, inner loop, outer loop PI parameters and filter parameters, and the network topology parameters include transmission line structure and line impedance.

3. The method for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 1, characterized in that: The calculation of the output current required by the static VAR compensator under overvoltage constraints based on the relevant parameters of the power electronic equipment and the network topology parameters includes: Based on the relevant parameters of the power electronic equipment and the network topology parameters, the overvoltage limit value V that the static VAR compensator can withstand is given l and q-axis output current I q0 Then, the output current required by the static VAR compensator is calculated using the following formula: Among them, I dm is the output current required by the static VAR compensator; I q0 =k l (0.9-U p0 ), k l is the reactive voltage coefficient during low-voltage wear, U p0 is the voltage in the steady-state stage of the fault; R and X are the line resistance and line reactance respectively; E is the infinite grid-side voltage.

4. The method for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 3, characterized in that: The obtaining of the transient optimal parameters according to the output current and the stability constraint comprises: to I dm The d-axis component I of the converter output current is obtained by performing an inverse Laplace transform on the expression d The expression is: I d (t)=L -1 [I dref -Y vsc (s)U d (s)] Get I d With proportional gain k ip With the feedforward time constant T ff ; Determine the overvoltage constraint k according to the change trend diagram ip , T ff Parameter set; The stability constraint is introduced as the lower limit of the parameter to obtain the transient optimal parameters.

5. The method for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 1, characterized in that: The step of obtaining the transient overcurrent capacity required by the static VAR compensator based on the output current comprises: The transient overcurrent capacity required by the static VAR compensator is obtained using the following formula: Among them, I max is the converter current limit; I dm is the output current required by the static VAR compensator; I q is the q-axis component of the converter output current.

6. A device for suppressing temporary overvoltage of a grid-connected static VAR compensator, characterized in that: The device comprises: A model building unit, used to build a transient impedance model of a grid-following static VAR compensator; A parameter acquisition unit, used to acquire relevant parameters of power electronic equipment and network topology parameters in the transient impedance model; An output current calculation unit, used for calculating the output current required by the static VAR compensator under overvoltage constraints based on relevant parameters of the power electronic equipment and the network topology parameters; An optimal parameter acquisition unit, used to obtain a transient optimal parameter according to the output current and the stability constraint; A transient overcurrent capacity acquisition unit, configured to obtain a transient overcurrent capacity required by the static VAR compensator based on the output current; A judging unit, used for judging whether the transient overcurrent capacity is less than the maximum overcurrent capacity; A control unit is used to switch to the transient optimal parameters during a fault period when the transient overcurrent capacity is less than the maximum overcurrent capacity, and switch back to the steady-state control parameters after the fault is recovered; and when the transient overcurrent capacity is greater than or equal to the maximum overcurrent capacity, reduce the output operation under the transient optimal parameters.

7. The device for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 6, characterized in that: The relevant parameters of the power electronic equipment include: phase-locked loop, inner loop, outer loop PI parameters and filter parameters, and the network topology parameters include transmission line structure and line impedance.

8. The device for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 6, characterized in that: The output current calculation unit is specifically used for: Based on the relevant parameters of the power electronic equipment and the network topology parameters, the overvoltage limit value V that the static VAR compensator can withstand is given l and q-axis output current I q0 Then, the output current required by the static VAR compensator is calculated using the following formula: Among them, I dm is the output current required by the static VAR compensator; I q0 =k l (0.9-U p0 ), k l is the reactive voltage coefficient during low-voltage wear, U p0 is the voltage in the steady-state stage of the fault; R and X are the line resistance and line reactance respectively; E is the infinite grid-side voltage.

9. The device for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 8, characterized in that: The optimal parameter acquisition unit is specifically used for: to I dm The d-axis component I of the converter output current is obtained by performing an inverse Laplace transform on the expression d The expression is: I d (t)=L -1 [I dref -Y vsc (s)U d (s)] Get I d With proportional gain k ip With the feedforward time constant T ff ; Determine the overvoltage constraint k according to the change trend diagram ip , T ff Parameter set; The stability constraint is introduced as the lower limit of the parameter to obtain the transient optimal parameters.

10. The device for suppressing temporary overvoltage of a grid-connected static VAR compensator according to claim 6, characterized in that: The transient overcurrent capacity acquisition unit is specifically used for: The transient overcurrent capacity required by the static VAR compensator is obtained using the following formula: Among them, I max is the converter current limit; I dm is the output current required by the static VAR compensator; I q is the q-axis component of the converter output current.

11. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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