Transient voltage stability support-oriented power supply control coordination optimization method and device

Abstract

The embodiment of the invention discloses a transient voltage stability support-oriented power supply control coordination optimization method and device, and the method comprises the steps: entering a low voltage ride through stage when the voltage of a grid connection point is lower than a preset low voltage ride through control threshold value and a three-phase grounding fault occurs, enabling an inverter to be switched to transient voltage support control at the moment, and enabling the inverter to be switched to the transient voltage support control; enabling the inverter to carry out current output based on the first active current and the first reactive current; and when the voltage of the grid-connected point exceeds a preset recovery threshold value, entering a recovery stage after low voltage ride through, switching the inverter into recovery control after low voltage ride through at the moment, and enabling the inverter to carry out current output based on the second active current and the second reactive current. The invention provides an inverter type power supply control coordination optimization scheme oriented to transient voltage stability support, and the voltage support effect on a power grid is improved.

Description

Technical Field

[0001] The present invention relates to the field of voltage safety control of power systems, and in particular to a power supply control coordination optimization method and device for transient voltage stability support. Background Art

[0002] With the high proportion of new energy connected to the power grid, the power structure has undergone essential changes. The dynamic reactive power support of the power system is insufficient after the disturbance fault, and the transient voltage safety faces new major challenges. It is urgent to use the flexibility of power electronic power supply control to improve the autonomous response support capability for transient voltage stability. Therefore, in order to improve the voltage support effect for the power grid, the present invention proposes an inverter-type power supply control coordination optimization scheme for transient voltage stability support. Summary of the invention

[0003] In order to solve at least one technical problem in the above-mentioned background technology, the present invention proposes a power supply control coordination optimization method and device for transient voltage stability support.

[0004] In order to achieve the above object, according to one aspect of the present invention, a power supply control coordination optimization method for transient voltage stability support is provided, the method comprising:

[0005] When the grid connection point voltage is lower than the preset low voltage ride-through control threshold and a three-phase ground fault occurs, the low voltage ride-through stage is entered, at which time the inverter is switched to transient voltage support control, so that the inverter outputs current based on a first active current and a first reactive current, wherein the first active current and the first reactive current are determined according to a preset maximum allowable current of the inverter during the low voltage ride-through period and a preset power factor;

[0006] When the grid connection point voltage exceeds a preset recovery threshold, it enters the recovery stage after low voltage ride-through. At this time, the inverter is switched to the recovery control after low voltage ride-through, so that the inverter outputs current based on the second active current and the second reactive current, wherein the second active current and the second reactive current smoothly transition in an exponential form, the second reactive current is determined according to the reactive current at the moment of entering the recovery stage after low voltage ride-through, a preset inverter steady-state reactive current setting value and an exponential parameter, and the second active current is determined according to the second reactive current and the maximum allowable current.

[0007] Optionally, the power supply control coordination optimization method for transient voltage stability support further includes:

[0008] When the inverter performs recovery control after low voltage ride-through, the inverter outputs active current based on the second active current and the maximum active current limit, wherein the maximum active current limit is determined based on the maximum allowable active power, the instantaneous voltage amplitude of the inverter grid-connected point, and the maximum allowable current.

[0009] Optionally, the power supply control coordination optimization method for transient voltage stability support further includes:

[0010] When the inverter performs transient voltage support control, when the active power reaches the maximum active output limit, the inverter switches from current output based on the first active current and the first reactive current to current output based on a third active current and a third reactive current, wherein the third active current is determined based on the maximum allowable active power and the instantaneous voltage amplitude of the inverter grid-connected point, and the third reactive current is determined based on the third active current and the maximum allowable current.

[0011] Optionally, the power supply control coordination optimization method for transient voltage stability support further includes:

[0012] Obtaining a preset mathematical form of a coordinated optimization problem, wherein the optimization objective of the mathematical form of the coordinated optimization problem is to minimize a transient voltage safety index, and the optimization parameters of the mathematical form of the coordinated optimization problem include: system state variables, system control variables, and a power factor of transient voltage support control, and the transient voltage safety index is the maximum value of the time integral of the voltage deviation of each node in the system;

[0013] Based on the mathematical form of the coordinated optimization problem, the power factor of transient voltage support control is solved by combining simulation calculation with numerical optimization.

[0014] Optionally, the power supply control coordination optimization method for transient voltage stability support further includes:

[0015] The mathematical form of the coordinated optimization problem is used to solve the power factor of transient voltage support control by combining simulation calculation with numerical optimization, including:

[0016] Time domain simulation is used to obtain node voltage trajectories under complex dynamic conditions of the system. By adjusting the system control variables of each distributed new energy device, the trajectory sensitivity of each system control variable with respect to the transient voltage safety index is calculated.

[0017] Iterative calculations are performed. In each iterative calculation, the index value of the transient voltage safety quantification index and the trajectory sensitivity result are passed into the numerical optimization algorithm to update the power factor of the transient voltage support control of each device. When the calculation result meets the requirements of the iterative constraints, the power factor used to maximize the system transient voltage support is output.

[0018] In order to achieve the above object, according to another aspect of the present invention, a power supply control coordination optimization device for transient voltage stability support is provided, the device comprising:

[0019] A transient voltage support control unit, used for entering a low voltage ride-through stage when the grid connection point voltage is lower than a preset low voltage ride-through control threshold and a three-phase grounding fault occurs, at which time the inverter is switched to transient voltage support control, so that the inverter outputs current based on a first active current and a first reactive current, wherein the first active current and the first reactive current are determined according to a preset maximum allowable current of the inverter during the low voltage ride-through period and a preset power factor;

[0020] A recovery control unit after low voltage ride-through is used to enter the recovery stage after low voltage ride-through when the grid connection point voltage exceeds a preset recovery threshold value. At this time, the inverter is switched to recovery control after low voltage ride-through, so that the inverter outputs current based on the second active current and the second reactive current, wherein the second active current and the second reactive current smoothly transition in an exponential form, the second reactive current is determined based on the reactive current at the moment of entering the recovery stage after low voltage ride-through, a preset inverter steady-state reactive current setting value and an exponential parameter, and the second active current is determined based on the second reactive current and the maximum allowable current.

[0021] Optionally, the power supply control coordination optimization device for transient voltage stability support further includes:

[0022] The maximum active current limiting unit is used to enable the inverter to output active current based on the second active current and the maximum active current limit when the inverter performs recovery control after low voltage ride-through, wherein the maximum active current limit is determined based on the maximum allowable active power, the instantaneous voltage amplitude of the inverter grid-connected point and the maximum allowable current.

[0023] Optionally, the power supply control coordination optimization device for transient voltage stability support further includes:

[0024] A maximized reactive current output control unit is used to switch the inverter from current output based on the first active current and the first reactive current to current output based on a third active current and a third reactive current when the active power reaches the maximum active output limit during transient voltage support control of the inverter, wherein the third active current is determined based on the maximum allowable active power and the instantaneous voltage amplitude of the inverter grid-connected point, and the third reactive current is determined based on the third active current and the maximum allowable current.

[0025] Optionally, the power supply control coordination optimization device for transient voltage stability support further includes:

[0026] A mathematical form acquisition unit for a coordinated optimization problem, used for acquiring a preset mathematical form of a coordinated optimization problem, wherein the optimization target of the mathematical form of the coordinated optimization problem is to minimize a transient voltage safety index, and the optimization parameters of the mathematical form of the coordinated optimization problem include: system state variables, system control variables, and a power factor of transient voltage support control, and the transient voltage safety index is the maximum value of the time integral of the voltage deviation of each node in the system;

[0027] The solving calculation unit is used to solve the power factor of transient voltage support control by combining simulation calculation with numerical optimization based on the mathematical form of the coordinated optimization problem.

[0028] Optionally, the solution calculation unit includes:

[0029] The trajectory sensitivity determination module is used to obtain the node voltage trajectory under the complex dynamics of the system by time domain simulation, and calculate the trajectory sensitivity of each system control variable with respect to the transient voltage safety index by adjusting the system control variables of each distributed new energy device;

[0030] The iterative calculation module is used to perform iterative calculations. In each iterative calculation, the index value of the transient voltage safety quantification index and the trajectory sensitivity result are passed into the numerical optimization algorithm to update the power factor of the transient voltage support control of each device. When the calculation result meets the requirements of the iterative constraints, the power factor used to maximize the system transient voltage support is output.

[0031] In order to achieve the above-mentioned purpose, according to another aspect of the present invention, a computer device is also provided, including 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-mentioned power supply control coordination optimization method for transient voltage stability support when executing the computer program.

[0032] In order to achieve the above-mentioned purpose, according to another aspect of the present invention, a computer-readable storage medium is further provided, on which a computer program / instruction is stored, and when the computer program / instruction is executed by a processor, the steps of the power supply control coordination optimization method for transient voltage stability support are implemented.

[0033] In order to achieve the above-mentioned purpose, according to another aspect of the present invention, a computer program product is also provided, including a computer program / instruction, which, when executed by a processor, implements the steps of the above-mentioned power supply control coordination optimization method for transient voltage stability support.

[0034] The beneficial effects of the present invention are:

[0035] The present invention enters a low voltage ride-through stage when the grid connection point voltage is lower than a preset low voltage ride-through control threshold and a three-phase grounding fault occurs, so that the inverter outputs current based on a first active current and a first reactive current, wherein the first active current and the first reactive current are determined based on a preset maximum allowable current of the inverter during the low voltage ride-through period and a preset power factor. When the grid connection point voltage exceeds a preset recovery threshold, the present invention enters a recovery stage after the low voltage ride-through, so that the inverter outputs current based on a second active current and a second reactive current, wherein the second active current and the second reactive current smoothly transition in an exponential form, wherein the second reactive current is determined based on the reactive current at the moment of entering the recovery stage after the low voltage ride-through, a preset inverter steady-state reactive current setting value and an exponential parameter, and the second active current is determined based on the second reactive current and the maximum allowable current, thereby improving the voltage support effect on the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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 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:

[0037] Figure 1 This is a first flow chart of a power supply control coordination optimization method for transient voltage stability support according to an embodiment of the present invention;

[0038] Figure 2 It is a second flow chart of the power supply control coordination optimization method for transient voltage stability support according to an embodiment of the present invention;

[0039] Figure 3 is a third flow chart of a power supply control coordination optimization method for transient voltage stability support according to an embodiment of the present invention;

[0040] Figure 4 It is a schematic diagram of the control flow of an embodiment of the present invention;

[0041] Figure 5 Schematic diagram of control coordination optimization calculation according to an embodiment of the present invention;

[0042] Figure 6 This is a first structural block diagram of a power supply control coordination optimization device for transient voltage stability support according to an embodiment of the present invention;

[0043] Figure 7 It is a second structural block diagram of the power supply control coordination optimization device for transient voltage stability support according to an embodiment of the present invention;

[0044] Figure 8 This is a third structural block diagram of a power supply control coordination optimization device for transient voltage stability support according to an embodiment of the present invention;

[0045] Fig. 9 It is a schematic diagram of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0047] 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.

[0048] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatus.

[0049] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0050] The present invention proposes a coordinated optimization method for inverter-type power supply control for transient voltage stability support. For inverter-type power supplies, this method fully considers the influence of high resistance-to-reactance ratio characteristics of feeders and load dynamics on the transient voltage support capability of equipment, improves the transient control strategy under low voltage ride-through, fully utilizes the active and reactive voltage support capabilities of equipment, and can maximize the improvement of transient voltage recovery under power grid faults through coordinated optimization.

[0051] Figure 1 is a first flow chart of a power supply control coordination optimization method for transient voltage stability support according to an embodiment of the present invention, such as Figure 1 As shown, in one embodiment of the present invention, the power supply control coordination optimization method for transient voltage stability support of the present invention includes step S101 and step S102.

[0052] Step S101, when the grid connection point voltage is lower than the preset low voltage ride-through control threshold and a three-phase ground fault occurs, the low voltage ride-through stage is entered, at which time the inverter is switched to transient voltage support control, so that the inverter outputs current based on a first active current and a first reactive current, wherein the first active current and the first reactive current are determined based on a preset maximum allowable current of the inverter during the low voltage ride-through period and a preset power factor.

[0053] The transient voltage support capability of distributed new energy equipment is mainly related to the maximum allowable current and the dynamic active and reactive current distribution during low voltage ride-through. In order to tap the transient voltage support potential, it is assumed that the inverter can continuously operate at the maximum allowable current I during low voltage ride-through. max When the output power of the equipment is not limited, the active current reference value I d,ref and reactive current reference value I q,ref Calculated as:

[0054] I d,ref =I max ×cosθ DVS ,I q,ref =I max ×sinθ DVS

[0055] In the formula, θ DVS is the power factor angle of the inverter for transient voltage support; cosθ DVS The power factor setting value PF for the inverter to support transient voltageDVS At this time, the inverter transient active power and reactive power output are calculated as follows:

[0056] P DR (t) = V PCC (t)×I max ×cosθ DVS

[0057] Q DR (t) = V PCC (t)×I max ×sinθ DVS

[0058] Where V PCC (t) is the instantaneous voltage amplitude at the inverter grid connection point at time t.

[0059] During the fault transient period, the inverter has three operating states: normal steady state, low voltage ride-through stage, and recovery stage after low voltage ride-through. Figure 4 As shown in Figure 1, after a fault disturbance occurs, the output result of the fault identification module can be used as the activation condition of the proposed control strategy, which is only for symmetrical three-phase grounding faults. When the control system detects that the grid voltage is lower than the low voltage ride-through control threshold V LVRT,in , and when a three-phase grounding fault occurs, the inverter switches to the transient voltage support control mode and sets the flag Flag = 1. DVS , the dynamic active and reactive current outputs are PF DVS ×I max and

[0060] In one embodiment of the present invention, the formulas for the first active current and the first reactive current are:

[0061] I d,ref =PF DVS ×I max

[0062]

[0063] Among them, I d,ref is the first active current, I q,ref is the first reactive current, I max is the maximum allowable current of the inverter during low voltage ride-through, PF DVS is the power factor.

[0064] In one embodiment of the present invention, the power factor is obtained by iterative calculation, specifically, by iterative calculation through the calculation process of step S201 and step S202, and step S301 and step S302.

[0065] Step S102, when the grid connection point voltage exceeds a preset recovery threshold, entering the recovery stage after low voltage ride-through, at this time, the inverter is switched to the recovery control after low voltage ride-through, so that the inverter outputs current based on the second active current and the second reactive current, wherein the second active current and the second reactive current smoothly transition in an exponential form, the second reactive current is determined according to the reactive current at the moment of entering the recovery stage after low voltage ride-through, the preset inverter steady-state reactive current setting value and the exponential parameter, and the second active current is determined according to the second reactive current and the maximum allowable current.

[0066] In the present invention, when the transient grid-connected point voltage recovers and exceeds the recovery threshold V LVRT,out When , the inverter switches to recovery control after low voltage ride-through, corresponding to the transition process between smooth transient voltage support control and steady-state control, the current reference value is set as follows:

[0067]

[0068] Where t0 is the moment when the inverter enters recovery control. is the reactive current at t0, I q,0 is the inverter steady-state reactive current setting value. The active and reactive currents transition smoothly in an exponential form under the maximum allowable current limit. a is an exponential parameter that determines the reactive transition rate.

[0069] In one embodiment of the present invention, the formula for the second active current is: q,R (t), the formula of the second reactive current is d,R (t).

[0070] In one embodiment of the present invention, the low voltage ride-through control threshold V LVRT,in and the recovery threshold V LVRT,out Set to 0.9pu and 0.95pu respectively.

[0071] In one embodiment of the present invention, the power supply control coordination optimization method for transient voltage stability support of the present invention further includes:

[0072] When the inverter performs recovery control after low voltage ride-through, the inverter outputs active current based on the second active current and the maximum active current limit, wherein the maximum active current limit is determined based on the maximum allowable active power, the instantaneous voltage amplitude of the inverter grid-connected point, and the maximum allowable current.

[0073] During transient recovery, the present invention takes into account that the active current may be subject to the maximum allowable active power P max Therefore, the maximum active current limit Id,max :

[0074]

[0075] Maximum active current limit I d,max To obtain the maximum allowable current I of the inverter during low voltage ride-through max and The smaller of max is the maximum allowable active power, V PCC (t) is the instantaneous voltage amplitude at the inverter grid connection point.

[0076] In one embodiment of the present invention, the power supply control coordination optimization method for transient voltage stability support of the present invention further includes:

[0077] When the inverter performs transient voltage support control, when the active power reaches the maximum active output limit, the inverter switches from current output based on the first active current and the first reactive current to current output based on a third active current and a third reactive current, wherein the third active current is determined based on the maximum allowable active power and the instantaneous voltage amplitude of the inverter grid-connected point, and the third reactive current is determined based on the third active current and the maximum allowable current.

[0078] The present invention takes into account that during low voltage ride-through, under the proposed power factor control, the active power of the inverter gradually increases as the grid connection point voltage recovers. When the active power reaches the maximum active output limit, the constant power factor control cannot be maintained. Thereafter, in order to make full use of the remaining capacity of the equipment, the control will maximize the reactive current output under the limit of the maximum allowable current and improve the voltage support capability, which is calculated as follows:

[0079]

[0080] In one embodiment of the present invention, the third active current I d The specific formula of (t) is:

[0081]

[0082] The third reactive current I q The specific formula of (t) is:

[0083]

[0084] Figure 2 is a second flow chart of the power supply control coordination optimization method for transient voltage stability support according to an embodiment of the present invention, such as Figure 2As shown, in one embodiment of the present invention, the power supply control coordination optimization method for transient voltage stability support of the present invention further includes step S201 and step S202.

[0085] Step S201, obtaining a mathematical form of a preset coordinated optimization problem, wherein the optimization goal of the mathematical form of the coordinated optimization problem is to minimize a transient voltage safety index, and the optimization parameters of the mathematical form of the coordinated optimization problem include: system state variables, system control variables, and power factors of transient voltage support control, and the transient voltage safety index is the maximum value of the time integral of the voltage deviation of each node in the system.

[0086] Step S202, based on the mathematical form of the coordinated optimization problem, a power factor of transient voltage support control is solved by combining simulation calculation with numerical optimization.

[0087] like Figure 5 As shown, the power factor setting for transient voltage support control needs to comprehensively consider multiple factors such as the dynamic characteristics, power size, and spatial distribution of each load node in the power grid. Therefore, the present invention introduces a solution algorithm based on the combination of simulation calculation and numerical optimization, and proposes an inverter-type power supply control coordinated optimization method that maximizes the transient voltage support of the system. The mathematical form of the coordinated optimization problem is as follows:

[0088]

[0089] 0 = g s (u,x,PF)

[0090] PF∈Ω PF

[0091] Where x is the system state variable, including node voltage, induction motor rotor speed, distributed renewable energy power, etc.; u is the system control variable, including LVRT control, current inner loop control, etc.; PF is the power factor setting value of the transient voltage support control (CPF) proposed by each distributed renewable energy, that is, the optimization decision variable; Ω PF is the feasible interval of power factor, which is set to [0, 1] in the present invention; STVI is the quantitative index of transient voltage safety of the system; C is the expected fault set of the upper main grid connected to the distribution network of interest. Facing the most serious expected fault in the system, the optimization goal is to minimize the transient voltage safety index under the corresponding planned working conditions. Function f s and g s It is a high-dimensional DAE that describes the system of interest, determines the dynamic process of the system after the fault disturbance, and can be numerically simulated by dynamic modeling. Based on the voltage trajectory of each node in the distribution network during the fault transient period, the transient voltage safety quantitative index STVI of the present invention is defined as follows:

[0092]

[0093] Where ΔV i,c (t) is the transient voltage deviation value of the ith node at time t under the expected fault c of the distribution network; I is the set of all nodes in the distribution network. According to the voltage stability guidelines of the power system and the requirements for the LVRT capability of the equipment, the present invention sets the voltage upper and lower limits Set to [0.9pu, 1.1pu]. Since the distribution network is generally radial, the voltage trajectory of each node under fault has a certain similarity. The maximum value of the voltage deviation integral among all nodes is selected to represent the overall transient voltage safety level. In order to focus on the voltage support capacity of distributed renewable energy during transient recovery, the time integral of the indicator calculation is set to the time from the fault clearing time t clear When the voltage first recovers to Time t in the range end .

[0094] It can be seen that STVI is based on the voltage trajectory of each node in the distribution network under the expected fault, and measures the maximum value of the voltage deviation through time integration. The time integration starts from the fault clearing time t clear When the voltage first recovers to the set range [0.9pu, 1.1pu], t end .

[0095] Figure 3 is a third flow chart of the power supply control coordination optimization method for transient voltage stability support according to an embodiment of the present invention, such as Figure 3 As shown, in one embodiment of the present invention, the above-mentioned step S202 is based on the mathematical form of the coordinated optimization problem, and solves the power factor of transient voltage support control by combining simulation calculation with numerical optimization, which specifically includes step S301 and step S302.

[0096] Step S301, using time domain simulation to obtain the node voltage trajectory under the complex dynamics of the system, and by adjusting the system control variables of each distributed new energy device, calculating the trajectory sensitivity of each system control variable with respect to the transient voltage safety index.

[0097] Step S302, perform iterative calculation. In each iterative calculation, the index value of the transient voltage safety quantification index and the trajectory sensitivity result are passed into the numerical optimization algorithm to update the power factor of the transient voltage support control of each device. When the calculation result meets the requirements of the iterative constraint, the power factor used to maximize the system transient voltage support is output.

[0098] In the initialization of the coordinated optimization calculation of inverter-type power supply control, it is necessary to build and adjust the corresponding system dynamic model based on the planned scenarios of different operating periods. Then, in order to solve the problem that the high-dimensional DAEs of the system are difficult to analyze and calculate, the coordinated optimization problem of large-scale distributed new energy control is decomposed and solved iteratively through numerical optimization and simulation calculation. Among them, time domain simulation is used to obtain the node voltage trajectory under the complex dynamics of the system, based on the quantitative transient voltage safety index. By adjusting the transient control parameters of each distributed new energy device, the trajectory sensitivity of each parameter with respect to the STVI index is calculated. In each iteration, the function objective value and the trajectory sensitivity result are passed into the corresponding numerical optimization algorithm to update the power factor set value of the transient voltage support control of each device. In order to improve the efficiency of iterative calculation, the synchronous disturbance stochastic approximation algorithm is used in numerical optimization. Finally, when the calculation results meet the requirements of the iteration constraints, the control pre-decision for maximizing the transient voltage support of the system is output, and the control command is issued to each device during the corresponding operating period of the day.

[0099] The present invention calculates the power factor for maximizing the transient voltage support of the system through the above-mentioned iterative calculation, and then performs transient voltage support control based on the power factor, thereby improving the support capacity of the power grid.

[0100] It can be seen from the above embodiments that the power supply control coordination optimization method for transient voltage stability support of the present invention achieves at least the following beneficial effects:

[0101] 1. The method of the present invention proposes a coordinated optimization method for inverter-type power supply control for transient voltage stability support. The transient control strategy based on constant power factor can effectively tap the active and reactive voltage support capabilities of the equipment during transient periods.

[0102] 2. The present invention takes into account the high resistance-to-reactance ratio characteristics and spatial distribution characteristics of the power grid feeder, and can effectively ensure the transient voltage safety of the system by coordinating and optimizing the control of massive inverter-type power supplies.

[0103] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0104] Based on the same inventive concept, an embodiment of the present invention further provides a power supply control coordination optimization device for transient voltage stability support, which can be used to implement the power supply control coordination optimization method for transient voltage stability support described in the above embodiment, as described in the following embodiment. Since the principle of solving the problem by the power supply control coordination optimization device for transient voltage stability support is similar to that of the power supply control coordination optimization method for transient voltage stability support, the embodiment of the power supply control coordination optimization device for transient voltage stability support can refer to the embodiment of the power supply control coordination optimization method for transient voltage stability support, and the repeated parts will not be repeated. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0105] Figure 6 is a first structural block diagram of a power supply control coordination optimization device for transient voltage stability support according to an embodiment of the present invention, such as Figure 6 As shown, in one embodiment of the present invention, the power supply control coordination optimization device for transient voltage stability support of the present invention includes:

[0106] A transient voltage support control unit 1, used for entering a low voltage ride-through stage when the grid connection point voltage is lower than a preset low voltage ride-through control threshold and a three-phase ground fault occurs, at which time the inverter is switched to transient voltage support control, so that the inverter outputs current based on a first active current and a first reactive current, wherein the first active current and the first reactive current are determined according to a preset maximum allowable current of the inverter during the low voltage ride-through period and a preset power factor;

[0107] The recovery control unit 2 after low voltage ride-through is used to enter the recovery stage after low voltage ride-through when the grid connection point voltage exceeds a preset recovery threshold value. At this time, the inverter is switched to the recovery control after low voltage ride-through, so that the inverter outputs current based on the second active current and the second reactive current, wherein the second active current and the second reactive current smoothly transition in an exponential form, the second reactive current is determined according to the reactive current at the moment of entering the recovery stage after low voltage ride-through, the preset inverter steady-state reactive current setting value and the exponential parameter, and the second active current is determined according to the second reactive current and the maximum allowable current.

[0108] In one embodiment of the present invention, the power supply control coordination optimization device for transient voltage stability support of the present invention further includes:

[0109] The maximum active current limiting unit is used to enable the inverter to output active current based on the second active current and the maximum active current limit when the inverter performs recovery control after low voltage ride-through, wherein the maximum active current limit is determined based on the maximum allowable active power, the instantaneous voltage amplitude of the inverter grid-connected point and the maximum allowable current.

[0110] In one embodiment of the present invention, the power supply control coordination optimization device for transient voltage stability support of the present invention further includes:

[0111] A maximized reactive current output control unit is used to switch the inverter from current output based on the first active current and the first reactive current to current output based on a third active current and a third reactive current when the active power reaches the maximum active output limit during transient voltage support control of the inverter, wherein the third active current is determined based on the maximum allowable active power and the instantaneous voltage amplitude of the inverter grid-connected point, and the third reactive current is determined based on the third active current and the maximum allowable current.

[0112] Figure 7 is a second structural block diagram of a power supply control coordination optimization device for transient voltage stability support according to an embodiment of the present invention, such as Figure 7 As shown, in one embodiment of the present invention, the power supply control coordination optimization device for transient voltage stability support of the present invention further includes:

[0113] A mathematical form acquisition unit 3 of a coordinated optimization problem is used to acquire a preset mathematical form of a coordinated optimization problem, wherein the optimization target of the mathematical form of the coordinated optimization problem is to minimize a transient voltage safety index, and the optimization parameters of the mathematical form of the coordinated optimization problem include: system state variables, system control variables, and a power factor of transient voltage support control, and the transient voltage safety index is the maximum value of the time integral of the voltage deviation of each node in the system;

[0114] The solving and calculating unit 4 is used to solve the power factor of the transient voltage support control by combining simulation calculation with numerical optimization based on the mathematical form of the coordinated optimization problem.

[0115] like Figure 8 As shown, in one embodiment of the present invention, the solution calculation unit 4 of the present invention includes:

[0116] The trajectory sensitivity determination module 401 is used to obtain the node voltage trajectory under the complex dynamics of the system by using time domain simulation, and calculate the trajectory sensitivity of each system control variable with respect to the transient voltage safety index by adjusting the system control variables of each distributed new energy device;

[0117] The iterative calculation module 402 is used to perform iterative calculations. In each iterative calculation, the index value of the transient voltage safety quantification index and the trajectory sensitivity result are passed into the numerical optimization algorithm to update the power factor of the transient voltage support control of each device. When the calculation result meets the requirements of the iterative constraints, the power factor used to maximize the system transient voltage support is output.

[0118] In order to achieve the above object, according to another aspect of the present application, a computer device is also provided. Fig. 9 As shown, the computer device includes a memory, a processor, a communication interface and a communication bus. A computer program that can be executed on the processor is stored in the memory. When the processor executes the computer program, the steps in the above-mentioned embodiment method are implemented.

[0119] The processor may be a central processing unit (CPU). The processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or a combination of the above chips.

[0120] The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer executable programs and units, such as the corresponding program units in the above method embodiments of the present invention. The processor executes various functional applications of the processor and works data processing by running the non-transitory software programs, instructions and modules stored in the memory, that is, implementing the method in the above method embodiments.

[0121] The memory may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created by the processor, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0122] The one or more units are stored in the memory, and when executed by the processor, the method in the above embodiment is performed.

[0123] The specific details of the above-mentioned computer device can be understood by referring to the corresponding related descriptions and effects in the above-mentioned embodiments, and will not be repeated here.

[0124] In order to achieve the above purpose, according to another aspect of the present application, a computer-readable storage medium is also provided, wherein the computer-readable storage medium stores a computer program, and the computer program implements the steps in the power supply control coordination optimization method for transient voltage stability support when executed in a computer processor. Those skilled in the art can understand that the implementation of all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and the program can include the processes of the embodiments of the above-mentioned methods when executed. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory (Flash Memory), a hard disk (Hard Disk Drive, abbreviated: HDD) or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above-mentioned types of memory.

[0125] In order to achieve the above-mentioned purpose, according to another aspect of the present application, a computer program product is also provided, including a computer program / instruction, which, when executed by a processor, implements the steps of the above-mentioned power supply control coordination optimization method for transient voltage stability support.

[0126] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A power supply control coordination optimization method for transient voltage stability support, characterized in that: include: When the grid connection point voltage is lower than the preset low voltage ride-through control threshold and a three-phase ground fault occurs, the low voltage ride-through stage is entered, at which time the inverter is switched to transient voltage support control, so that the inverter outputs current based on a first active current and a first reactive current, wherein the first active current and the first reactive current are determined according to a preset maximum allowable current of the inverter during the low voltage ride-through period and a preset power factor; When the grid connection point voltage exceeds a preset recovery threshold, it enters the recovery stage after low voltage ride-through. At this time, the inverter is switched to the recovery control after low voltage ride-through, so that the inverter outputs current based on the second active current and the second reactive current, wherein the second active current and the second reactive current smoothly transition in an exponential form, the second reactive current is determined according to the reactive current at the moment of entering the recovery stage after low voltage ride-through, a preset inverter steady-state reactive current setting value and an exponential parameter, and the second active current is determined according to the second reactive current and the maximum allowable current.

2. The power supply control coordination optimization method for transient voltage stability support according to claim 1 is characterized in that: Also includes: When the inverter performs recovery control after low voltage ride-through, the inverter outputs active current based on the second active current and the maximum active current limit, wherein the maximum active current limit is determined based on the maximum allowable active power, the instantaneous voltage amplitude of the inverter grid-connected point, and the maximum allowable current.

3. The power supply control coordination optimization method for transient voltage stability support according to claim 1 is characterized in that: Also includes: When the inverter performs transient voltage support control, when the active power reaches the maximum active output limit, the inverter switches from current output based on the first active current and the first reactive current to current output based on a third active current and a third reactive current, wherein the third active current is determined based on the maximum allowable active power and the instantaneous voltage amplitude of the inverter grid-connected point, and the third reactive current is determined based on the third active current and the maximum allowable current.

4. The power supply control coordination optimization method for transient voltage stability support according to claim 1, characterized in that: Also includes: Obtaining a preset mathematical form of a coordinated optimization problem, wherein the optimization objective of the mathematical form of the coordinated optimization problem is to minimize a transient voltage safety index, and the optimization parameters of the mathematical form of the coordinated optimization problem include: system state variables, system control variables, and a power factor of transient voltage support control, and the transient voltage safety index is the maximum value of the time integral of the voltage deviation of each node in the system; Based on the mathematical form of the coordinated optimization problem, the power factor of transient voltage support control is solved by combining simulation calculation with numerical optimization.

5. The power supply control coordination optimization method for transient voltage stability support according to claim 4 is characterized in that: The mathematical form of the coordinated optimization problem is used to solve the power factor of transient voltage support control by combining simulation calculation with numerical optimization, including: Time domain simulation is used to obtain node voltage trajectories under complex dynamic conditions of the system. By adjusting the system control variables of each distributed new energy device, the trajectory sensitivity of each system control variable with respect to the transient voltage safety index is calculated. Iterative calculations are performed. In each iterative calculation, the index value of the transient voltage safety quantification index and the trajectory sensitivity result are passed into the numerical optimization algorithm to update the power factor of the transient voltage support control of each device. When the calculation result meets the requirements of the iterative constraints, the power factor used to maximize the system transient voltage support is output.

6. A power supply control coordination optimization device for transient voltage stability support, characterized in that: include: A transient voltage support control unit, used for entering a low voltage ride-through stage when the grid connection point voltage is lower than a preset low voltage ride-through control threshold and a three-phase grounding fault occurs, at which time the inverter is switched to transient voltage support control, so that the inverter outputs current based on a first active current and a first reactive current, wherein the first active current and the first reactive current are determined according to a preset maximum allowable current of the inverter during the low voltage ride-through period and a preset power factor; A recovery control unit after low voltage ride-through is used to enter the recovery stage after low voltage ride-through when the grid connection point voltage exceeds a preset recovery threshold value. At this time, the inverter is switched to recovery control after low voltage ride-through, so that the inverter outputs current based on the second active current and the second reactive current, wherein the second active current and the second reactive current smoothly transition in an exponential form, the second reactive current is determined based on the reactive current at the moment of entering the recovery stage after low voltage ride-through, a preset inverter steady-state reactive current setting value and an exponential parameter, and the second active current is determined based on the second reactive current and the maximum allowable current.

7. The power supply control coordination optimization device for transient voltage stability support according to claim 6, characterized in that: Also includes: The maximum active current limiting unit is used to enable the inverter to output active current based on the second active current and the maximum active current limit when the inverter performs recovery control after low voltage ride-through, wherein the maximum active current limit is determined based on the maximum allowable active power, the instantaneous voltage amplitude of the inverter grid-connected point and the maximum allowable current.

8. The power supply control coordination optimization device for transient voltage stability support according to claim 6, characterized in that: Also includes: A maximized reactive current output control unit is used to switch the inverter from current output based on the first active current and the first reactive current to current output based on a third active current and a third reactive current when the active power reaches the maximum active output limit during transient voltage support control of the inverter, wherein the third active current is determined based on the maximum allowable active power and the instantaneous voltage amplitude of the inverter grid-connected point, and the third reactive current is determined based on the third active current and the maximum allowable current.

9. The power supply control coordination optimization device for transient voltage stability support according to claim 6, characterized in that: Also includes: A mathematical form acquisition unit for a coordinated optimization problem, used for acquiring a preset mathematical form of a coordinated optimization problem, wherein the optimization target of the mathematical form of the coordinated optimization problem is to minimize a transient voltage safety index, and the optimization parameters of the mathematical form of the coordinated optimization problem include: system state variables, system control variables, and a power factor of transient voltage support control, and the transient voltage safety index is the maximum value of the time integral of the voltage deviation of each node in the system; The solving calculation unit is used to solve the power factor of transient voltage support control by combining simulation calculation with numerical optimization based on the mathematical form of the coordinated optimization problem.

10. The power supply control coordination optimization device for transient voltage stability support according to claim 9, characterized in that: The solution calculation unit comprises: The trajectory sensitivity determination module is used to obtain the node voltage trajectory under the complex dynamics of the system by time domain simulation, and calculate the trajectory sensitivity of each system control variable with respect to the transient voltage safety index by adjusting the system control variables of each distributed new energy device; The iterative calculation module is used to perform iterative calculations. In each iterative calculation, the index value of the transient voltage safety quantification index and the trajectory sensitivity result are passed into the numerical optimization algorithm to update the power factor of the transient voltage support control of each device. When the calculation result meets the requirements of the iterative constraints, the power factor used to maximize the system transient voltage support is output.

11. A computer 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 / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

13. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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