Operation control method, apparatus and device for multiple grid-forming converters, and storage medium

Abstract

The present application relates to the field of power electronics. Disclosed are an operation control method, apparatus and device for multiple grid-forming converters, and a storage medium, which are used for improving the control efficiency. The method comprises: constructing a multi-grid-forming-converter simulation system having a steady-state operating point, wherein the multi-grid-forming-converter simulation system is controlled on the basis of a virtual synchronous generator; on the basis of a first simulated operating condition, determining a virtual synchronous generator control category for each grid-forming converter in the multi-grid-forming-converter simulation system; on the basis of a second simulated operating condition, determining accumulated acceleration energy and accumulated deceleration energy for each grid-forming converter in the multi-grid-forming-converter simulation system; and controlling multiple grid-forming converters on the basis of the accumulated acceleration energy, the accumulated deceleration energy and the virtual synchronous generator control category that correspond to each grid-forming converter.

Description

Operation control method, device, equipment and storage medium of multi-network type converter

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 22, 2023, with application number 202311789266.4 and invention name “Operation control method, device, equipment and storage medium of multi-configuration grid-type converter”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of power electronics, and in particular to a method, device, equipment and storage medium for controlling the operation of a multi-grid converter. Background Art

[0003] Grid-connected converters simulate synchronous generators to achieve grid connection. By simulating the swing equations and output characteristics of synchronous generators, they can independently provide inertia support and grid voltage support. They are the primary method for stabilizing the power grid system when a high proportion of renewable energy is connected to the grid. However, grid-connected converters have synchronization characteristics similar to synchronous generators. Therefore, under fault interference, they may experience transient instability similar to synchronous generators.

[0004] In existing technologies, the operating capacity of a converter is often improved by adjusting the control parameters of a single converter. However, due to the interactive influence of parameters of multiple grid-type converters in a power grid system, only considering the operating capacity of a single grid-type converter results in poor control effect and low control efficiency.

[0005] Summary of the Invention

[0006] The main purpose of this application is to provide a multi-grid type converter operation control method, device, equipment and storage medium, which are used to solve the problem of low operating efficiency of a single control grid type converter and improve control efficiency.

[0007] The first aspect of the present application provides an operation control method for a multi-grid converter, including: constructing a multi-grid converter simulation system with a steady-state operating point, wherein the multi-grid converter simulation system is based on virtual synchronous machine control; determining the virtual synchronous machine control category of each grid-type converter in the multi-grid converter simulation system according to a first simulation working condition; determining the cumulative acceleration energy and cumulative deceleration energy of each grid-type converter in the multi-grid converter simulation system according to a second simulation working condition; and controlling the multi-grid converter according to the cumulative acceleration energy, cumulative deceleration energy and virtual synchronous machine control category corresponding to each grid-type converter.

[0008] The second aspect of the present application provides an operation control device for a multi-grid converter, including: a construction module for constructing a multi-grid converter simulation system with a steady-state operating point, wherein the multi-grid converter simulation system is based on virtual synchronous machine control; a first determination module for determining the virtual synchronous machine control category of each grid-type converter in the multi-grid converter simulation system according to a first simulation working condition; a second determination module for determining the cumulative acceleration energy and cumulative deceleration energy of each grid-type converter in the multi-grid converter simulation system according to a second simulation working condition; and a control module for controlling the multi-grid converter according to the cumulative acceleration energy, cumulative deceleration energy and virtual synchronous machine control category corresponding to each grid-type converter.

[0009] The third aspect of the present application provides an operation control device of a multi-configuration grid-type converter, comprising: a memory and at least one processor, wherein the memory stores instructions; the at least one processor calls the instructions in the memory so that the operation control device of the multi-configuration grid-type converter executes the above-mentioned operation control method of the multi-configuration grid-type converter.

[0010] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions, which, when executed on a computer, enable the computer to execute the above-mentioned operation control method of the multi-grid converter.

[0011] In the technical solution provided in the present application, a multi-grid converter simulation system with a steady-state operating point is constructed. The multi-grid converter simulation system is based on virtual synchronous machine control. The virtual synchronous machine control category of each grid-type converter in the multi-grid converter simulation system is determined according to a first simulation working condition. The cumulative acceleration energy and cumulative deceleration energy of each grid-type converter in the multi-grid converter simulation system are determined according to a second simulation working condition. The multi-grid converter is controlled according to the cumulative acceleration energy, cumulative deceleration energy and virtual synchronous machine control category corresponding to each grid-type converter. The present application constructs a multi-grid converter simulation system with a steady-state operating point, and classifies the grid converters in the simulation system in advance to facilitate subsequent classified control of multiple grid converters and improve control accuracy. The cumulative acceleration energy and cumulative deceleration energy of each grid converter are calculated separately. The cumulative acceleration energy and cumulative deceleration energy can be used to determine whether the operating capacity of the grid converter matches the multi-grid converter simulation system. Multiple grid converters are controlled according to the cumulative acceleration energy and cumulative deceleration energy of each grid converter and the virtual synchronous machine control category. Multiple grid converters can be controlled simultaneously and accurately, thereby improving control efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG1 is a schematic diagram of an embodiment of a method for controlling the operation of a multi-grid converter according to an embodiment of the present application;

[0013] FIG2 is a schematic diagram of another embodiment of an operation control method of a multi-grid converter according to an embodiment of the present application;

[0014] FIG3 is a schematic diagram of the topological structure of a multi-network converter simulation system according to an embodiment of the present application;

[0015] FIG4 is a schematic diagram of a simulation control signal in an embodiment of the present application;

[0016] FIG5 is a schematic diagram of an embodiment of an operation control device for a multi-grid converter according to an embodiment of the present application;

[0017] FIG6 is a schematic diagram of an embodiment of an operation control device of a multi-grid converter in an embodiment of the present application. DETAILED DESCRIPTION

[0018] The embodiments of the present application provide an operation control method, apparatus, device and storage medium for a multi-grid converter, which are used to improve control efficiency.

[0019] The terms "first," "second," "third," "fourth," and the like (if any) in the specification and claims of this application and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" or "having" and any variations thereof 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 explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] For ease of understanding, the specific process of the embodiment of the present application is described below. It can be understood that the execution subject of the present application can be an operation control device of a multi-network converter, or a terminal, which is not specifically limited here.

[0021] Referring to FIG1 , an embodiment of an operation control method of a multi-grid converter according to an embodiment of the present application includes:

[0022] 101. Construct a multi-grid converter simulation system with a steady-state operating point. The multi-grid converter simulation system is based on virtual synchronous machine control.

[0023] Since the grid-type converter has synchronization characteristics similar to those of synchronous generators, during the process of new energy grid connection, the interaction between multiple grid-type converters will cause abnormal transient stability problems in the grid-type converter under fault interference. Transient stability refers to the ability of the grid-type converter to operate and transition to a new steady state or restore the original steady-state operation mode after the power system suffers severe interference. Severe disturbances generally refer to short-circuit faults, sudden changes in load capacity, and the removal of transmission or substation equipment. Therefore, it is necessary to build a simulation system containing multiple grid-type converters, and judge the operation status of the grid-type converter based on the simulation results of the simulation system, and then make targeted adjustments.

[0024] The simulation system can be built based on the grid-connected system of the actual scenario. In order to reduce the interference data generated by the later simulation, it is necessary to build a system with a steady-state operating point under a small interference state, that is, a simulation system with a steady-state operating point.

[0025] A simulation system having a steady-state operating point and based on virtual synchronous machine control is determined to be a multi-grid converter simulation system, and the multi-grid converter simulation system includes multiple grid converters.

[0026] 102. Determine a virtual synchronous machine control category of each grid-type converter in the multi-grid-type converter simulation system according to the first simulation operating condition.

[0027] Since the multi-grid converter simulation system is controlled based on virtual synchronous machine technology, a virtual speed-time curve will be generated when simulating the electromagnetic transient operating characteristics of the multi-grid converter simulation system under preset fault interference. The virtual speed-time curve can map the swing characteristics of the traditional motor.

[0028] Therefore, the simulation results of the electromagnetic transient operating characteristics of the multi-grid converter simulation system under the preset fault interference are determined as the first simulation working condition. According to the first simulation working condition, the grid-type converters in the multi-grid converter simulation system are classified to obtain the virtual synchronous machine control category corresponding to each grid-type converter. The virtual synchronous machine control category is a virtual forward swing category or a virtual reverse swing category. Specifically, the virtual speed change rate corresponding to each grid-type converter is calculated based on the virtual speed time curve of each grid-type converter. The virtual synchronous machine control category corresponding to the grid-type converter with a virtual speed change rate greater than 0 is determined as the virtual forward swing category, and the virtual synchronous machine control category corresponding to the grid-type converter with a virtual speed change rate less than 0 is determined as the virtual reverse swing category.

[0029] 103. Determine the accumulated acceleration energy and accumulated deceleration energy of each grid-type converter in the multi-grid-type converter simulation system according to the second simulation working condition.

[0030] The simulation results of the multi-grid converter simulation system under the alternating introduction and removal of preset fault interference are determined as the second simulation working condition. The cumulative acceleration energy of each grid converter in the process of introducing the preset fault interference and the cumulative deceleration energy in the process of clearing the preset fault interference are calculated according to the second simulation working condition. The acceleration energy refers to the energy generated in the process of introducing the preset fault interference, and the deceleration energy refers to the energy generated in the process of clearing the preset fault interference. The energy is the integral of the difference between the electromagnetic power and the mechanical power of the grid converter over a certain period of time, and is a quantitative indicator reflecting whether the converter can operate stably.

[0031] 104. Control the multi-grid converter according to the accumulated acceleration energy, accumulated deceleration energy, and virtual synchronous machine control type corresponding to each grid converter.

[0032] If the accumulated acceleration energy of the grid-type converter is less than or equal to the accumulated deceleration energy, it is determined that the grid-type converter is in good operating condition; if the accumulated acceleration energy of the grid-type converter is greater than the accumulated deceleration energy, it is determined that the grid-type converter is at risk of instability.

[0033] When it is determined that there is a grid-type converter with an instability risk in the multi-grid-type converter simulation system, the grid-type converter with the instability risk is selected from the multi-grid-type converter simulation system, and the parameters of the grid-type converter with the instability risk are adjusted according to the virtual synchronous machine control category until a new second simulation operating condition indicates that there is no grid-type converter in the multi-grid-type converter simulation system whose cumulative acceleration energy is greater than the cumulative deceleration energy.

[0034] When it is determined that no grid-type converter in the multi-grid-type converter simulation system has an instability risk, no control operation is performed on the grid-type converter in the multi-grid-type converter simulation system.

[0035] In an embodiment of the present application, a multi-grid converter simulation system with a steady-state operating point is constructed, and the grid converters in the simulation system are classified in advance to facilitate subsequent classified control of multiple grid converters and improve control accuracy. The cumulative acceleration energy and cumulative deceleration energy of each grid converter are calculated separately when a fault is introduced and a fault is cleared. The cumulative acceleration energy and cumulative deceleration energy can be used to determine whether the operating capacity of the grid converter matches the multi-grid converter simulation system. Multiple grid converters are controlled according to the cumulative acceleration energy and cumulative deceleration energy of each grid converter and the virtual synchronous machine control category. Multiple grid converters can be controlled simultaneously and accurately, thereby improving control efficiency.

[0036] Referring to FIG. 2 , another embodiment of the multi-grid converter operation control method in the present application includes:

[0037] 201. Construct an initial simulation system, which includes a grid connection point and multiple parallel circuits.

[0038] Construct an initial simulation system. The initial simulation system can be built based on the grid-connected system in the actual scenario. The initial simulation system is based on virtual synchronous machine control. The topology of the initial simulation system is shown in Figure 3. The initial simulation system includes a grid-connected point and multiple parallel loops. Each parallel loop includes a grid-connected converter, a local load, and a line impedance. Multiple parallel loops are connected to the grid-connected point through a busbar.

[0039] 202. Obtain an actual short-circuit ratio and a minimum short-circuit ratio of the initial simulation system.

[0040] In order to reduce the interference data generated by the later simulation, the short-circuit ratio is used to detect whether the initial simulation system has a steady-state operating point. A large actual short-circuit ratio means that the input and switching of the equipment have little impact on the system, and the system has a steady-state operating point. A small actual short-circuit ratio means that the input and switching of the equipment have a large impact on the system, and the system does not have a steady-state operating point. The size of the actual short-circuit ratio is bounded by the minimum short-circuit ratio.

[0041] Specifically, the impedance value of the line impedance in each parallel loop in the initial simulation system is determined, the product of the impedance values ​​of all parallel loops and the sum of the impedance values ​​of all parallel loops are calculated, and the quotient of the impedance product and the impedance sum is determined as the actual short-circuit ratio. The calculation formula is as follows:

[0042] Among them, SCR is the actual short-circuit ratio, i is the number of the grid-type converter, n is the number of the grid-type converter, X Ti is the impedance value of the i-th loop.

[0043] Determine the power of each local load, the voltage of the grid-connected converter, and the voltage of the grid connection point in the initial simulation system. Calculate the minimum short-circuit ratio based on the power of each local load, the voltage of the grid-connected converter, and the voltage of the grid connection point. The specific calculation formula is as follows:

[0044] Among them, SCR min is the minimum short-circuit ratio, i is the number of the grid-type converter, n is the number of the grid-type converter, P Li is the power of the local load on the i-th line, V0 is the voltage of the grid-type converter, V g is the voltage of the grid connection point.

[0045] 203. When the actual short-circuit ratio is greater than the minimum short-circuit ratio, the initial simulation system is determined to be a multi-grid converter simulation system with a steady-state operating point.

[0046] When the actual short-circuit ratio is greater than the minimum short-circuit ratio, it is determined that the initial simulation system has a steady-state operating point, and the initial simulation system is determined to be a multi-grid converter simulation system with a steady-state operating point.

[0047] 204. When the actual short circuit ratio is less than or equal to the minimum short circuit ratio, update the number of parallel loops in the initial simulation system until the actual short circuit ratio of the updated initial simulation system is greater than the minimum short circuit ratio.

[0048] When the actual short-circuit ratio is less than or equal to the minimum short-circuit ratio, it is determined that the initial simulation system does not have a steady-state operating point, and a parallel loop in the initial simulation system is reduced. After the initial simulation system is updated, a new actual short-circuit ratio and a new minimum short-circuit ratio are obtained based on the updated initial simulation system. The new actual short-circuit ratio and the new minimum short-circuit ratio are continued to be compared. If the new actual short-circuit ratio is less than or equal to the new minimum short-circuit ratio, another parallel loop in the initial simulation system is reduced, and this process is repeated until the actual short-circuit ratio of the updated initial simulation system is greater than the minimum short-circuit ratio.

[0049] Furthermore, when the actual short-circuit ratio is less than or equal to the minimum short-circuit ratio, it is determined that the initial simulation system does not have a steady-state operating point, and the short-circuit ratio difference between the minimum short-circuit ratio and the actual short-circuit ratio is calculated. When the short-circuit ratio difference is greater than the threshold, it is determined that two parallel loops will be reduced when the initial simulation system is updated next time. When the short-circuit ratio difference is less than or equal to the threshold, it is determined that one parallel loop will be reduced when the initial simulation system is updated next time. After the initial simulation system is updated, a new actual short-circuit ratio and a new minimum short-circuit ratio are obtained based on the updated initial simulation system, and the new actual short-circuit ratio and the new minimum short-circuit ratio are continued to be compared, and this process is repeated until the actual short-circuit ratio of the updated initial simulation system is greater than the minimum short-circuit ratio.

[0050] 205. The updated initial simulation system is determined to be a multi-grid converter simulation system with a steady-state operating point.

[0051] When the actual short-circuit ratio in the updated initial simulation system is greater than the minimum short-circuit ratio, the updated initial simulation system is determined as a multi-grid converter simulation system with a steady-state operating point, reducing the interference caused by the simulation system itself and improving the accuracy of subsequent simulation result data.

[0052] 206. Determine a virtual synchronous machine control category of each grid-type converter in the multi-grid-type converter simulation system according to the first simulation operating condition.

[0053] The multi-grid converter simulation system is operated under preset fault interference to obtain multiple virtual speed time curves. The multiple virtual speed time curves correspond one-to-one to multiple grid converters in the multi-grid converter simulation system. Optionally, the preset fault is a three-phase short circuit fault at the grid connection point.

[0054] The virtual speed change rate of each virtual speed time curve is calculated to obtain multiple virtual speed change rates. These virtual speed change rates correspond one-to-one to multiple grid-type converters, i.e., each grid-type converter corresponds to a virtual speed change rate. Considering the oscillation characteristics of grid-type converters simulating synchronous machines, grid-type converters with virtual speed change rates greater than 0 are assigned a virtual forward swing control category, while those with virtual speed change rates less than 0 are assigned a virtual reverse swing control category.

[0055] 207. Generate a simulation control signal, where the simulation control signal is used to introduce a three-phase short circuit fault at the grid connection point at the beginning of each cycle and to clear the three-phase short circuit fault at the grid connection point at the midpoint of each cycle.

[0056] The simulation control signal is a pulse signal. One of the two adjacent pulses is used to introduce a three-phase short-circuit fault at the grid connection point into the multi-grid converter simulation system, and the other is used to clear the three-phase short-circuit fault at the grid connection point for the multi-grid converter simulation system. The first pulse of the simulation control signal is used to introduce a three-phase short-circuit fault at the grid connection point. The time period between the two adjacent pulses for introducing the three-phase short-circuit fault is one cycle. As shown in Figure 4, S1 is a pulse signal for introducing a three-phase short-circuit fault at the grid connection point, S2 is a pulse signal for clearing the three-phase short-circuit fault at the grid connection point, and T is one cycle.

[0057] 208. Control the multi-grid converter simulation system to run a preset number of cycles through a simulation control signal to obtain multiple simulation results.

[0058] The multi-grid converter simulation system is controlled by a simulation control signal to run a preset number of cycles to obtain multiple simulation results. The preset number is a positive integer greater than 1, and each simulation result is the energy change result of a grid converter within the preset number of cycles.

[0059] 209. Determine the accumulated acceleration energy and accumulated deceleration energy of each grid-type converter simulator based on multiple simulation results.

[0060] Determine the mechanical power and electromagnetic power of each meshed converter in the multi-mesh converter simulation system, determine the difference between the mechanical power and the electromagnetic power as a first power difference, and calculate the cumulative acceleration energy of each meshed converter within a preset number of cycles based on the first power difference. The calculation formula is as follows:

[0061] in, is the accumulated acceleration energy, t is the serial number of the operation cycle, N is the preset number of cycles, P m is the mechanical power of the converter, Pe is the electromagnetic power of the converter, δ t0 is the starting time of the tth operation cycle, δ t1 is the end time of the tth operation cycle.

[0062] The difference between the electromagnetic power and the mechanical power is determined as a second power difference. Based on the second power difference, the cumulative deceleration energy of each grid-type converter within a preset number of cycles is calculated using the following formula:

[0063] in, is the accumulated deceleration energy, t is the serial number of the operation cycle, N is the preset number of cycles, P m is the mechanical power of the converter, P e is the electromagnetic power of the converter, δ t0 is the starting time of the tth operation cycle, δ t1 is the end time of the tth operation cycle.

[0064] 210. Control the multi-grid converter according to the accumulated acceleration energy, accumulated deceleration energy and virtual synchronous machine control type corresponding to each grid converter.

[0065] The specific control method is as follows: (1) The grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy and corresponds to the virtual forward swing type is determined as the first type of converter; the grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy and corresponds to the virtual reverse swing type is determined as the second type of converter.

[0066] (2) Increasing the virtual inertia constant of each meshed converter in the first type converter and reducing the virtual inertia constant of each meshed converter in the second type converter to obtain an updated multi-mesh converter simulation system.

[0067] Each time, the virtual inertia constant of each meshed converter in the first converter set is increased by a preset value, and each time, the virtual inertia constant of each meshed converter in the second converter set is decreased by a preset value. Because the value of the virtual inertia constant is within a preset range, when a meshed converter with a virtual inertia constant increasing to a maximum value within the preset range or decreasing to a minimum value within the preset range occurs, the meshed converter with a virtual inertia constant increasing to a maximum value within the preset range or decreasing to a minimum value within the preset range is marked, and in subsequent parameter adjustments, the marked meshed converter is no longer adjusted.

[0068] Furthermore, the energy difference of each meshed converter in the first converter set and the second converter set is calculated. The energy difference is the difference between the accumulated acceleration energy and the accumulated deceleration energy. The larger the energy difference, the greater the adjustment of the virtual inertia constant of the meshed converter.

[0069] For example, the increase in the virtual inertia constant of the grid-type converters in the first converter set is calculated according to the following formula: T j =K×L×X j

[0070] Among them, T j is the increase in the virtual inertia constant of the jth grid-type converter in the first converter set, K is the adjustment coefficient, L is the range of the virtual inertia constant, and the range is the difference between the maximum and minimum values ​​in the range, X j is the energy difference corresponding to the j-th grid-type converter in the first converter set.

[0071] Set k to 0.01, N to 5, when the cumulative acceleration energy of the j-th grid-type converter in the first converter set is 50, and the cumulative deceleration energy is 20, X j Equal to 30, T j =1.5; when the cumulative acceleration energy of the jth grid-type converter in the first converter set is 60 and the cumulative deceleration energy is 20, X j Equal to 40, T j Equal to 2.

[0072] The above formula is also applicable to calculating the reduction value of the virtual inertia constant of the grid-type converters in the second converter set. The calculation method is similar and will not be repeated here.

[0073] It should be noted that the grid-type converters whose cumulative acceleration energy is greater than the cumulative deceleration energy may all be first-type converters or all be second-type converters, and the first converter set or the second converter set may be an empty set. If the first converter set or the second converter set may be an empty set, no operation will be performed on the empty set.

[0074] (3) The virtual inertia constants of each grid-type converter are updated according to the simulation results of the updated multi-grid-type converter simulation system until there is no grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy in the updated multi-grid-type converter simulation system.

[0075] When the simulation results of the updated multi-grid converter simulation system indicate that there is a grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy, the virtual inertia constant corresponding to the grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy is adjusted; when the simulation results of the updated multi-grid converter simulation system indicate that there is no grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy, the multi-grid converter simulation system is refreshed with the virtual inertia constants of the current grid-type converters.

[0076] In an embodiment of the present application, a multi-grid converter simulation system with a steady-state operating point is constructed based on the short-circuit ratio to reduce interference data generated by the simulation system itself during simulation, and the grid converters in the simulation system are classified. The cumulative acceleration energy and cumulative deceleration energy of the grid converter are calculated respectively when a fault is introduced and cleared. When the cumulative acceleration energy of the grid converter is greater than the cumulative deceleration energy of the converter, it is determined that the operating capability of the grid converter does not match the multi-grid converter simulation system, and the converters with cumulative acceleration energy greater than cumulative deceleration energy are screened out. According to the grid converter categories corresponding to the screened converters, the virtual inertia constants of multiple converters are adjusted simultaneously to increase the inertia of the simulation system as soon as possible and improve the control efficiency.

[0077] Referring to FIG5 , another embodiment of the multi-grid converter operation control device in the embodiment of the present application includes:

[0078] A construction module 501 is used to construct a multi-grid converter simulation system with a steady-state operating point, wherein the multi-grid converter simulation system is based on virtual synchronous machine control;

[0079] A first determining module 502 is configured to determine a virtual synchronous machine control type of each grid-type converter in the multi-grid-type converter simulation system according to a first simulation operating condition;

[0080] A second determining module 503 is configured to determine the accumulated acceleration energy and accumulated deceleration energy of each grid-type converter in the multi-grid-type converter simulation system according to the second simulation operating condition;

[0081] The control module 504 is configured to control the multi-grid converter according to the accumulated acceleration energy, accumulated deceleration energy, and virtual synchronous machine control type corresponding to each grid converter.

[0082] Optionally, building block 501 includes:

[0083] A construction unit 5011 is configured to construct an initial simulation system, wherein the initial simulation system includes a grid connection point and multiple parallel loops, each of which includes a grid-connected converter, a local load, and a line impedance;

[0084] A first calculation unit 5012 is configured to obtain an actual short-circuit ratio and a minimum short-circuit ratio of the initial simulation system;

[0085] A first determining unit 5013 is configured to determine, when the actual short-circuit ratio is greater than the minimum short-circuit ratio, the initial simulation system as a multi-grid converter simulation system having a steady-state operating point;

[0086] an updating unit 5014, configured to update the number of parallel loops in the initial simulation system when the actual short circuit ratio is less than or equal to the minimum short circuit ratio, until the actual short circuit ratio of the updated initial simulation system is greater than the minimum short circuit ratio;

[0087] The second determining unit 5015 is configured to determine the updated initial simulation system as a multi-grid converter simulation system having a steady-state operating point.

[0088] Optionally, the calculation unit 5012 is specifically configured to:

[0089] Determine the impedance value of the line in each parallel circuit in the initial simulation system; obtain the product of the impedance values ​​of all the parallel circuits and the sum of the impedance values ​​of all the parallel circuits, and determine the quotient of the product of the impedances and the sum of the impedances as the actual short-circuit ratio; determine the power of each local load, the voltage of the grid-type converter and the voltage of the grid connection point in the initial simulation system; determine the minimum short-circuit ratio based on the power of each local load, the voltage of the grid-type converter and the voltage of the grid connection point.

[0090] Optionally, the first determining module 502 is specifically configured to:

[0091] The multi-grid converter simulation system is operated under a preset fault interference to obtain multiple virtual speed time curves, and the multiple virtual speed time curves correspond one-to-one to the multiple grid converters in the multi-grid converter simulation system; the virtual speed change rate of each virtual speed time curve is obtained to obtain multiple virtual speed change rates, and the multiple virtual speed change rates correspond one-to-one to the multiple grid converters; the virtual synchronous machine control category corresponding to the grid converter with a virtual speed change rate greater than 0 is determined as a virtual forward swing category; the virtual synchronous machine control category corresponding to the grid converter with a virtual speed change rate less than 0 is determined as a virtual reverse swing category.

[0092] Optionally, the second determining module 503 includes:

[0093] A generating unit 5031 is configured to generate a simulation control signal, wherein the simulation control signal is used to introduce a three-phase short circuit fault at the grid connection point at the beginning of each cycle and to clear the three-phase short circuit fault at the grid connection point at the midpoint of each cycle;

[0094] A control unit 5032 is configured to control the multi-grid converter simulation system to run a preset number of cycles through the simulation control signal to obtain a plurality of simulation results, wherein the plurality of simulation results correspond one-to-one to the plurality of grid converters;

[0095] The third determining unit 5033 is configured to determine the accumulated acceleration energy and accumulated deceleration energy of each grid-connected converter according to the plurality of simulation results.

[0096] Optionally, the third determining unit 5033 is specifically configured to:

[0097] Determine the mechanical power and electromagnetic power of each meshed converter in the multi-mesh converter simulation system; determine the difference between the mechanical power and the electromagnetic power as a first power difference; calculate the cumulative acceleration energy of each meshed converter within a preset number of cycles based on the first power difference; determine the difference between the electromagnetic power and the mechanical power as a second power difference; and calculate the cumulative deceleration energy of each meshed converter within a preset number of cycles based on the second power difference.

[0098] Optionally, the control module 504 is specifically configured to:

[0099] A grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy and whose virtual synchronous machine control category is a virtual forward swing type is determined as a first type of converter; a grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy and whose virtual synchronous machine control category is a virtual reverse swing type is determined as a second type of converter; the virtual inertia constant of each grid-type converter in the first type of converter is increased, and the virtual inertia constant of each grid-type converter in the second type of converter is reduced to obtain an updated multi-grid-type converter simulation system; the virtual inertia constant of each grid-type converter is updated according to the simulation results of the updated multi-grid-type converter simulation system until there is no grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy in the updated multi-grid-type converter simulation system.

[0100] In an embodiment of the present application, a multi-grid converter simulation system with a steady-state operating point is constructed based on the short-circuit ratio to reduce interference data generated by the simulation system itself during simulation, and the grid converters in the simulation system are classified. The cumulative acceleration energy and cumulative deceleration energy of the grid converter are calculated respectively when a fault is introduced and cleared. When the cumulative acceleration energy of the grid converter is greater than the cumulative deceleration energy of the converter, it is determined that the operating capability of the grid converter does not match the multi-grid converter simulation system, and the converters with cumulative acceleration energy greater than cumulative deceleration energy are screened out. According to the grid converter categories corresponding to the screened converters, the virtual inertia constants of multiple converters are adjusted simultaneously to increase the inertia of the simulation system as soon as possible and improve the control efficiency.

[0101] As shown in Figure 6, the operation control device of the multi-configuration grid-type converter includes a processor 600 and a memory 601. The memory 601 stores machine executable instructions that can be executed by the processor 600. The processor 600 executes the machine executable instructions to implement the above-mentioned operation control method of the multi-configuration grid-type converter.

[0102] Furthermore, the operation control device of the multi-grid converter shown in FIG6 further includes a bus 602 and a communication interface 603 , and the processor 600 , the communication interface 603 and the memory 601 are connected via the bus 602 .

[0103] Memory 601 may include high-speed random access memory (RAM) and may also include non-volatile memory (non-volatile memory), such as at least one disk storage device. Communication between the system network element and at least one other network element is achieved through at least one communication interface 603 (which may be wired or wireless), and may utilize the Internet, a wide area network, a local area network, a metropolitan area network, etc. Bus 602 may be an ISA bus, a PCI bus, or an EISA bus. The bus may be classified as an address bus, a data bus, a control bus, etc. For ease of illustration, FIG6 shows only one bidirectional arrow, but this does not imply that there is only one bus or only one type of bus.

[0104] The processor 600 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by hardware integrated logic circuits or software instructions in the processor 600. The above processor 600 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present disclosure. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in conjunction with the embodiments of the present disclosure can be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the memory 601 , and the processor 600 reads the information in the memory 601 and completes the method steps of the aforementioned embodiment in combination with its hardware.

[0105] The present application also provides a computer-readable storage medium, which may be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are executed on a computer, the computer executes the steps of the multi-grid converter operation control method, which specifically include:

[0106] A multi-grid converter simulation system with a steady-state operating point is constructed, and the multi-grid converter simulation system is based on virtual synchronous machine control; the virtual synchronous machine control category of each grid-type converter in the multi-grid converter simulation system is determined according to a first simulation condition, and the virtual synchronous machine control category is a virtual forward swing type or a virtual reverse swing type. The first simulation condition is a simulation result of the multi-grid converter simulation system under a preset fault interference; the cumulative acceleration energy and the cumulative deceleration energy of each grid-type converter in the multi-grid converter simulation system are calculated according to a second simulation condition, and the second simulation condition is a simulation result of the multi-grid converter simulation system under alternately introducing a preset fault interference and clearing the preset fault interference; the multi-grid converter is controlled according to the cumulative acceleration energy, cumulative deceleration energy and virtual synchronous machine control category corresponding to each grid-type converter. In an embodiment of the present application, a multi-grid converter simulation system with a steady-state operating point is constructed, and the grid converters in the simulation system are classified in advance to facilitate subsequent classified control of multiple grid converters and improve control accuracy. The cumulative acceleration energy and cumulative deceleration energy of each grid converter are calculated separately when a fault is introduced and a fault is cleared. The cumulative acceleration energy and cumulative deceleration energy can be used to determine whether the operating capacity of the grid converter matches the multi-grid converter simulation system. Multiple grid converters are controlled according to the cumulative acceleration energy and cumulative deceleration energy of each grid converter and the virtual synchronous machine control category. Multiple grid converters can be controlled simultaneously and accurately, thereby improving control efficiency.

[0107] The above-mentioned construction of a multi-grid converter simulation system with a steady-state operating point includes: constructing an initial simulation system, the initial simulation system includes a grid connection point and multiple parallel loops, each parallel loop includes a grid converter, a local load and a line impedance; calculating the actual short-circuit ratio and the minimum short-circuit ratio of the initial simulation system; when the actual short-circuit ratio is greater than the minimum short-circuit ratio, determining the initial simulation system as a multi-grid converter simulation system with a steady-state operating point; when the actual short-circuit ratio is less than or equal to the minimum short-circuit ratio, updating the number of parallel loops in the initial simulation system until the actual short-circuit ratio of the updated initial simulation system is greater than the minimum short-circuit ratio; determining the updated initial simulation system as a multi-grid converter simulation system with a steady-state operating point.

[0108] The above calculation of the actual short-circuit ratio and the minimum short-circuit ratio of the initial simulation system includes: determining the impedance value of the line impedance in each parallel circuit in the initial simulation system; calculating the product of the impedance values ​​of all parallel circuits and the sum of the impedance values ​​of all parallel circuits, and determining the quotient of the impedance product and the impedance sum as the actual short-circuit ratio; determining the power of each local load, the voltage of the grid-type converter and the voltage of the grid connection point in the initial simulation system; and calculating the minimum short-circuit ratio based on the power of each local load, the voltage of the grid-type converter and the voltage of the grid connection point.

[0109] The above-mentioned method of determining the virtual synchronous machine control category of each grid-type converter in the multi-grid-type converter simulation system according to the first simulation working condition includes: operating the multi-grid-type converter simulation system under a preset fault interference to obtain multiple virtual speed time curves, the multiple virtual speed time curves correspond one-to-one to the multiple grid-type converters in the multi-grid-type converter simulation system, and the preset fault is a three-phase short circuit fault at the grid connection point; calculating the virtual speed change rate of each virtual speed time curve to obtain multiple virtual speed change rates, the multiple virtual speed change rates correspond one-to-one to the multiple grid-type converters; determining the virtual synchronous machine control category corresponding to the grid-type converter with a virtual speed change rate greater than 0 as a virtual forward swing category; determining the virtual synchronous machine control category corresponding to the grid-type converter with a virtual speed change rate less than 0 as a virtual reverse swing category.

[0110] The above-mentioned calculation of the cumulative acceleration energy and cumulative deceleration energy of each grid-type converter in the multi-grid-type converter simulation system according to the second simulation working condition includes: generating a simulation control signal, the simulation control signal is used to introduce a three-phase short-circuit fault at the grid connection point at the beginning of each cycle and clear the three-phase short-circuit fault at the grid connection point at the midpoint of each cycle; controlling the multi-grid-type converter simulation system to run a preset number of cycles through the simulation control signal to obtain multiple simulation results, and the multiple simulation results correspond one-to-one to the multiple grid-type converters; and calculating the cumulative acceleration energy and cumulative deceleration energy of each grid-type converter based on the multiple simulation results.

[0111] The above-mentioned calculation of the cumulative acceleration energy and the cumulative deceleration energy of each meshed converter based on multiple simulation results includes: determining the mechanical power and electromagnetic power of each meshed converter in the multi-mesh converter simulation system; determining the difference between the mechanical power and the electromagnetic power as a first power difference; calculating the cumulative acceleration energy of each meshed converter within a preset number of cycles based on the first power difference; determining the difference between the electromagnetic power and the mechanical power as a second power difference; and calculating the cumulative deceleration energy of each meshed converter within a preset number of cycles based on the second power difference.

[0112] The above-mentioned control of the multi-grid converter according to the cumulative acceleration energy, cumulative deceleration energy and virtual synchronous machine control category corresponding to each grid converter includes: determining the grid converter whose cumulative acceleration energy is greater than the cumulative deceleration energy and corresponds to the virtual forward swing type as the first type of converter; determining the grid converter whose cumulative acceleration energy is greater than the cumulative deceleration energy and corresponds to the virtual reverse swing type as the second type of converter; increasing the virtual inertia constant of each grid converter in the first type of converter, and reducing the virtual inertia constant of each grid converter in the second type of converter to obtain an updated multi-grid converter simulation system; updating the virtual inertia constant of each grid converter according to the simulation results of the updated multi-grid converter simulation system until there is no grid converter whose cumulative acceleration energy is greater than the cumulative deceleration energy in the updated multi-grid converter simulation system.

[0113] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0114] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0115] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling the operation of a multi-grid converter, characterized in that: The operation control method of the multi-grid converter comprises: Constructing a multi-grid converter simulation system with a steady-state operating point, wherein the multi-grid converter simulation system is based on virtual synchronous machine control; Determining a virtual synchronous machine control category of each grid-type converter in the multi-grid-type converter simulation system according to the first simulation condition; Determine the accumulated acceleration energy and accumulated deceleration energy of each grid-type converter in the multi-grid-type converter simulation system according to the second simulation working condition; The multi-grid converter is controlled according to the accumulated acceleration energy, accumulated deceleration energy and virtual synchronous machine control category corresponding to each grid converter.

2. The operation control method of the multi-grid converter according to claim 1, characterized in that: The multi-grid converter simulation system with a steady-state operating point is constructed, comprising: Constructing an initial simulation system, wherein the initial simulation system includes a grid connection point and a plurality of parallel loops, each of the parallel loops including a grid-connected converter, a local load and a line impedance; Obtaining an actual short-circuit ratio and a minimum short-circuit ratio of the initial simulation system; When the actual short-circuit ratio is greater than the minimum short-circuit ratio, determining the initial simulation system as a multi-grid converter simulation system with a steady-state operating point; When the actual short circuit ratio is less than or equal to the minimum short circuit ratio, updating the number of parallel loops in the initial simulation system until the actual short circuit ratio of the updated initial simulation system is greater than the minimum short circuit ratio; The updated initial simulation system is determined as a multi-grid converter simulation system with a steady-state operating point.

3. The operation control method of the multi-grid converter according to claim 2, characterized in that: The obtaining of the actual short circuit ratio and the minimum short circuit ratio of the initial simulation system comprises: Determining the impedance value of the line in each parallel loop in the initial simulation system; Obtaining the product of the impedance values ​​of all the parallel loops and the sum of the impedance values ​​of all the parallel loops, and determining the quotient of the product of the impedances and the sum of the impedances as the actual short-circuit ratio; Determining the power of each local load in the initial simulation system, the voltage of the grid-connected converter and the voltage of the grid connection point; The minimum short-circuit ratio is determined according to the power of each local load, the voltage of the grid-connected converter and the voltage of the grid connection point.

4. The operation control method of the multi-grid converter according to claim 1, characterized in that: The step of determining the virtual synchronous machine control category of each grid-type converter in the multi-grid-type converter simulation system according to the first simulation working condition includes: Running the multi-grid converter simulation system under a preset fault disturbance to obtain a plurality of virtual speed time curves, wherein the plurality of virtual speed time curves correspond one-to-one to a plurality of grid converters in the multi-grid converter simulation system; Acquire a virtual speed change rate of each virtual speed time curve to obtain a plurality of virtual speed change rates, wherein the plurality of virtual speed change rates correspond one to one to the plurality of grid-type converters; The virtual synchronous machine control category corresponding to the grid-type converter whose virtual speed change rate is greater than 0 is determined as a virtual positive swing category; The virtual synchronous machine control category corresponding to the grid-type converter whose virtual speed change rate is less than 0 is determined as the virtual reverse swing category.

5. The operation control method of the multi-grid converter according to claim 1, characterized in that: The step of determining the accumulated acceleration energy and accumulated deceleration energy of each grid-type converter in the multi-grid-type converter simulation system according to the second simulation working condition includes: Generate a simulation control signal, wherein the simulation control signal is used to introduce a three-phase short circuit fault at the grid connection point at the beginning of each cycle and clear the three-phase short circuit fault at the grid connection point at the midpoint of each cycle; Controlling the multi-grid-type converter simulation system to run a preset number of cycles through the simulation control signal to obtain a plurality of simulation results, wherein the plurality of simulation results correspond one-to-one to the plurality of grid-type converters; The accumulated acceleration energy and accumulated deceleration energy of each grid-connected converter are determined according to the multiple simulation results.

6. The operation control method of the multi-grid converter according to claim 5, characterized in that: The step of determining the accumulated acceleration energy and accumulated deceleration energy of each grid-connected converter according to the plurality of simulation results comprises: Determining the mechanical power and electromagnetic power of each grid-type converter in the multi-grid-type converter simulation system; determining the difference between the mechanical power and the electromagnetic power as a first power difference value; Calculating the accumulated acceleration energy of each grid-connected converter within a preset number of cycles based on the first power difference; determining the difference between the electromagnetic power and the mechanical power as a second power difference value; The accumulated deceleration energy of each grid-connected converter within a preset number of cycles is calculated based on the second power difference.

7. The operation control method of a multi-grid converter according to any one of claims 1 to 6, characterized in that: The controlling of the multi-grid-type converter according to the accumulated acceleration energy, accumulated deceleration energy and virtual synchronous machine control category corresponding to each grid-type converter includes: The grid-forming converter whose accumulated acceleration energy is greater than the accumulated deceleration energy and whose virtual synchronous machine control category is the virtual forward swing category is determined as the first category converter; The grid-connected converter whose accumulated acceleration energy is greater than the accumulated deceleration energy and whose virtual synchronous machine control category is the virtual reverse swing category is determined as the second category converter; Increasing the virtual inertia constant of each grid-type converter in the first type of converter, and reducing the virtual inertia constant of each grid-type converter in the second type of converter, to obtain an updated multi-grid-type converter simulation system; The virtual inertia constant of each grid-type converter is updated according to the simulation results of the updated multi-grid-type converter simulation system until there is no grid-type converter whose cumulative acceleration energy is greater than the cumulative deceleration energy in the updated multi-grid-type converter simulation system.

8. An operation control device for a multi-grid type converter, characterized in that: The operation control device of the multi-grid converter comprises: A construction module for constructing a multi-grid converter simulation system with a steady-state operating point, wherein the multi-grid converter simulation system is based on virtual synchronous machine control; A first determination module is used to determine the virtual synchronous machine control category of each grid-type converter in the multi-grid-type converter simulation system according to a first simulation condition; A second determination module is used to determine the accumulated acceleration energy and accumulated deceleration energy of each grid-type converter in the multi-grid-type converter simulation system according to the second simulation condition; The control module is used to control the multi-grid converter according to the accumulated acceleration energy, accumulated deceleration energy and virtual synchronous machine control category corresponding to each grid converter.

9. An operation control device for a multi-grid type converter, characterized in that: The operation control device of the multi-grid converter comprises: a memory and at least one processor, wherein the memory stores instructions; The at least one processor calls the instructions in the memory so that the operation control device of the multi-configuration grid-type converter executes the operation control method of the multi-configuration grid-type converter as described in any one of claims 1-7.

10. A computer-readable storage medium having instructions stored thereon, characterized in that: When the instruction is executed by the processor, the operation control method of the multi-grid converter as described in any one of claims 1 to 7 is implemented.

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