Virtual synchronous machine control method and system based on virtual power plant cluster inertia cooperation

Abstract

The present application belongs to the field of new energy grid-connected power generation control technology, and particularly relates to a virtual synchronous machine control method and system based on virtual power plant cluster inertia cooperation. The system performs global operation and parameter distribution by a virtual power plant control platform, and performs local high-speed virtual synchronous machine closed loop by an inverter. The platform collects grid rated angular velocity, rated apparent power of each inverter, real-time power, total active power and total reactive power scheduling instructions, calculates total rated apparent power, total virtual inertia and total damping, iteratively updates virtual angular velocity and generates global unified synchronous power angle, and distributes active power, reactive power, inertia and damping four-way parameters according to rated capacity proportion and issues them at a first preset period. The inverter takes the unified power angle as the initial phase, independently completes the virtual synchronous machine closed loop at a second preset period, synthesizes three-phase reference voltage and generates driving pulses by space vector pulse width modulation, and realizes multi-VSG inertia sharing and unified synchronization, thereby improving grid stability.

Description

Technical Field

[0001] This invention belongs to the field of new energy grid-connected power generation control technology, specifically relating to a virtual synchronous machine control method and system based on virtual power plant cluster inertia coordination. Background Technology

[0002] With the continuous and rapid growth of new energy power generation systems such as wind power, photovoltaics, and electrochemical energy storage, the proportion of new energy power generation equipment in the power system has also increased. This has led to the power grid exhibiting characteristics of low inertia, weak damping, and high power electronics, making it prone to power oscillations, voltage and frequency instability. Currently, new energy grid-connected systems all use Virtual Synchronous Generator (VSG) technology to control inverters to overcome the shortcomings of low inertia and weak damping of power electronic equipment and improve the robustness of the power grid system. However, a single virtual synchronous generator has small inertia and weak damping, resulting in insufficient support capacity under grid faults; multiple virtual synchronous generators operating independently are prone to power angle loss of synchronization, uneven power distribution, large circulating current, and group generator oscillations. Currently, traditional virtual power plants only achieve power dispatch, without unified coordinated control of inertia, damping, and synchronization phase, lacking closed-loop linkage with the underlying inverters, and exhibiting poor adaptability to weak grids.

[0003] In the prior art, there are control schemes for the parallel operation of multiple virtual synchronous machines. For example, Chinese Patent No. CN118739335A discloses a distributed adaptive virtual inertia calculation method for the parallel operation of multiple virtual synchronous machines. This method uses a distributed control architecture and calculates additional inertia terms through information interaction between adjacent virtual synchronous machines to suppress frequency oscillations. Chinese Patent No. CN119518979A discloses a power allocation method for multiple virtual synchronous generators operating in parallel. This method uses a small-signal model of VSG parallel operation to predict and control dynamic response to achieve power allocation. Although the above schemes have achieved optimization of grid inertia and damping and improvement of grid system stability to a certain extent, they all rely on distributed communication or local information interaction between inverters. They lack global unified control at the virtual power plant level. Each virtual synchronous machine generates its own phase, lacking a unified synchronization reference. The inertia of each machine changes independently or is only tuned through offline models. It is impossible to achieve real-time unified and coordinated configuration of inertia and damping at the virtual power plant level, making it difficult to fundamentally solve the problems of multi-machine power angle loss of synchronization and group machine oscillation. In addition, traditional single virtual synchronous machines (VSGs) are limited by single-machine capacity and hardware performance, and have weak inertia support and damping adjustment capabilities. They are prone to instability in weak grid environments with a high proportion of new energy grid connection. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a virtual synchronous machine control method and system based on virtual power plant cluster inertia coordination, which improves the phase synchronization of multiple VSGs in the virtual power plant cluster, enhances the frequency stability and anti-interference capability of the power grid with new energy power generation system access, reduces the probability of multiple VSGs being off-center or overloaded, extends the service life of equipment, and improves the stability and reliability of the entire system.

[0005] The technical solution adopted by this invention to solve this technical problem is: a virtual synchronous machine control method based on virtual power plant cluster inertia coordination, comprising the following steps: S1. Collect and calculate the real-time active power and real-time reactive power at the output terminals of each inverter; collect the rated angular velocity of the power grid, the actual angular velocity of the grid connection point when the virtual power plant cluster system is first powered on, the rated apparent power of each inverter, and the total active power target value and total reactive power target value of the virtual power plant cluster issued by the power grid dispatch center; calculate the total rated apparent power and measured total active power of the virtual power plant cluster. S2. Calculate the power grid frequency deviation, the formula for calculating the power grid frequency deviation is as follows: ; in, This represents the grid frequency deviation, and m represents the current loop iteration calculation order of the virtual power plant cluster system. m is a positive integer greater than or equal to 1. This refers to the virtual angular velocity generated by the power grid iteration in the previous calculation cycle, which is used by the platform during the m-th iteration. Indicates the rated angular velocity of the power grid; when the system is first powered on, , ; This represents the actual angular velocity when the power grid is connected to the grid; S3. Calculate the total virtual inertia and total virtual damping of the virtual power plant cluster based on the total rated apparent power and grid frequency deviation of the virtual power plant cluster. The total apparent power and grid frequency deviation are positively correlated with the total virtual inertia of the virtual power plant cluster, and the total apparent power and grid frequency deviation are positively correlated with the total virtual damping. S4. Substitute the total virtual inertia, total virtual damping, total active target value and measured total active power of the virtual power plant cluster into the virtual synchronous machine rotor motion equation to calculate the rate of change of angular velocity of the entire virtual power plant cluster. S5. Iterate the virtual angular velocity of the virtual power plant cluster in the current platform calculation period based on the first preset period and the rate of change of the angular velocity of the entire virtual power plant cluster. S6. Generate a global unified synchronous power angle based on the virtual angular velocity iterated in step S5. Use the global unified synchronous power angle as the initial phase angle reference for the local phase integration of all inverters every first preset period. S7. Calculate the active power, reactive power, unit inertia and unit damping allocated to each inverter according to the rated capacity ratio of each inverter, and allocate, update the allocation information of active power, reactive power, unit inertia and unit damping every first preset cycle and send it to the corresponding inverter. S8. Each inverter takes the global unified synchronous power angle as the initial phase and independently performs multiple second preset cycle virtual synchronous machine closed-loop iterative calculations and grid-connected control between the two receiving steps S6-S7 for the parameters; the first preset cycle is greater than the second preset cycle.

[0006] Furthermore, the formula for calculating the total virtual inertia of the virtual power plant cluster is as follows: ; in, This represents the total virtual inertia of the virtual power plant cluster. This represents the inertia support coefficient of the entire cluster under normal operating conditions. This represents the total rated apparent power of the virtual power plant cluster. The frequency-adaptive inertia coefficient represents the total virtual inertia of the virtual power plant cluster, 50≤ ≤200; The formula for calculating the total virtual damping of the virtual power plant cluster is as follows: ; in, This represents the total virtual damping of the virtual power plant cluster. This represents the basic oscillation suppression coefficient of the virtual power plant cluster. The frequency adaptive damping coefficient represents the total virtual damping of the virtual power plant cluster.

[0007] Furthermore, the formula for calculating the rate of change of angular velocity in step S4 is as follows: ; in, This represents the rate of change of the angular velocity of the entire virtual power plant cluster. This represents the total active power target value of the virtual power plant cluster. This represents the measured total active power of the virtual power plant cluster. This represents the total virtual damping of the virtual power plant cluster.

[0008] Furthermore, in step S5, the virtual angular velocity of the virtual power plant cluster during the current platform calculation period... Calculate using the following formula: ; in, Indicates the first preset period; The global unified synchronous power angle in step S6 is calculated using the following formula: ; in, For the current calculation cycle, the global unified synchronous power angle, This represents the cumulative phase value of the previous platform's calculation cycle; when the system is powered on for the first time, , .

[0009] Furthermore, the active power calculation formula for each inverter allocated to each inverter in step S7 is expressed as follows: ; in, This represents the target active power value allocated to the i-th inverter. This represents the total active power target value of the virtual power plant cluster. This represents the rated apparent power of the i-th inverter. This represents the total rated apparent power of the virtual power plant cluster; The reactive power calculation formula allocated to each inverter in step S7 is expressed as follows: ; in, This represents the target reactive power value allocated to the i-th inverter. This represents the total reactive power target value of the virtual power plant cluster; The formula for calculating the unit inertia allocated to each inverter in step S7 is expressed as follows: ; in, This represents the unit inertia allocated to the i-th inverter. This represents the total virtual inertia of the virtual power plant cluster; The formula for calculating the unit damping allocated to each inverter in step S7 is expressed as follows: ; in, This represents the unit damping allocated to the i-th inverter. This represents the total virtual inertia of the virtual power plant cluster.

[0010] Furthermore, the first preset period is 0.1s, and the second preset period is 0.0001s.

[0011] Furthermore, step S8 includes the following steps: S8.1 Each inverter substitutes its received active power, unit inertia, unit damping, and its own real-time output active power into the virtual synchronous machine rotor motion equation to calculate its actual rate of change of angular velocity. After integration, the voltage phase command is obtained. ; S8.2 Each inverter generates a voltage amplitude command based on the reactive power allocation command it receives and the real-time reactive power acquired locally. S8.3, Based on voltage amplitude command With voltage phase command The three-phase reference voltage is synthesized and then used by the inverter's own SVPWM module to generate IGBT drive pulses to drive the inverter switching transistors, thus completing the grid-connected control of the inverter. The execution cycle of steps S8.1 to S8.3 is the second preset cycle.

[0012] Furthermore, step S8.1 includes the following steps: S8.1-A, Calculate the rate of change of the angular velocity of the i-th inverter; ; in, This represents the rate of change of the angular velocity of the i-th inverter. This represents the active power allocated to the i-th inverter. This represents the real-time active power at the output of the i-th inverter. This represents the angular velocity state value of the i-th inverter during the k-th second preset cycle within the same first preset cycle; The rated angular velocity of the power grid; S8.1-B, Update the next second preset cycle The formula for calculating the angular velocity of the i-th inverter in the next second preset cycle is as follows: ; in, This indicates the angular velocity of the i-th inverter in the next second preset cycle. Indicates the duration of the second preset cycle; S8.1-C, Update the phase of the i-th inverter in the next second preset cycle; =

[0013] in, This indicates the phase of the i-th inverter in the next second preset cycle. Let be the phase of the i-th inverter within the current second preset cycle, and k be the order in which the inverter executes the second preset cycle within the same first preset cycle. k is a positive integer greater than or equal to 1. When k=1, This is the initial phase of the first preset period.

[0014] Furthermore, the voltage amplitude command in step S8.2 is calculated using the following formula: ; in, This indicates the voltage amplitude command for the i-th inverter. Indicates the rated phase voltage amplitude of the power grid. This represents the reactive power-voltage droop factor. This represents the target reactive power value allocated to the i-th inverter. This represents the actual reactive power of the i-th inverter.

[0015] A virtual synchronous machine control system for inertia coordination of a virtual power plant cluster includes multiple new energy power generation systems, each new energy power generation system including an inverter, and the new energy power generation system is connected to the AC power grid through the inverter; characterized in that: it further includes a data acquisition module and a virtual power plant group main control platform, the virtual power plant group main control platform being communicatively connected to the inverter and the data acquisition module respectively; The data acquisition module is used to acquire the real-time active power and real-time reactive power at the inverter output terminal in step S1. The virtual power plant group main control platform is used to execute steps S1-S7, and the inverter is used to execute step S8.

[0016] Furthermore, the virtual power plant group master control platform includes: The data preprocessing module has its input end communicatively connected to the output end of the data acquisition module; the data preprocessing module is used to receive the output data of the data acquisition module, calculate the total rated apparent power and the measured total active power of the virtual power plant cluster, and transmit the processed data to the inertia damping calculation module. The inertia damping calculation module is used to execute the above step S3 and send the output total virtual inertia and total virtual damping data to the angular velocity power angle iteration module; The angular velocity-power angle iteration module is used to execute steps S4-S6 and output the global unified synchronous power angle. To the inverter; The parameter allocation and distribution module is used to execute the above step S7 and transmit the obtained active power target value, reactive power target value, unit inertia and unit damping allocation to each inverter to the corresponding inverter. The cluster scheduling module is used to receive active and reactive power command information from the power grid and transmit the total active power target value and total reactive power target value of the virtual power plant cluster issued by the power grid dispatch center to the parameter allocation and distribution module.

[0017] Furthermore, the inverter is a distributed power inverter, and multiple distributed inverters are connected in parallel to the same power grid; the distributed power inverter includes a VSG closed-loop module and an SVPWM drive module, the input terminal of the VSG closed-loop module is communicatively connected to the output terminals of the angular velocity-power angle iteration module and the parameter allocation and distribution module, respectively, and the input terminal of the SVPWM drive module is communicatively connected to the output terminal of the VSG closed-loop module; The VSG closed-loop module is used to execute steps S8.1 to S8.2 and output the voltage amplitude command. With voltage phase command Output to the SVPWM driver module; The SVPWM drive module is used to synthesize a three-phase sinusoidal reference voltage based on voltage amplitude and voltage phase commands, and to generate IGBT switching drive pulses to control the operation of the inverter power circuit through space vector pulse width modulation technology.

[0018] Compared with existing technologies, this invention provides a virtual synchronous machine control method and system based on virtual power plant cluster inertia coordination. The beneficial effects of this invention include: 1. By setting up a virtual power plant cluster main control platform that communicates with multiple inverters and constructing a unified VSG rotor motion equation at the virtual power plant level within it, the total rated capacity and frequency deviation of the cluster are simultaneously incorporated into the quantitative calculation of inertia and damping through a combination of total capacity allocation and frequency adaptive method. This increases the total inertia of the cluster to the same order of magnitude as the total rated capacity, thereby making multiple distributed inverters equivalent to a large-capacity synchronous generator. This breaks through the capacity bottleneck of a single virtual synchronous machine, makes up for the inherent defects of low inertia and weak damping in the power grid, improves the frequency stability and anti-disturbance capability of the power grid, and provides core support for the safe grid connection of high proportion of new energy. 2. By generating a unified synchronous power angle across the entire virtual power plant cluster through the main control platform, an identical phase reference is provided for all inverter units within the cluster. This phase angle is refreshed with a first preset cycle. At the beginning of each refresh cycle, the local phase integrator of the inverter is inserted as the initial value for integration, so that all inverters in the cluster start from the same phase starting point. In the subsequent second preset cycle, the phase update depends entirely on the local rotor motion equation of the inverter to integrate on its own, no longer relying on platform communication. This eliminates the phase difference between each inverter from the root, and eliminates the phase difference of each unit's operating state from the source of the control logic, as well as the grid circulating current and low-frequency oscillation caused by the phase difference of multiple virtual synchronous machines. This ensures that the virtual power plant cluster can maintain the phase synchronization of each unit under normal operating conditions and after fault interruption recovery, and realizes the absolute synchronous grid connection of multiple new energy power generation units. 3. A distribution mechanism based on the rated apparent power ratio of each inverter is adopted to fairly allocate total active power, total reactive power, total inertia, and total damping to each virtual synchronous machine, ensuring balanced output of each synchronous machine within the cluster, eliminating off-center loads and overloads, and extending the service life of the inverters. Adaptive tuning of inertia and damping is performed using the cluster's rated apparent power as a base and frequency deviation as the driving force. When the grid frequency deviates from the rated value, the system automatically increases damping and inertia output, and automatically reverts when the frequency returns to normal. This ensures support strength during faults while avoiding excessive adjustment under normal operating conditions, preventing long-term overload operation of equipment, and extending the service life of the inverters and main grid equipment.

[0019] 4. A dual-cycle decoupled control architecture for the platform and inverter is adopted. The platform performs global calculations and parameter distribution in the first preset cycle, while the inverter independently completes local closed loop in the second preset cycle. The first preset cycle is much longer than the second preset cycle. The inverter can independently execute multiple high-speed closed loop cycles between two rounds of platform parameter distribution without real-time communication with the platform. This reduces the frequency of communication interaction and data traffic, reduces the requirements for bandwidth and hardware performance of the on-site communication network, realizes cluster collaborative control under low communication load, and saves engineering implementation costs. 5. The inverter independently completes closed-loop calculations in an ultra-high-speed cycle of 0.0001s, including the discrete update of the angular velocity / phase of the active-inertia-damping loop and the generation of the voltage amplitude of the reactive-voltage loop. The entire process does not rely on platform communication, enabling the inverter to have a microsecond-level dynamic response speed. It can make adjustment responses within milliseconds when the grid experiences frequency fluctuations, voltage drops, or load changes, thus breaking free from the limitations of communication delays. It can quickly and in real time smooth out power fluctuations, ensuring the control accuracy of output power and power quality. 6. Adopting a layered distributed architecture with upper-level master control and lower-level execution, the master control platform is responsible for global decision-making, while the inverters are responsible for local execution. Even under extreme conditions of short-term communication link interruption, each inverter can still maintain stable operation based on the last received parameter commands and its own high-speed closed-loop control, achieving uninterrupted power supply and grid connection under communication interruption and ensuring the reliability of power supply to critical loads. Simultaneously, the unified synchronization mechanism also enhances the system's ability to overcome grid faults, ensuring the uninterrupted operation of the virtual power plant during grid fluctuations. 7. During the system power-on initialization phase, the initial virtual angular velocity is directly assigned to the grid's rated angular velocity. Combined with a smooth iterative calculation closed loop, this eliminates the inrush current caused by the inconsistency between the traditional VSG and the grid frequency during startup. This enables the virtual power plant cluster to connect to the grid without disturbance, and to start up and switch smoothly. It minimizes the impact on the grid voltage and frequency at the point of common coupling, improves the grid-friendliness of the equipment, and complies with grid connection and dispatch standards. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the system topology of the present invention; Figure 2 This is a flowchart of the virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to the present invention; Figure 3 This is a flowchart of step S8 in this invention.

[0021] Figure descriptions: 1-Inverter; 11-VSG closed-loop module; 12-SVPWM drive module; 2-Data acquisition module; 3-Virtual power plant group main control platform; 31-Data preprocessing module; 32-Inertia damping calculation module; 33-Angular velocity and power angle iteration module; 34-Parameter allocation and distribution module; 35-Cluster scheduling module. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In the present invention... , , and All coefficients include comprehensive coefficients for dimensional conversion.

[0023] As attached Figure 1-3 As shown, a virtual synchronous machine control method based on virtual power plant cluster inertia coordination includes the following steps: S1. Collect and calculate the real-time active power at the output of each inverter. and real-time reactive power Collect the rated angular velocity of the power grid. Actual grid-connected angular velocity of the virtual power plant cluster system upon initial power-on Rated apparent power of each inverter The total active power target value of the virtual power plant cluster issued by the power grid dispatch center Total reactive power target value ; Calculate the total rated apparent power of the virtual power plant cluster and measured total active power ; The system typically includes voltage sensors for real-time monitoring of the three-phase voltage at the output terminals of each inverter, current sensors for real-time monitoring of the three-phase current at the output terminals of each inverter, and sensors for calculating the real-time active power of each inverter. and real-time reactive power The local controller, along with various voltage and current sensors, monitors the real-time three-phase voltages. , , and real time , , After the three-phase current data is transmitted to their respective local controllers, the local controllers obtain the dq-axis components in the synchronous rotating coordinate system through Clark and Park transformations. , , , Calculated according to instantaneous power theory , The real-time average power value is obtained after low-pass filtering. , This allows the virtual power plant control platform to read data via the industrial communication network.

[0024] Rated angular velocity of the power grid It is a fixed value, which is based on the rated frequency of the power grid. calculate, Taking the Chinese power grid as an example, the rated frequency of the power grid... If the frequency is 50Hz, then the rated angular velocity of the power grid is... .

[0025] Rated apparent power of each inverter The rated apparent power indicated on its nameplate is a fixed value. Specifically, the total rated apparent power of the virtual power plant cluster... = The measured total active power of the virtual power plant cluster , i = (1, 2, ..., a), where a is the number of inverters in the virtual power plant cluster.

[0026] S2. Calculate the power grid frequency deviation, the formula for calculating the power grid frequency deviation is as follows: ; in, This represents the grid frequency deviation, and m represents the current iterative calculation order of the virtual power plant cluster system, which is also the iterative calculation order of the power plant control platform; m is a positive integer greater than or equal to 1. This refers to the virtual angular velocity generated by the power grid iteration in the previous calculation cycle, which is used by the platform during the m-th iteration. Indicates the rated angular velocity of the power grid; when the system is first powered on, , , This represents the actual angular velocity of the power grid connection.

[0027] During the system power-on initialization phase, the initial virtual angular velocity is directly assigned to the actual angular velocity of the grid connection point. Combined with a smooth iterative calculation closed loop, the inrush current caused by the inconsistency between the traditional VSG and the grid frequency during startup is eliminated. This enables the virtual power plant cluster to achieve disturbance-free grid connection, smooth startup and switching, minimizes the impact on the grid voltage and frequency at the point of common coupling, improves the grid-friendliness of the equipment, and complies with grid connection and dispatch standards.

[0028] S3, Total rated apparent power based on virtual power plant cluster and grid frequency deviation Calculate the total virtual inertia of the virtual power plant cluster. Total virtual damping The total amount is assumed to be power. and grid frequency deviation Each is related to the total virtual inertia of the virtual power plant cluster. The total amount is positively correlated with the apparent power. and grid frequency deviation Each with the total virtual damping Positive correlation; Step S3 involves setting up a virtual power plant cluster master control platform that communicates with multiple inverters and constructing a unified VSG rotor motion equation at the virtual power plant level within it. By combining total capacity allocation with frequency adaptation, the total rated capacity and frequency deviation of the cluster are simultaneously incorporated into the quantitative calculation of inertia and damping, thereby increasing the total inertia of the cluster to the same order of magnitude as the total rated capacity. This allows multiple distributed inverters to be equivalent to a large-capacity synchronous generator, breaking through the capacity bottleneck of a single virtual synchronous machine, compensating for the inherent defects of low inertia and weak damping in the power grid, improving the frequency stability and anti-disturbance capability of the power grid, and providing core support for the safe grid connection of high proportion of new energy.

[0029] Step S3 is generally implemented through a pre-established functional relationship, that is, by constructing a total apparent power. Grid frequency deviation Total virtual inertia of the virtual power plant cluster The total virtual inertia of the virtual power plant cluster is calculated using a functional relationship between three variables. By constructing a total apparent power Grid frequency deviation Total virtual damping of virtual power plant cluster The total virtual damping of the virtual power plant cluster is calculated using a functional relationship between three variables. This, in turn, increases the total virtual inertia of the virtual power plant cluster. Total virtual damping The values ​​all vary with the total rated apparent power of the virtual power plant cluster. and grid frequency deviation Positive correlation changes. This ensures that the inertia and damping of the virtual power plant cluster adaptively increase as the cluster capacity increases or the grid frequency deviates significantly, resulting in stronger support capabilities with larger physical capacity and a stronger response with greater frequency deviation. The total virtual inertia of the virtual power plant cluster. Total virtual damping The calculation formula can be set according to the actual needs of the power grid. Specifically, the calculation formula for the total virtual inertia of the virtual power plant cluster is expressed as follows: ; in, This represents the total virtual inertia of the virtual power plant cluster. This represents the inertia support coefficient of the entire cluster under normal operating conditions. This represents the total rated apparent power of the virtual power plant cluster. The frequency-adaptive inertia coefficient representing the total virtual inertia of the virtual power plant cluster is required to be 50 ≤ ≤200, typical values ​​for general engineering projects are fixed. .

[0030] Total virtual inertia The calculation formula enables the virtual power plant cluster to have a total apparent power near the rated frequency. The basic inertia level is proportional to the horizontal level. Among them, the coefficient... To ensure that the entire cluster has sufficient inertia support under normal operating conditions, the coefficient Positive values ​​can be selected based on the virtual power plant cluster capacity and the strength of the grid connection. If the value is too small, it will reduce the foundation inertia support capacity under rated operating conditions; if the value is too large, it will slow down the frequency regulation response speed under normal operating conditions. Therefore, for conventional medium-sized wind-solar-storage clusters... Preferably select coefficient 2 for small distributed clusters Take 1~1.5 for large-scale weak current grid stations. Take a value between 2.5 and 4. After adjusting this coefficient, the adaptive inertia coefficient of the tuning frequency needs to be synchronized and matched. To ensure system stability. As an adaptive incremental term, the higher the risk of grid instability, the greater the additional inertia automatically added by the system. Among these, the frequency adaptive inertia coefficient... The value of is used to control the response sensitivity of the system's inertia to additional increments. If a more sensitive response to the system's inertia is desired, the frequency-adaptive inertia coefficient can be considered. Take a larger value, for example, in a weak power grid system. Setting it to 150 enhances the frequency deviation response; in high-voltage power grid systems, A value of 50 is used to avoid excessive inertia adjustment that could exceed the expected total virtual inertia of the virtual power plant cluster. .

[0031] Specifically, the formula for calculating the total virtual damping of the virtual power plant cluster is as follows: ; in, This represents the total virtual damping of the virtual power plant cluster. This represents the basic oscillation suppression coefficient of the virtual power plant cluster. The frequency adaptive damping coefficient represents the total virtual damping of the virtual power plant cluster.

[0032] Basic oscillation suppression coefficient A positive number between 3 and 8 can be selected based on the station capacity and the strength of the power grid. If the value is too small, it will weaken the ability to suppress steady-state oscillations; if the value is too large, it will slow down the frequency regulation response speed. Taking the engineering compromise benchmark value of 5, therefore, in this invention... . Used to provide basic damping, ensuring the power grid has basic oscillation suppression capabilities near its rated frequency; the rated apparent power of the entire virtual power plant cluster. The larger the voltage, the greater the damping required to smooth out power fluctuations in the power grid and make the entire system more stable.

[0033] Frequency adaptive damping coefficient A value between 2 and 15 is chosen, with the specific value determined comprehensively based on grid strength, renewable energy penetration rate, and power plant installed capacity. Renewable energy penetration rate refers to the proportion of renewable energy power generation capacity within a regional power grid or power plant to the total active power output of the region's total installed power generation capacity; it is a core indicator for measuring the proportion of renewable energy in the power grid. A higher renewable energy penetration rate results in fewer synchronous rotating components in the grid and weaker inherent damping support for the power cluster; therefore, a larger value is preferable. Strengthening damping effectively suppresses wideband oscillations; the lower the penetration rate of new energy sources, the more sufficient the natural damping within the synchronous generator cluster, so a smaller damping should be selected. Ensure the frequency recovers quickly after a disturbance. The installed capacity of a power station refers to the sum of the rated power of all grid-connected generating equipment within the station. If... When the value is too small and the frequency deviates significantly from the rated frequency, the damping increase is insufficient, which will lead to a decrease in the rate of decay of disturbance oscillations; if If the value is too large, excessive damping torque will be generated under large frequency difference conditions. Although the oscillation is strongly suppressed, it will also delay the frequency recovery speed, causing overshoot or long-term deviation. The embodiment of the present invention selects a benchmark value of 8 as an engineering compromise, that is, It takes into account both strong and weak power grid operation scenarios, retains the ability to quickly adjust frequency under small steady-state frequency difference, and can quickly improve damping to suppress oscillation under large frequency difference of high power disturbance. The total damping of the entire cluster system increases with the increase of frequency deviation. When the frequency deviates significantly from the rated value, the risk of frequency oscillation increases, and stronger damping is required to quickly quell frequency disturbances.

[0034] S4. The total virtual inertia of the virtual power plant cluster. Total virtual damping Total active power target value and measured total active power Substitute the rotor motion equations of the virtual synchronous machine into the equations of motion to calculate the rate of change of angular velocity of the entire virtual power plant cluster. Specifically, the rate of change of angular velocity of the entire virtual power plant cluster mentioned in step S4. The calculation formula is expressed as follows: ; in, This represents the rate of change of the angular velocity of the entire virtual power plant cluster. This represents the total active power target value of the virtual power plant cluster. This represents the measured total active power of the virtual power plant cluster; S5, Based on the first preset period and the rate of change of angular velocity of the entire virtual power plant cluster Iteratively update the virtual angular velocity of the virtual power plant cluster in the current platform computing cycle. ; ; This week's iterations yielded As the next calculation cycle This enables continuous dynamic updating of the virtual angular velocity. When the system is first powered on... , For example, assuming this is the third iteration update, then at this time... This was obtained during the second update iteration of the system. Iterative updates obtained As input for the fourth update iteration.

[0035] S6. Based on the virtual angular velocity obtained after iteration in step S5. Generate a global unified synchronous power angle Every first preset period Unify the synchronization angle across the entire domain As the initial phase angle reference for the local phase integration of all inverters; ; in, For the current calculation cycle, the global unified synchronous power angle, This represents the cumulative phase value of the previous platform's calculation cycle; when the system is powered on for the first time, , .

[0036] Unified synchronous power angle across the entire domain It is mainly used to achieve global phase alignment of inverters in a virtual power plant cluster system during startup, grid connection, fault recovery, and communication reconnection, avoiding phase divergence and circulating current generation among multiple units. In other words, it achieves unified synchronous power angle across the entire system. Not directly involved in each second preset cycle of the inverter Instead of real-time phase integration, it is performed every first preset period. This will update the same synchronization angle of all inverters once again. This information is then incorporated into the inverter's local phase integrator, serving as the initial phase angle reference for the local phase integration of all inverters during initial inverter startup, fault recovery, and signal interruption. This occurs every first preset cycle. After the control is completed, the platform will obtain the results of this execution. The value overwrites the one obtained last time. The value obtained in this execution The value is stored in the internal register as the next first preset cycle. Pre-substituted .

[0037] Generate a unified synchronous power angle across the entire domain through the virtual power plant cluster master control platform. The same phase reference is provided for all inverter units within the cluster, with the phase angle set at a first preset period. For periodic refresh, at the beginning of each refresh cycle, the local phase integrator of the inverter is set as the initial value for integration, so that all inverters in the cluster start from the same phase starting point. In the subsequent second preset cycle, the phase update depends entirely on the local rotor motion equation of the inverter to integrate itself, no longer relying on platform communication. This eliminates the phase difference between the inverters at the source, and eliminates the phase difference of the operating state of each unit from the source of the control logic, as well as the grid circulating current and low-frequency oscillation caused by the phase difference of multiple virtual synchronous machines. This ensures that the virtual power plant cluster can maintain the phase synchronization of each unit in normal working state and after fault interruption recovery, and realizes the absolute synchronous grid connection of multiple new energy power generation units.

[0038] S7. Calculate the active power allocated to each inverter according to the rated capacity ratio of each inverter. reactive power Unit inertia With unit damping Every first preset period Allocate and update the active power reactive power Unit inertia With unit damping The allocation information is then sent to the respective inverters once. The percentage of rated capacity of each inverter refers to the apparent power of the rated capacity of each inverter. The total apparent power of the entire virtual power plant cluster accounts for The ratio. And the active power pre-allocated to each inverter. reactive power Unit inertia With unit damping Information is sent to the corresponding inverters; active power is pre-allocated to each inverter. reactive power Unit inertia With unit damping Information is typically sent to the corresponding inverter every first preset cycle. The power is issued once. Specifically, the calculation formula for the active power target value allocated to each inverter in step S7 is expressed as follows: ; in, This represents the target active power value allocated to the i-th inverter. This represents the total active power target value of the virtual power plant cluster. This represents the rated apparent power of the i-th inverter. This represents the total rated apparent power of the virtual power plant cluster; The formula for calculating the reactive power target value allocated to each inverter in step S7 is expressed as follows: ; in, This represents the target reactive power value allocated to the i-th inverter. This represents the total reactive power target value of the virtual power plant cluster; ; in, This represents the unit inertia allocated to the i-th inverter. This represents the total virtual inertia of the virtual power plant cluster; The formula for calculating the unit damping allocated to each inverter in step S7 is expressed as follows: ; in, This represents the unit damping allocated to the i-th inverter. This represents the total virtual damping of the virtual power plant cluster.

[0039] Steps S1 to S7 are generally controlled and completed by the control platform of the virtual power plant cluster, every first preset cycle. One data iteration is completed, that is, each of steps S1 to S7 is performed within the first preset period. Execute once. Steps S1 and S2 have no specific order requirement; they only need to be completed before step S3. Steps S6 and S7 also have no specific order requirement; generally, steps S6 and S7 output their respective results simultaneously.

[0040] S8, Each inverter uses the aforementioned global unified synchronous power angle. As the initial phase, multiple second preset cycles are executed independently between the parameter transmissions in the two receiving steps S6-S7. Virtual synchronous machine closed-loop iterative calculation and grid-connected control; > That is, the first preset period is greater than the second preset period.

[0041] After each inverter receives the parameters sent by the platform, As the initial phase, with a second preset period Each inverter independently completes its own VSG closed-loop calculation locally, without relying on frequent communication with the central control platform. Furthermore, the inverter independently executes multiple second preset cycles between two platform parameter distributions. The virtual synchronous machine performs closed-loop iterative calculations and grid-connected control to ensure the inverter's rapid dynamic response. For example, during the first preset cycle... =0.1s, second preset period At this time, the global calculation and parameter allocation of steps S1-S7 are completed once every 0.1 seconds, with a moderate communication frequency and stable engineering implementation. That is to say, the power angle of the entire domain is uniformly synchronized every 0.1 seconds. After the update, the initial integral value is used as the input to the local phase integrator of each inverter. The updated active power is iteratively updated every 0.1 seconds. reactive power Unit inertia With unit damping The data is distributed to each inverter, which performs a virtual synchronous machine closed-loop iterative calculation and grid-connected control every 0.0001 seconds. In other words, within the time interval between two data transmissions from the central control platform to the inverter, the inverter completes 1000 virtual synchronous machine closed-loop iterative calculations and grid-connected control. > This means that the platform's global calculation cycle is longer than the inverter's local closed-loop cycle, with a difference of orders of magnitude. Global calculations and parameter distribution are performed in a first preset cycle, while the inverter independently completes its local closed-loop operation in a second preset cycle. Since the first preset cycle is significantly longer than the second, the inverter can independently execute multiple high-speed closed-loop cycles between two rounds of platform parameter distribution, eliminating the need for real-time communication with the platform. This reduces the frequency of communication interactions and data traffic, lowers the requirements for on-site communication network bandwidth and hardware performance, enables cluster collaborative control under low communication load, and saves on engineering implementation costs.

[0042] Preferably, =0.1s, =0.0001s, forming a dual-cycle decoupled control architecture of low-speed platform calculation and high-speed inverter closed loop. The inverter independently completes the closed-loop calculation with an ultra-high-speed cycle of 0.0001s, including the discrete update of angular velocity / phase of the active-inertia-damping loop and the generation of voltage amplitude of the reactive-voltage loop. The whole process does not rely on platform communication, which enables the inverter to have a microsecond-level dynamic response speed. It can make adjustment responses within milliseconds when the grid experiences frequency fluctuations, voltage drops, or load changes, and is freed from the limitation of communication delay. It can quickly and in real time suppress power fluctuations and ensure the control accuracy of output power and power quality.

[0043] The inverter's closed-loop calculation includes calculating the received global uniform synchronous power angle. Active power allocated to each inverter reactive power Unit inertia With unit damping The parameters and the real-time power generation voltage amplitude and phase acquired in step S1 are used to synthesize a three-phase reference voltage and drive the grid connection. In a preferred embodiment of the present invention, step S8 includes the following steps: S8.1, The inverter receives active power Unit inertia Unit damping and its own real-time active power Substituting the values ​​into the equations of motion of the virtual synchronous machine rotor to calculate its actual rate of change of angular velocity, and integrating the results, the voltage phase command is obtained. Specifically, step S8.1 includes the following steps: S8.1-A, Calculate the rate of change of the angular velocity of the i-th inverter. The formula for calculating the rate of change of the angular velocity of the i-th inverter is as follows: ; in, This represents the rate of change of the angular velocity of the i-th inverter. This represents the target active power value allocated to the i-th inverter. This represents the real-time active power at the output of the i-th inverter. This indicates that the i-th inverter is in the same first preset cycle. The k-th second preset period within Angular velocity state value at that time; S8.1-B, Update the next second preset cycle The angular velocity of the i-th inverter The formula for calculating the angular velocity of the i-th inverter in the next second preset cycle is expressed as: ; in, This indicates the angular velocity of the i-th inverter in the next second preset cycle. Indicates the duration of the second preset cycle; S8.1-C, Update the next second preset cycle Phase of the i-th inverter The phase calculation formula for the i-th inverter in the next second preset cycle is expressed as: ; in, This indicates the phase of the i-th inverter in the next second preset cycle. Let k be the phase of the i-th inverter within the current second preset cycle, and k be the phase of the inverter within the same first preset cycle. The second preset cycle to be executed within The order, k is a positive integer greater than or equal to 1, when k=1, For the first preset period The initial phase; Let be the virtual inertia received by the i-th inverter. Let be the active power received by the i-th inverter. Let be the active power output in real time by the i-th inverter. The virtual damping received by the i-th inverter. This is obtained through iterative processing over this period. As the next calculation cycle This enables continuous dynamic updating of the phase of the i-th inverter.

[0044] S8.2, Each inverter, based on the reactive power allocation command it receives. and locally collected real-time reactive power Generate voltage amplitude command The voltage amplitude command mentioned in step S8.2 Calculate using the following formula:

[0045] in, This indicates the voltage amplitude command for the i-th inverter. Indicates the rated phase voltage amplitude of the power grid. This represents the reactive power-voltage droop factor. This represents the target reactive power value allocated to the i-th inverter. This represents the actual reactive power of the i-th inverter; The unit is V / var, which characterizes the adjustment gain of reactive power deviation on the inverter output voltage amplitude. The larger the value, the faster the reactive power voltage regulation response. This coefficient is set according to the station capacity and grid voltage stability requirements, and the value range is usually 0.01~0.3V / var. It is used to simulate the excitation voltage regulation droop characteristics of synchronous generators to realize the inverter's autonomous adjustment of the grid connection point voltage amplitude based on reactive power. When the actual reactive power... Less than the reactive power received by the inverter When sending data, the voltage amplitude command is... At the rated phase voltage amplitude of the power grid The voltage is raised based on the voltage level, and lowered if the voltage is lower, thus enabling the inverter to achieve precise tracking of reactive power through voltage regulation.

[0046] S8.3, Set voltage amplitude command With voltage phase command The three-phase reference voltage is synthesized and then used by the inverter's own SVPWM module to generate IGBT drive pulses to drive the inverter switching transistors, thus completing the grid-connected control of the inverter. In step S8.3, the voltage amplitude command is... With voltage phase command Synthetic three-phase reference voltage , and :

[0047] Space vector pulse width modulation is used to generate drive pulses to drive the inverter switching transistors, thereby completing the grid-connected control of the inverter.

[0048] Steps S8.1 and S8.2 have no specific order requirement, as long as they are completed before step S8.3 begins. The execution time of one cycle from step S8.1 to step S8.3 is the second preset period. During the time interval between two consecutive times when the inverter receives allocation information data from the control platform, steps S8.1 to S8.3 are executed repeatedly.

[0049] A virtual synchronous machine control system for inertia coordination of a virtual power plant cluster includes multiple new energy power generation systems. Each new energy power generation system includes an inverter 1, which is connected to the AC power grid. The system also includes a data acquisition module 2 and a virtual power plant group master control platform 3, which is communicatively connected to both the inverter 1 and the data acquisition module 2. The data acquisition module 2 is used to acquire the real-time active power output of the inverter 1 in step S1. and real-time reactive power The virtual power plant group master control platform 3 is used to execute steps S1-S7, and the inverter 1 is used to execute step S8. The virtual power plant group master control platform 3 performs each first preset cycle. Complete the global calculation and parameter allocation in steps S1-S7 and allocate the output allocation parameters and initial phase data to the corresponding inverter 1. Each inverter 1 is assigned every first preset period. Update the input parameters of the virtual power plant group master control platform 3 once, and every second preset cycle. Complete step S8 once.

[0050] New energy power generation systems include wind power systems, solar power systems, and other devices that generate electricity using clean energy. Data acquisition module 2 is primarily used to provide data input and support to the virtual power plant group control platform 3. It generally has data filtering and outlier removal functions to ensure the accuracy and reliability of the data collected and transmitted to the virtual power plant group control platform 3, thereby ensuring the control accuracy and reliability of the entire system. Data acquisition module 2 generally includes a current sensor for monitoring the current at the output terminal of inverter 1 and a voltage sensor for monitoring the voltage at the output terminal of inverter 1.

[0051] The virtual power plant group control platform 3 can be constructed by communication connection of one or more of the following: industrial computer, PLC controller, and other existing control devices, and it takes the data from the data acquisition module 2 as input data. Specifically, the virtual power plant group control platform 3 includes: a data preprocessing module 31, whose input end is communicatively connected to the output end of the data acquisition module 2; The data preprocessing module 31 is used to receive the output data of the data acquisition module 2 and calculate the total rated apparent power of the virtual power plant cluster. and measured total active power The processed data is then sent to the inertia damping calculation module. The inertia damping calculation module is used to execute step S3 and output the total virtual inertia. Total virtual damping The data is transmitted to the angular velocity-power angle iteration module, which is the core computing unit for realizing adaptive adjustment of cluster inertia damping; The angular velocity-power angle iteration module is used to execute steps S4-S6 and output the global unified synchronous power angle. To the inverter 1, ensure that all distributed inverters 1 in the cluster have a unified synchronization reference, and avoid the problem of multi-machine power angle loss of synchronization from the root cause; The parameter allocation and distribution module is used to execute step S7 and obtain the active power. reactive power Unit inertia and unit damping According to the rated capacity ratio of each distributed inverter 1 unit, the total active power, total reactive power, total inertia and total damping are fairly allocated, and four independent control parameters are generated. The parameters are sent to each inverter 1 at regular intervals through the industrial communication link. The communication cycle is fixed at 0.1s, which takes into account both communication reliability and control real-time performance. The cluster scheduling module is used to receive active and reactive power command information from the power grid and to process the total active power target value of the virtual power plant cluster issued by the power grid dispatch center. Total reactive power target value It is then sent to the parameter allocation and distribution module.

[0052] The data preprocessing module 31 has its input terminal communicatively connected to the output terminal of the data acquisition module 2. The inertia damping calculation module has its input terminal communicatively connected to the output terminal of the data preprocessing module 31. The angular velocity-power angle iteration module has its output terminal communicatively connected to the output terminal of the inertia damping calculation module. The parameter allocation and distribution module has its input terminal communicatively connected to the output terminals of the cluster scheduling module, the data preprocessing module 31, and the inertia damping calculation module, respectively. The output terminals of the parameter allocation and distribution module and the angular velocity-power angle iteration module are respectively communicatively connected to the inverter 1. In addition, a dedicated communication module is generally provided. The output terminals of the parameter allocation and distribution module and the angular velocity-power angle iteration module are respectively communicatively connected to the inverter 1 through the dedicated communication module to complete data parsing and verification. The communication link of the dedicated communication module generally adopts industrial Ethernet or a dedicated power communication network, which has low transmission latency, strong anti-interference capability, and is suitable for complex electromagnetic environments in industrial sites. It meets the communication requirements of the virtual power plant group main control platform 3 for 0.1s parameter distribution and the inverter 1 for high-speed local control, ensuring accurate and stable transmission of control commands. The dedicated communication module has a communication interruption fault tolerance mechanism, which can maintain the last parameter stable operation for a short period of time, that is, maintain the last parameter stable operation for at least 2 first preset cycles.

[0053] The inverter 1 described in this invention is generally a distributed inverter, allowing independent connection and optimization of multiple new energy power generation devices to enhance system adaptability. Preferably, the inverter 1 is a distributed power inverter, with multiple such distributed inverters connected in parallel to the same power grid; the distributed power inverter includes: a VSG closed-loop module and an SVPWM drive module, the input terminal of the VSG closed-loop module being communicatively connected to the output terminals of the angular velocity-power angle iteration module and the parameter allocation and distribution module, respectively, and the input terminal of the SVPWM drive module being communicatively connected to the output terminal of the VSG closed-loop module; the VSG closed-loop module is used to execute steps S8.1 to S8.2 and output voltage amplitude commands. With voltage phase command The output is sent to the SVPWM drive module, which has a fast calculation speed and timely dynamic response, and can quickly smooth out power fluctuations and suppress system oscillations. It generally operates independently with a high-speed control cycle of 0.0001s. The SVPWM drive module is used for voltage amplitude commands. With voltage phase command A three-phase sinusoidal reference voltage is synthesized, and space vector pulse width modulation technology is used to generate IGBT switching drive pulses to control the operation of inverter 1's power circuit, thereby achieving precise regulation of grid-connected power.

[0054] To facilitate the explanation of the present invention, the rated angular velocity of the power grid is given. =314 rad / s. The entire virtual power plant cluster includes two inverters: the first inverter and the second inverter. The rated apparent power of the first inverter is... The rated apparent power of the second inverter The two inverters and the second inverter are controlled by the same virtual power plant control platform. The calculation and distribution cycle of the virtual power plant control platform is 0.1 seconds, meaning that the iterative control cycle of the entire virtual power plant cluster is the first preset cycle. =0.1s, the iterative control cycle of each inverter is the second preset cycle. =0.0001s. Adaptive inertia coefficient at a given frequency. =100, the inertia support coefficient of the entire cluster under normal operating conditions. 2. Basic oscillation suppression coefficient 5. Total active power target value of the virtual power plant cluster Total reactive power target value of virtual power plant cluster The measured total active power of the virtual power plant cluster =100kW.

[0055] Step S1: Collect the real-time active power and real-time reactive power at the inverter output terminals, and collect the rated apparent power of each inverter, the actual angular velocity of the grid connection point when the virtual power plant cluster system is first powered on, and so on. Rated apparent power of each inverter The total active power target value of the virtual power plant cluster issued by the power grid dispatch center Total reactive power target value ; Calculate the total rated apparent power of the virtual power plant cluster and measured total active power Parameters; 313.98 rad / s = 313.98 rad / s; Step S2: Calculate the frequency deviation ; Step S3: Calculate the total inertia of the cluster and cluster total damping ; = ; = ; Step S4: Calculate the rate of change of angular velocity ; ; Step S5, Iterative Update ; ; Step S6: Generate a global unified synchronous power angle ; ; Step S7: The platform distributes four sets of parameters every 0.1 seconds; , , ; = ; Step S8: The inverter performs a local closed-loop calculation every 0.0001s, which includes the following steps: S8.1 single-machine virtual angular velocity and output phase iteration, taking the first inverter as an example, a single platform cycle contains multiple rounds of microsecond-level iterations, denoted as the iteration sequence number. First iteration Read the reference issued by the platform: initial phase Initial angular velocity The specific steps include: S8.1-A calculates the rate of change of the angular velocity of the i-th inverter: ; In the formula This represents the measured active power at the output of the first inverter. S8.1-B updates the first inverter to the next second preset cycle. virtual angular velocity : ; S8.1-C updates the first inverter to the next second preset cycle. Modulation absolute phase : ; Output It represents the absolute phase in the stationary abc coordinate system and is directly used for three-phase voltage modulation.

[0056] S8.2 receives the reactive power allocation command. and locally collected real-time reactive power Generate voltage amplitude command Assume the measured reactive power of the first inverter is... Based on the local reactive power regulation coefficient, calculate the reference value for the output voltage amplitude. The reactive power loop is also refreshed at a high speed of 0.0001s to suppress voltage fluctuations at the grid connection point.

[0057] This method uses the rated phase voltage amplitude at the grid connection point and is applied to 380V low-voltage distribution networks. =311V; The reactive power-voltage droop factor is used in this embodiment. Take 0.05 as the baseline value. The platform issues single-machine reactive power allocation instructions. The system collects the output reactive power of the first inverter in real time. When the inverter's output reactive power is greater than the target reactive power, the voltage amplitude reference value decreases to suppress the rise in grid connection voltage; when the output reactive power is less than the target reactive power, the voltage amplitude reference value increases to raise the grid connection voltage, thus achieving reactive power-voltage droop regulation.

[0058] S8.3SVPWM modulation and drive output

[0059] The active power loop outputs the absolute phase. , reactive power loop output voltage amplitude The voltage is synthesized into a three-phase reference sinusoidal voltage; space vector pulse width modulation technology is used to generate IGBT switching drive pulses to control the output of the first inverter power circuit, achieving millisecond-level precise adjustment of grid-connected power.

[0060] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A virtual synchronous machine control method based on virtual power plant cluster inertia coordination, characterized in that, Including the following steps: S1. Collect and calculate the real-time active power and real-time reactive power at the output terminals of each inverter; collect the rated angular velocity of the power grid, the actual angular velocity of the grid connection point when the virtual power plant cluster system is first powered on, the rated apparent power of each inverter, and the total active power target value and total reactive power target value of the virtual power plant cluster issued by the power grid dispatch center. Calculate the total rated apparent power and measured total active power of the virtual power plant cluster; S2. Calculate the power grid frequency deviation, the formula for calculating the power grid frequency deviation is as follows: ; in, This represents the grid frequency deviation, and m represents the current iterative calculation order of the virtual power plant cluster system, where m is a positive integer greater than or equal to 1. This refers to the virtual angular velocity generated by the power grid iteration in the previous calculation cycle, which is used by the platform during the m-th iteration. Indicates the rated angular velocity of the power grid; when the system is first powered on, , ; This refers to the actual angular velocity of the power grid connection. S3. Calculate the total virtual inertia and total virtual damping of the virtual power plant cluster based on the total rated apparent power and grid frequency deviation of the virtual power plant cluster. The total apparent power and grid frequency deviation are positively correlated with the total virtual inertia of the virtual power plant cluster, and the total apparent power and grid frequency deviation are positively correlated with the total virtual damping. S4. Substitute the total virtual inertia, total virtual damping, total active target value and measured total active power of the virtual power plant cluster into the virtual synchronous machine rotor motion equation to calculate the rate of change of angular velocity of the entire virtual power plant cluster. S5. Iterate the virtual angular velocity of the virtual power plant cluster in the current platform calculation period based on the first preset period and the rate of change of the angular velocity of the entire virtual power plant cluster. S6. Generate a global unified synchronous power angle based on the virtual angular velocity iterated in step S5. Use the global unified synchronous power angle as the initial phase angle reference for the local phase integration of all inverters every first preset period. S7. Calculate the active power, reactive power, unit inertia and unit damping allocated to each inverter according to the rated capacity ratio of each inverter, and allocate, update the allocation information of active power, reactive power, unit inertia and unit damping every first preset cycle and send it to the corresponding inverter. S8. Each inverter takes the global unified synchronous power angle as the initial phase and independently performs multiple second preset cycle virtual synchronous machine closed-loop iterative calculations and grid-connected control between the two receiving steps S6-S7 for the parameters; the first preset cycle is greater than the second preset cycle.

2. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 1, characterized in that, The formula for calculating the total virtual inertia of the virtual power plant cluster is as follows: ； in, This represents the total virtual inertia of the virtual power plant cluster. This represents the inertia support coefficient of the entire cluster under normal operating conditions. This represents the total rated apparent power of the virtual power plant cluster. The frequency-adaptive inertia coefficient represents the total virtual inertia of the virtual power plant cluster, 50≤ ≤200; The formula for calculating the total virtual damping of the virtual power plant cluster is as follows: ； in, This represents the total virtual damping of the virtual power plant cluster. This represents the basic oscillation suppression coefficient of the virtual power plant cluster. The frequency adaptive damping coefficient represents the total virtual damping of the virtual power plant cluster.

3. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 2, characterized in that, The formula for calculating the rate of change of angular velocity of the entire virtual power plant cluster in step S4 is expressed as follows: ； in, This represents the rate of change of the angular velocity of the entire virtual power plant cluster. This represents the total active power target value of the virtual power plant cluster. This represents the measured total active power of the virtual power plant cluster. This represents the total virtual inertia of the virtual power plant cluster.

4. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 3, characterized in that, The virtual angular velocity of the virtual power plant cluster in the current platform calculation cycle mentioned in step S5 is... Calculate using the following formula: ； in, Indicates the first preset period; The global unified synchronous power angle in step S6 is calculated using the following formula: ； in, For the current calculation cycle, the global unified synchronous power angle, This represents the cumulative phase value of the previous platform's calculation cycle; when the system is powered on for the first time, , .

5. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 1, characterized in that, The calculation formula for the active power target value of each inverter allocated to each inverter in step S7 is expressed as follows: ; in, This represents the target active power value allocated to the i-th inverter. This represents the total active power target value of the virtual power plant cluster. This represents the rated apparent power of the i-th inverter. This represents the total rated apparent power of the virtual power plant cluster; The formula for calculating the reactive power target value allocated to each inverter in step S7 is expressed as follows: ； in, This represents the target reactive power value allocated to the i-th inverter. This represents the total reactive power target value of the virtual power plant cluster; The formula for calculating the unit inertia allocated to each inverter in step S7 is expressed as follows: ； in, This represents the unit inertia allocated to the i-th inverter. This represents the total virtual inertia of the virtual power plant cluster; The formula for calculating the unit damping allocated to each inverter in step S7 is expressed as follows: ； in, This represents the unit damping allocated to the i-th inverter. This represents the total virtual damping of the virtual power plant cluster.

6. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 1, characterized in that, The first preset period is 0.1s, and the second preset period is 0.0001s.

7. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 5, characterized in that, Step S8 includes the following steps: S8.1 Each inverter substitutes the received active power, unit inertia, unit damping and its own output real-time active power into the virtual synchronous machine rotor motion equation to calculate its own actual angular velocity change rate, and obtains the voltage phase command after integration. S8.2 Each inverter generates a voltage amplitude command based on the reactive power allocation command it receives and the real-time reactive power acquired locally. S8.

3. Based on the voltage amplitude command and voltage phase command, the three-phase reference voltage is synthesized, and the inverter's own SVPWM module generates IGBT drive pulses to drive the inverter switching transistors, thus completing the grid-connected control of the inverter. The execution cycle of steps S8.1 to S8.3 is the second preset cycle.

8. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 7, characterized in that, Step S8.1 includes the following steps: S8.1-A, Calculate the rate of change of the angular velocity of the i-th inverter; ； in, This represents the rate of change of the angular velocity of the i-th inverter. This represents the active power allocated to the i-th inverter. This represents the real-time active power at the output of the i-th inverter. This represents the angular velocity state value of the i-th inverter during the k-th second preset cycle within the same first preset cycle; The rated angular velocity of the power grid; S8.1-B, Update the angular velocity of the i-th inverter in the next second preset cycle. The formula for calculating the angular velocity of the i-th inverter in the next second preset cycle is as follows: ； in, This indicates the angular velocity of the i-th inverter in the next second preset cycle. Indicates the duration of the second preset cycle; S8.1-C, Update the phase of the i-th inverter in the next second preset cycle. The formula for calculating the phase of the i-th inverter in the next second preset cycle is as follows: = ； in, This indicates the phase of the i-th inverter in the next second preset cycle. Let k be the phase of the i-th inverter within the current second preset cycle, and k be the phase of the inverter within the same first preset cycle. The second preset cycle to be executed within The order, k is a positive integer greater than or equal to 1, when k=1, This is the initial phase of the first preset period.

9. The virtual synchronous machine control method based on virtual power plant cluster inertia coordination according to claim 7, characterized in that, The voltage amplitude command for each inverter in step S8.2 is calculated using the following formula: ； in, This indicates the voltage amplitude command for the i-th inverter. Indicates the rated phase voltage amplitude of the power grid. This represents the reactive power-voltage droop factor. This represents the target reactive power value allocated to the i-th inverter. This represents the actual reactive power of the i-th inverter.

10. A virtual synchronous machine control system based on virtual power plant cluster inertia coordination, comprising multiple new energy power generation systems, wherein each new energy power generation system includes an inverter (1), and the new energy power generation system is connected to the AC power grid through the inverter (1); characterized in that: It also includes a data acquisition module (2) and a virtual power plant group control platform (3), wherein the virtual power plant group control platform (3) is communicatively connected to the inverter (1) and the data acquisition module (2), respectively; The data acquisition module (2) is used to acquire the real-time active power and real-time reactive power at the output of the inverter (1), the virtual power plant group main control platform (3) is used to execute steps S1-S7 as described in claim 1, and the inverter (1) is used to execute step S8 as described in claim 1.

11. The virtual synchronous machine control system based on virtual power plant cluster inertia coordination according to claim 10, characterized in that, The virtual power plant group control platform (3) includes: The data preprocessing module (31) has its input end connected to the output end of the data acquisition module (2); the data preprocessing module (31) is used to receive the output data of the data acquisition module (2), calculate the total rated apparent power and measured total active power of the virtual power plant cluster, and transmit the processed data to the inertia damping calculation module (32). The inertia damping calculation module (32) is used to perform step S3 as described in claim 1 and transmit the output total virtual inertia and total virtual damping data to the angular velocity power angle iteration module (33). The angular velocity power angle iteration module (33) is used to execute steps S4-S6 as described in claim 1 and output the global unified synchronous power angle to the inverter (1). The parameter allocation and distribution module (34) is used to execute step S7 as described in claim 1 and transmit the obtained active power target value, reactive power target value, unit inertia and unit damping allocated to each inverter to the corresponding inverter (1). The cluster scheduling module (35) is used to receive the active and reactive power command information of the power grid and transmit the total active power target value and total reactive power target value of the virtual power plant cluster issued by the power grid dispatch center to the parameter allocation and distribution module.

12. The virtual synchronous machine control system based on virtual power plant cluster inertia coordination according to claim 11, characterized in that, The inverter (1) is a distributed power inverter (1), and multiple distributed power inverters (1) are connected in parallel to the same power grid; the distributed power inverter (1) includes a VSG closed-loop module (11) and an SVPWM drive module (12). The input terminal of the VSG closed-loop module (11) is communicatively connected to the output terminal of the angular velocity power angle iteration module (33) and the parameter allocation and distribution module, respectively. The input terminal of the SVPWM drive module (12) is communicatively connected to the output terminal of the VSG closed-loop module (11). The VSG closed-loop module (11) is used to execute steps S8.1 to S8.2 as described in claim 7, and outputs the voltage amplitude command. With voltage phase command Output to the SVPWM driver module (12); The SVPWM drive module (12) is used to synthesize a three-phase sinusoidal reference voltage based on voltage amplitude command and voltage phase command, and to generate IGBT switch drive pulses through space vector pulse width modulation technology to control the power circuit operation of the distributed power inverter (1).

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