Photovoltaic storage and charging active support and cooperative control method and system based on voltage stability

Abstract

The application relates to the technical field of micro-grid cooperative control, and discloses a photovoltaic-storage-charging active support and cooperative control method and system based on voltage stability, which comprises the following steps: based on the reduced-order expression of the multi-time scale dynamic response relationship of photovoltaic-storage equipment, the dynamic coupling among various control characteristics is decoupled, and a control parameter cooperative design condition is generated; according to the control parameter cooperative design condition, the control parameters are determined, and combined with real-time operation data of various virtual synchronous generator equipment, the equivalent inertia value at a common coupling point is calculated; then, combined with network impedance parameters, the time-domain response relationship between the voltage amplitude variation and the reactive power injection amount is derived, and an inertia support capability quantitative evaluation index is generated; finally, the dynamic reactive power compensation instruction is generated according to the index, and is sent to each local control terminal to adjust the reactive power output, so that the active voltage support control is completed; the application can improve the voltage support capability and the reactive power compensation matching precision of the photovoltaic-storage-charging system under extreme weather disturbance, and shorten the voltage recovery time.

Description

Technical Field

[0001] This invention relates to the field of microgrid collaborative control technology, and in particular to a method and system for active support and collaborative control of photovoltaic, energy storage and charging based on voltage stability. Background Technology

[0002] In integrated photovoltaic-storage-charging systems, photovoltaic power generation equipment, energy storage equipment, and charging load equipment are connected to a common bus via power electronic converters, forming a multi-machine parallel operation architecture. In recent years, virtual synchronous generator technology has been widely applied to the converter control of photovoltaic-storage-charging systems. By simulating the inertial response and damping characteristics of a synchronous generator, it enables the power electronic converter to exhibit voltage source characteristics, thereby providing necessary voltage support for the distribution network. However, integrated photovoltaic-storage-charging systems face multiple challenges in actual operation: the output of photovoltaic power generation equipment is significantly random and intermittent due to environmental factors such as light intensity and temperature; the charging load equipment has high uncertainty in terms of temporal and spatial distribution; and the state of charge of energy storage equipment changes dynamically with the charging and discharging process. The superposition of these multiple uncertainties poses a severe test to the voltage stability at the common coupling point of the integrated photovoltaic-storage-charging virtual generator parallel system. Especially under extreme weather conditions, a sudden drop in photovoltaic output and a surge in charging load may occur simultaneously, causing a significant voltage drop at the common coupling point in a short period, posing a serious threat to the safe and stable operation of the system.

[0003] To address the aforementioned voltage stability issues, some technical attempts have been made in this field. Some existing solutions preset reactive voltage droop coefficients in the local controllers of each virtual synchronous generator device, enabling each device to automatically adjust its reactive power output by a fixed proportion when voltage deviation occurs at the common coupling point, thereby achieving local autonomous voltage regulation. However, in this solution, the reactive voltage droop coefficients of each device are usually independently set based on the rated capacity of the device. When the system operating status (such as actual photovoltaic output, energy storage state of charge, and load level) changes significantly, the pre-set fixed droop coefficients cannot dynamically adjust to follow the changes in system operating status. The reactive power regulation potential of each device cannot be differentiated according to its current actual output capacity, resulting in some devices approaching their regulation limits while others still have a large margin but fail to fully utilize their potential. Another approach proposes collecting the common coupling point voltage signal through a central controller, performing unified calculations, and then issuing reactive power adjustment commands to each virtual synchronous generator. However, this approach involves multiple serial processing stages for voltage signal acquisition, transmission, calculation, and command issuance. Inherent communication and calculation delays exist between these stages, making it difficult to meet the rapid voltage support requirements on millisecond to hundreds of millisecond timescales. Within the complete time span from the occurrence of a voltage disturbance to the completion of the adjustment command, the common coupling point voltage has already experienced a significant drop. Furthermore, both of these approaches isolate the reactive power adjustment actions of each virtual synchronous generator from the system's current overall inertia level. That is, they do not correlate reactive power adjustment with the system's inertia support capability. When the system inertia level decreases due to changes in photovoltaic output or energy storage state of charge, existing solutions cannot dynamically adjust the reactive power compensation target value based on real-time changes in inertia. This results in the injected reactive power failing to match the system's actual voltage support requirements, leading to over-compensation or under-compensation, further affecting the accuracy and stability of voltage control. Summary of the Invention

[0004] This invention provides a method and system for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a voltage-stable active support and coordinated control method for photovoltaic energy storage and charging, comprising: Step 1: Based on the reduced-order expression of the dynamic response relationship of multiple time scales in the photovoltaic storage device terminal, decouple the dynamic coupling relationship between various control characteristics to generate the collaborative design conditions of the control parameters of the photovoltaic storage device terminal. Step 2: Based on the collaborative design conditions of the control parameters, determine the control parameters corresponding to the reduced-order expression, and determine the equivalent inertia value of the optical storage device terminal at the common coupling point through the real-time operating status data of each virtual synchronous generator device in the optical storage device terminal; Step 3: Based on the equivalent inertia value and the control parameters, and combined with the network impedance parameters of the photovoltaic storage device terminal, derive the time-domain response relationship between the voltage amplitude change and reactive power injection at the common coupling point of the photovoltaic storage device terminal, so as to generate a quantitative evaluation index of the inertia support capability of the photovoltaic storage device terminal. Step 4: The dynamic reactive power compensation command generated based on the quantitative evaluation index of inertia support capability is sent to the local control terminal of each virtual synchronous generator device to adjust the reactive power output value in real time, thereby completing the active voltage support control of the photovoltaic energy storage device terminal.

[0006] To address the aforementioned problems, this invention also provides a voltage-stable active support and coordinated control system for photovoltaic energy storage and charging, the system comprising: The control parameter coordination condition generation module is used to decouple the dynamic coupling relationship between various control characteristics based on the reduced-order expression of the dynamic response relationship of multiple time scales in the optical storage device terminal, and generate the control parameter coordination design conditions of the optical storage device terminal. The equivalent inertia value determination module is used to determine the control parameters corresponding to the reduced-order expression based on the control parameter collaborative design conditions, and to determine the equivalent inertia value of the optical storage device terminal at the common coupling point through the real-time operating status data of each virtual synchronous generator device in the optical storage device terminal; The inertia support capability assessment module is used to derive the time-domain response relationship between the voltage amplitude change and reactive power injection of the optical storage device terminal at the common coupling point based on the equivalent inertia value and the control parameters, combined with the network impedance parameters of the optical storage device terminal, so as to generate a quantitative assessment index of the inertia support capability of the optical storage device terminal. The active voltage support execution module is used to send dynamic reactive power compensation commands generated based on the quantitative evaluation index of inertia support capability to the local control terminal of each virtual synchronous generator device, and to adjust the reactive power output value in real time to complete the active voltage support control of the photovoltaic energy storage device terminal.

[0007] Compared with the prior art, the present invention has the following beneficial effects: 1. The photovoltaic-storage-charging active support and coordinated control method provided by this invention constructs a reduced-order expression based on multi-timescale dynamic response relationships and decouples the dynamic coupling relationships between various control characteristics. This generates coordinated design conditions for control parameters, ensuring that the fast, medium, and slow dynamic control links of the photovoltaic power generation equipment, energy storage equipment, and charging load equipment each have clear parameter selection criteria and cross-timescale parameter matching constraints at their respective timescales. This avoids response mismatch problems caused by crosstalk between control dynamics at different timescales, ensuring the control continuity and response consistency of the system under all operating conditions, and providing a stable and reliable control foundation for subsequent voltage support control. Simultaneously, this method determines the real-time power ratio of each virtual synchronous generator by collecting its real-time active power output value, and weights and integrates the virtual inertia time constants of each device according to this real-time power ratio. This allows the equivalent inertia value at the common coupling point to be dynamically updated according to the changes in the real-time operating state of each device, thus truly reflecting the actual inertia level of the multi-machine parallel system at the current moment, providing an accurate system state perception basis for voltage support control.

[0008] 2. This invention further derives the time-domain response relationship between voltage amplitude change and reactive power injection at the common coupling point and generates a quantitative evaluation index for inertia support capability. This enables the system to quantitatively assess its support capability for voltage amplitude changes based on the current equivalent inertia value. Based on this quantitative evaluation index, a dynamic reactive power compensation command matching the system's current inertia level is generated, thereby achieving adaptive following of the reactive power compensation target value to the system's inertia state and improving the matching accuracy between the reactive power injection and the system's actual voltage support requirements. Furthermore, when the system is determined to be under extreme weather disturbance, this method determines the remaining adjustable reactive power capacity of each virtual synchronous generator based on its real-time reactive power output value. The total reactive power compensation target value is then allocated to each device according to the proportion of each device's remaining capacity to the total remaining capacity. This ensures that each virtual synchronous generator can undertake its corresponding share of the compensation task based on its current actual output reactive power adjustment margin, preventing some devices from entering saturation or protection states due to exceeding adjustment limits. Simultaneously, it ensures that the reactive power adjustment potential of each device is released and fully utilized in an orderly manner. Furthermore, this method shortens the overall time span from the occurrence of disturbance to the completion of the adjustment command by sending dynamic reactive power compensation commands to the local control terminals of each virtual synchronous generator device, and having each local control terminal execute its own adjustment task in parallel. This improves the response speed and execution efficiency of voltage support control, enabling the real-time voltage amplitude at the common coupling point of the system to be restored in a timely manner and stabilized within the safe voltage operating range. The four steps work together and cooperate to enable the photovoltaic-storage-charging integrated virtual generator parallel system to achieve rapid voltage recovery and stable operation under both normal and extreme weather disturbance conditions. Attached Figure Description

[0009] Figure 1 This is a flowchart illustrating a voltage-stable active support and coordinated control method for photovoltaic energy storage and charging provided in an embodiment of the present invention. Figure 2 This is a functional block diagram of a voltage-stable active support and collaborative control system for photovoltaic energy storage and charging provided in an embodiment of the present invention.

[0010] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0011] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0012] This application provides a voltage-stable active support and coordinated control method for optical storage and charging. The executing entity of this voltage-stable active support and coordinated control method includes, but is not limited to, at least one of the following electronic devices that can be configured to execute the method provided in this application: a server, a terminal, etc. In other words, the voltage-stable active support and coordinated control method for optical storage and charging can be executed by software or hardware installed on a terminal device or a server device. The server includes, but is not limited to, a single server, a server cluster, a cloud server, or a cloud server cluster. The server can be an independent server or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDN), and big data and artificial intelligence platforms.

[0013] Reference Figure 1 The diagram shown is a flowchart illustrating a voltage-stable active support and coordinated control method for photovoltaic energy storage and charging according to an embodiment of the present invention. In this embodiment, the voltage-stable active support and coordinated control method for photovoltaic energy storage and charging includes: Step 1: Based on the reduced-order expression of the dynamic response relationship of multiple time scales in the photovoltaic storage device terminal, decouple the dynamic coupling relationship between various control characteristics to generate the collaborative design conditions of the control parameters of the photovoltaic storage device terminal. In this embodiment of the invention, the reduced-order expression of the multi-timescale dynamic response relationship in the optical storage device terminal includes: The response time scales of the maximum power tracking control loop of the photovoltaic power generation equipment, the charge and discharge management control loop of the energy storage equipment, the virtual inertia control loop and primary voltage regulation control loop of each virtual synchronous generator equipment, and the power distribution control loop of the charging load equipment are obtained in the photovoltaic storage equipment terminal. According to the order of response time scale from shortest to longest, the maximum power point tracking control and the primary voltage regulation control are classified into the fast dynamic control characteristic group, the virtual inertia control and the charge / discharge management control are classified into the medium dynamic control characteristic group, and the power distribution control is classified into the slow dynamic control characteristic group. The fast dynamic control characteristic group, the medium dynamic control characteristic group, and the slow dynamic control characteristic group are respectively subjected to equivalent merging processing to obtain a reduced-order expression of the dynamic response relationship of multiple time scales in the optical storage device terminal.

[0014] The process of decoupling the dynamic coupling relationships between various control characteristics to generate collaborative design conditions for the control parameters of the optical storage device terminal includes: Based on the time scales corresponding to the fast dynamic control characteristic group, the medium dynamic control characteristic group, and the slow dynamic control characteristic group, the dynamic interaction path between adjacent time scale control characteristic groups is identified. The dynamic interaction path includes the fast disturbance propagation path from the fast dynamic control characteristic group to the medium dynamic control characteristic group, and the slow influence propagation path from the medium dynamic control characteristic group to the slow dynamic control characteristic group. Along the dynamic interaction path, starting with the fast dynamic control characteristic group with the shortest time scale, the dynamic coupling between the fast dynamic control characteristic group and the medium dynamic control characteristic group, as well as between the medium dynamic control characteristic group and the slow dynamic control characteristic group, are separated in sequence. The independent dynamic behaviors of each control characteristic group after separation are integrated into the overall control parameter collaborative design conditions of the optical storage device terminal. The collaborative design conditions include the parameter selection range of each control characteristic group on its own time scale and parameter matching constraints across time scales.

[0015] The step response settling time constants of the closed-loop control loops of the photovoltaic power generation equipment's maximum power point tracking control loop, the energy storage equipment's charge and discharge management control loop, the virtual inertia control loop of each virtual synchronous generator equipment, the primary voltage regulation control loop of each virtual synchronous generator equipment, and the power distribution control loop of the charging load equipment are collected. The step response settling time constants are determined by applying a step signal with an amplitude equal to 10% of the rated control value of each control loop to the input terminal of each control loop and waiting for the difference between the output value and the steady-state output value of the loop to shrink to 0.5% of the rated control value. The settling time constant of the photovoltaic power generation equipment's maximum power point tracking control loop is fixed at 20ms, the settling time constant of each virtual synchronous generator equipment's primary voltage regulation control loop is fixed at 80ms, the settling time constant of each virtual synchronous generator equipment's virtual inertia control loop is fixed at 1200ms, the settling time constant of the energy storage equipment's charge and discharge management control loop is fixed at 1800ms, and the settling time constant of the charging load equipment's power distribution control loop is fixed at the order of 12000ms.

[0016] All collected stable time constants were sorted in ascending order of value. Using stable time constants of 200ms and 10000ms as two fixed thresholds, three groups of dynamic control characteristics were defined. The maximum power point tracking control of photovoltaic power generation equipment and the primary voltage regulation control of each virtual synchronous generator were classified into the fast dynamic control characteristic group. The virtual inertia control of each virtual synchronous generator and the charging and discharging management control of energy storage equipment were classified into the medium dynamic control characteristic group. The power distribution control of charging load equipment with a stable time constant of 10000ms or more was classified into the slow dynamic control characteristic group.

[0017] For the two control loops within the fast dynamic control characteristic group and the two control loops within the medium dynamic control characteristic group, the balanced truncation order reduction algorithm is used to complete the equivalent merging process. The balanced truncation order reduction algorithm first reads the original multi-order transfer function matrix of each control loop in the group, performs a dimensionless scaling operation on the input and output channels of the transfer function matrix to eliminate the singular value deviation caused by the difference in physical dimensions of power, voltage, and time, and then performs a minimum realization simplification operation on the scaled transfer function matrix to cancel the internal zero-pole cancellation redundancy state. Finally, the Hankel singular value of the simplified system is calculated and set to 1×10⁻ 5 As a singular value retention threshold, system state variables with singular values ​​less than the threshold are discarded. Based on the remaining valid state variables, a balanced transformation projection matrix is ​​constructed. The projection matrix is ​​then multiplied by the system state matrix and the input matrix on the left and by the output matrix on the right to obtain the corresponding first-order equivalent reduced-order transfer function for each group. The fast dynamic control characteristic group is equivalently merged to obtain the fast dynamic equivalent reduced-order sub-model, the medium dynamic control characteristic group is equivalently merged to obtain the medium dynamic equivalent reduced-order sub-model, and the slow dynamic control characteristic group, which contains only a single control element, directly uses the original transfer function as the slow dynamic equivalent reduced-order sub-model. The fast dynamic equivalent reduced-order sub-model, the medium dynamic equivalent reduced-order sub-model, and the slow dynamic equivalent reduced-order sub-model are then combined to generate a reduced-order expression of the dynamic response relationship across multiple time scales in the photovoltaic storage device terminal.

[0018] The stable time constant values ​​of the fast dynamic equivalent reduced-order sub-model, the medium dynamic equivalent reduced-order sub-model, and the slow dynamic equivalent reduced-order sub-model are read. The relative time scales of the three sets of equivalent reduced-order sub-models are compared to determine the hierarchical relationship. The fast dynamic equivalent reduced-order sub-model with the smallest value and the medium dynamic equivalent reduced-order sub-model with the middle value form the first set of adjacent time scales. The medium dynamic equivalent reduced-order sub-model with the middle value and the slow dynamic equivalent reduced-order sub-model with the largest value form the second set of adjacent time scales. The real-time voltage regulation power increment signal output by the fast dynamic equivalent reduced-order sub-model is directly connected to the input port of the medium dynamic equivalent reduced-order sub-model to form a fast disturbance propagation path from the fast dynamic control characteristic group to the medium dynamic control characteristic group. The energy storage charging and discharging power reference signal output by the medium dynamic equivalent reduced-order model is directly connected to the input port of the slow dynamic equivalent reduced-order model to form a slow influence propagation path from the medium dynamic control characteristic group to the slow dynamic control characteristic group. The two propagation paths together constitute a complete dynamic interaction path.

[0019] Based on the singular perturbation decoupling algorithm, the cross-scale dynamic coupling effect separation is completed along the dynamic interaction path. The algorithm uses the ratio of the stable time constant of the fast dynamic equivalent reduced-order sub-model to the stable time constant of the medium dynamic equivalent reduced-order sub-model as the first singular perturbation parameter, with a fixed calculated value of 0.0667. It uses the ratio of the stable time constant of the medium dynamic equivalent reduced-order sub-model to the stable time constant of the slow dynamic equivalent reduced-order sub-model as the second singular perturbation parameter, with a fixed calculated value of 0.15. The overall reduced-order model of the optical storage device terminal is then decomposed according to the first singular perturbation parameter. The equations of the fast dynamic independent subsystem and the medium-to-slow coupled joint equations are obtained. The medium-to-slow coupled joint equations are then decomposed according to the second singular perturbation parameter to obtain the equations of the medium-to-dynamic independent subsystem and the equations of the slow dynamic independent subsystem. During the decomposition process, the coupling terms of the output variables of the fast dynamic independent subsystem to the state variables of the medium dynamic independent subsystem and the coupling terms of the output variables of the medium dynamic independent subsystem to the state variables of the slow dynamic independent subsystem are eliminated simultaneously. This completes the separation of all dynamic coupling effects between the fast dynamic control characteristic group and the medium dynamic control characteristic group, and between the medium dynamic control characteristic group and the slow dynamic control characteristic group.

[0020] After the coupling separation process is completed, all parameter value boundaries and cross-level variable constraint equations within the fast dynamic independent subsystem equations, medium dynamic independent subsystem equations, and slow dynamic independent subsystem equations are extracted. The parameter selection range for the fast dynamic independent subsystem includes the maximum power tracking bandwidth of the photovoltaic power generation equipment from 1Hz to 10Hz and the primary voltage regulation bandwidth of each virtual synchronous generator from 30Hz to 50Hz. The parameter selection range for the medium dynamic independent subsystem includes the virtual inertia time constant from 0.5s to 5s and the energy storage charge and discharge response coefficient from 0.1 to 0.5. The parameter selection range for the slow dynamic independent subsystem includes the charging load power distribution adjustment step size from 5kW to 20kW. The parameter matching constraints across time scales include the frequency domain isolation difference constraint between the fast dynamic bandwidth and the medium dynamic response coefficient, and the response speed matching constraint between the medium dynamic inertia time constant and the slow dynamic power adjustment step size. All internal parameter selection ranges and cross-time scale parameter matching constraints are integrated and summarized into a constraint set in a unified text format. This constraint set is the collaborative design condition for the control parameters of the photovoltaic and energy storage equipment terminal.

[0021] Step 2: Based on the collaborative design conditions of the control parameters, determine the control parameters corresponding to the reduced-order expression, and determine the equivalent inertia value of the optical storage device terminal at the common coupling point through the real-time operating status data of each virtual synchronous generator device in the optical storage device terminal; In this embodiment of the invention, determining the control parameters corresponding to the reduced-order expression based on the control parameter co-design conditions includes: Extract the first frequency domain isolation constraint between the maximum power tracking control loop of the photovoltaic power generation equipment and the primary voltage regulation control loop of each virtual synchronous generator equipment from the collaborative design conditions of the control parameters; Extract the second response speed matching constraint between the charging and discharging management control link of the energy storage device and the virtual inertia control link of each virtual synchronous generator device from the collaborative design conditions of the control parameters; Based on the first frequency domain isolation constraint, the maximum power point tracking control parameters of the photovoltaic power generation equipment and the primary voltage regulation control parameters of each virtual synchronous generator equipment are determined, so that the response frequency of the maximum power point tracking control loop and the response frequency of the primary voltage regulation control loop maintain a preset frequency domain isolation band. Based on the second response speed matching constraint, the charging and discharging management control parameters of the energy storage device and the virtual inertia time constant and damping coefficient of each virtual synchronous generator device are determined so that the response speed of the charging and discharging management control link matches the response speed of the virtual inertia control link. Based on the first frequency domain isolation constraint and the second response speed matching constraint, the power allocation control parameters of the charging load device are determined, such that the response speed of the power allocation control loop is slower than the response speed of the virtual inertia control loop.

[0022] The step of determining the equivalent inertia value of the photovoltaic storage device terminal at the common coupling point using real-time operating status data of each virtual synchronous generator device in the photovoltaic storage device terminal includes: The virtual inertia time constant and real-time active power output value of each virtual synchronous generator device in the optical storage equipment terminal are collected to form the inertia contribution dataset of each virtual synchronous generator device. The sum of the real-time active power output values ​​of all virtual synchronous generator devices in the photovoltaic storage device terminal is calculated as the total active power output value of the photovoltaic storage device terminal at the common coupling point. Based on the ratio of the real-time active power output value of each virtual synchronous generator to the total active power output value, the inertia contribution weight coefficient of each virtual synchronous generator is determined. The virtual inertia time constant of each virtual synchronous generator device is multiplied by its corresponding inertia contribution weight coefficient, and all product results are summed. The summation result is used as the equivalent inertia value of the photovoltaic storage device terminal at the common coupling point.

[0023] Read the complete text set in the constraint storage unit of the control parameters collaborative design conditions of the photovoltaic and energy storage equipment terminal, filter the text entries in the text set that simultaneously record the frequency value range of the maximum power point tracking control link of the photovoltaic power generation equipment, the frequency value range of the primary voltage regulation control link of each virtual synchronous generator equipment, and the minimum frequency difference standard of the two types of links, extract the complete entry and save it separately, and define the extracted entry as the first frequency domain isolation constraint condition between the maximum power point tracking control link of the photovoltaic power generation equipment and the primary voltage regulation control link of each virtual synchronous generator equipment.

[0024] Read the complete text set in the constraint storage unit of the control parameters collaborative design conditions of the storage device terminal, filter the text entries in the text set that simultaneously record the response time interval of the energy storage device's charge and discharge management control link, the response time interval of the virtual inertia control link of each virtual synchronous generator device, and the standard of the response time difference between the two types of links, extract the complete entry and save it separately, and define the extracted entry as the second response speed matching constraint condition between the energy storage device's charge and discharge management control link and the virtual inertia control link of each virtual synchronous generator device.

[0025] The lower and upper limits of the response frequency of the maximum power point tracking (MPPT) control loop of the photovoltaic (PV) power generation equipment, the lower and upper limits of the response frequency of the primary voltage regulation control loop of each virtual synchronous generator (PSG) device, and the preset frequency isolation value (which can be selected within the range of 10Hz to 30Hz based on the actual system bandwidth) are read from the first frequency domain isolation constraint condition. The frequency boundary benchmark is obtained by adding the upper limit of the response frequency of the PV power point tracking control loop to the preset fixed value of the frequency domain isolation band, thus limiting the frequency of each virtual synchronous generator. The lower limit of the response frequency of the primary voltage regulation control loop of the photovoltaic power generation equipment is equal to the frequency boundary reference. The maximum power tracking bandwidth and power regulation ratio coefficient of the photovoltaic power generation equipment are determined according to the value boundary as the maximum power tracking control parameters of the photovoltaic power generation equipment. The proportional coefficient and integral coefficient of the primary voltage regulation loop of each virtual synchronous generator equipment are determined according to the value boundary as the primary voltage regulation control parameters of each virtual synchronous generator equipment. After both sets of parameters are completed, the response frequency of the maximum power tracking control loop of the photovoltaic power generation equipment and the response frequency of the primary voltage regulation control loop of each virtual synchronous generator equipment can stably maintain a preset frequency domain isolation band of 20 Hz.

[0026] The minimum and maximum response times of the energy storage device's charge / discharge management control link, the minimum and maximum response times of each virtual synchronous generator's virtual inertia control link, and the allowable difference of 600 milliseconds between the two types of links are read from the internal constraints of the second response speed matching condition. This limits the difference between the response times of any value in the energy storage device's charge / discharge management control link and the response times of any value in each virtual synchronous generator's virtual inertia control link to not exceed 600 milliseconds. Based on this boundary, the energy storage device's charge / discharge power adjustment ratio coefficient and charge / discharge switching delay parameter are determined as the energy storage device's charge / discharge management control parameters. Similarly, based on this boundary, the virtual inertia time constant and virtual damping coefficient of each virtual synchronous generator are determined as the virtual inertia control parameters of each virtual synchronous generator. After both sets of parameters are fully evaluated, the response speed of the energy storage device's charge / discharge management control link and the response speed of each virtual synchronous generator's virtual inertia control link are matched.

[0027] The frequency value boundary recorded by the first frequency domain isolation constraint and the response time value boundary recorded by the second response speed matching constraint are read synchronously. The minimum value of the complete adjustment time of the power distribution control loop of the charging load device is limited to be greater than the maximum value of the complete adjustment time of the virtual inertia control loop of each virtual synchronous generator device. The order of magnitude of the difference between the two durations is kept consistent to ensure the decoupling effectiveness of the slow dynamic loop to the fast dynamic loop. According to the duration boundary corresponding to the dual constraints, the single-step power adjustment amplitude and power distribution switching delay parameter of the charging load device are determined as the power distribution control parameters of the charging load device. After all the parameters are set, the response speed of the power distribution control loop of the charging load device remains slower than the response speed of the virtual inertia control loop of each virtual synchronous generator device.

[0028] The virtual inertia time constant and real-time active power output value are collected at fixed intervals by the local measurement and control loop of each virtual synchronous generator device within the photovoltaic storage equipment terminal. The collection period is uniformly set to 20 milliseconds. The collected virtual inertia time constant is taken from the fixed value stored in the solidified parameter storage unit of the virtual inertia control link of each virtual synchronous generator device. The collected real-time active power output value is obtained by converting the three-phase voltage sampling signal and three-phase current sampling signal at the output terminal of each virtual synchronous generator device point by point through active power calculation logic. Each virtual synchronous generator device corresponds to a set of one-to-one matched virtual inertia time constant and real-time active power output value. All the matched two sets of parameters are uniformly collected and summarized to form the inertia contribution dataset of each virtual synchronous generator device.

[0029] Extract the real-time active power output value corresponding to each virtual synchronous generator device within the inertia contribution dataset, and perform continuous accumulation operation on all real-time active power output values. The execution benchmark for the accumulation operation is that all entries in the dataset are read without omission. The real-time active power output value of any virtual synchronous generator device is not removed during the accumulation operation. After the accumulation operation is completed, a unique constant value is obtained. This constant value is defined as the total active power output value of the photovoltaic storage device terminal at the common coupling point.

[0030] Extract the real-time active power output value corresponding to a single virtual synchronous generator within the inertia contribution dataset. Use this value as the dividend and the total active power output value at the common coupling point as the divisor to perform a division operation. The division operation retains four significant decimal places as the result. The unique value obtained from this division operation represents the proportion of the active power output of the corresponding single virtual synchronous generator within the total active power output of the system. This proportion is directly defined as the inertia contribution weight coefficient of each virtual synchronous generator. Perform a complete division operation independently for each virtual synchronous generator in the dataset to obtain all inertia contribution weight coefficients corresponding to the number of virtual synchronous generators.

[0031] The virtual inertia time constant corresponding to a single virtual synchronous generator device within the inertia contribution dataset is extracted. This virtual inertia time constant is used as the multiplicand, and the inertia contribution weight coefficient generated by the same device is used as the multiplier to perform multiplication. Each virtual synchronous generator device independently completes the multiplication operation of its corresponding parameter. The product values ​​generated by all multiplication operations are collected and then continuously summed. The summation operation does not omit the product value corresponding to any device. After the summation operation is completed, a unique fixed value is obtained, which is directly used as the equivalent inertia value of the photovoltaic storage device terminal at the common coupling point.

[0032] Step 3: Based on the equivalent inertia value and the control parameters, and combined with the network impedance parameters of the photovoltaic storage device terminal, derive the time-domain response relationship between the voltage amplitude change and reactive power injection at the common coupling point of the photovoltaic storage device terminal, so as to generate a quantitative evaluation index of the inertia support capability of the photovoltaic storage device terminal. In this embodiment of the invention, the step of deriving the time-domain response relationship between the voltage amplitude change and reactive power injection at the common coupling point of the optical storage device terminal, based on the equivalent inertia value and the control parameter co-design conditions and in conjunction with the network impedance parameters of the optical storage device terminal, includes: Based on the control parameters and collaborative design conditions, the equivalent virtual inertia time constant and equivalent damping coefficient of the photovoltaic energy storage device terminal at the common coupling point are extracted from the virtual inertia time constant and damping coefficient of each virtual synchronous generator device. Based on the network impedance parameters of the optical storage device terminal, the line reactance parameters and line resistance parameters of each access branch from the common coupling point to the optical storage device terminal are extracted to generate the equivalent line impedance value at the common coupling point. Based on the equivalent virtual inertia time constant, the equivalent damping coefficient, and the equivalent line impedance value, a dynamic correlation between reactive power and voltage at the common coupling point of the photovoltaic storage device terminal is constructed. The dynamic correlation between reactive power and voltage represents the dynamic correspondence between the change in reactive power injection and the change in voltage amplitude at the common coupling point. The initial voltage amplitude of the photovoltaic storage device terminal at the common coupling point is obtained. Combined with the dynamic correlation between reactive power and voltage, the change in reactive power injection is solved in the time domain, and the time domain response relationship of the change in voltage amplitude as the reactive power injection changes is derived. The voltage response rise time parameter, voltage response settling time parameter, and steady-state voltage deviation parameter of the photovoltaic energy storage device terminal at the common coupling point in the time-domain response formula are used as the basic parameters for the quantitative evaluation index of the inertia support capability.

[0033] The quantitative evaluation index for the inertia support capability of the generated optical storage device terminal includes: Based on the voltage response rise time parameter and the equivalent inertia value, the inertia response speed index of the photovoltaic energy storage device terminal at the common coupling point is calculated. The inertia response speed index characterizes how quickly the voltage amplitude of the photovoltaic energy storage device terminal starts to respond after being subjected to reactive power disturbance. Based on the voltage response settling time parameter and the equivalent damping coefficient, the voltage recovery capability index of the photovoltaic energy storage device terminal at the common coupling point is calculated. The voltage recovery capability index characterizes the time required for the voltage amplitude of the photovoltaic energy storage device terminal to recover to a stable state after being subjected to reactive power disturbance. Based on the steady-state voltage deviation parameter and the change in reactive power injection, the voltage regulation accuracy index of the photovoltaic storage device terminal at the common coupling point is calculated. The voltage regulation accuracy index characterizes the steady-state deviation of the voltage amplitude of the photovoltaic storage device terminal from the initial voltage amplitude after the reactive power injection is completed. The inertia response speed index, the voltage recovery capability index, and the voltage regulation accuracy index are weighted and integrated to generate a quantitative evaluation index of the inertia support capability of the photovoltaic storage device terminal.

[0034] The system reads the complete text set of constraint storage units containing the collaborative design conditions of the control parameters of the optical storage equipment terminal. It then filters out complete text entries recording the value ranges of the virtual inertia time constants, damping coefficients, and equivalent weighted calculation rules for multiple virtual synchronous generators. The system extracts the virtual inertia time constants and damping coefficients of all individual virtual synchronous generators recorded in these entries. Using the same active power output weighted calculation logic as in the previous solution of the equivalent inertia value, the system multiplies the virtual inertia time constant of each virtual synchronous generator by its corresponding inertia contribution weight coefficient and sums the results to obtain the equivalent virtual inertia time constant of the optical storage equipment terminal at the common coupling point. Finally, it multiplies the damping coefficient of each virtual synchronous generator by its corresponding inertia contribution weight coefficient and sums the results to obtain the equivalent damping coefficient of the optical storage equipment terminal at the common coupling point.

[0035] It should be noted that both the equivalent virtual inertia time constant and the equivalent damping coefficient are per-unit converted values. In the actual physical equations, they need to be multiplied by the ratio of the square of the voltage reference value to the capacity reference value to achieve dimensional restoration, so as to ensure that the dimensions of the left and right sides of the subsequent differential equations are unified as power dimensions.

[0036] All network impedance parameters stored in the internal line impedance acquisition loop of the photovoltaic storage device terminal are read. The network impedance parameters are obtained by segment-by-segment conversion of the voltage drop and current values ​​under rated operating conditions of each access branch voltage transformer and current transformer. The line reactance parameters and line resistance parameters corresponding to each virtual synchronous generator access branch from the common coupling point are extracted one by one. The total equivalent resistance component is obtained by performing series accumulation operation on the line resistance parameters of all access branches, and the total equivalent reactance component is obtained by performing series accumulation operation on the line reactance parameters of all access branches. The total equivalent resistance component is used as the real part value and the total equivalent reactance component is used as the imaginary part value to complete the numerical combination. This combined value is defined as the equivalent line impedance value at the common coupling point.

[0037] The actual inertia coefficient, actual damping coefficient, and equivalent line impedance value, after being converted and restored from the above benchmark values, are substituted as fixed coefficients into the second-order dynamic differential equation construction logic. The left side of the differential equation sets the second-order derivative term, the first-order derivative term, and the steady-state term of the voltage amplitude change with respect to time. The second-order derivative term matches the inertial constraint relationship corresponding to the equivalent virtual inertia time constant, the first-order derivative term matches the oscillation suppression constraint relationship corresponding to the equivalent damping coefficient, and the steady-state term matches the reactive power-voltage static coupling constraint relationship corresponding to the equivalent line impedance value. The right side of the differential equation sets the reactive power injection change as the excitation input. The constructed differential equation fully characterizes the dynamic correspondence between the reactive power injection change and the voltage amplitude change at the common coupling point. This differential equation is defined as the reactive power-voltage dynamic correlation relationship of the photovoltaic storage device terminal at the common coupling point.

[0038] The voltage amplitude value collected during the steady-state operation of the voltage acquisition circuit at the common coupling point is read. This value is fixed as the initial voltage amplitude of the photovoltaic energy storage device terminal at the common coupling point. A fixed duration of 20 milliseconds is selected as the time-domain integration step size. The initial voltage amplitude is used as the differential equation to solve the initial boundary conditions. The change in reactive power injection is iteratively calculated step by step using a single-step explicit time-domain integration solution logic. After each integration calculation, the voltage amplitude change at the corresponding time is recorded. The iteration continues until the voltage amplitude change no longer produces a value fluctuation greater than one-thousandth of the rated voltage. The time values ​​and voltage amplitude change values ​​corresponding to all time nodes are summarized to form a corresponding mapping relationship. This mapping relationship completely describes the law of voltage amplitude change in the time domain as reactive power injection changes. The continuous expression corresponding to this mapping relationship is the time-domain response relationship.

[0039] Three sets of fixed basic parameters are extracted from the complete mapping data of the time-domain response relationship. The voltage response rise time parameter is the time from when the reactive power injection changes to when the voltage amplitude change reaches 90% of the steady-state value. The voltage response settling time parameter is the time from when the reactive power injection changes to when the voltage amplitude change fluctuation is less than one-thousandth of the rated voltage. The steady-state voltage deviation parameter is the absolute value of the constant difference between the voltage amplitude after the voltage amplitude stabilizes and the initial voltage amplitude. The three extracted time values ​​and difference values ​​are used as the basic parameters for the quantitative evaluation index of inertia support capability.

[0040] The voltage response rise time parameter is read, and the equivalent inertia value is used as the reference matching coefficient to complete the numerical conversion. The conversion operation uses the voltage response rise time parameter as the dividend and the equivalent inertia value as the divisor to perform the division operation. The division operation retains four significant digits after the decimal point to obtain a unique constant value. This constant value is defined as the inertia response speed index of the photovoltaic energy storage device terminal at the common coupling point. This index value directly corresponds to the judgment basis of how quickly the voltage amplitude of the photovoltaic energy storage device terminal starts to respond after being subjected to reactive power disturbance.

[0041] The duration value corresponding to the voltage response settling time parameter is read, and the equivalent damping coefficient is used as the reference matching coefficient to complete the numerical conversion. The conversion operation uses the voltage response settling time parameter as the dividend and the equivalent damping coefficient as the divisor to perform the division operation. The division operation retains four significant digits after the decimal point to obtain a unique constant value. This constant value is defined as the voltage recovery capability index of the photovoltaic energy storage device terminal at the common coupling point. This index value directly corresponds to the judgment basis of the time required for the voltage amplitude of the photovoltaic energy storage device terminal to recover to a stable state after being subjected to reactive power disturbance.

[0042] The difference value corresponding to the steady-state voltage deviation parameter is read, and the change in reactive power injection is used as the reference matching coefficient to complete the numerical conversion. The conversion operation uses the steady-state voltage deviation parameter as the dividend and the change in reactive power injection as the divisor to perform the division operation. The division operation retains four significant digits after the decimal point to obtain a unique constant value. This constant value is defined as the voltage regulation accuracy index of the photovoltaic energy storage device terminal at the common coupling point. This index value directly corresponds to the judgment basis of the steady-state deviation of the voltage amplitude of the photovoltaic energy storage device terminal after completing reactive power injection relative to the initial voltage amplitude.

[0043] The above three indicators are normalized: the rated voltage reference value and rated capacity reference value of the photovoltaic storage equipment terminal are obtained, the impedance reference value is calculated, and the rated nominal value of the virtual inertia time constant of each virtual synchronous generator equipment is taken as the time reference value. The inertia response speed index is divided by 1, the voltage recovery capability index is divided by the time reference value, and the voltage regulation accuracy index is divided by the impedance reference value to obtain three dimensionless normalized index values.

[0044] Three sets of fixed weighted values ​​are preset to perform weighted integration calculations on the three standardized index values ​​mentioned above. The inertia response speed index is matched with a fixed weight of 0.4, the voltage recovery capability index is matched with a fixed weight of 0.4, and the voltage regulation accuracy index is matched with a fixed weight of 0.2. The sum of the three sets of weighted values ​​is fixed to one. The inertia response speed index value is multiplied by its corresponding weighted value, the voltage recovery capability index value is multiplied by its corresponding weighted value, and the voltage regulation accuracy index value is multiplied by its corresponding weighted value. The product values ​​generated by the three sets of multiplication operations are then continuously summed. After the summation operation is completed, a unique fixed comprehensive value is obtained. This comprehensive value is directly defined as the quantitative evaluation index of the inertia support capability of the photovoltaic energy storage equipment terminal.

[0045] Step 4: The dynamic reactive power compensation command generated based on the quantitative evaluation index of inertia support capability is sent to the local control terminal of each virtual synchronous generator device to adjust the reactive power output value in real time, thereby completing the active voltage support control of the photovoltaic energy storage device terminal.

[0046] In this embodiment of the invention, the dynamic reactive power compensation command generated based on the quantitative evaluation index of inertia support capability includes: When the rate of change of light intensity in the environment where the optical storage device terminal is located exceeds a preset rate of change threshold, it is determined that the optical storage device terminal is in an extreme weather disturbance state. Based on the quantitative evaluation index of inertia support capability, the target value of total reactive power compensation that the photovoltaic storage equipment terminal needs to inject into the common coupling point under the extreme weather disturbance state is determined. Obtain the rated reactive capacity and real-time reactive power output value of each virtual synchronous generator device, and determine the remaining adjustable reactive capacity of each virtual synchronous generator device based on the difference between the rated reactive capacity and the real-time reactive power output value. Based on the proportion of the remaining adjustable reactive power capacity of each virtual synchronous generator to the total remaining adjustable reactive power capacity of all virtual synchronous generators, the total reactive power compensation target value is allocated to each virtual synchronous generator, resulting in reactive power compensation components corresponding to each virtual synchronous generator. The reactive power compensation components corresponding to each virtual synchronous generator device are combined according to the device identifier to generate the dynamic reactive power compensation instruction.

[0047] The real-time adjustment of the reactive power output value to achieve active voltage support control of the photovoltaic energy storage device terminal includes: The dynamic reactive power compensation command is sent to the local control terminal of each virtual synchronous generator device, and each local control terminal parses the reactive power compensation amount of its corresponding virtual synchronous generator device from the received dynamic reactive power compensation command. Each local control terminal generates a local reactive power adjustment signal based on the parsed reactive power compensation amount, and adjusts the reactive power output value of the virtual synchronous generator equipment according to the local reactive power adjustment signal; During the process of adjusting the reactive power output value of each virtual synchronous generator device, the real-time voltage amplitude of the photovoltaic storage device terminal at the common coupling point is continuously monitored; The real-time voltage amplitude is compared with the safe operating voltage range of the photovoltaic storage device terminal. When the real-time voltage amplitude is within the safe operating voltage range, it is determined that the photovoltaic storage device terminal has completed active voltage support control.

[0048] The system continuously acquires instantaneous ambient light intensity values ​​using a fixed 50-millisecond acquisition cycle from the site's light acquisition device. The difference between two consecutive sets of acquired values ​​is calculated and divided by the single acquisition interval to obtain the real-time light intensity change rate. A preset fixed light intensity change rate threshold is used as a unified judgment benchmark. The complete value of the real-time light intensity change rate is compared with the preset change rate threshold. When the real-time light intensity change rate is greater than the preset change rate threshold, the photovoltaic storage equipment terminal is directly determined to be in an extreme weather disturbance state.

[0049] Read the fixed values ​​of the quantitative evaluation index of the inertia support capability of the complete photovoltaic storage equipment terminal, establish the corresponding conversion logic between the index values ​​and the total reactive power compensation by preset fixed linear conversion coefficients, and perform multiplication operation on the quantitative evaluation index values ​​of inertia support capability and the linear conversion coefficients to obtain a unique constant reactive power value. This constant reactive power value is defined as the target value of total reactive power compensation that the photovoltaic storage equipment terminal needs to inject into the common coupling point under extreme weather disturbance conditions.

[0050] The fixed parameters of rated reactive power capacity, which are stored in the local storage unit of each virtual synchronous generator device, are retrieved. Simultaneously, the real-time reactive power output value of the current output circuit of each virtual synchronous generator device is acquired at a sampling period of 20 milliseconds. The rated reactive power capacity value of a single device is used as the minuend, and the real-time reactive power output value of the same device is used as the subtrahend to perform a subtraction operation. The non-negative constant value obtained by the subtraction operation is the remaining adjustable reactive power capacity of the corresponding virtual synchronous generator device. The complete subtraction operation is performed on all virtual synchronous generator devices one by one to obtain the corresponding total remaining adjustable reactive power capacity.

[0051] Extract the remaining adjustable reactive power capacity values ​​corresponding to all virtual synchronous generator devices and perform continuous summation to obtain the total remaining adjustable reactive power capacity. Use the remaining adjustable reactive power capacity value of a single virtual synchronous generator device as the dividend and the total remaining adjustable reactive power capacity as the divisor to perform division, retaining four significant decimal places to obtain the reactive power allocation ratio of a single device. Perform multiplication between the total reactive power compensation target value and the reactive power allocation ratio of a single device to obtain the corresponding reactive power adjustment value of a single device. This adjustment value is defined as the reactive power compensation component corresponding to each virtual synchronous generator device. Perform the allocation operation sequentially for all virtual synchronous generator devices to obtain the complete set of reactive power compensation components.

[0052] Retrieve the unique device identifier code configured at the factory for each virtual synchronous generator device, bind the device identifier code of a single device with the corresponding reactive power compensation component obtained from the calculation, and store the items. Integrate all the bound identifier and compensation component items into a standardized structured data set, which is defined as a dynamic reactive power compensation instruction.

[0053] The integrated dynamic reactive power compensation instructions are transmitted one by one to the local control terminals of all virtual synchronous generator devices through the communication link. Each local control terminal reads the complete structured data set of dynamic reactive power compensation instructions, retrieves the corresponding entry within the set that matches its own device identification code, and extracts the reactive power adjustment value recorded in the entry. The extracted adjustment value is the reactive power compensation amount of the corresponding virtual synchronous generator device.

[0054] The local control terminal of each virtual synchronous generator device inputs the retrieved reactive power compensation amount into the reactive power adjustment loop logic unit. The reactive power adjustment loop logic unit generates a continuous adjustment level signal with amplitude matching reactive power compensation amount successively according to a fixed unit reactive power adjustment step size. This level signal is defined as the local reactive power adjustment signal. The local reactive power adjustment signal is directly connected to the reactive power output control loop of the virtual synchronous generator device. The reactive power output control loop continuously adjusts the output duty cycle of the reactive power modulation link inside the device according to the level signal, thereby changing the reactive power output value of the virtual synchronous generator device.

[0055] During the complete period of reactive power value adjustment by the reactive power output control loop of each virtual synchronous generator, the voltage acquisition loop of the common coupling point continuously acquires and records the real-time voltage amplitude at the common coupling point at a fixed acquisition cycle of 20 milliseconds. The acquired voltage values ​​are uniformly stored in the voltage storage unit of the local control terminal for interval comparison and judgment.

[0056] The system reads the fixed upper and lower limits of the voltage safety operating range preset in the photovoltaic storage device terminal. The lower limit of the voltage safety operating range is 0.93 of the rated voltage per unit, and the upper limit of the voltage safety operating range is 1.07 of the rated voltage per unit. The system retrieves the complete value of the real-time voltage amplitude and compares it with the lower limit and upper limit of the range in sequence. When the real-time voltage amplitude is greater than or equal to the lower limit of the range and less than or equal to the upper limit of the range, it is directly determined that the photovoltaic storage device terminal has completed active voltage support control.

[0057] The preferred embodiment is applied to an integrated photovoltaic-storage-charging power station in an industrial and commercial park. The power station is equipped with four virtual synchronous generators (VSGs), each with a rated active power of 500 kW and a rated reactive power of 300 kW. The total capacity of the photovoltaic array is 1,800 kW, the total capacity of the energy storage PCS is 2,000 kW, and the total rated power of the charging pile cluster is 1,200 kW. There are four access branches from the power station to the common coupling point. The resistance and reactance parameters of each branch are measured offline by an impedance tester and recorded in the controller storage unit in advance. The power station is equipped with a light irradiance sensor, a grid connection point voltage sampling device, and local measurement and control terminals for each VSG. The controller works together to execute the complete control process of this invention. The preset threshold for the rate of change of light intensity is 100 W / (m²·s), and the safe operating range of voltage is set to 0.93 to 1.07 per unit of rated voltage. The standard response time constant, parameter constraint range, weighting coefficient, and integral step size of each control link all adopt the fixed reference values ​​recorded in the previous implementation process, completely reproducing the entire control logic.

[0058] The collaborative controller first collects the step response stability time constants of five control links: photovoltaic MPPT, energy storage charging and discharging, VSG virtual inertia, VSG primary voltage regulation, and charging pile power distribution. The corresponding values ​​are 20ms, 1800ms, 1200ms, 80ms, and 12000ms, respectively. Using 200ms and 10000ms as grouping thresholds, the controller divides the dynamic control characteristic groups into fast, medium, and slow groups. Based on the balanced truncation order reduction algorithm, the two groups of multi-link control groups are equivalently merged to generate three equivalent reduced-order sub-models. The controller identifies the two-layer dynamic interaction paths of fast to medium and medium to slow, and uses singular perturbation decoupling. The algorithm peels away cross-scale coupling terms layer by layer, integrates the parameter ranges of each link with cross-scale matching constraints to obtain the collaborative design conditions for control parameters. The constraints specify the frequency range of photovoltaic MPPT from 1 to 10 Hz and the frequency range of VSG primary voltage regulation from 30 to 50 Hz. The two types of links maintain a preset frequency domain isolation band. The difference in response time between energy storage charging and discharging and VSG inertia links does not exceed 600 milliseconds. The total power regulation time of the charging pile is greater than the longest regulation time of VSG inertia of 10,000 milliseconds. The controller strictly follows the constraints to complete the unified tuning of all control parameters, avoiding the power oscillation phenomenon caused by independent tuning of multiple control loop parameters.

[0059] The collaborative controller collects the virtual inertia time constants and real-time active power outputs of the four VSGs at a fixed 20-millisecond cycle to construct a complete inertia contribution dataset. The real-time active power outputs of the four devices are summed to obtain the total active power output at the common coupling point of the station. Based on the weighted calculation of the active power output ratio, the inertia contribution weight coefficients of each device are calculated. The inertia constant and weight coefficient are multiplied item by item and then summed to obtain the equivalent inertia value of the common coupling point of the station. The same weighting logic is used to extract the damping coefficients of the four VSGs, calculate the equivalent damping coefficient of the common coupling point, and read four data points. The measured resistance and reactance values ​​of the connected branch are summed in series to obtain the equivalent line impedance value. The equivalent virtual inertia time constant, equivalent damping coefficient, and equivalent line impedance value are substituted into the second-order reactive power-voltage dynamic differential equation to construct the dynamic correlation between reactive power and voltage. The steady-state voltage at the grid connection point is used as the initial voltage amplitude. An explicit time-domain iterative solution is carried out with an integration step size of 20 milliseconds. The time-domain response relationship between the voltage amplitude change and the reactive power injection is derived. From the relationship, three sets of basic parameters are extracted: voltage response rise time, settling time, and steady-state voltage deviation.

[0060] The controller combines the equivalent inertia value to calculate the inertia response speed index, the equivalent damping coefficient to calculate the voltage recovery capability index, and the reactive power change to calculate the voltage regulation accuracy index. It uses fixed weights of 0.4, 0.4, and 0.2 to complete the weighted summation of the three indexes and generate a quantitative evaluation index of the station's inertia support capability. The index value directly reflects the station's current voltage and reactive power support potential. This is different from the traditional scheme that relies solely on passive voltage amplitude adjustment, and it achieves pre-quantitative prediction of support capability.

[0061] The light sensor collects ambient light intensity at a 50-millisecond cycle and calculates the real-time light intensity change rate. When the value exceeds the preset change rate threshold, the station is determined to have entered an extreme weather disturbance state. Based on the linear conversion relationship, the station calculates the total reactive power compensation target value using the inertia support capacity quantitative evaluation index. The rated reactive power capacity and real-time reactive power output value of the four VSGs are retrieved, and the remaining adjustable reactive power capacity of each device is obtained by subtracting them one by one. After accumulating all the remaining capacity, the total reactive power compensation target is allocated according to the proportion of the remaining capacity of each device, generating a reactive power compensation component corresponding to each VSG. The unique identifier of the device is bound and integrated with the corresponding compensation component to generate a dynamic reactive power compensation command, which is sent to the local control terminal of the four VSGs through the communication link.

[0062] Each local control terminal analyzes its own matched reactive power compensation amount, generates a local reactive power adjustment signal according to a fixed adjustment step size, continuously adjusts the output duty cycle of the reactive power modulation link inside the VSG to change the reactive power output value, continuously collects the real-time voltage amplitude of the common coupling point throughout the adjustment process, continuously compares the real-time voltage with the upper and lower limits of the preset safe operating range, and terminates the reactive power adjustment process when the real-time voltage stably falls within the range, thus completing the active voltage support control of the station.

[0063] To verify the effectiveness of this invention, a photovoltaic-storage-charging system model identical to the aforementioned preferred embodiment was built using the MATLAB / Simulink simulation platform. The total photovoltaic capacity was 1800kW, the total energy storage PCS capacity was 2000kW, the total charging pile power was 1200kW, and four VSGs (Voltage Storage Generators) each had a capacity of 500kW / 300kvar. Line impedance parameters were the same as above. A unified test condition was set: initial illumination intensity of 1000W / m², which jumped to 200W / m² within 0.1s at t=5s and continued to operate under low illumination. The traditional comparative scheme uses a fixed droop coefficient VSG voltage regulation control, with the droop coefficient set according to the equipment's rated capacity, lacking multi-scale decoupling and adaptive inertia adjustment.

[0064] During the operation of this embodiment, a comparative test was conducted under extreme light drop conditions. Under the traditional fixed-parameter VSG voltage regulation scheme without multi-scale decoupling and inertia quantification evaluation, the maximum voltage drop at the grid connection point reached 0.12 per unit of the rated voltage, and the voltage recovery time reached 12 seconds. There were continuous small power oscillations during the adjustment process. After adopting the complete control process of this invention, the maximum voltage drop at the grid connection point under the same light disturbance conditions was only 0.03 per unit of the rated voltage, and the voltage recovery time was shortened to about 3 seconds. There were no power oscillations throughout the process. This demonstrates the effectiveness of multi-timescale decoupling constraints and equivalent inertia quantification index in suppressing grid connection point voltage deviation caused by severe photovoltaic fluctuations. Multi-timescale decoupling constraints are used to achieve coordinated matching of multi-unit parameters. The equivalent inertia quantification index is used to finely allocate reactive power compensation capacity. Combined with feedforward prediction of the rate of change of light, early intervention in disturbances is achieved, thereby weakening the grid connection point voltage deviation caused by severe photovoltaic fluctuations from a mechanistic perspective.

[0065] like Figure 2 The diagram shown is a functional block diagram of an active support and collaborative control system for photovoltaic energy storage and charging based on voltage stability, provided in an embodiment of the present invention.

[0066] The voltage-stable active support and coordinated control system M00 for optical storage and charging described in this invention can be installed in an electronic device. Depending on the functions implemented, the voltage-stable active support and coordinated control system M00 may include a control parameter coordination condition generation module M01, an equivalent inertia value determination module M02, an inertia support capability evaluation module M03, and an active voltage support execution module M04. The module described in this invention can also be called a unit, referring to a series of computer program segments that can be executed by the processor of an electronic device and perform a fixed function, stored in the memory of the electronic device.

[0067] In this embodiment, the functions of each module / unit are as follows: The control parameter coordination condition generation module M01 is used to decouple the dynamic coupling relationship between various control characteristics based on the reduced-order expression of the dynamic response relationship of multiple time scales in the optical storage device terminal, and generate the control parameter coordination design conditions of the optical storage device terminal. The equivalent inertia value determination module M02 is used to determine the control parameters corresponding to the reduced-order expression based on the control parameter collaborative design conditions, and to determine the equivalent inertia value of the optical storage device terminal at the common coupling point through the real-time operating status data of each virtual synchronous generator device in the optical storage device terminal; The inertia support capability assessment module M03 is used to derive the time-domain response relationship between the voltage amplitude change and reactive power injection of the optical storage device terminal at the common coupling point based on the equivalent inertia value and the control parameter design conditions, combined with the network impedance parameters of the optical storage device terminal, so as to generate a quantitative assessment index of the inertia support capability of the optical storage device terminal. The active voltage support execution module M04 is used to send the dynamic reactive power compensation command generated according to the quantitative evaluation index of inertia support capability to the local control terminal of each virtual synchronous generator device, and to adjust the reactive power output value in real time to complete the active voltage support control of the photovoltaic energy storage device terminal.

[0068] In the several embodiments provided by this invention, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and other division methods may be used in actual implementation.

[0069] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

Claims

1. A method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability, characterized in that, The method includes: Step 1: Based on the reduced-order expression of the dynamic response relationship of multiple time scales in the photovoltaic storage device terminal, decouple the dynamic coupling relationship between various control characteristics to generate the collaborative design conditions of the control parameters of the photovoltaic storage device terminal. Step 2: Based on the collaborative design conditions of the control parameters, determine the control parameters corresponding to the reduced-order expression, and determine the equivalent inertia value of the optical storage device terminal at the common coupling point through the real-time operating status data of each virtual synchronous generator device in the optical storage device terminal; Step 3: Based on the equivalent inertia value and the control parameters, and combined with the network impedance parameters of the photovoltaic storage device terminal, derive the time-domain response relationship between the voltage amplitude change and reactive power injection at the common coupling point of the photovoltaic storage device terminal, so as to generate a quantitative evaluation index of the inertia support capability of the photovoltaic storage device terminal. Step 4: The dynamic reactive power compensation command generated based on the quantitative evaluation index of inertia support capability is sent to the local control terminal of each virtual synchronous generator device to adjust the reactive power output value in real time, thereby completing the active voltage support control of the photovoltaic energy storage device terminal.

2. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 1, characterized in that, The reduced-order expression of the multi-timescale dynamic response relationship in the photovoltaic storage device terminal includes: The response time scales of the maximum power tracking control loop of the photovoltaic power generation equipment, the charge and discharge management control loop of the energy storage equipment, the virtual inertia control loop and primary voltage regulation control loop of each virtual synchronous generator equipment, and the power distribution control loop of the charging load equipment are obtained in the photovoltaic storage equipment terminal. According to the order of response time scale from shortest to longest, the maximum power point tracking control and the primary voltage regulation control are classified into the fast dynamic control characteristic group, the virtual inertia control and the charge / discharge management control are classified into the medium dynamic control characteristic group, and the power distribution control is classified into the slow dynamic control characteristic group. The fast dynamic control characteristic group, the medium dynamic control characteristic group, and the slow dynamic control characteristic group are respectively subjected to equivalent merging processing to obtain a reduced-order expression of the dynamic response relationship of multiple time scales in the optical storage device terminal.

3. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 2, characterized in that, The process of decoupling the dynamic coupling relationships between various control characteristics to generate collaborative design conditions for the control parameters of the optical storage device terminal includes: Based on the time scales corresponding to the fast dynamic control characteristic group, the medium dynamic control characteristic group, and the slow dynamic control characteristic group, the dynamic interaction path between adjacent time scale control characteristic groups is identified. The dynamic interaction path includes the fast disturbance propagation path from the fast dynamic control characteristic group to the medium dynamic control characteristic group, and the slow influence propagation path from the medium dynamic control characteristic group to the slow dynamic control characteristic group. Along the dynamic interaction path, starting with the fast dynamic control characteristic group with the shortest time scale, the dynamic coupling between the fast dynamic control characteristic group and the medium dynamic control characteristic group, as well as between the medium dynamic control characteristic group and the slow dynamic control characteristic group, are separated in sequence. The independent dynamic behaviors of each control characteristic group after separation are integrated into the overall control parameter collaborative design conditions of the optical storage device terminal. The collaborative design conditions include the parameter selection range of each control characteristic group on its own time scale and parameter matching constraints across time scales.

4. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 3, characterized in that, The step of determining the control parameters corresponding to the reduced-order expression based on the collaborative design conditions of the control parameters includes: Extract the first frequency domain isolation constraint between the maximum power tracking control loop of the photovoltaic power generation equipment and the primary voltage regulation control loop of each virtual synchronous generator equipment from the collaborative design conditions of the control parameters; Extract the second response speed matching constraint between the charging and discharging management control link of the energy storage device and the virtual inertia control link of each virtual synchronous generator device from the collaborative design conditions of the control parameters; Based on the first frequency domain isolation constraint, the maximum power point tracking control parameters of the photovoltaic power generation equipment and the primary voltage regulation control parameters of each virtual synchronous generator equipment are determined, so that the response frequency of the maximum power point tracking control loop and the response frequency of the primary voltage regulation control loop maintain a preset frequency domain isolation band. Based on the second response speed matching constraint, the charging and discharging management control parameters of the energy storage device and the virtual inertia time constant and damping coefficient of each virtual synchronous generator device are determined so that the response speed of the charging and discharging management control link matches the response speed of the virtual inertia control link. Based on the first frequency domain isolation constraint and the second response speed matching constraint, the power allocation control parameters of the charging load device are determined, such that the response speed of the power allocation control loop is slower than the response speed of the virtual inertia control loop.

5. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 4, characterized in that, The step of determining the equivalent inertia value of the photovoltaic storage device terminal at the common coupling point using real-time operating status data of each virtual synchronous generator device in the photovoltaic storage device terminal includes: The virtual inertia time constant and real-time active power output value of each virtual synchronous generator device in the optical storage equipment terminal are collected to form the inertia contribution dataset of each virtual synchronous generator device. The sum of the real-time active power output values ​​of all virtual synchronous generator devices in the photovoltaic storage device terminal is calculated as the total active power output value of the photovoltaic storage device terminal at the common coupling point. Based on the ratio of the real-time active power output value of each virtual synchronous generator to the total active power output value, the inertia contribution weight coefficient of each virtual synchronous generator is determined. The virtual inertia time constant of each virtual synchronous generator device is multiplied by its corresponding inertia contribution weight coefficient, and all product results are summed. The summation result is used as the equivalent inertia value of the photovoltaic storage device terminal at the common coupling point.

6. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 1, characterized in that, The step of deriving the time-domain response relationship between the voltage amplitude change and reactive power injection at the common coupling point of the optical storage device terminal, based on the equivalent inertia value and the control parameters in conjunction with the network impedance parameters of the optical storage device terminal, includes: Based on the control parameters and collaborative design conditions, the equivalent virtual inertia time constant and equivalent damping coefficient of the photovoltaic energy storage device terminal at the common coupling point are extracted from the virtual inertia time constant and damping coefficient of each virtual synchronous generator device. Based on the network impedance parameters of the optical storage device terminal, the line reactance parameters and line resistance parameters of each access branch from the common coupling point to the optical storage device terminal are extracted to generate the equivalent line impedance value at the common coupling point. Based on the equivalent virtual inertia time constant, the equivalent damping coefficient, and the equivalent line impedance value, a dynamic correlation between reactive power and voltage at the common coupling point of the photovoltaic storage device terminal is constructed. The dynamic correlation between reactive power and voltage represents the dynamic correspondence between the change in reactive power injection and the change in voltage amplitude at the common coupling point. The initial voltage amplitude of the photovoltaic storage device terminal at the common coupling point is obtained. Combined with the dynamic correlation between reactive power and voltage, the change in reactive power injection is solved in the time domain, and the time domain response relationship of the change in voltage amplitude as the reactive power injection changes is derived. The voltage response rise time parameter, voltage response settling time parameter, and steady-state voltage deviation parameter of the photovoltaic energy storage device terminal at the common coupling point in the time-domain response formula are used as the basic parameters for the quantitative evaluation index of the inertia support capability.

7. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 6, characterized in that, The quantitative evaluation index for the inertia support capability of the generated optical storage device terminal includes: Based on the voltage response rise time parameter and the equivalent inertia value, the inertia response speed index of the photovoltaic energy storage device terminal at the common coupling point is calculated. The inertia response speed index characterizes how quickly the voltage amplitude of the photovoltaic energy storage device terminal starts to respond after being subjected to reactive power disturbance. Based on the voltage response settling time parameter and the equivalent damping coefficient, the voltage recovery capability index of the photovoltaic energy storage device terminal at the common coupling point is calculated. The voltage recovery capability index characterizes the time required for the voltage amplitude of the photovoltaic energy storage device terminal to recover to a stable state after being subjected to reactive power disturbance. Based on the steady-state voltage deviation parameter and the change in reactive power injection, the voltage regulation accuracy index of the photovoltaic storage device terminal at the common coupling point is calculated. The voltage regulation accuracy index characterizes the steady-state deviation of the voltage amplitude of the photovoltaic storage device terminal from the initial voltage amplitude after the reactive power injection is completed. The inertia response speed index, the voltage recovery capability index, and the voltage regulation accuracy index are weighted and integrated to generate a quantitative evaluation index of the inertia support capability of the photovoltaic storage device terminal.

8. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 1, characterized in that, The dynamic reactive power compensation command generated based on the quantitative evaluation index of inertia support capability includes: When the rate of change of light intensity in the environment where the optical storage device terminal is located exceeds a preset rate of change threshold, it is determined that the optical storage device terminal is in an extreme weather disturbance state. Based on the quantitative evaluation index of inertia support capability, the target value of total reactive power compensation that the photovoltaic storage equipment terminal needs to inject into the common coupling point under the extreme weather disturbance state is determined. Obtain the rated reactive capacity and real-time reactive power output value of each virtual synchronous generator device, and determine the remaining adjustable reactive capacity of each virtual synchronous generator device based on the difference between the rated reactive capacity and the real-time reactive power output value. Based on the proportion of the remaining adjustable reactive power capacity of each virtual synchronous generator to the total remaining adjustable reactive power capacity of all virtual synchronous generators, the total reactive power compensation target value is allocated to each virtual synchronous generator, resulting in reactive power compensation components corresponding to each virtual synchronous generator. The reactive power compensation components corresponding to each virtual synchronous generator device are combined according to the device identifier to generate the dynamic reactive power compensation instruction.

9. The method for active support and coordinated control of photovoltaic energy storage and charging based on voltage stability as described in claim 8, characterized in that, The real-time adjustment of the reactive power output value to achieve active voltage support control of the photovoltaic energy storage device terminal includes: The dynamic reactive power compensation command is sent to the local control terminal of each virtual synchronous generator device, and each local control terminal parses the reactive power compensation amount of its corresponding virtual synchronous generator device from the received dynamic reactive power compensation command. Each local control terminal generates a local reactive power adjustment signal based on the parsed reactive power compensation amount, and adjusts the reactive power output value of the virtual synchronous generator equipment according to the local reactive power adjustment signal; During the process of adjusting the reactive power output value of each virtual synchronous generator device, the real-time voltage amplitude of the photovoltaic storage device terminal at the common coupling point is continuously monitored; The real-time voltage amplitude is compared with the safe operating voltage range of the photovoltaic storage device terminal. When the real-time voltage amplitude is within the safe operating voltage range, it is determined that the photovoltaic storage device terminal has completed active voltage support control.

10. A voltage-stable active support and coordinated control system for photovoltaic energy storage and charging, characterized in that, The system for implementing the voltage-stable active support and coordinated control method for photovoltaic energy storage and charging as described in claim 1 includes: The control parameter coordination condition generation module is used to decouple the dynamic coupling relationship between various control characteristics based on the reduced-order expression of the dynamic response relationship of multiple time scales in the optical storage device terminal, and generate the control parameter coordination design conditions of the optical storage device terminal. The equivalent inertia value determination module is used to determine the control parameters corresponding to the reduced-order expression based on the control parameter collaborative design conditions, and to determine the equivalent inertia value of the optical storage device terminal at the common coupling point through the real-time operating status data of each virtual synchronous generator device in the optical storage device terminal; The inertia support capability assessment module is used to derive the time-domain response relationship between the voltage amplitude change and reactive power injection of the optical storage device terminal at the common coupling point based on the equivalent inertia value and the control parameters, combined with the network impedance parameters of the optical storage device terminal, so as to generate a quantitative assessment index of the inertia support capability of the optical storage device terminal. The active voltage support execution module is used to send dynamic reactive power compensation commands generated based on the quantitative evaluation index of inertia support capability to the local control terminal of each virtual synchronous generator device, and to adjust the reactive power output value in real time to complete the active voltage support control of the photovoltaic energy storage device terminal.

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