Network construction type energy storage converter control method, device, equipment and medium

Abstract

The invention relates to the technical field of network construction type converters, and discloses a network construction type energy storage converter control method, device, equipment and medium, and the method comprises the steps: obtaining a power grid impedance parameter and charge state data of each energy storage unit through monitoring and converting three-phase voltage and current signals of a grid-connected point, generating a virtual impedance compensation voltage and a power correction signal; and the reference voltage is superposed to a basic voltage reference of the virtual synchronous generator to form a corrected reference voltage. And then a modulation signal is generated by adopting voltage outer loop-current inner loop double closed loop control to drive a converter to output, so that self-adaptive adjustment and balanced distribution of active power of each parallel energy storage unit are realized. In a weak power grid environment, the voltage supporting capability and the dynamic stability of the system can be improved, and the over-discharge of the SOC unit in the low state of charge is avoided.

Description

Technical Field

[0001] This invention relates to the field of grid-type converter technology, specifically to a grid-type energy storage converter control method, device, equipment, and medium. Background Technology

[0002] In recent years, with the rapid development of global renewable energy and distributed power generation technologies, power systems are gradually transforming from traditional centralized power generation to distributed and microgrid structures. Energy storage technology, as an important means of balancing the volatility of new energy sources and improving system stability, has received widespread attention for its application in the power grid. Traditional energy storage converters typically employ grid-following control strategies, achieving power transmission through two-stage power conversion. However, this method is prone to causing system frequency and voltage fluctuations under conditions of low-inertia grids and high proportion of new energy integration, thus affecting grid stability. The introduction of virtual synchronous generator (VSR) control technology provides energy storage converters with the possibility of simulating the dynamic characteristics of synchronous generators (such as inertia and damping), enabling energy storage devices to actively participate in frequency and voltage regulation and improve grid dynamic response. However, traditional VSR control strategies mostly use fixed parameters, making it difficult to adapt to dynamic changes in grid impedance and fluctuations in the energy storage system's own state of charge (SOC). This can lead to problems such as uneven power distribution, oscillations, and over-discharge of low-SOC units during actual system operation. At the same time, with the gradual promotion of grid-type power systems, how to achieve coordinated operation of multi-machine parallel energy storage converters in the power grid, improve overall power balance and dynamic response capabilities, has become an urgent technical problem to be solved.

[0003] While existing technologies have made some progress in virtual synchronous generator control and multi-unit parallel operation, several shortcomings remain. First, fixed-parameter virtual synchronous generator control cannot cope with dynamic changes in grid impedance and the state of charge (SOC) of energy storage units, easily leading to voltage and frequency regulation failures and consequently system instability. Second, in multi-unit parallel systems, when the SOC of each energy storage converter differs significantly, its active power output control strategy lacks an effective adaptive mechanism, potentially causing overload of units with low SOC, shortening equipment lifespan, or even causing power outages. Furthermore, existing methods typically rely on centralized control or communication coordination for power allocation, resulting in poor real-time performance and insufficient anti-interference capabilities. To address these shortcomings, this invention introduces dynamic coupling nonlinear integral calculation based on grid impedance parameters and SOC data to generate a real-time power correction signal. This correction signal is then superimposed and fused with the traditional virtual synchronous generator reference voltage and virtual impedance compensation voltage using a dual-closed-loop control structure, thereby achieving adaptive adjustment of the active power output of each energy storage converter and system-level power balancing. This technical solution not only breaks through the limitations of fixed parameters in traditional virtual synchronous generator control, but also significantly improves the stability and reliability of multi-machine parallel grid-type energy storage systems in weak grid environments through an active protection strategy for power derating of units under low charge state, providing a brand-new technical approach and solution for the construction of large-capacity microgrids. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a control method, device, equipment, and medium for grid-connected energy storage converters. This solves the problems of uneven power distribution, oscillation, and excessive discharge of low-charge-state (SOC) units caused by dynamic changes in grid impedance and uneven energy storage state of charge in the operation of multiple grid-connected energy storage converters in parallel.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a control method for a grid-type energy storage converter, characterized in that it includes: S1: Monitor the three-phase AC electrical quantities at the grid connection point of the energy storage converter and convert them into... stationary coordinate system and Electrical signal components in a rotating coordinate system; S2: Based on the above The electrical signal components in the stationary coordinate system are used to extract the harmonic components of the preset frequency through a composite filter, calculate the real-time grid impedance, and generate a virtual impedance compensation voltage. S3: Real-time acquisition of state-of-charge (SOC) data of each energy storage converter in a multi-machine parallel system; calculation of SOC deviation of each unit relative to the system average based on the SOC data; generation of power correction signal through dynamic coupling nonlinear integral operation in combination with grid impedance parameters; and adjustment of active power reference value of each energy storage converter according to the correction signal to trigger power derating of low SOC units and achieve system-level power balance distribution. S4: Superimpose the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal to generate the compensated voltage. The reference voltage is used to generate a modulation signal to drive the output of the energy storage converter through a dual closed-loop control of the voltage outer loop and the current inner loop. At the same time, the virtual impedance compensation voltage and power correction signal are dynamically updated according to real-time feedback data. S5: Real-time acquisition of AC side voltage, current, and state of charge data of each energy storage converter and energy storage unit; dynamic adjustment of virtual impedance compensation voltage based on updated grid impedance parameters; recalculation of power correction signal based on latest state of charge data; generation of new correction reference voltage and modulation signal based on the updated virtual impedance compensation voltage and power correction signal; driving energy storage converter to perform closed-loop adaptive adjustment until the system reaches dynamic stability.

[0006] Preferably, S1 further includes: The three-phase AC electrical quantities at the grid connection point of the energy storage converter are collected in real time using voltage transformers and current transformers; the three-phase AC electrical quantities include three-phase AC voltage signals and three-phase AC current signals. The real-time phase angle of the power grid is obtained through a phase-locked loop, and based on the real-time phase angle, the three-phase AC voltage signal and the three-phase AC current signal are sequentially converted to the desired values ​​using Clarke transform and Park transform. stationary coordinate system and Electrical signal components in a rotating coordinate system; the electrical signal components include Voltage components in stationary coordinate system Current components in a stationary coordinate system, and Voltage components in rotating coordinate system and Current components in a rotating coordinate system.

[0007] Preferably, S2 further includes: The Voltage components in stationary coordinate system and the The current component input in the stationary coordinate system is processed by the composite filter, which is composed of a second-order generalized integrator and a complex filter, to extract the preset frequency harmonic components; the preset frequency harmonic components include voltage harmonic components and current harmonic components at the preset frequency. The real-time grid impedance is calculated using the following formula:

[0008] in, This refers to the voltage harmonic components extracted by the composite filter at a preset frequency; This refers to the current harmonic components extracted by the composite filter at a preset frequency; This represents the real-time measured power grid resistance component; This represents the real-time measured power grid reactance component; Represents the imaginary unit; Based on the aforementioned grid impedance, the virtual impedance parameters are calculated using the following formula:

[0009]

[0010] in, and These represent the resistance and reactance components of the virtual impedance obtained in real time, respectively. and The preset virtual impedance scaling factor has a value range of [value range missing]. ; And according to the following formula The virtual impedance compensation voltage is generated in a rotating coordinate system:

[0011]

[0012] in, and They represent in In a rotating coordinate system, shaft and Virtual impedance compensation voltage in the axial direction; and These represent the output current of the energy storage converter at... coordinate system shaft and Axial components; The value is .

[0013] Preferably, the real-time acquisition of the state of charge (SOC) data of each energy storage converter in the multi-machine parallel system, and the calculation of the SOC deviation of each unit relative to the system average based on the SOC data, includes: The battery management system built into each energy storage converter collects the state of charge (SOC) data of each converter in real time and uploads it to the central controller. After synchronizing the SOC data, the central controller calculates the average SOC of the system according to the following formula:

[0014] in, This indicates the total number of parallel energy storage converters. Indicates the first Real-time state of charge of the energy storage converter; For each energy storage converter, its state of charge deviation relative to the average state of charge of the system is calculated based on the state of charge data, using the following formula: .

[0015] Preferably, the step of combining the grid impedance parameters and the state of charge deviation to generate a power correction signal through dynamically coupled nonlinear integral calculation, and adjusting the active power reference value of each energy storage converter according to the correction signal to trigger power derating of low state of charge units and achieve system-level power balancing, includes: The central controller, combining the grid resistance and reactance components measured in real time in the areas where each energy storage converter is located, generates a power correction signal using a dynamically coupled nonlinear integral operation. This dynamically coupled nonlinear integral operation employs an integral algorithm that combines grid impedance with exponentially weighted attenuation, and its mathematical expression is as follows:

[0016] in, For integration variables; This is the time decay constant, used to assign exponential decay weights to historical data during the integration process; The nonlinear adjustment index determines the degree of nonlinear influence of the state-of-charge deviation on the correction signal; For the integration period; Indicates the first The area where each energy storage unit is located at time Measured grid resistance; Indicates the first The area where each energy storage unit is located at time Measured grid reactance; Based on the power correction signal, the active power reference value of each energy storage converter is adjusted to generate a corrected active power reference value. The adjustment formula is as follows:

[0017] in, The preset state-of-charge protection threshold; Indicates the first The original active power reference value set for the energy storage converter; This is a normalization factor used to ensure that the adjustment range is reasonable. If the state of charge of a certain energy storage converter is lower than the threshold, the active power output of that unit is limited to protect the energy storage. Units with a higher state of charge can increase power generation to achieve power balance in the entire system.

[0018] Preferably, the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal are superimposed to generate the compensated voltage. Shaft reference voltage, including: The outer loop of a traditional virtual synchronous generator is calculated using preset base voltage, active power deviation, and primary frequency regulation coefficient. coordinate system The original reference voltage of the shaft is calculated using the following formula:

[0019] in, Preset base voltage; This is the primary frequency regulation coefficient, used to convert active power deviation into voltage correction. The active power deviation at the current moment is obtained from the difference between the preset active power reference value and the actual measured value. Simultaneously, using preset base voltage, reactive power deviation, and primary voltage regulation coefficient, the outer loop of the traditional virtual synchronous generator is calculated. coordinate system The original reference voltage of the shaft is calculated using the following formula:

[0020] in, This is the primary voltage regulation coefficient; This represents the reactive power deviation at the current moment. The power correction signal is converted into a voltage correction value according to a preset conversion factor, and combined with the virtual impedance compensation voltage, the final value is generated through a superposition formula. The shaft reference voltage is calculated using the following formula:

[0021]

[0022] in, Preset conversion factor; and This is the power allocation normalization factor.

[0023] Preferably, the step of generating a modulation signal to drive the energy storage converter output through dual closed-loop control of the voltage outer loop and the current inner loop, while dynamically updating the virtual impedance compensation voltage and power correction signal based on real-time feedback data, includes: The final Shaft reference voltage and measured voltage The shaft voltage component is input to the outer voltage loop of the dual closed-loop control system; the outer voltage loop uses a PI controller with proportional-integral parameters to generate a current reference signal using the following formula:

[0024]

[0025] in, and These are the voltage outer loop outputs. shaft current reference signal and Shaft current reference signal; and These are the voltage outer loop proportional control coefficient and the voltage outer loop integral control coefficient, respectively. and They are in coordinate system Real-time voltage components of the shaft and Real-time voltage components of the shaft; The inner current loop receives the current reference signal and compares it with the measured inductor current output by the LCL filter, and generates a modulation signal through PI control. The modulated signal is converted by the inverse Parker transform. The modulation component in the stationary coordinate system uses space vector pulse width modulation technology to generate the trigger signal for driving the power switch tube of the energy storage converter, and collects the output voltage and inductor current in real time to update the virtual impedance compensation voltage and power correction signal in a closed loop.

[0026] This invention also provides a grid-type energy storage converter control device, the device comprising: The multi-signal acquisition and coordinate transformation module is used to monitor the three-phase AC electrical quantities at the grid connection point of the energy storage converter and convert them into coordinates. stationary coordinate system and Electrical signal components in a rotating coordinate system; The composite filtering and virtual impedance calculation module is used to calculate based on the above. The electrical signal components in the stationary coordinate system are used to extract the harmonic components of the preset frequency through a composite filter, calculate the real-time grid impedance, and generate a virtual impedance compensation voltage. The state-of-charge (POC) sensitive power correction module is used to collect the POC data of each energy storage converter in a multi-machine parallel system in real time. Based on the POC data, it calculates the POC deviation of each unit relative to the system average value. Combining the grid impedance parameters with the POC deviation, it generates a power correction signal through dynamic coupling nonlinear integral operation. Based on the correction signal, it adjusts the active power reference value of each energy storage converter to trigger power derating of low POC units and achieve system-level power balance distribution. The reference voltage fusion and closed-loop modulation module is used to superimpose the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal to generate the compensated voltage. The reference voltage is used to generate a modulation signal to drive the output of the energy storage converter through a dual closed-loop control of the voltage outer loop and the current inner loop. At the same time, the virtual impedance compensation voltage and power correction signal are dynamically updated according to real-time feedback data. The real-time feedback and adaptive update module is used to collect AC side voltage and current of each energy storage converter and state of charge data of the energy storage unit in real time. It dynamically adjusts the virtual impedance compensation voltage according to the updated grid impedance parameters, and recalculates the power correction signal based on the latest state of charge data. Based on the updated virtual impedance compensation voltage and power correction signal, a new correction reference voltage and modulation signal are generated to drive the energy storage converter to perform closed-loop adaptive adjustment until the system reaches a dynamic stable state.

[0027] This invention also provides an electronic device, including at least one processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the grid-type energy storage converter control method as described in any one of claims 1 to 7.

[0028] This invention also provides a computer-readable storage medium storing a computer program, characterized in that: the computer program is executed by a processor to implement the method as described in any one of claims 1-7.

[0029] (III) Beneficial Effects Compared with the prior art, the present invention provides a control method for grid-type energy storage converters, which has the following advantages: 1. This grid-connected energy storage converter control method employs an improved composite filter, consisting of a second-order generalized integrator (SOGI) and a complex filter (CCF), to extract high-resolution harmonics from the signal. It decomposes the actual impedance of the power grid into two components: resistance and reactance. Virtual impedance parameters are then dynamically calculated using a preset proportional coefficient, and a compensation voltage is generated through fractional operations. This technology can dynamically track changes in grid impedance and precisely compensate for voltage deviations caused by impedance fluctuations, thereby suppressing the risk of subsynchronous oscillations and enhancing the system's anti-disturbance capability.

[0030] 2. This grid-type energy storage converter control method accurately acquires the State of Charge (SOC) data of each energy storage unit through high-speed acquisition and time synchronization, and calculates the system average SOC and the deviation of each unit. Then, using an integral formula with exponential decay and nonlinear power-law adjustment characteristics, the SOC deviation is coupled with the grid impedance information of each region to generate a power correction signal. This correction signal is used to dynamically adjust the active power reference value of each energy storage converter, ensuring that units with low SOC can automatically reduce their output power to protect themselves, while allowing units with high SOC to moderately increase their output power, achieving a balanced power distribution across the entire system. This overcomes the shortcomings of traditional fixed-parameter control, which lacks the ability to dynamically adjust.

[0031] 3. This grid-connected energy storage converter control method calculates the original virtual synchronous generator reference voltage by presetting the base voltage and primary frequency and voltage regulation coefficients. Then, it superimposes the virtual impedance compensation voltage obtained in step S2 and the voltage correction amount calculated in step S3 to generate the final corrected dq-axis reference voltage. Next, by performing dual closed-loop PI control on this reference voltage and the actual measured signal, a corresponding current reference value is generated. This current reference value is then generated through inverse coordinate transformation and SVPWM / PWM modulation to control the switching trigger signal of the energy storage converter output. Simultaneously, this step also dynamically updates the virtual impedance and power correction signal through real-time feedback closed-loop updates, ensuring that the system maintains adaptive closed-loop control under grid disturbances and load changes, thereby achieving high-precision and stable power balance distribution. Attached Figure Description

[0032] Figure 1 A flowchart illustrating the control method for a grid-type energy storage converter is provided for embodiments of the present invention. Figure 2 This is a schematic block diagram of a grid-type energy storage converter control device disclosed in an embodiment of the present invention. Detailed Implementation

[0033] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0035] Please see Figure 1 , Figure 1 A flowchart illustrating a control method for a grid-type energy storage converter, as provided in this embodiment of the invention, includes: S1: Monitor the three-phase AC electrical quantities at the grid connection point of the energy storage converter and convert them into... stationary coordinate system and Electrical signal components in a rotating coordinate system; Furthermore, the three-phase AC electrical quantities at the grid connection point of the energy storage converter are collected in real time using voltage transformers and current transformers; the three-phase AC electrical quantities include three-phase AC voltage signals and three-phase AC current signals. The real-time phase angle of the power grid is obtained through a phase-locked loop, and based on the real-time phase angle, the three-phase AC voltage signal and the three-phase AC current signal are sequentially converted to the desired values ​​using Clarke transform and Park transform. stationary coordinate system and Electrical signal components in a rotating coordinate system; the electrical signal components include Voltage components in stationary coordinate system Current components in a stationary coordinate system, and Voltage components in rotating coordinate system and Current components in a rotating coordinate system.

[0036] Specifically, the three-phase AC voltage signal at the grid connection point of the energy storage converter is acquired in real time through voltage transformers and current transformers. and three-phase alternating current signal Subsequently, a phase-locked loop (PLL) is used to extract the real-time phase angle of the power grid from the acquired three-phase voltage signal. In its implementation, the PLL circuit compares the phase of the input voltage signal with that of the internal reference oscillator. Through phase comparison, low-pass filtering, and voltage-controlled oscillator modulation, it continuously adjusts the output until it is synchronized with the input signal, thereby obtaining an accurate real-time phase angle. This provides a reference phase for subsequent coordinate transformations.

[0037] Next, the obtained real-time phase angle of the power grid is used The signal in the three-phase stationary coordinate system is converted to the signal in the two-phase stationary coordinate system using Clarke transform. Components. Specifically, this involves linearly combining the input three-phase signals according to a predetermined transformation matrix, for example:

[0038] Similarly, a Clarke transform is performed on the current signal to obtain... , Then, the Park transform is performed, which utilizes the phase angle obtained from the PLL. Will Signal conversion from stationary coordinates to rotating coordinates Coordinate system, its formula is:

[0039] Similarly, the current signal is also obtained through the Park transform. , After the Clarke and Park transformations described above, the AC signal that originally varied sinusoidally with time is transformed into an approximate DC value in a rotating coordinate system. This value is used for instantaneous value acquisition and filtering calculations in the subsequent control process, while ensuring that the control system can perform fast and decoupled processing of voltage and current in a synchronous reference frame.

[0040] S2: Based on the above The electrical signal components in the stationary coordinate system are used to extract the harmonic components of the preset frequency through a composite filter, calculate the real-time grid impedance, and generate a virtual impedance compensation voltage. Furthermore, the aforementioned Voltage components in stationary coordinate system and the The current component input in the stationary coordinate system is processed by the composite filter, which is composed of a second-order generalized integrator and a complex filter, to extract the preset frequency harmonic components; the preset frequency harmonic components include voltage harmonic components and current harmonic components at the preset frequency. The real-time grid impedance is calculated using the following formula:

[0041] in, This refers to the voltage harmonic components extracted by the composite filter at a preset frequency; This refers to the current harmonic components extracted by the composite filter at a preset frequency; This represents the real-time measured power grid resistance component; This represents the real-time measured power grid reactance component; Represents the imaginary unit; Based on the aforementioned grid impedance, the virtual impedance parameters are calculated using the following formula:

[0042]

[0043] in, and These represent the resistance component and reactance component of the virtual impedance obtained in real time, respectively. and The preset virtual impedance scaling factor has a value range of [value range missing]. ; And according to the following formula The virtual impedance compensation voltage is generated in a rotating coordinate system:

[0044]

[0045] in, and They represent in In a rotating coordinate system, shaft and Virtual impedance compensation voltage in the axial direction; and These represent the output current of the energy storage converter at... coordinate system shaft and Axial components; The value is .

[0046] Specifically, based on the electrical signal components in the stationary coordinate system obtained in step S1, the grid impedance is calculated in real time, and a corresponding virtual impedance compensation voltage is generated. Specifically, the voltage components in the stationary coordinate system... , and current components , The input signal is fed into a composite filter consisting of a second-order generalized integrator (SOGI) and a complex coefficient filter (CCF) to extract the voltage and current harmonic components of the power grid at a preset frequency. This preset frequency is preferentially selected from the power grid fundamental frequency (e.g., 50Hz) or specific frequency components that may cause system oscillations, thereby achieving high-resolution extraction of the target frequency components. In this embodiment, the input signal is processed by the SOGI to generate two orthogonal output signals, whose corresponding transfer functions are as follows:

[0047]

[0048] in, This is the reference angular frequency in the design. The adjustment coefficient is used. Through these two channels, the signal output by SOGI and the resulting complex signal can be expressed as:

[0049]

[0050]

[0051] Next, a complex coefficient filter (CCF) is used to further filter out other frequency components in order to extract the preset frequency. The harmonic components. The CCF can be designed as a bandpass filter, and its complex transfer function can be expressed as:

[0052] in, This is the bandwidth parameter, which controls the frequency selectivity of the filter. When... At that time, At this point, the filter response reaches its maximum. The transfer function of the overall composite filter is:

[0053] In the time domain, the output of this composite filter is the extracted harmonic component at the preset frequency, denoted as:

[0054] in, and These represent amplitude and phase, respectively. Furthermore, to achieve complex decomposition in the time domain, those skilled in the art can use Discrete Fourier Transform (DFT) or algorithms based on orthogonal filters to directly combine the orthogonal signals output by SOGI into complex form, thereby achieving accurate quantitative extraction of harmonic components.

[0055] After processing with a composite filter, the voltage harmonic components at the corresponding frequency can be obtained. and current harmonic components (In complex form, including amplitude and phase information). Based on the extracted harmonic components, the real-time equivalent impedance of the power grid is calculated according to the real-time power grid impedance formula. This process decomposes the actual impedance of the power grid at the frequency of interest into two components: resistance and reactance, reflecting the current impedance characteristics of the power grid. The power grid resistance component... The active power damping of the grid-connected line is characterized by the grid reactance component, while the reactive power impedance (such as inductive reactance) of the grid-connected line is characterized by the reactive power impedance. Then, the controller uses the measured data... and The virtual impedance parameters are calculated according to a preset scaling factor to generate the required virtual impedance value. In the calculation formula for the virtual impedance parameters, an appropriate virtual impedance scaling factor is selected. and This allows the virtual impedance to be adjusted proportionally to the actual grid impedance, with the preferred value being... When the virtual impedance is equal to the current grid impedance, full compensation is achieved; choosing a smaller coefficient achieves partial compensation, thus balancing the system's voltage support capability and damping characteristics. Finally, based on the calculated virtual impedance, the corresponding virtual impedance compensation voltage is generated in a rotating coordinate system. and Virtual impedance compensation voltage and The calculation process is essentially equivalent to connecting a virtual impedance in series at the output of the converter. The voltage drop generated by the output current is considered. This voltage drop is added as a compensation to the converter's control reference (superimposed on the reference voltage in subsequent step S4) to offset the voltage deviation caused by the actual grid impedance, simulating the effect of connecting the converter to a virtual impedance. This is achieved through dynamic adjustment. The controller can track changes in grid impedance in real time: when grid impedance increases (in the case of a weak grid), the correspondingly increased compensation voltage can preemptively offset potential bus voltage drops; when grid impedance decreases (in the case of a stronger grid), the compensation amount automatically decreases, preventing the introduction of excessive losses. This technique, on the one hand, precisely compensates for output voltage deviations caused by grid impedance fluctuations, enhancing system voltage support and disturbance rejection capabilities; on the other hand, it provides additional damping when grid impedance changes abruptly, suppressing the risk of subsynchronous oscillations that may be caused by impedance mutations.

[0056] S3: Real-time acquisition of state-of-charge (SOC) data of each energy storage converter in a multi-machine parallel system; calculation of SOC deviation of each unit relative to the system average based on the SOC data; generation of power correction signal through dynamic coupling nonlinear integral operation in combination with grid impedance parameters; and adjustment of active power reference value of each energy storage converter according to the correction signal to trigger power derating of low SOC units and achieve system-level power balance distribution. Furthermore, the real-time acquisition of the state of charge (SOC) data of each energy storage converter in the multi-machine parallel system, and the calculation of the SOC deviation of each unit relative to the system average based on the SOC data, includes: The battery management system built into each energy storage converter collects the state of charge (SOC) data of each converter in real time and uploads it to the central controller. After synchronizing the SOC data, the central controller calculates the average SOC of the system according to the following formula:

[0057] in, This indicates the total number of parallel energy storage converters. Indicates the first Real-time state of charge of the energy storage converter; For each energy storage converter, its state of charge deviation relative to the average state of charge of the system is calculated based on the state of charge data, using the following formula: .

[0058] Furthermore, the step of combining the grid impedance parameters and the state of charge deviation to generate a power correction signal through dynamically coupled nonlinear integral calculation, and adjusting the active power reference value of each energy storage converter according to the correction signal to trigger power derating of low state of charge units and achieve system-level power balancing, includes: The central controller, combining the grid resistance and reactance components measured in real time in the areas where each energy storage converter is located, generates a power correction signal using a dynamically coupled nonlinear integral operation. This dynamically coupled nonlinear integral operation employs an integral algorithm that combines grid impedance with exponentially weighted attenuation, and its mathematical expression is as follows:

[0059] in, For integration variables; This is the time decay constant, used to assign exponential decay weights to historical data during the integration process; The nonlinear adjustment index determines the degree of nonlinear influence of the state-of-charge deviation on the correction signal; For the integration period; Indicates the first The area where each energy storage unit is located at time Measured grid resistance; Indicates the first The area where each energy storage unit is located at time Measured grid reactance; Based on the power correction signal, the active power reference value of each energy storage converter is adjusted to generate a corrected active power reference value. The adjustment formula is as follows:

[0060] in, The preset state-of-charge protection threshold; Indicates the first The original active power reference value set for the energy storage converter; This is a normalization factor used to ensure that the adjustment range is reasonable. If the state of charge of a certain energy storage converter is lower than the threshold, the active power output of that unit is limited to protect the energy storage. Units with a higher state of charge can increase power generation to achieve power balance in the entire system.

[0061] Specifically, the current state of charge (SOC) percentage of the battery in each energy storage converter is obtained through its built-in Battery Management System (BMS). The SOC data of all energy storage units is uploaded to the central controller via a high-speed communication network. The central controller performs time synchronization processing on the received SOC data to ensure that the SOC values ​​of each unit are comparable under the same time reference, avoiding deviations caused by communication delays. Then, the average SOC of the system and the deviation of each converter from the average value are calculated, and the SOC deviation value of each energy storage converter is then calculated; for the first... Taiwan energy storage converter, This indicates the degree of deviation of its current state of charge (SOC) from the system average. When the value is negative, it indicates that the state of charge (SOC) of the energy storage unit is lower than the system average (relatively insufficient energy). A positive value indicates that the state of charge (SOC) of the cell is higher than the average level (relatively sufficient charge).

[0062] Based on each unit After obtaining the grid impedance parameters in step S2, this invention introduces a dynamically coupled nonlinear integral algorithm in the central controller to generate a power correction signal. This power correction signal characterizes the amount of active power correction required due to the imbalance of the State of Charge (SOC) of each unit. Specifically, an integrator with exponential decay memory is used to accumulate the SOC deviation, and the grid impedance is introduced as a coupling factor to adjust the contribution of each unit's deviation to the overall correction. In the power correction signal formula, the numerator is a weighted sum of the SOC deviations of each unit, with weighting coefficients of... This coefficient incorporates the grid impedance magnitude as a coupling factor; the denominator is the integral value of the exponentially decaying function over the same time interval, which is equivalent to normalizing the integral result of the numerator to ensure... The value of does not increase unbounded with the length of the integration time window. The result obtained through the above integration calculation... This reflects the active power correction value required by the system at the current moment, used to correct power distribution deviations caused by differences in the State of Charge (SOC) of each energy storage unit. Introducing an exponentially decaying weight in the dynamic integral calculation is to make the controller pay more attention to recent changes in SOC deviation. Specifically, relatively new SOC deviation signals are multiplied by a larger weight. (when The weights are close to 0 (i.e., close to the current time, with weights approaching 1), while earlier deviations are due to... The larger the value, the higher its weight. This significantly reduces outdated information, thus gradually "forgetting" it. This design avoids the excessive influence of historical accumulated biases on current control, prevents overshoot caused by stale data, and makes power correction smoother. Simultaneously, by adjusting parameters... The value of can balance the response speed and stability of the State of Charge (SOC) equalization control: a larger value... This means a longer memory depth. The changes are smoother, but the equilibration process is relatively slow; smaller... This makes the integral more sensitive to newly emerging deviations and can correct state of charge (SOC) imbalances more quickly, but may introduce larger dynamic fluctuations. Therefore, The settings can be configured according to the system's requirements for dynamic response speed and stability to achieve optimal control performance. Grid impedance is embedded as a coupling factor in the power correction calculation, aiming to coordinate the SOC (State of Charge) equalization adjustment based on the strength of the connection between each energy storage converter and the grid. For a given unit... If the equivalent impedance magnitude at its grid connection point A larger value indicates weak electrical coupling between the unit and the system, limiting its ability to influence the overall system through power adjustment in a parallel system. Therefore, the State of Charge (SOC) deviation term for this unit in the above equation is weakened by a larger denominator amplification factor (reduced weight) to avoid applying excessively strong power correction at weak coupling points, preventing local voltage fluctuations or instability. Conversely, for units with lower impedance and tighter coupling to the grid, their SOC deviation is given greater weight due to the smaller denominator, allowing these electrically connected units to undertake more power regulation tasks. Through this dynamic coupling design, the power correction signal... It can comprehensively consider the impedance characteristics of different energy storage units located in different grid locations, and more effectively achieve state of charge (SOC) equalization control while ensuring system stability. Furthermore, a power-law exponent is introduced into the SOC deviation. The nonlinear calculation is used to adjust the control response characteristics to different magnitudes of State of Charge (SOC) deviations. When In this case, the larger deviation value will be non-linearly amplified in the calculation, while the smaller deviation will have a relatively lower weight after being raised to the power of the power. This means that only when the state of charge (SOC) deviation is significant will the effect be amplified. This produces a more noticeable impact, thus avoiding unnecessary fluctuations caused by frequent adjustments to the power reference value due to slight deviations; conversely, when the state of charge (SOC) deviation is small and uniformly distributed, The value will also approach zero, keeping the system in its original power distribution state. However, if you choose... (For example, 0.5) will amplify small deviations, potentially driving adjustment as soon as slight unevenness in the state of charge (SOC) appears. In this embodiment, a value of 0.5 is preferred. (That is, the SOC deviation is squared) to achieve a nonlinear response characteristic of "weakening small deviations and strengthening large deviations": when the SOC difference between energy storage units is small, the power correction amount does not change significantly, and the system output is stable; when some units have a significantly higher or lower SOC, the power correction amount will be increased, correspondingly strengthening the correction of the imbalance state. This is achieved by adjusting... This power-law parameter allows for flexible setting of the sensitivity and intensity of the State of Charge (SOC) equalization control, balancing system stability and equalization speed.

[0063] The above calculations yielded the following results. Subsequently, the controller adjusts the active power reference value of each energy storage converter accordingly based on the power correction signal, thereby correcting the output power distribution. Specifically, for each energy storage converter, its current state of charge (SOC) is compared with a preset SOC threshold. If a certain unit of Below the threshold If the current state is low, the active power reference value of the unit will be set to 50% of the original reference value (i.e., the power will be dragged to half of its original value); if If the charge level is above the threshold, the state of charge is considered normal. The base power reference output by this unit remains unchanged according to the original strategy, with an additional power correction amount added. To simplify control and ensure fairness, the power correction amount... The correction is evenly distributed among all cells with a State of Charge (SOC) above the threshold, and the number of cells participating in this distribution is denoted as . Then the active power reference value of each normal unit increases from the original value. For example, when no cells are in a low-charge state (SOC), All units adjust their output power equally; if there are The state of charge (SOC) of each cell is below the threshold. Then this Each unit reduces its reference power to half of its original value, and the rest... The power correction amount is distributed equally among all units, i.e. Each normal unit increases Through the above logic, each energy storage converter obtains a calibrated active power reference value, enabling dynamic adjustment of power commands.

[0064] In the power reference adjustment strategy described above, the State of Charge (SOC) threshold... The selection of the "0.5" derating factor is crucial and should be set appropriately based on the characteristics of the system and battery. This is used to determine whether the state of charge (SOC) of the energy storage unit is too low, so as to trigger protective measures in a timely manner. In this embodiment, tests were conducted on the relationship between the discharge efficiency and SOC of the lithium-ion battery. When the SOC is below 20%, the discharge efficiency drops sharply from 95% to 60%, while the internal resistance increases by 50%. Based on this, a threshold is set. The threshold is set to 20% of the rated capacity (i.e., when the remaining battery capacity is below 20%, it is considered a low state of charge). This value can be adjusted according to the specific battery's safe depth of discharge and lifespan requirements. For example, it is generally recommended to retain a certain margin for lithium batteries to prevent damage from over-discharge. By setting the threshold to 20%, the control strategy can be ensured to intervene in time when the capacity of a cell drops to a low level, limiting its power output and preventing continued rapid discharge that could lead to excessive battery depletion or even damage. At the same time, this threshold should not be too high to avoid prematurely limiting the output of normal cells—the 20% level ensures battery safety while allowing the energy storage cells to operate without derating for most of the operating time, without affecting the overall power supply capacity of the system.

[0065] Regarding the power derating ratio, this embodiment adopts a scheme that reduces the active power reference value of the low state of charge (SOC) unit to 50% of its original value. The design aims to achieve a balance between protecting the battery and maintaining system stability. On one hand, retaining 50% of the output power means that even if a unit is in a low state of charge, it still maintains half of its output power, ensuring it does not completely exit grid-connected operation, thus continuing to play a role in voltage support and frequency stability. On the other hand, halving the output power can significantly reduce the unit's discharge current and power burden, slowing down the rate of further decline in SOC, and even creating conditions for it to recover its SOC (e.g., by absorbing excess power to charge the battery in subsequent periods). Compared to completely cutting off the output or only slightly reducing the power, a 50% derating is a mild but effective measure: it avoids the disturbance to the system caused by sudden output stoppage while significantly reducing the battery's discharge pressure. By reasonably setting the above threshold... The derating factor effectively protects units with low state of charge (SOC) and extends battery life. Simultaneously, it works in conjunction with other units to moderately increase output power to share the system load, ensuring the continuity of system output power remains unaffected. In summary, the series of control measures in step S3 achieves an automatic derating mechanism when individual energy storage converters enter a low state of charge, with other units actively compensating. This gradually balances the SOC of each unit while meeting system power requirements, preventing over-discharging or over-charging of individual units, ultimately maintaining a balanced and stable SOC across the multi-unit system.

[0066] S4: Superimpose the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal to generate the compensated voltage. The reference voltage is used to generate a modulation signal to drive the output of the energy storage converter through a dual closed-loop control of the voltage outer loop and the current inner loop. At the same time, the virtual impedance compensation voltage and power correction signal are dynamically updated according to real-time feedback data. Furthermore, the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal are superimposed to generate the compensated voltage. Shaft reference voltage, including: The outer loop of a traditional virtual synchronous generator is calculated using preset base voltage, active power deviation, and primary frequency regulation coefficient. coordinate system The original reference voltage of the shaft is calculated using the following formula:

[0067] in, Preset base voltage; This is the primary frequency regulation coefficient, used to convert active power deviation into voltage correction. The active power deviation at the current moment is obtained from the difference between the preset active power reference value and the actual measured value. Simultaneously, using preset base voltage, reactive power deviation, and primary voltage regulation coefficient, the outer loop of the traditional virtual synchronous generator is calculated. coordinate system The original reference voltage of the shaft is calculated using the following formula:

[0068] in, This is the primary voltage regulation coefficient; This represents the reactive power deviation at the current moment. The power correction signal is converted into a voltage correction value according to a preset conversion factor, and combined with the virtual impedance compensation voltage, the final value is generated through a superposition formula. The shaft reference voltage is calculated using the following formula:

[0069]

[0070] in, Preset conversion factor; and This is the power allocation normalization factor.

[0071] Furthermore, the method of generating a modulation signal through dual closed-loop control of the voltage outer loop and the current inner loop to drive the energy storage converter output, and simultaneously dynamically updating the virtual impedance compensation voltage and power correction signal based on real-time feedback data, includes: The final Shaft reference voltage and measured voltage The shaft voltage component is input to the outer voltage loop of the dual closed-loop control system; the outer voltage loop uses a PI controller with proportional-integral parameters to generate a current reference signal using the following formula:

[0072]

[0073] in, and These are the voltage outer loop outputs. shaft current reference signal and Shaft current reference signal; and These are the voltage outer loop proportional control coefficient and the voltage outer loop integral control coefficient, respectively. and They are in coordinate system Real-time voltage components of the shaft and Real-time voltage components of the shaft; The inner current loop receives the current reference signal and compares it with the measured inductor current output by the LCL filter, and generates a modulation signal through PI control. The modulated signal is converted by the inverse Parker transform. The modulation component in the stationary coordinate system uses space vector pulse width modulation technology to generate the trigger signal for driving the power switch tube of the energy storage converter, and collects the output voltage and inductor current in real time to update the virtual impedance compensation voltage and power correction signal in a closed loop.

[0074] Specifically, the base voltage reference values ​​for the d-axis and q-axis are first generated using a traditional virtual synchronous generator (VSG) control algorithm. For The shaft's base voltage reference value is based on a preset base voltage. Real-time active power deviation and primary frequency modulation coefficient Calculations are performed, in which, The preset base value is to match the rated voltage amplitude of the power grid (e.g., 311V DC amplitude for a 220V AC system). This is the active power droop factor, with a value ranging from 0.1 to 0.5 V / kW, depending on the system's requirements for frequency regulation response speed. Active power deviation. The voltage amplitude is obtained by low-pass filtering the difference between the preset reference power and the measured value, and is used to dynamically adjust the voltage amplitude to achieve power balance. If multiple energy storage converters operate in parallel, the voltage amplitude of each unit... Allocation based on capacity ratio (e.g., units accounting for 30% of the capacity are allocated). This ensures that output is proportional to capacity. For Shaft, generation of base reference voltage, This is the reactive power droop factor (values ​​range from 0.05 to 0.2 V / kVar; this parameter can be adjusted through simulation or experimental debugging). To minimize the deviation between the preset reactive power and the measured value, adjustments are made. The shaft voltage component achieves a balanced distribution of reactive power.

[0075] After obtaining the base value, the power correction signal generated in step S3 is... According to the preset conversion factor This is converted to a voltage correction factor. This factor is set based on the rated relationship between system power and voltage. For example, when the rated power is 100kW and the target correction is ±5% of the base voltage, A value of 0.05 V / kW can be used. The power correction voltage and the virtual impedance compensation voltage calculated in step S2 are superimposed on the base reference voltage to obtain the final compensated reference voltage. During the superposition process, the normalization factor is adjusted. and This is used to allocate correction amounts based on the capacity weight of each energy storage unit. For example, if the system has Unit capacity is respectively The energy storage converter, then for the first Taiwan equipment, .

[0076] After compensation shaft and The shaft reference voltage is input to the outer voltage loop, and is compared with the actual voltage component. and The error is used to generate a current reference signal through a proportional-integral (PI) controller. The proportional coefficient... and The tuning needs to match the LCL filter parameters: for a typical filter (inductor) ,capacitance The voltage loop bandwidth is selected as 100 Hz. , This parameter enables the current reference to quickly track changes in the voltage reference while suppressing high-frequency disturbances.

[0077] The inner current loop receives a reference current from the outer loop and compares it with the inductor current output from the LCL filter. The error signal is then used by another set of PI controllers to generate a modulation voltage. The control equation for the current loop is:

[0078]

[0079] The current loop bandwidth is typically set to 2 kHz, parameters , Through the aforementioned PI regulation, the outer voltage loop generates corresponding current commands based on the deviation between the reference and measured voltages: when the actual output voltage is lower than the reference value, the PI regulator outputs a positive current reference, indicating that a larger current is needed to boost the voltage; conversely, when the voltage is higher, it outputs a negative current reference, reducing the current output to lower the voltage. The integral term in the PI controller ensures zero steady-state error, enabling the output voltage to strictly track the reference value. The output of the outer voltage loop sets a dynamic target for the inner current loop. Next, in the inner current loop, the value given by the outer voltage loop is... , The current error is compared with the actual measured inverter output inductor current (typically, the inductor current closest to the inverter side in the LCL filter is selected as the feedback to ensure direct control of the inverter output current). The current error is processed by a current PI regulator, and the output is... shaft and The modulated voltage signal of the shaft. The function of the inner current loop PI control is to quickly track the current command and offset current transients caused by load changes or power grid fluctuations, thereby stabilizing the output current. Thanks to the fast response of the inner current loop, the entire system can correct voltage deviations in a very short time when subjected to disturbances, greatly improving the bandwidth and stability of the control system. The outer voltage loop and the inner current loop form a cascaded control structure: the voltage loop is slower, focusing on eliminating steady-state errors and ensuring output accuracy; the current loop is faster, focusing on suppressing transient errors and ensuring rapid system stability. The parameters of the two loops can be tuned separately according to the system characteristics to achieve a trade-off between damping and dynamic performance optimization.

[0080] Current inner loop output , For rotation To apply the modulation signal in the coordinate system to a practical three-phase inverter, inverse coordinate transformation and PWM modulation are required. First, based on the synchronization phase angle provided by the phase-locked loop... ,Will , The modulation voltage components are converted back to the two-phase stationary coordinate system using the Park inverse transform, and then the corresponding three-phase modulation voltage command is obtained using the Clarke inverse transform. Subsequently, Space Vector Pulse Width Modulation (SVPWM) technology is used to generate the trigger signal sequence for driving the power switches of the energy storage converter bridge arm based on the obtained three-phase signals. SVPWM optimizes the selection of the conduction time of each switch by calculating the approximation of the three-phase modulation command in the finite switching state space of the inverter to achieve the required output voltage vector. Compared with traditional sinusoidal PWM, SVPWM makes fuller use of the DC bus voltage, reduces output harmonics, and improves the quality of the converter output voltage. While modulation is being executed, the controller continuously collects the converter output voltage and inductor current (feedback signal) in real time to update the virtual impedance compensation voltage and power correction signal in the next control cycle, realizing closed-loop dynamic adaptive control. Thus, through dual-loop control and SVPWM modulation, the three-phase AC voltage output by the energy storage converter is strictly regulated to follow the reference, maintaining the desired amplitude and phase while possessing good dynamic response. The dead time of the trigger pulse is set to 1 μs, and the switching frequency is set to 10 kHz to balance efficiency and harmonic suppression. The update period of the virtual impedance is set to 5 ms, and the grid impedance parameters are re-detected every cycle. The power correction signal related to the state of charge (SOC) is recalculated every 100 ms based on the latest SOC of the energy storage units. This dual-closed-loop dynamic adjustment mechanism ensures that the system can converge to a new steady state within 200 ms when the grid fluctuates or the load changes, achieving the control target that the difference in SOC between the energy storage units does not exceed ±5% and the voltage deviation is less than 2%.

[0081] S5: Real-time acquisition of AC side voltage, current, and state of charge data of each energy storage converter and energy storage unit; dynamic adjustment of virtual impedance compensation voltage based on updated grid impedance parameters; recalculation of power correction signal based on latest state of charge data; generation of new correction reference voltage and modulation signal based on the updated virtual impedance compensation voltage and power correction signal; driving energy storage converter to perform closed-loop adaptive adjustment until the system reaches dynamic stability.

[0082] Specifically, this step describes the cyclic execution and adaptive adjustment mechanism of the above control process. The controller continuously refreshes measurement data and control commands at a predetermined sampling period, gradually bringing the system to a stable state. Preferably, the sampling period for fast electrical quantities such as voltage and current can be set in the millisecond range (e.g., once every 20ms, i.e., refreshed 5 times per cycle; the specific frequency can be selected according to the converter switching frequency and control requirements), while slowly changing state quantities such as state of charge (SOC) can be updated over a longer period (e.g., acquiring the latest SOC data every 1-5 seconds). Within each control cycle, the central controller and each converter control unit collaboratively perform the following actions: First, acquire the latest three-phase AC side voltage and current signals through sensors and monitoring units, and acquire the current SOC percentage of each energy storage unit through the battery management system (BMS). Then, recalculate the virtual impedance compensation voltage using the newly updated grid impedance parameters. , For example, the controller calculates the equivalent grid impedance at this moment based on the latest voltage and current harmonic components, then updates the virtual impedance and generates the corresponding new compensation voltage value according to the method in step S2. Simultaneously, based on the latest acquired SOC data, the algorithm in step S3 is executed: the central controller compares the new SOC values ​​of each unit with the system average to obtain the current state of charge (SOC) deviation, and combines this with the latest measured impedance components of the region where each unit is located, using dynamically coupled nonlinear integral calculation to obtain a new power correction signal. As the grid impedance parameters and SOC data are continuously refreshed, the virtual impedance compensation voltage and power correction signal are also dynamically adjusted in each cycle, ensuring that the converter's reference voltage command always matches the current system state.

[0083] To obtain the updated virtual impedance compensation voltage , After adjusting the power correction, the controller adjusts the reference voltage and generates a new PWM modulation signal to drive the converter, achieving closed-loop adaptive control. That is, the superposition and dual-loop control process in step S4 is repeatedly executed in each control cycle: the new compensation voltage and correction are added to the base voltage reference to obtain a new... shaft and The axis reference voltage is used to adjust the converter output to track the reference voltage through voltage and current control loops. Since each adjustment is relatively small and continuous, the system output changes gradually, and the power distribution of each energy storage converter gradually tends towards equilibrium. During this continuous adaptive adjustment process, the controller needs to determine convergence criteria to judge when the system reaches a dynamic steady state. From a control perspective, convergence can be judged by monitoring the rate of change of the power correction signal or related state variables: for example, a threshold can be set, and when the change in the power correction signal gradually decreases and approaches zero (or fluctuates within a preset very small range) over several consecutive cycles, the power distribution of the system can be considered to have tended towards equilibrium; or, if the SOC deviation of each energy storage unit converges to a very small range (e.g., below 1%), and the output power command no longer undergoes significant adjustments, it indicates that the difference in the state of charge of each unit has been eliminated to a negligible level. When these conditions are met, it indicates that through repeated adjustments in the aforementioned steps, the system has entered a dynamic steady state. In this steady state, the active power reference value and output voltage of each energy storage converter remain near the new equilibrium point. Only routine fine-tuning is needed to cope with minor disturbances, without the need for major corrections. In other words, after a period of closed-loop adaptive adjustment, the output power of each converter is reasonably redistributed (the low-charge state of charge (SOC) units have been derated, and other units have completed compensation), the bus voltage and frequency of the entire parallel system remain constant, the SOC of multiple energy storage units remains balanced and stable, and the dynamic process ends.

[0084] In summary, the grid-connected energy storage converter control method provided by this invention achieves dynamic adaptive stability control of the energy storage converter in weak grid and multi-unit parallel environments through close coordination among its various steps. Utilizing real-time grid impedance identification and virtual impedance injection, the system gains rapid response capability to changes in grid conditions, significantly suppressing oscillations that may occur in weak grids. Combined with a state-of-charge (SOC) sensitive power correction and allocation strategy, it ensures balanced state of charge among multiple energy storage units, allowing low-SOC units to rest and high-SOC units to take on more output, avoiding over-discharge of individual units, thereby achieving balanced power output distribution and extending energy storage lifespan. Dual closed-loop control and SVPWM technology ensure stable and high-quality output voltage. Thanks to the above-mentioned coordinated control, even under extreme conditions of low grid inertia and severe fluctuations, the method of this invention can maintain reliable voltage stability and power sharing, significantly improving the system's disturbance rejection stability and power allocation accuracy, achieving technical effects that cannot be expected by existing technologies.

[0085] like Figure 2 As shown in the figure, an embodiment of the present invention also discloses a grid-type energy storage converter control device, the device comprising: The multi-signal acquisition and coordinate transformation module is used to monitor the three-phase AC electrical quantities at the grid connection point of the energy storage converter and convert them into coordinates. stationary coordinate system and Electrical signal components in a rotating coordinate system; The composite filtering and virtual impedance calculation module is used to calculate based on the above. The electrical signal components in the stationary coordinate system are used to extract the harmonic components of the preset frequency through a composite filter, calculate the real-time grid impedance, and generate a virtual impedance compensation voltage. The state-of-charge (POC) sensitive power correction module is used to collect the POC data of each energy storage converter in a multi-machine parallel system in real time. Based on the POC data, it calculates the POC deviation of each unit relative to the system average value. Combining the grid impedance parameters with the POC deviation, it generates a power correction signal through dynamic coupling nonlinear integral operation. Based on the correction signal, it adjusts the active power reference value of each energy storage converter to trigger power derating of low POC units and achieve system-level power balance distribution. The reference voltage fusion and closed-loop modulation module is used to superimpose the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal to generate the compensated voltage. The reference voltage is used to generate a modulation signal to drive the output of the energy storage converter through a dual closed-loop control of the voltage outer loop and the current inner loop. At the same time, the virtual impedance compensation voltage and power correction signal are dynamically updated according to real-time feedback data. The real-time feedback and adaptive update module is used to collect AC side voltage and current of each energy storage converter and state of charge data of the energy storage unit in real time. It dynamically adjusts the virtual impedance compensation voltage according to the updated grid impedance parameters, and recalculates the power correction signal based on the latest state of charge data. Based on the updated virtual impedance compensation voltage and power correction signal, a new correction reference voltage and modulation signal are generated to drive the energy storage converter to perform closed-loop adaptive adjustment until the system reaches a dynamic stable state.

[0086] This invention also discloses an electronic device, including at least one processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the processor executing the computer program to implement the method as described in the foregoing embodiments.

[0087] This invention also discloses a computer-readable storage medium storing a computer program, characterized in that the computer program is executed by a processor to implement the method described in the foregoing embodiments.

[0088] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, systems (apparatus), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0089] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A control method for a grid-type energy storage converter, characterized in that, include: S1: Monitor the three-phase AC electrical quantities at the grid connection point of the energy storage converter and convert them into... stationary coordinate system and Electrical signal components in a rotating coordinate system; S2: Based on the above The electrical signal components in the stationary coordinate system are used to extract the harmonic components of the preset frequency through a composite filter, calculate the real-time grid impedance, and generate a virtual impedance compensation voltage. S3: Real-time acquisition of state-of-charge (SOC) data of each energy storage converter in a multi-machine parallel system; calculation of SOC deviation of each unit relative to the system average based on the SOC data; generation of power correction signal through dynamic coupling nonlinear integral operation in combination with grid impedance parameters; and adjustment of active power reference value of each energy storage converter according to the correction signal to trigger power derating of low SOC units and achieve system-level power balance distribution. S4: Superimpose the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal to generate the compensated voltage. The reference voltage is used to generate a modulation signal to drive the output of the energy storage converter through a dual closed-loop control of the voltage outer loop and the current inner loop. At the same time, the virtual impedance compensation voltage and power correction signal are dynamically updated according to real-time feedback data. S5: Real-time acquisition of AC side voltage, current, and state of charge data of each energy storage converter and energy storage unit; dynamic adjustment of virtual impedance compensation voltage based on updated grid impedance parameters; recalculation of power correction signal based on latest state of charge data; generation of new correction reference voltage and modulation signal based on the updated virtual impedance compensation voltage and power correction signal; driving energy storage converter to perform closed-loop adaptive adjustment until the system reaches dynamic stability.

2. The control method for a grid-type energy storage converter according to claim 1, characterized in that, S1 further includes: The three-phase AC electrical quantities at the grid connection point of the energy storage converter are collected in real time using voltage transformers and current transformers; the three-phase AC electrical quantities include three-phase AC voltage signals and three-phase AC current signals. The real-time phase angle of the power grid is obtained through a phase-locked loop, and based on the real-time phase angle, the three-phase AC voltage signal and the three-phase AC current signal are sequentially converted to the desired values ​​using Clarke transform and Park transform. stationary coordinate system and Electrical signal components in a rotating coordinate system; the electrical signal components include Voltage components in stationary coordinate system Current components in a stationary coordinate system, and Voltage components in rotating coordinate system and Current components in a rotating coordinate system.

3. The control method for a grid-type energy storage converter according to claim 2, characterized in that, S2 further includes: The Voltage components in stationary coordinate system and the The current component input in the stationary coordinate system is processed by the composite filter, which is composed of a second-order generalized integrator and a complex filter, to extract the preset frequency harmonic components; the preset frequency harmonic components include voltage harmonic components and current harmonic components at the preset frequency. The real-time grid impedance is calculated using the following formula: ； in, This refers to the voltage harmonic components extracted by the composite filter at a preset frequency; This refers to the current harmonic components extracted by the composite filter at a preset frequency; This represents the real-time measured power grid resistance component; This represents the real-time measured power grid reactance component; Represents the imaginary unit; Based on the aforementioned grid impedance, the virtual impedance parameters are calculated using the following formula: ； ； in, and These represent the resistance and reactance components of the virtual impedance obtained in real time, respectively. and This is a preset virtual impedance scaling factor, with a value range of [value range missing]. ; And according to the following formula The virtual impedance compensation voltage is generated in a rotating coordinate system: ； ； in, and They represent in In a rotating coordinate system, shaft and Virtual impedance compensation voltage in the axial direction; and These represent the output current of the energy storage converter at... coordinate system shaft and Axial components; The value is .

4. The control method for a grid-type energy storage converter according to claim 3, characterized in that, The real-time acquisition of state-of-charge (POC) data of each energy storage converter in the multi-machine parallel system, and the calculation of the POC deviation of each unit relative to the system average based on the POC data, including: The battery management system built into each energy storage converter collects the state of charge (SOC) data of each converter in real time and uploads it to the central controller. After synchronizing the SOC data, the central controller calculates the average SOC of the system according to the following formula: ； in, This indicates the total number of parallel energy storage converters. Indicates the first Real-time state of charge of the energy storage converter; For each energy storage converter, its state of charge deviation relative to the average state of charge of the system is calculated based on the state of charge data, using the following formula: 。 5. The control method for a grid-type energy storage converter according to claim 4, characterized in that, The process of combining grid impedance parameters and the state-of-charge deviation to generate a power correction signal through dynamically coupled nonlinear integral calculation, and adjusting the active power reference value of each energy storage converter according to the correction signal, in order to trigger power derating of low-state-of-charge units and achieve system-level power balancing, includes: The central controller, combining the grid resistance and reactance components measured in real time in the areas where each energy storage converter is located, generates a power correction signal using a dynamically coupled nonlinear integral operation. This dynamically coupled nonlinear integral operation employs an integral algorithm that combines grid impedance with exponentially weighted attenuation, and its mathematical expression is as follows: ;in, For integration variables; This is the time decay constant, used to assign exponential decay weights to historical data during the integration process; The nonlinear adjustment index determines the degree of nonlinear influence of the state-of-charge deviation on the correction signal; For the integration period; Indicates the first The area where each energy storage unit is located at time Measured grid resistance; Indicates the first The area where each energy storage unit is located at time Measured grid reactance; Based on the power correction signal, the active power reference value of each energy storage converter is adjusted to generate a corrected active power reference value. The adjustment formula is as follows: ;in, The preset state-of-charge protection threshold; Indicates the first The original active power reference value set for the energy storage converter; This is a normalization factor used to ensure that the adjustment range is reasonable. If the state of charge of a certain energy storage converter is lower than the threshold, the active power output of that unit is limited to protect the energy storage. Units with a higher state of charge can increase power generation to achieve power balance in the entire system.

6. The control method for a grid-type energy storage converter according to claim 5, characterized in that, The base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal are superimposed to generate the compensated voltage. Shaft reference voltage, including: The outer loop of a traditional virtual synchronous generator is calculated using preset base voltage, active power deviation, and primary frequency regulation coefficient. coordinate system The original reference voltage of the shaft is calculated using the following formula: ； in, Preset base voltage; This is the primary frequency regulation coefficient, used to convert active power deviation into voltage correction. The active power deviation at the current moment is obtained from the difference between the preset active power reference value and the actual measured value. Simultaneously, using preset base voltage, reactive power deviation, and primary voltage regulation coefficient, the outer loop of the traditional virtual synchronous generator is calculated. coordinate system The original reference voltage of the shaft is calculated using the following formula: ； in, This is the primary voltage regulation coefficient; This represents the reactive power deviation at the current moment. The power correction signal is converted into a voltage correction value according to a preset conversion factor, and combined with the virtual impedance compensation voltage, the final value is generated through a superposition formula. The shaft reference voltage is calculated using the following formula: ； ； in, Preset conversion factor; and This is the power allocation normalization factor.

7. The control method for a grid-type energy storage converter according to claim 6, characterized in that, The method of generating a modulation signal through a dual closed-loop control of an outer voltage loop and an inner current loop to drive the output of the energy storage converter, and simultaneously dynamically updating the virtual impedance compensation voltage and power correction signal based on real-time feedback data, includes: The final Shaft reference voltage and measured voltage The shaft voltage component is input to the outer voltage loop of the dual closed-loop control system; the outer voltage loop uses a PI controller with proportional-integral parameters to generate a current reference signal using the following formula: ； ； in, and These are the voltage outer loop outputs. shaft current reference signal and Shaft current reference signal; and These are the voltage outer loop proportional control coefficient and the voltage outer loop integral control coefficient, respectively. and They are in coordinate system Real-time voltage components of the shaft and Real-time voltage components of the shaft; The inner current loop receives the current reference signal and compares it with the measured inductor current output by the LCL filter, and generates a modulation signal through PI control. The modulated signal is converted by the inverse Parker transform. The modulation component in the stationary coordinate system uses space vector pulse width modulation technology to generate the trigger signal for driving the power switch tube of the energy storage converter, and collects the output voltage and inductor current in real time to update the virtual impedance compensation voltage and power correction signal in a closed loop.

8. A grid-type energy storage converter control device, the device comprising: The multi-signal acquisition and coordinate transformation module is used to monitor the three-phase AC electrical quantities at the grid connection point of the energy storage converter and convert them into coordinates. stationary coordinate system and Electrical signal components in a rotating coordinate system; The composite filtering and virtual impedance calculation module is used to calculate based on the above. The electrical signal components in the stationary coordinate system are used to extract the harmonic components of the preset frequency through a composite filter, calculate the real-time grid impedance, and generate a virtual impedance compensation voltage. The state-of-charge (POC) sensitive power correction module is used to collect the POC data of each energy storage converter in a multi-machine parallel system in real time. Based on the POC data, it calculates the POC deviation of each unit relative to the system average value. Combining the grid impedance parameters with the POC deviation, it generates a power correction signal through dynamic coupling nonlinear integral operation. Based on the correction signal, it adjusts the active power reference value of each energy storage converter to trigger power derating of low POC units and achieve system-level power balance distribution. The reference voltage fusion and closed-loop modulation module is used to superimpose the base voltage reference value generated by the traditional virtual synchronous generator control, the virtual impedance compensation voltage, and the voltage correction amount generated based on the power correction signal to generate the compensated voltage. The reference voltage is used to generate a modulation signal to drive the output of the energy storage converter through a dual closed-loop control of the voltage outer loop and the current inner loop. At the same time, the virtual impedance compensation voltage and power correction signal are dynamically updated according to real-time feedback data. The real-time feedback and adaptive update module is used to collect AC side voltage and current of each energy storage converter and state of charge data of the energy storage unit in real time. It dynamically adjusts the virtual impedance compensation voltage according to the updated grid impedance parameters, and recalculates the power correction signal based on the latest state of charge data. Based on the updated virtual impedance compensation voltage and power correction signal, a new correction reference voltage and modulation signal are generated to drive the energy storage converter to perform closed-loop adaptive adjustment until the system reaches a dynamic stable state.

9. An electronic device comprising at least one processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the grid-type energy storage converter control method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: The computer program is executed by a processor to implement the grid-type energy storage converter control method as described in any one of claims 1-7.

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