Frequency stability control method and system for grid-forming type optical storage parallel system containing electric vehicle load

Abstract

The invention discloses a frequency stability control method and system for a network construction type optical storage parallel system containing an electric vehicle load. The method comprises the following steps: generating reference power; obtaining the state of charge (SOC) of an energy storage battery, a three-phase bus voltage instantaneous value # imgabs0 # and the maximum power # imgabs1 # of a photovoltaic panel, and calculating to generate a photovoltaic inverter reference active power # imgabs2 # and an energy storage inverter reference active power # imgabs3 #; calculating instantaneous power; the instantaneous active power # imgabs4 # and the instantaneous reactive power # imgabs5 # of the photovoltaic inverter and the instantaneous active power # imgabs6 # and the instantaneous reactive power # imgabs7 # of the energy storage inverter are calculated respectively; photovoltaic reserved capacity VSG control is carried out; energy storage constant-frequency VSG control is carried out; the system comprises a reference power generation module, an instantaneous power calculation module, a photovoltaic reserved capacity VSG control module, an energy storage constant frequency VSG control module and a PWM modulation module.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a frequency stabilization control method and system for a grid-connected photovoltaic and energy storage parallel system containing electric vehicle loads. Background Art

[0002] Against the backdrop of the continuous increase in the penetration rate of renewable energy, the power system is undergoing a profound transformation from the traditional synchronous motor-dominated mode to a new "double-high" architecture (high proportion of renewable energy and high proportion of power electronic equipment). This structural change significantly reduces the system's rotational inertia, causing the power grid to gradually show weak grid characteristics. The resulting stability issues have become a key bottleneck restricting the large-scale development of new energy. Focusing on the photovoltaic-storage parallel microgrid, its typical control architecture is as follows: the photovoltaic inverter adopts a grid-following control strategy to achieve stable power output according to the upper current command; the energy storage converter is mostly configured with a grid-forming control mode, assuming the core function of bus voltage and frequency support. However, due to the inherent capacity scale of the microgrid and the insufficient system inertia, the access of electric vehicle loads will bring challenges to the stable operation of the system. Unlike traditional steady-state loads, electric vehicle loads have the characteristics of high power demand and fast charging and discharging speed. The input of electric vehicle loads will lead to drastic changes in system load power, causing serious frequency deviations in the system frequency, and then triggering chain reactions such as unit disconnection.

[0003] Some literature has conducted research on improving the stability of grid-connected photovoltaic and energy storage parallel systems: The article entitled "Active Oscillation Suppression Strategy for Diesel-Storage Microgrid Based on Active Proportional Differential Feedforward VSG" (Renewable Energy, 2024) improves the traditional grid control technology based on the principle of damping compensation, optimizes the system damping characteristics, improves the steady-state control accuracy of the output power of the photovoltaic and energy storage grid-connected units, and reduces the reserve demand for system energy storage power. On this basis, the parameters of the grid controller are quantitatively evaluated by using frequency security warning and controller dynamic performance constraints, and a frequency support control strategy for the grid-connected photovoltaic and energy storage system based on damping compensation is proposed. However, the proposed frequency stability control strategy has limited applicability in off-grid operation mode, especially in application scenarios where the capacity of the photovoltaic and energy storage parallel system is limited, and its control performance needs to be further optimized.

[0004] The article titled "Transient Stability Analysis of Grid-Connected System of Photovoltaic Energy Storage with Improved VSG Grid-Forming Inverter" (Control Engineering, 2025) takes the grid connection of a photovoltaic energy storage system through VSG as the research object, introduces an improved first-order inertia link based on the tanh function into the inertia to achieve smooth adjustment of the inertia during the system's adaptive process. In addition, aiming at problems such as power angle instability that may occur when the system suffers large disturbances, the selection of parameter damping and inertia is optimized, and the influence of VSG external characteristic parameters on transient stability is analyzed. However, the proposed optimization method can only improve the power angle stability of the system and is difficult to improve the frequency stability. In addition, the proposed method does not consider the influence of the state of charge of the energy storage system, which may cause overcharge / overdischarge problems of the energy storage battery. Summary of the Invention

[0005] In view of this, the present invention provides a frequency stability control method and system for a grid-forming photovoltaic energy storage parallel system containing electric vehicle loads, so as to at least solve the problem that the traditional control method in the prior art is difficult to improve the frequency stability.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A frequency stability control method for a grid-forming photovoltaic energy storage parallel system containing electric vehicle loads, characterized by comprising the following steps: Generate reference power; obtain the state of charge SOC of the energy storage battery, the instantaneous value of the three-phase bus voltage and the maximum power of the photovoltaic panel Calculate and generate the reference active power of the photovoltaic inverter and the reference active power of the energy storage inverter ; Calculate the instantaneous power; according to the sampled instantaneous values of the three-phase output voltages and the instantaneous values of the three-phase output currents of the photovoltaic inverter, calculate the instantaneous active power and the instantaneous reactive power of the photovoltaic inverter respectively; according to the sampled instantaneous values of the three-phase output voltages and the instantaneous values of the three-phase output currents of the energy storage inverter, calculate the instantaneous active power and the instantaneous reactive power of the energy storage inverter respectively; Photovoltaic reserved capacity VSG control; according to the reference active power of the photovoltaic inverter, the instantaneous active power and the instantaneous reactive power of the photovoltaic inverter, calculate the phase and the amplitude of the internal potential of the photovoltaic inverter, and for the phase and the amplitude of the internal potential of the photovoltaic inverter Generate the modulation wave of the PV inverter through PWM modulation ; Energy storage constant-frequency VSG control; according to the reference active power of the energy storage inverter , the instantaneous active power of the energy storage inverter and the instantaneous reactive power calculate the phase of the internal electromotive force of the energy storage inverter and its amplitude , and perform PWM modulation on the phase of the internal electromotive force of the energy storage inverter and amplitude to generate the modulation wave of the energy storage inverter .

[0007] Preferably, the specific content of generating the reference power includes: ; wherein, is the integral coefficient of the reference power of the energy storage inverter; and are respectively the proportional coefficient and integral coefficient of the bus voltage frequency-locked loop; is the q-axis component of the bus voltage, which is generated by the instantaneous values of the three-phase bus voltage through dq transformation, is the rated frequency of the system; is the angular frequency of the bus voltage.

[0008] Preferably, the specific content of calculating the phase of the internal electromotive force of the PV inverter and its amplitude includes: ; wherein, and and are respectively the virtual inertia, droop coefficient and instantaneous value of angular frequency of the PV reserved capacity VSG control; , and are respectively the excitation control coefficient, reactive power droop coefficient and reference reactive power of the PV reserved capacity VSG control, is the rated voltage of the system, is the rated frequency of the system.

[0009] Preferably, the specific content of calculating the phase of the internal electromotive force of the energy storage inverter and its amplitude includes: ; wherein, and are the virtual inertia, droop coefficient, and instantaneous angular frequency value of the energy storage constant-frequency VSG control, respectively; and are the excitation control coefficient, reactive power droop coefficient, and reference reactive power of the energy storage constant-frequency VSG control, respectively, is the rated voltage of the system, is the rated frequency of the system.

[0010] The frequency stability control system of the network-forming photovoltaic and energy storage parallel system with electric vehicle loads includes: a reference power generation module, an instantaneous power calculation module, a photovoltaic reserved capacity VSG control module, an energy storage constant-frequency VSG control module, and a PWM modulation module; The reference power generation module is used to obtain the state of charge SOC of the energy storage battery, the instantaneous value of the three-phase bus voltage and the maximum power of the photovoltaic panel to calculate and generate the reference active power of the photovoltaic inverter and the reference active power of the energy storage inverter ; The instantaneous power calculation module is used to calculate the instantaneous active power and the instantaneous reactive power of the photovoltaic inverter respectively according to the instantaneous value of the three-phase output voltage and the instantaneous value of the three-phase output current sampled from the photovoltaic inverter; to calculate the instantaneous active power and the instantaneous reactive power of the energy storage inverter respectively according to the instantaneous value of the three-phase output voltage and the instantaneous value of the three-phase output current sampled from the energy storage inverter; The photovoltaic reserved capacity VSG control module is used to calculate the phase and amplitude of the internal potential of the photovoltaic inverter according to the reference active power of the photovoltaic inverter, the instantaneous active power and the instantaneous reactive power ; The energy storage constant-frequency VSG control module is used to calculate the phase and amplitude of the internal potential of the energy storage inverter according to the reference active power of the energy storage inverter, the instantaneous active power and the instantaneous reactive power ; The PWM modulation module is used to perform PWM modulation on the phase and amplitude of the internal potential of the photovoltaic inverter to generate the modulation wave , and the potential phase and amplitude in the energy storage inverter are PWM - modulated to generate the modulation wave of the energy storage inverter .

[0011] It can be seen from the above - mentioned technical solutions that, compared with the prior art, the present invention discloses a frequency - stability control method for a grid - forming type photovoltaic - energy storage parallel system with electric - vehicle loads, which has the following beneficial effects: In the present invention, the photovoltaic inverter adopts a reserved - capacity control strategy and realizes coordinated operation with the energy storage system by dynamically adjusting the power - output margin. When the electric - vehicle load is connected to the micro - grid, the photovoltaic inverter and the energy storage inverter can jointly support the change of the load power, significantly reducing the amplitude of the frequency drop caused by load mutation, and the maximum deviation of the system frequency is significantly reduced compared with the traditional control method; In terms of system - frequency regulation, the energy storage inverter applies a constant - frequency control technology based on a phase - locked loop. By tracking the grid phase in real - time and implementing active - power compensation, the frequency fluctuation of the micro - grid is strictly controlled near the rated frequency, effectively improving the frequency stability of the photovoltaic - energy storage parallel system; The present invention effectively constructs a dynamic coupling mechanism between the SOC of the energy storage battery and the photovoltaic - power generation power. The power reference value of the photovoltaic inverter is adaptively generated by the SOC of the energy storage. When the SOC increases, the photovoltaic input power is reduced, and when the SOC is too low, the input power of the photovoltaic array is increased; this coordinated control strategy based on the energy state not only ensures good photovoltaic power - consumption ability but also avoids system instability caused by energy surplus. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following - described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0013] Figure 1 is the structure diagram of the grid - forming type photovoltaic - energy storage parallel system provided in this embodiment; Figure 2 is the control principle diagram of the frequency - stability control method for the grid - forming type photovoltaic - energy storage parallel system with electric - vehicle loads provided by the present invention; Figure 3 is the control principle diagram of the reference - power generation link in the frequency - stability control method for the grid - forming type photovoltaic - energy storage parallel system with electric - vehicle loads provided by the present invention; Figure 4 is the time - domain waveform diagram of the bus frequency when the photovoltaic - energy storage parallel system in this embodiment adopts traditional grid - following / grid - forming hybrid control; Figure 5 The time-domain waveform diagram of the bus frequency when the grid-connected photovoltaic and energy storage parallel system in this embodiment adopts the control method proposed by the present invention. Specific implementation manners

[0014] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0015] The present invention provides a frequency stability control method for a grid-forming photovoltaic and energy storage parallel system with electric vehicle loads, including the following steps: Generate reference power; obtain the state of charge SOC of the energy storage battery, the instantaneous values of the three-phase bus voltage and the maximum power of the photovoltaic panel Calculate and generate the reference active power of the photovoltaic inverter and the reference active power of the energy storage inverter ; Calculate the instantaneous power; according to the sampled instantaneous values of the three-phase output voltage and the instantaneous values of the three-phase output current of the photovoltaic inverter, calculate the instantaneous active power and the instantaneous reactive power of the photovoltaic inverter respectively; according to the sampled instantaneous values of the three-phase output voltage and the instantaneous values of the three-phase output current of the energy storage inverter, calculate the instantaneous active power and the instantaneous reactive power of the energy storage inverter respectively; Photovoltaic reserved capacity VSG control; according to the reference active power of the photovoltaic inverter, the instantaneous active power and the instantaneous reactive power of the photovoltaic inverter, calculate the phase and the amplitude of the internal potential of the photovoltaic inverter, and perform PWM modulation on the phase and the amplitude of the internal potential of the photovoltaic inverter to generate the modulation wave of the photovoltaic inverter; Energy storage constant frequency VSG control; according to the reference active power of the energy storage inverter, the instantaneous active power and the instantaneous reactive power of the energy storage inverter, calculate the phase and the amplitude , the potential phase in the energy storage inverter and amplitude are subjected to PWM modulation to generate the modulation wave of the energy storage inverter .

[0016] It should be noted that: Figure 1 is the structure diagram of the grid-forming photovoltaic and energy storage parallel system. In the figure, and are the output filter inductors of the photovoltaic inverter and the energy storage inverter respectively; and are the output filter capacitors of the photovoltaic inverter and the energy storage inverter respectively; and are the line impedances of the photovoltaic inverter and the energy storage inverter connected to the AC bus respectively; and are the instantaneous values of the output three-phase voltages of the photovoltaic inverter and the energy storage inverter respectively; is the instantaneous value of the three-phase voltage of the AC bus; and are the output three-phase currents of the photovoltaic inverter and the energy storage inverter respectively; and are the three-phase modulation waves of the photovoltaic inverter and the energy storage inverter respectively. and are the amplitudes of the internal potentials of the photovoltaic inverter and the energy storage inverter respectively, and are the phases of the internal potentials of the photovoltaic inverter and the energy storage inverter respectively. The photovoltaic inverter, the energy storage inverter and the load are connected to the same AC bus, and the load includes conventional steady-state loads and electric vehicle loads.

[0017] Figure 2 is the control schematic diagram of the method proposed by the present invention; Figure 3 is the control schematic diagram of the reference power generation link in the method proposed by the present invention.

[0018] In the present invention, the photovoltaic inverter adopts a reserved capacity control strategy to achieve coordinated operation with the energy storage system by dynamically adjusting the power output margin. When the electric vehicle load is connected to the microgrid, the photovoltaic inverter and the energy storage inverter can jointly support the load power change, significantly reducing the amplitude of frequency drop caused by load mutation. The maximum deviation of the system frequency is significantly reduced compared with the traditional control method. The energy storage inverter applies a constant frequency control technology based on a phase-locked loop. By tracking the grid phase in real time and implementing active power compensation, the frequency of the microgrid is strictly controlled near the rated frequency, effectively improving the frequency stability of the photovoltaic-storage parallel system. The present invention innovatively constructs a dynamic coupling mechanism between the SOC of the energy storage battery and the photovoltaic power generation. The power reference value of the photovoltaic inverter is adaptively generated by the SOC of the energy storage. When the SOC increases, the photovoltaic input power is reduced, and when the SOC is too low, the input power of the photovoltaic array is increased. This coordinated control strategy based on the energy state not only ensures good photovoltaic accommodation ability but also avoids system instability caused by energy surplus.

[0019] To further implement the above technical solution, the specific content of generating the reference power includes: ; Among them, is the integral coefficient of the reference power of the energy storage inverter; and are the proportional coefficient and integral coefficient of the bus voltage frequency-locked loop respectively; is the q-axis component of the bus voltage, which is generated by the instantaneous value of the three-phase bus voltage through dq transformation, is the rated frequency of the system; is the angular frequency of the bus voltage.

[0020] To further implement the above technical solution, the specific content of calculating the internal potential phase of the photovoltaic inverter and its amplitude includes: ; Among them, and and are the virtual inertia, droop coefficient, and instantaneous value of the angular frequency of the photovoltaic reserved capacity VSG control respectively; and are the excitation control coefficient, reactive power droop coefficient, and reference reactive power of the photovoltaic reserved capacity VSG control respectively, is the rated voltage of the system, is the rated frequency of the system.

[0021] To further implement the above technical solution, calculate the internal potential phase of the energy storage inverter and its amplitude The specific content includes: ; Among them, and are respectively the virtual inertia, droop coefficient and instantaneous value of angular frequency of the energy storage constant-frequency VSG control; and are respectively the excitation control coefficient, reactive power droop coefficient and reference reactive power of the energy storage constant-frequency VSG control, is the rated voltage of the system, is the rated frequency of the system.

[0022] The frequency stability control system of the grid-forming type photovoltaic and energy storage parallel system with electric vehicle load includes: a reference power generation module, an instantaneous power calculation module, a photovoltaic reserved capacity VSG control module, an energy storage constant-frequency VSG control module and a PWM modulation module; The reference power generation module is used to obtain the state of charge SOC of the energy storage battery, the instantaneous value of the three-phase bus voltage and the maximum power of the photovoltaic panel to calculate and generate the reference active power of the photovoltaic inverter and the reference active power of the energy storage inverter ; The instantaneous power calculation module is used to calculate the instantaneous active power of the photovoltaic inverter and the instantaneous reactive power , and the instantaneous active power of the energy storage inverter and the instantaneous reactive power ; The photovoltaic reserved capacity VSG control module is used to calculate the internal potential phase of the photovoltaic inverter according to the reference active power of the photovoltaic inverter , the instantaneous active power of the photovoltaic inverter and the instantaneous reactive power and its amplitude ; The energy storage constant-frequency VSG control module is used to calculate the internal potential phase of the energy storage inverter according to the reference active power of the energy storage inverter , the instantaneous active power of the energy storage inverter and the instantaneous reactive power and its amplitude ; The PWM modulation module is used to perform PWM modulation on the internal potential phase and amplitude of the photovoltaic inverter to generate the modulation wave of the photovoltaic inverter, and to perform PWM modulation on the internal potential phase and amplitude Generate the modulation wave of the energy storage inverter through PWM modulation 。

[0023] The present invention will be further described through specific experiments as follows: Figure 4 Fig. 1 is the time-domain waveform diagram of the bus frequency when the traditional grid-following / grid-forming hybrid control is adopted in the photovoltaic-storage parallel system. When the electric vehicle load is connected and disconnected, there are large time-domain offsets in the system frequency, and the frequency offsets are 2.42 rad / s and 2.06 rad / s respectively. Moreover, after the electric vehicle load is connected, it is difficult for the system frequency to recover to the rated frequency (314.16 rad / s).

[0024] Figure 5 Fig. 2 is the time-domain waveform diagram of the bus frequency when the control method proposed in the present invention is adopted in the photovoltaic-storage parallel system. When the electric vehicle load is connected and disconnected, the system frequency offset is significantly limited, and the frequency offsets are 0.33 rad / s and 0.35 rad / s respectively. Moreover, after the electric vehicle load is connected, the system frequency will quickly recover to the vicinity of the rated frequency (314.16 rad / s), and the system frequency is not affected by the load change. Compared with the traditional control method, the control method proposed in the present invention can make the grid-forming photovoltaic-storage parallel system have stronger frequency stability.

[0025] In this embodiment, it is considered that the power of the conventional steady-state load remains unchanged, and the power of the electric vehicle load will have a step change at a certain moment, thereby causing fluctuations in the load power.

[0026] Photovoltaic maximum power The measurement methods of SOC, as well as the parameter settings of the frequency-locked loop, photovoltaic VSG, and energy storage VSG links are relatively mature, so there is no need for excessive introduction.

[0027] Parameter settings determine the speed at which the reference power of the energy storage converter follows the frequency change. The larger , the faster the reference power of the energy storage converter changes, but being too large may cause instability in the energy storage VSG control. Therefore, in this embodiment, = 100 / S n , S n is the total rated capacity of the grid-forming photovoltaic-storage parallel system.

[0028] ​The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A frequency stability control method for a grid-connected photovoltaic and energy storage parallel system containing electric vehicle loads, characterized in that: The following steps are involved: Generate reference power; obtain the energy storage battery state of charge SOC and the instantaneous value of the three-phase bus voltage And the maximum power of photovoltaic panels Calculate and generate reference active power for photovoltaic inverter and energy storage inverter reference active power ; Calculate instantaneous power; based on the instantaneous value of the three-phase output voltage of the photovoltaic inverter obtained by sampling And the instantaneous value of three-phase output current , respectively calculate the instantaneous active power of the photovoltaic inverter and instantaneous reactive power ; According to the instantaneous value of the three-phase output voltage of the energy storage inverter obtained by sampling And the instantaneous value of three-phase output current , respectively calculate the instantaneous active power of the energy storage inverter and instantaneous reactive power ; Photovoltaic reserved capacity VSG control; according to the reference active power of the photovoltaic inverter , Photovoltaic inverter instantaneous active power and instantaneous reactive power Calculate the potential phase in the photovoltaic inverter and its amplitude , the potential phase in the photovoltaic inverter and amplitude Perform PWM modulation to generate photovoltaic inverter modulation wave ; Energy storage constant frequency VSG control; based on the energy storage inverter reference active power , Instantaneous active power of energy storage inverter and instantaneous reactive power Calculate the potential phase in the energy storage inverter and its amplitude , the potential phase in the energy storage inverter and amplitude Perform PWM modulation to generate energy storage inverter modulation wave .

2. The frequency stability control method of a grid-connected photovoltaic and energy storage parallel system containing electric vehicle loads according to claim 1 is characterized in that: The specific contents of generating reference power include: ； in, is the reference power integral coefficient of the energy storage inverter; and They are the proportional coefficient and integral coefficient of the bus voltage frequency-locked loop respectively; is the q-axis component of the bus voltage, which is the instantaneous value of the three-phase bus voltage Generated by dq transformation, is the system rated frequency; is the bus voltage angular frequency.

3. The frequency stability control method of a grid-connected photovoltaic and energy storage parallel system containing electric vehicle loads according to claim 1 is characterized in that: Calculate the potential phase in the photovoltaic inverter and its amplitude The specific contents include: ； in, and and They are the virtual inertia, droop coefficient and instantaneous value of angular frequency of photovoltaic reserved capacity VSG control respectively; , and They are the excitation control coefficient, reactive power droop coefficient and reference reactive power of the photovoltaic reserved capacity VSG control. is the system rated voltage, is the rated frequency of the system.

4. The frequency stability control method of a grid-connected photovoltaic and energy storage parallel system containing electric vehicle loads according to claim 1 is characterized in that: Calculate the potential phase in the energy storage inverter and its amplitude The specific contents include: ； in, and They are the virtual inertia, droop coefficient and instantaneous value of angular frequency of energy storage constant frequency VSG control respectively; and They are the excitation control coefficient, reactive power droop coefficient and reference reactive power of energy storage constant frequency VSG control, is the system rated voltage, is the rated frequency of the system.

5. A frequency stability control system for a grid-connected photovoltaic and energy storage parallel system containing electric vehicle loads, based on a frequency stability control method for a grid-connected photovoltaic and energy storage parallel system containing electric vehicle loads as described in any one of claims 1 to 4, characterized in that: include: Reference power generation module, instantaneous power calculation module, photovoltaic reserved capacity VSG control module, energy storage constant frequency VSG control module and PWM modulation module; Reference power generation module, used to obtain the energy storage battery state of charge SOC and the instantaneous value of the three-phase bus voltage And the maximum power of photovoltaic panels Calculate and generate reference active power for photovoltaic inverter and energy storage inverter reference active power ; The instantaneous power calculation module is used to calculate the instantaneous value of the three-phase output voltage of the photovoltaic inverter according to the sampling And the instantaneous value of three-phase output current , respectively calculate the instantaneous active power of the photovoltaic inverter and instantaneous reactive power ; According to the instantaneous value of the three-phase output voltage of the energy storage inverter obtained by sampling And the instantaneous value of three-phase output current , respectively calculate the instantaneous active power of the energy storage inverter and instantaneous reactive power ; Photovoltaic reserved capacity VSG control module is used to control the active power of the photovoltaic inverter according to the reference , Photovoltaic inverter instantaneous active power and instantaneous reactive power Calculate the potential phase in the photovoltaic inverter and its amplitude ; Energy storage constant frequency VSG control module, used to reference active power of energy storage inverter , Instantaneous active power of energy storage inverter and instantaneous reactive power Calculate the potential phase in the energy storage inverter and its amplitude ; PWM modulation module, used to adjust the potential phase in the photovoltaic inverter and amplitude Perform PWM modulation to generate photovoltaic inverter modulation wave , and the potential phase in the energy storage inverter and amplitude Perform PWM modulation to generate energy storage inverter modulation wave .

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