204 results about "Virtual synchronization" patented technology

The invention discloses a network construction type inverter for a photovoltaic energy storage system and a virtual synchronous machine control method. The network construction type inverter comprises an inverter power module and a central controller. The central controller is used for collecting power grid operation data in real time and generating a power grid impedance state vector through online impedance identification; and dynamically adjusting virtual inertia and damping parameters of the inverter power module according to the impedance state vector by using an adaptive mapping function so as to realize cooperative control and circulating current suppression between the modules. Performing stability boundary evaluation based on the adjusted parameters, then performing intelligent early warning of the photovoltaic energy storage system, and smoothly switching the operation mode of the inverter power module; according to the invention, through deep integration of a modular hardware architecture and intelligent adaptive control, the inverter has strong autonomous network construction capability, the problems of weak power grid adaptability and transient stability are effectively solved, and the dynamic response and reliability of a photovoltaic energy storage system are improved.

The invention discloses a grid-connected inverter control method, system and device and a medium. The method comprises the steps of obtaining a power grid operation parameter, a system power instruction and a direct current bus voltage provided by a photovoltaic side hybrid energy storage system; a virtual inertia parameter is dynamically adjusted through an active-frequency control loop of the virtual synchronous machine in combination with an adaptive inertia algorithm, and a virtual rotor angular speed and an active power reference value are obtained through calculation according to a second-order motion equation of the synchronous generator; in combination with a reactive power instruction, a virtual internal potential amplitude is calculated according to a reactive-voltage droop relation through a reactive-voltage control loop of the virtual synchronous machine; and generating a three-phase voltage reference signal of the grid-connected inverter through synchronous rotation coordinate transformation. According to the invention, the dynamic performance, the operation efficiency and the grid-connected stability of the system under complex working conditions are obviously improved.

The present invention discloses a charging and discharging control method and system for an electric vehicle based on virtual synchronization, and relates to the technical field of virtual synchronization. The method includes: establishing connection between a power grid and the electric vehicle, and acquiring a charging and discharging operation demand; acquiring, according to the charging and discharging operation demand, a corresponding control instruction and constraint condition, and executing a charging and discharging operation; and providing a human-computer interaction interface for measuring and settling charging and discharging energy, along with authentication. The present invention achieves efficient and coordinated charging and discharging control, precise measurement and convenient authentication, and improves availability and reliability of the system.

The invention discloses a wind and light energy storage power generation distribution control method and system. The method comprises the following steps: acquiring related parameters of a wind and light energy storage system; a multi-target control function is constructed based on a multi-target Harris eagle optimization algorithm, and system constraint conditions are combined in the directions of wind and light output fluctuation suppression, energy storage charge and discharge loss reduction and power grid supply and demand matching degree improvement; monitoring and adjusting the state of charge of the multi-mode hybrid energy storage unit through a wind storage combined wide-area SOC virtual synchronous control strategy, establishing association mapping and determining an initial threshold value; preliminarily distributing a power difference value between wind and light output and a power grid load by using the platform; iteratively optimizing the preliminary distribution power and then outputting target power; and sending a control instruction to realize real-time distribution. The number of the system is six, and all the units work cooperatively. According to the invention, the energy storage resource utilization efficiency and the system operation stability are improved, and the dynamic adaptation capability of the wind-solar energy storage system to the power grid load is enhanced.

The invention relates to an alternating-current trunk line or an alternating-current power distribution network, in particular to a method for improving the stability of a wind power system through combined control of network construction type energy storage and a nine-switch UPQC. The method comprises the following steps: firstly, proposing an active regulation and inertial support control method based on a virtual synchronous machine mechanism for network construction type energy storage; and secondly, by constructing a coordination control framework, dynamic response complementation of the energy storage system and the UPQC under disturbance is realized, so that the overall frequency stability and voltage supporting capability of the system are improved. And finally, building a system model in Matlab / Simulink, setting three typical working conditions of wind power fluctuation, frequency disturbance and serious voltage drop, and carrying out scheme validity verification. Simulation results show that the method can effectively stabilize the wind power output fluctuation, enhance the frequency and voltage support capability, and significantly improve the stability of a wind power system.

The invention discloses a village island micro-grid virtual synchronous machine parameter optimization and cooperative control method oriented to frequency support, and relates to the technical field of electrical automation, and the method comprises the steps: obtaining village power distribution network parameters and load side parameters, and basic technical parameters of each virtual synchronous machine unit; constructing a standard dynamic model of the virtual synchronous machine based on the obtained parameters; introducing uncertainty integrated design on the basis of the standard dynamic model of the virtual synchronous machine, and performing equivalent aggregation on all the virtual synchronous machines to obtain a virtual synchronous machine uncertainty model; based on the uncertainty model of the virtual synchronous machine, establishing a cooperative control model by taking system frequency fluctuation minimization as a target; and solving the cooperative control model by using a commercial solver, and solving the power of each device. According to the invention, by constructing an optimization and cooperative control mechanism oriented to frequency support, the problem of over-limit of frequency deviation and frequency change rate is effectively suppressed, and the dynamic response capability of the island micro-grid under the condition of sudden load change is improved.

The invention provides a network construction type bidirectional low-harmonic energy storage converter based on virtual synchronous control and an intelligent load identification method thereof, and belongs to the field of power electronics. The converter comprises a power module and a control module, wherein the power module is used for bidirectional conversion and output of electric energy; the control module comprises a virtual synchronous control module and a harmonic suppression control module, and the virtual synchronous control module adopts a virtual synchronous generator technology to realize active / reactive power bidirectional adjustment during electric energy bidirectional conversion of the power module and network construction level voltage and frequency support during electric energy output; and the harmonic suppression module is provided with a parallel QPR controller group (comprising a first QPR controller, a second QPR controller and a third QPR controller) which are used for processing third-time, fifth-time and seventh-time characteristic harmonics respectively and suppressing the characteristic harmonics of the electric energy output side of the power module. According to the invention, the dual modules are arranged in the control module, so that the cooperation of a network construction function and low harmonic output is realized, and the electric energy quality and the system operation stability are effectively improved.

The invention provides a method and a system for suppressing low-frequency oscillation of a network-forming converter under a weak power grid, and the method comprises the steps: obtaining a power grid short-circuit ratio through employing a preset dual-mode identification strategy, adaptively adjusting the control parameters of the network-forming converter through a preset parameter mapping relation, carrying out the stability sufficiency verification of the adjusted control parameters, and obtaining the low-frequency oscillation of the network-forming converter under the weak power grid. After verification is passed, the adjusted control parameters are applied to a virtual synchronous machine control algorithm to execute grid-connected control, low-frequency oscillation characteristics are extracted from monitored grid-connected point frequency signals, and an enhanced suppression mechanism is triggered after the low-frequency oscillation characteristics exceed a threshold value; real-time sensing of power grid intensity, multi-parameter collaborative adaptive adjustment, active monitoring and rapid suppression of low-frequency oscillation and continuous self-learning optimization are realized, stability adequacy check is realized, and the problem of low-frequency oscillation of a grid-forming converter under a weak power grid is effectively solved.

The invention relates to the technical field of distributed energy grid-connected control, in particular to an intelligent monitoring ball enhanced distributed power supply coordination pre-synchronization control method and system, and the method comprises the steps: deploying a master intelligent monitoring ball at a grid-connected point, deploying slave intelligent monitoring balls at the output ends of all distributed power supplies, and forming a star-shaped sensing network; based on a multi-objective optimization algorithm, calculating a pre-synchronization target parameter and an adjustment weight of each distributed power supply, and generating a coordination control instruction; the virtual synchronous motor module receives the coordination control instruction, dynamically adjusts a virtual inertia and a damping coefficient, and adjusts output voltage, frequency and phase through a pre-synchronization execution unit; and after the synchronization reaches the standard, sequentially closing the grid-connected switches according to a preset power supply response priority sequence to complete the grid-connected action. According to the invention, a technical architecture of global monitoring-coordinated decision-precise execution-closed loop optimization is constructed, so that the stability and precise control problem during high-permeability distributed energy grid connection is solved.

The invention belongs to the technical field related to operation control of a power system, and provides a transient instability judgment method and system of a network-building type converter in order to solve the problem that an existing transient instability judgment method of the network-building type converter is prone to causing maloperation or missed judgment of a control strategy, and a nonlinear equivalent circuit model of the network-building type converter is established. Calculating transient total energy and critical instability energy of the system in real time, and adaptively switching a control mode according to the magnitude relationship of the transient total energy and the critical instability energy; during normal operation, an original control strategy of the virtual synchronous machine is maintained, and oscillation is suppressed by using the damping characteristic of the virtual synchronous machine, so that the voltage and frequency supporting capacity of a power grid is maximized; and when an instability risk is detected, entering a fault ride-through mode to realize rapid and accurate identification and control of the instability risk.

The invention discloses a dual-frequency positive-sequence impedance modeling method for a network-building type energy storage converter considering frequency coupling. The method comprises the following steps: 1, injecting a dual-frequency positive-sequence disturbance voltage signal at a grid-connected point of the network-building type energy storage converter based on a virtual synchronous machine; 2, establishing a linearized small signal model for each control link of an active-frequency loop, a reactive-voltage loop, a virtual impedance-containing voltage and current double closed loop and the like to form a multi-frequency signal model; and 3, according to the multi-frequency coupling relationship between the current and the voltage, constructing a frequency coupling impedance matrix, and reducing a coupling term into output impedance to obtain the positive sequence output impedance and the negative sequence output impedance of the converter considering the frequency coupling, thereby simplifying the model stability analysis. According to the method, dual-frequency positive sequence disturbance is introduced, the coupling effect between different frequency components is effectively described, the defect that a traditional single-frequency modeling method cannot reflect the multi-frequency interaction characteristic is overcome, and the accuracy and applicability of the impedance model of the network construction type energy storage converter under the multi-frequency disturbance scene are remarkably improved.

The invention relates to the technical field of grid-connected control of a power system, and discloses an island detection and self-synchronizing grid-connected method for an offshore floating power generation device, which is used for solving the problem that transient oscillation is difficult to effectively suppress in a self-synchronizing grid-connected process after island detection in a traditional method. According to the method, firstly, voltage and frequency signals are collected at a grid-connected interface, and accurate island identification is achieved in combination with multi-cycle deviation judgment and a self-adaptive threshold value; a virtual synchronous machine mode is switched after the island is confirmed, and transient power fluctuation and phase difference are utilized to set damping and perform voltage closed-loop calibration, so that the device is converged to be aligned with the phase and voltage of the power grid; after an alignment condition is met, gradual power injection is adopted to complete grid connection, voltage, frequency and power balance is verified and monitored through a parameter period, and graded adjustment or back-off is carried out when necessary, so that transient oscillation and power impact are suppressed in the whole process from island detection to grid connection again and stable operation, and grid connection stability and adaptability are improved.

The invention discloses a transient stability constraint-based network construction type energy storage and phase modifier coordinated configuration method. The method comprises the following steps of S1, constructing a target function taking the minimum comprehensive cost in a new energy base as a target; s2, constructing constraint conditions, wherein the constraint conditions comprise a power flow constraint, an investment cost constraint, a new energy base delivery power constraint, a new energy unit power constraint, a network construction type energy storage equipment constraint and a transient stability constraint; s3, adopting an improved sparrow algorithm to solve the target function; s4, obtaining a coordinated configuration scheme of the network construction type energy storage and the phase modifier; according to the method, a power angle and frequency stability constraint model of a new energy base is established on the influence of transient power angle stability and frequency stability generated by access of network-building type equipment based on a virtual synchronous inertia quantification model of network-building type energy storage and network-building type wind and light equipment, and the power angle and frequency stability constraint model of the new energy base is established by taking the minimum comprehensive cost as a target and fully considering constraint conditions. The frequency stability of the system is improved to a certain extent, and the total cost is reduced.

The invention discloses a smooth transition method and system for sensorless field directional control, and relates to the technical field of permanent magnet synchronous motor sensorless control. According to the method, an error between an I-f starting virtual synchronous reference coordinate system and a sensorless observer estimation coordinate system is eliminated through a dual-core mechanism of a robust transition strategy and a position error compensation strategy, and then rotor position deviation caused by non-ideal factors is corrected through an exclusive compensation module; the system constructs a multi-stage switching control framework based on the method, and seamless transition from I-f open-loop starting to sensorless FOC closed-loop control is achieved. Complex parameter adjustment is not needed, transition is fast and stable, torque magnetic flux control precision can be optimized, copper loss is reduced, system efficiency and robustness are improved, and the method is suitable for industrial driving scenes such as air conditioner compressors.

The invention relates to a multi-mode coordinated optical storage charging and discharging micro-grid operation control system, which relates to the technical field of new energy micro-grids and comprises a multi-source sensing layer, an energy management optimization layer, a coordination control execution layer and a seamless switching control module. According to the method, an improved model predictive control algorithm is combined with historical data training, the capacity of accurately pre-judging the multi-source energy trend is achieved, the virtual synchronous machine technology is adopted to be matched with a feedforward compensation algorithm under high-frequency sampling, the energy storage converter has the physical inertia supporting and top-speed response characteristics, and the energy storage efficiency is improved. Instantaneous load fluctuation generated by charging pile access and the like can be captured and counteracted in a parallel second level, bus voltage fluctuation is effectively stabilized, meanwhile, phase active compensation and current accurate injection of a switching transient state are achieved through deep cooperation of grid-connected protection and voltage frequency pre-synchronization, voltage drop and transient impact of the switching transient state are effectively inhibited, and the switching transient state of the charging pile is effectively stabilized. And the problem of rigid switching is solved.

The invention discloses a power control method and system of a virtual synchronous converter, and belongs to the technical field of power control of the virtual synchronous converter, and the method comprises the steps: collecting the per unit value of the grid-connected point voltage of the virtual synchronous converter, and obtaining a voltage state signal; calculating a first active amplitude limiting value, a second active amplitude limiting value and a third active amplitude limiting value according to the voltage state signal; taking the minimum value as an equivalent mechanical power amplitude limiting value Pm, and limiting a mechanical power reference value of the virtual synchronous converter by using the Pm to realize active power output constraint; the voltage state is judged according to the voltage state signal, and different control means are adopted based on different voltage states. According to the method, active and reactive collaborative optimization control during a voltage fault period can be realized, stable operation of the converter and a power grid is guaranteed, and meanwhile, the voltage supporting capability and the frequency stability during low voltage ride through are improved.

Electrical apparatus (20) includes an inverter (24) having input terminals for receiving DC input power and output terminals for coupling to an AC power grid. A pulse-width modulation (PWM) generator and drivers (26) drive the switches so as to control respective amplitudes, frequencies, and phases of the output current waveforms of the inverter. Control circuitry (28) receives measurements of respective time-varying voltages and currents on the input and output terminals, computes a model (40) that includes three virtual currents flowing in a synchronous machine that is emulated by the apparatus, wherein the three virtual currents are associated respectively with the three output current waveforms, and controls the PWM generator and drivers responsively to the three virtual currents so as to synchronize the amplitudes, frequencies, and phases of the three output current waveforms of the inverter with the three phases of the AC power grid.

The invention provides a control method and device for improving strong network adaptability of a network construction converter and a storage medium, and relates to the technical field of power grids. The method comprises the following steps: acquiring active power and reactive power of a grid-connected point, and inputting the active power and the reactive power into a VSG ring to obtain a virtual synchronous machine internal potential amplitude and a virtual synchronous machine internal potential phase; adaptively acquiring a reference node phase, and subtracting the reference node phase from the internal potential phase of the virtual synchronous machine to obtain a power angle; generating an active reference current and a reactive reference current based on the power angle and the potential amplitude in the virtual synchronous machine; and inputting the active reference current and the reactive reference current into a current inner ring to obtain a switching control signal of the target grid-connected converter. The power angle observer is added in the power outer loop, the current reference value is generated according to the power angle, dependence on a voltage loop is not needed, the reference node phase is obtained in a self-adaptive mode, and better stability performance is achieved under a strong power grid and a weak power grid.

The invention discloses a multi-inverter module off-grid parallel operation control method and a storage medium. According to the control method, a three-ring series control method comprising a power ring, a voltage ring and a current ring is adopted for each inverter module; power distribution is carried out among the multiple inverter modules according to an agreed droop curve; the power loop is used for controlling power output of the system; the power loop introduces virtual synchronous machine control and power correction according to an agreed droop curve to obtain voltage frequency and amplitude needing to be output; the voltage loop is used for maintaining the stability of system output voltage; the current loop is used for controlling output current; the voltage loop and the current loop are respectively controlled by positive and negative sequences. Real-time communication of the inverter modules is removed, configuration of the master and slave modules is removed, the inverter modules operate independently, the master and slave modules are not separated, and the problems of power coordinated distribution and the like caused by downtime of part of modules in a multi-inverter module parallel system are solved.

The invention discloses an energy storage synchronization coordination management method and system based on a virtual synchronization technology, and belongs to the technical field of power system automation control, and the method comprises the steps: obtaining the power grid operation state data of an energy storage inverter grid-connected point; inputting the power grid operation state data into the power grid strength identification model, and outputting a power grid strength grade identifier; selecting a target parameter mapper from a preset parameter mapper set according to the power grid strength grade identifier; inputting the power grid operation state data into the target parameter mapper, and outputting a virtual inertia coefficient, a virtual damping coefficient and a droop control coefficient which are matched with the current power grid strength; and loading the virtual inertia coefficient, the virtual damping coefficient and the droop control coefficient to a virtual synchronous machine control model, generating an active power reference value and a reactive power reference value, and driving an energy storage inverter to execute power output. The frequency stability is remarkably improved, power overshoot and oscillation are restrained, the voltage supporting precision is enhanced, and the safe operation life of equipment is prolonged.

The present application belongs to the technical field of power system operation control, in order to solve the problem that the existing transient instability discrimination method of grid-forming converter is easy to cause the misoperation or missed judgment of control strategy, a kind of transient instability discrimination method and system of grid-forming converter is proposed, a nonlinear equivalent circuit model of grid-forming converter is established, the transient total energy and critical instability energy of the system are calculated in real time, and the control mode is adaptively switched according to the size relationship between the two; In normal operation, maintain the original virtual synchronous machine control strategy, use its damping characteristics to suppress oscillation, and maximize the voltage and frequency support capability of the power grid; When the instability risk is detected, enter the fault ride-through mode, realize the rapid and accurate identification and control of instability risk.

This invention discloses a method and system for frequency oscillation transfer analysis under multi-machine islanding. The method includes: establishing a transfer function; substituting the operating parameters of each operating condition into the transfer function; if stable, determining whether it is stable; if stable, it indicates that the system on the second VSG side is stable; if unstable, jumping to S3.1 to determine the cause of frequency oscillations on the second VSG side and the first VSG side; if unstable, it indicates that the frequency oscillations on the second VSG side are caused by insufficient stability margin of the second VSG side itself. The advantage of this invention is that it more accurately explains the cause of low-frequency oscillations in the system, thereby guiding the design of virtual synchronous machine controller parameters.

According to one embodiment, a power supply / demand device includes a virtual synchronous inverter and a storage battery. The virtual synchronous inverter is connected to a power system. Charging and discharging of the storage battery are controlled by the virtual synchronous inverter. The virtual synchronous inverter is connected to the power system in parallel with other inverters. The virtual synchronous inverter is capable of calculating a first standby time having any length and performing control of the storage battery corresponding to an operation instruction after a lapse of the first standby time, when receiving the operation instruction accompanied by output of power to the power system or input of power from the power system.

The invention relates to the technical field of power grids, and provides a network construction device transient stability evaluation method and system considering damping and current limiting, and the method comprises the steps: based on the actual angular frequency of a virtual synchronous machine, the rated angular frequency of a power grid, and the active reference value of a network construction type inverter converter, combining the transient stability critical condition of the virtual synchronous machine and an energy function, and evaluating the transient stability of the network construction device; carrying out simultaneous solution to obtain a critical fault clearing angle so as to quantify the transient stability of the network construction device; wherein the transient stability critical condition of the virtual synchronous machine is obtained by introducing an equivalent damping deceleration area and incorporating the equivalent damping deceleration area into an equal area rule, and calculation of the damping deceleration area is simplified by analyzing the concavity and convexity of an angular frequency track. The conservative property of a traditional transient stability criterion is effectively reduced, and a more accurate design basis is provided for control parameter setting of the network-forming converter.

An energy supporting device for a high voltage direct current, HVDC, transmission system includes an energy supporting device for providing grid forming and / or virtual synchronous machine, VSM, capabilities to the HVDC transmission system. The energy supporting device comprises a plurality of cells configured to be connected to the HVDC transmission system, and a cell includes a full-bridge arrangement of power switches, an energy storage device electrically connected to the full-bridge arrangement, a resistor electrically connected between the plurality of cells and an electrical reference potential, and a bypass switch configured to allow the resistor to be bypassed. The energy supporting device is configured to be operated in a dissipation mode, in which the bypass switch is in an open state for allowing the resistor to dissipate electrical energy from the HVDC transmission system, and in which the energy storage devices of the plurality of cells are bypassed.

The invention discloses a micro power supply capacity optimization configuration and cooperative control method for a weak power grid, and belongs to the technical field of power systems, and the method comprises the steps: generating a capacity matching and day-ahead output plan containing each micro power supply based on a multi-objective optimization algorithm; monitoring system operation data in real time, and calculating a multi-energy complementary coupling coefficient representing a system adjustment margin; according to the wind and light permeability monitored in real time, control parameters of a virtual synchronous machine of the net-building type energy storage device are dynamically corrected so as to adjust system equivalent damping in a self-adaptive mode; energy storage output is controlled according to the corrected virtual synchronous machine control parameters so as to support the bus voltage frequency, and when the multi-energy complementary coupling coefficient is lower than a preset threshold value or the frequency deviation exceeds the limit, the micro pumped storage device is cooperatively triggered to carry out power compensation, and electric quantity balance and stable control of the micro-grid are completed. Through parameter dynamic correction and multi-energy cooperative compensation, the frequency stability, the power supply reliability and the clean energy consumption rate of the weak interconnection micro-grid are effectively improved.

The invention discloses a virtual synchronous machine control method for improving transient voltage inertia of a grid-connected inverter. The virtual synchronous machine control method comprises an active power control loop and a reactive power control loop with transient voltage inertia. On the basis of a traditional virtual synchronous machine control method, an inertia link is introduced into a reactive power control loop, and a reactive voltage loop is transformed into a second-order system from a first-order system so as to improve the dynamic response of an inverter when the voltage of a power grid drops. According to the invention, the change rate of the output voltage of the grid-connected inverter in the transient process can be effectively reduced, the power angle characteristic, the frequency characteristic and the voltage characteristic of the grid-connected inverter are improved, the negative influence caused by the voltage drop of the power grid is reduced, and the transient stability of the inverter is improved.

According to the flexible interconnection switch adaptive virtual inertia control method and system, a flexible interconnection switch comprises a series voltage source type converter, a parallel voltage source type converter and a battery energy storage system, the parallel voltage source type converter adopts virtual synchronous motor control, and the virtual synchronous motor control comprises an active frequency ring and a reactive voltage ring; the method comprises the following steps: step 1, obtaining the sum of active power output by a series voltage source type converter and a parallel voltage source type converter as active power injected by a battery energy storage system; step 2, determining the SOC of the battery energy storage system; step 3, adjusting the active self-adaptive virtual inertia in the active frequency loop and the reactive self-adaptive virtual inertia in the reactive voltage loop according to the SOC; and 4, updating the active power output by the parallel voltage source converter and the active power injected by the battery energy storage system, and returning to the step 2. According to the invention, the problem of coordinated operation control of the series and parallel converters in the flexible interconnection switch is solved.

The application discloses a kind of grey-box isomeric doubly-fed wind farm low-frequency oscillation suppression method based on virtual damping modulation, comprising: 1 grey-box isomeric doubly-fed wind farm is divided into white box and black box unit, and the state space model of all white box units of traditional doubly-fed induction generator, virtual synchronous machine control and installation additional damping controller is established;2 improve subspace identification method to obtain black box unit model;3. white box and black box model are coupled by feedback interconnection, and the overall state space model of wind farm is constructed;4 determine target low-frequency oscillation mode based on coefficient matrix;5 real-time extraction and target mode strong correlation common bus power signal, combined with adaptive time-varying gain generates virtual synchronous machine damping coefficient adjustment amount;6 according to complex mode controllability factor and unit distribution coefficient, allocate the virtual damping modulation instruction of each white box unit.The application realizes the identification and suppression of grey-box isomeric doubly-fed wind farm low-frequency oscillation, and improves the ability of wind farm damping low-frequency oscillation.

The invention discloses a control method and device of an energy storage converter multi-machine parallel system and a storage medium, and belongs to the technical field of energy storage converter control. According to the control method, high-frequency circulation is suppressed in real time through dynamic virtual impedance compensation; dividing a multi-mode response strategy according to the voltage drop depth of the power grid, and triggering the characteristics of the virtual synchronous machine during deep drop; and a distributed consistency algorithm is adopted to realize balanced power distribution. The problems of circulating current suppression, rapid voltage recovery and weak communication fault tolerance of a multi-machine parallel system are solved, and THDlt is realized; and the voltage recovery time is less than or equal to 80ms, so that the stability and the reliability of the energy storage system under a power grid fault are remarkably improved.