61results about How to "Improve fault ride-through capability" patented technology

The invention discloses a PR (proportional resonant) controller-based NMC-HVDC (modular multilevel converter-high voltage direct current) circulating current suppression method. PR controller-based circulating current suppression is adopted at the inverter end to suppress positive-sequence and negative-sequence circulating currents, and meanwhile, a zero-sequence circulating current controller is used to suppress DC voltage fluctuation and zero-sequence circulating current; PR controller circulating current suppression is adopted at the rectifier end; or PR controller circulating current suppression is used at the rectifier end to suppress positive-sequence and negative-sequence circulating current, meanwhile, the zero-sequence circulating current controller is used to suppress the DC voltage fluctuation and zero-sequence circulating current, and PR controller circulating current suppression is adopted at the inverter end; or both the rectifier end and the inverter end use PR controller circulating current suppression to suppress positive-sequence and negative-sequence components and both use the zero-sequence circulating current controller to suppress the DC voltage fluctuation and zero-sequence circulating current. In each AC side system failure, the positive-sequence, negative-sequence and zero-sequence components of the circulating current can all be completely suppressed; the DC voltage fluctuation can also be suppressed; fault ride-through ability of an AC system during a fault can be improved; the problems occurring in the use of the traditional PR control method in NMC-HVDC are solved.

The invention provides a modularization multi-level converter redundancy fault-tolerant control method. According to the method, an inverter controller is arranged on the alternating current side of a modularization multi-level converter; redundancy fault-tolerant model prediction control is carried out on the modularization multi-level converter, wherein the redundancy fault-tolerant model prediction control is composed of three control objects of alternating current tracking, sub-module capacitive voltage equalization and circulation suppression; each control object defines an objective function to calculate all possible switching state objective function values under the corresponding objective function; an alternating current tracking objective function and a sub-module capacitive voltage equalization objective function calculate numerical values under all switching states of MMC; a circulation suppression objective function calculates numerical values under all circulation suppression compensation levels; the minimum value of the objective functions is selected; the switching state corresponding to the minimum value of the objective functions is recorded; and the switching state is input into the MMC and is used as the switching state of the MMC of next moment. Circulation suppression and sub-module capacitive voltage equalization of the modularization multi-level converter in the case of redundancy fault-tolerance are realized.

The invention discloses an unsymmetrical fault ride-through method of a double-fed wind generating set. According to the method, a rotor-side convertor control circuit comprises a rotating speed outer ring and a rotor positive and negative sequence current control inner ring, and in order to eliminate the influence of direct-current decrement of a stator flux linkage, a corresponding compensation item is introduced at an outlet of a positive sequence current controller; in order to avoid the overcurrent or overvoltage of the rotor convertor, a novel current amplitude limiting link is designed, and an integral saturation link and an output amplitude limiting link are respectively introduced for the current controller; according to a network-side convertor, actual active power of a rotor is introduced in an outer ring direct-current voltage circuit to balance power on the two sides of a direct-current bus in real time; meanwhile, actual measurement negative sequence network voltage is an inner ring positive sequence current control circuit to eliminate the influence of negative sequence voltage. The defect that an existing control strategy cannot take the influences, on the network-side / rotor-side convertor, of occurrence of the generator terminal negative sequence voltage and the requirement for idle supporting of a power network in the failure period into account at the same time yet is overcome, and therefore the fault ride-through capacity of the double-fed wind generating set is improved.

The invention discloses an integrated offshore wind electric field fault ride-through method based on HVAC grid connected. The method comprises steps that 1), reactive demands under fault ride-throughconditions is calculated; 2), a reactive output limit of each set and a real-time reactive output limit of the whole offshore wind electric field set are calculated; 3), in a low voltage ride-throughcontrol mode, a dynamic reactive power compensator is cooperated by the wind electric field set to carry out layered capacitive reactive support; 4), in a low voltage ride-through continuity period,early removal of a crowbar circuit is considered, stator side reactive output capability of the set is recovered; 5), for the set of which a rotor transverter is under control and a reactive injectioncurrent can not satisfy requirements in the low voltage ride-through continuity period, through limiting output of active power, reactive output capability is enhanced; and 6), in a high voltage ride-through control mode, the dynamic reactive power compensator is cooperated by the wind electric field set to carry out layered sensitive reactive support. The method is advantaged in that offshore wind electric field fault ride-through capability is effectively improved.

The invention discloses a DFIG (doubly fed induction generator) control method based on resonant feedback in an unbalanced power network. By the aid of resonant feedback control technology, the DFIG control method in the unbalanced power network can be simplified, positive and negative sequence separation for the electromagnetic volume of a system and negative sequence current reference value calculation link for a rotor in any links are omitted, accordingly, the problems of time delay, phase angle and amplitude detection errors and the like caused by the positive and negative sequence separation process can be avoided, the requirements of different targets are met, and fine dynamic characteristics are realized. By the aid of the DFIG control method, reinforced operation and control of a DFIG system can be realized under the condition of the unbalanced power network, and fault ride-through capability of the DFIG system is improved. Moreover, the DFIG control method can be applied to various PWM (pulse width modulation) three-phase or single-phase inverter devices such as a solar power generation and biomass energy grid-connected inverter device and an alternating-current transmission inversion device, so that different control effects in the unbalanced power network are achieved.

The invention discloses a low-voltage ride-through realization method for a double-fed wind turbine generator with an adaptive function on voltage drop. A comprehensive strategy is divided into two modes by considering voltage drop degree and stator variable resistance crowbar protective applicable range: when the grid-connected point voltage U of a wind power plant is within Xp.u-0.9p.u, low-voltage ride-through of the unit is realized by a unloading circuit and grid side dynamic reactive control by combination with a static var generator; and when U is less than Xp.u, low-voltage ride-through of the unit is realized by stator variable resistance crowbar protection, the unloading circuit and the grid side dynamic reactive control by combination with the static var generator, wherein the grid side dynamic reactive control and the stator variable resistance crowbar protection are subjected to parameter adjustment by taking the grid-connected point voltage as the reference so as to realize the adaptive function on the voltage drop degree. By adoption of the method, the low-voltage ride-through capability, the fault ride-through capability and transient state vibration resistance of the unit are greatly improved while the stable operating capability of the unit and the system after fault ride through is improved.

The invention discloses a hybrid wind power plant group coordination control method under power grid asymmetrical faults, and relates to control of a grid-side converter and a machine-side converter of a permanent magnet direct drive wind power system; the hybrid wind power plant group comprises a permanent magnet direct drive wind power plant and an asynchronous wind power plant; in the premise of not increasing hardware equipment, the active power output of the permanent magnet direct drive wind power plant is limited while the current margin of the grid-side converter is fully utilized; on the basis of controlling the output of the grid-side converter to satisfy positive sequence reactive power of the power grid guiding rule, the residual current margin is utilized to output a negative sequence current to realize synergistic inhibition of the grid-connected point negative sequence voltage, reduce adverse influence of the operation behaviors of the permanent magnet direct drive wind power plant to the operation behaviors of the asynchronous wind power plant, and effectively improve the power-grid fault operation capability and the grid-connected electric energy quality of the asynchronous wind power plant.

The invention discloses a method for controlling a photovoltaic grid-connected inverter. The method comprises: obtaining output voltage and output power of a photovoltaic cell at preset moment; according to variation trends of the output voltage and output power, performing iterative computation on an output current set value, until an output current reference value of a maximum power point tracking (MPPT) control module at a maximum power point of the photovoltaic cell is obtained; according to the output current reference value, calculating to obtain a current set value of a current inner loop, finally, based on a proportional resonance (PR) control strategy, realizing maximum power point tracking and photovoltaic inverter grid connected. Through the variation trends of the output voltage and output power of the photovoltaic cell, iterative computation is directly performed on the output current set value, and finally the current set value of the current inner loop is obtained. Compared with the prior art, voltage outer loop control is not needed, the method can track the maximum power point more rapidly and accurately, and simplifies a photovoltaic grid-connected inverter control system, and photovoltaic grid-connected fault through capability is improved, so as to ensure safe operation of a power grid.

The invention belongs to the technical field of hybrid micro-grids and power distribution networks, and specifically relates to a suppression method for series compensation transformer direct currentmagnetic bias between a micro-grid and a power distribution network. Thus, the problems of series compensation transformer direct current magnetic bias between an alternating current / direct current micro-grid and a power distribution network caused by the rapid output of series link voltage can be solved. The method includes collecting the voltage amplitude of the power distribution network in real time; judging whether voltage dropping occurs, and recording alpha and voltage dropping depth; and calculating the first half period amplitude of compensation voltage and outputting the compensationvoltage until the voltage dropping disappears. The suppression on the series compensation transformer direct current magnetic bias under fault situations of single-phase voltage dropping and three-phase voltage dropping of a power grid can be realized, so that the normal operation of series links can be guaranteed, the normal operation of loads carried by an alternating current bus and the safetyof power electronic devices can be effective guaranteed, the fault ride-through capabilities of alternating current / direct current HMG on the voltage dropping of the power distribution network can beenhanced, and the power supply quality of the alternating current bus can be improved as well.

The invention provides a control method for the fault ride-through of a doubly-fed wind power generation system. The method includes the following steps that: S1, a preset robust H-infinity control model is solved, rotor-side converter excitation voltage control signals are acquired, the objective of the preset robust H-infinity control model is to maximize the interference suppression effect of the wind power generation system and improve the dynamic response performance of the wind power generation system during a fault; and S2, the turning off of a converter is controlled according to the rotor-side converter excitation voltage control signals, and therefore, the fault ride-through of the doubly-fed wind power generation system is realized. The mathematical model of a controlled objectis updated based on an ISS theory, so that the stability of the controlled system can be theoretically guaranteed. The control method of the invention robustly controls the doubly-fed wind power generation system based on an SDRE technology, and improves the fault ride-through capability of the doubly-fed wind power generation system.

The invention discloses a sub-module redundancy configuration method and system of a modular multilevel converter. The method comprises the following steps: determining the number of fault sub-modulesin the modular multilevel converter; calculating and acquiring a capacitance reference voltage of the sub-modules of the modular multilevel converter based on the number of the fault sub-modules; obtaining a target output voltage of an upper bridge arm and a target output voltage of a lower bridge arm of the modular multilevel converter; and determining the number of sub-modules input by the upper bridge arm by utilizing the capacitance reference voltage and the target output voltage of the upper bridge arm, and determining the number of sub-modules input by the lower bridge arm by utilizingthe capacitance reference voltage and the target output voltage of the lower bridge arm. In the invention, a maximum voltage output capability is reserved by increasing a capacitor voltage so that thesystem operates stably, and a fault ride-through capability is enhanced; and loss of a converter valve is reduced, redundant modules are fully utilized, a harmonic content of an output voltage is reduced, and operation performance of the modular multilevel converter is optimized.

The invention discloses a double-fed induction wind turbine generator continuous fault ride-through control method. The method comprises the following steps: calculating a stator flux linkage througha stator three-phase voltage and current signal, calculating a stator flux linkage component psi st_alpha beta, and further obtaining the amplitude thereof so as to obtain kde; obtaining psi st_d andpsi st_q through psi st_alpha beta transformation, and obtaining a rotor de-excitation current instruction value in combination with kde; calculating a rotor reactive current instruction value when the machine end voltage is continuously changed; calculating a rotor current instruction value; and inputting the rotor current instruction value into a rotor side converter current inner loop control link to obtain a control voltage of the rotor side converter: performing space vector modulation on the control voltage to obtain a machine side converter PWM driving signal, thereby realizing the fault ride-through control of a doubly-fed induction wind turbine generator under the condition of the continuous change of a machine end voltage. According to the method, the fault ride-through capability of the doubly-fed induction wind turbine generator under the condition of the continuous change of the machine end voltage can be enhanced, and the continuous fault ride-through of the doubly-fed induction wind turbine generator is realized.

The invention discloses a ride-through control method applied to an enhanced Direct Current (DC) short-circuit fault of a Modular Multi-level Converter (MMC). The short-circuit fault is a single-polegrounded short-circuit fault occurred by only one pole in positive and negative poles, and the control method relates to the control of the pole where the fault is located and the control of the otherpole opposite to the pole where the fault is located. According to the method, not only is a control target of each of the positive and negative poles (the pole where the fault is located and the other pole) of a sending end and a receiving end when a Modular Multi-level Converter-High Voltage Direct Current (MMC-HVDC) system takes place a DC single-pole grounded short-circuit fault stated, but also a principle for configuring active and reactive powers is optimized; the capacity of the MMC-HVDC system can be fully used to provide active and reactive supports for a power grid, so that the MMC-HVDC can implement fault ride-through under the DC single-pole grounded short-circuit fault by fully using the own capacity; and thus, the fault ride-through capacity of the MMC-HVDC system under theDC single-pole grounded short circuit and the stable operation capacity of a connected alternating-current power grid thereof are improved.

The invention provides a fault ride-through control system for an alternating-current excitation power supply. When a point of common coupling (PCC) voltage drops slightly, a three-phase electronic switch K1 is switched on, K2 is switched off, a current inner loop in a double-loop control strategy adopts a method combining proportional integral resonant control and variable damper control, and a PCC voltage valid value outer loop output serves as a given value of current inner loop current. When the PCC voltage drops deeply, the three-phase electronic switch K1 is switched off, K2 is switchedon, direct-current voltage output loops of a machine-side converter (MC) and a grid-side converter (GC) adopt a proportional integral resonant control method, and a current inner loop adopts a proportional integral resonant control method. Through adoption of the control system, rotor overcurrent of a doubly fed induction generator (DFIG) caused by a PCC voltage dropping fault is restrained; ripple voltage on a direct-current side of the alternating-current excitation power supply caused by a PCC voltage asymmetrical dropping fault can be reduced; and the alternating-current size current resonant content is lowered.

The invention relates to an offshore wind power system fault combined ride-through method based on a flexible direct current MMC converter. According to the method, a grid-side MMC is allowed to redistribute an active and reactive reference current through a reactive priority link when a fault happens to a power grid and the voltage drops, and reactive current support is provided for the voltage recovery of the power grid. The wind power plant increases the pitch angle of a fan and reduces the active output of the fan by adjusting the active power set value of the fan, that is, the absorptionof wind power during a fault period is reduced, the power imbalance phenomenon between a grid-side MMC and an offshore MMC is improved, excessive power in a direct current link is effectively prevented from being stored in a direct current capacitor, the MMC converter is prevented from being damaged due to overvoltage during a fault period, so that the fault ride-through capability of the offshoreflexible direct-current wind power system is effectively improved, and the safe and stable operation of the system is ensured.

An embodiment of the invention discloses fault ride-through control method for an inversion type new energy power supply. The method includes: adding a positive and negative sequence current limiter into a vector orientation based positive and negative sequence d-q current control loop of the inversion type new energy power supply; monitoring network voltage positive sequence component and direct-current bus voltage of the inversion type new energy power supply; using the network voltage positive sequence component to start or stop control signals of a direct-current unloading circuit of the inversion type new energy power supply, and balancing unbalanced power on a direct-current side of an inverter by the aid of a direct-current voltage PI (proportional integral) controller. The control method is used for overcoming defects of existing unbalanced control strategies to improve fault ride-through capability of the inversion type new energy power supply.

The invention discloses a fault ride-through control method and system for a double-wind-wheel wind generating set, and belongs to the technical field of wind power generation. The method comprises the steps of judging whether a parallel power grid has a voltage fault or not by detecting the voltage of a grid-connected point of a three-port fan converter, and if the parallel power grid has the voltage fault, calculating the voltage value of a direct-current bus of the three-port fan converter and the rotating speed of a wind wheel with a relatively lower rotating speed in a current double-wind-wheel generator set; and according to the real-time rotating speed and the power value of the low-speed wind wheel, switching the working state of the machine-side converter corresponding to the low-rotating-speed wind wheel rapidly, so that the electric and power generation state of the motor is changed, and the low-rotating-speed wind wheel absorbs instantaneous electric energy from a direct-current bus or releases electric energy to a power grid system through a three-port fan converter. According to the technical scheme, the double wind wheels of the wind turbine generator are rapidly controlled to be mutually loaded, the problems of low efficiency, high cost, poor safety and the like caused by the fact that fan fault ride-through is achieved through the consumption electric energy consumption of the resistors in the prior art, are solved, and the method has good application prospect.

The invention discloses an MMC alternating current side fault energy balance control method based on feedforward control. A feedforward control strategy is provided so that voltage balance of amodular multilevel converter under an unbalanced power grid condition is improved. The method comprises the following steps of analyzing the coupling relationship between the bridge arm energy and each electrical signal and establishing a bridge arm energy mathematical model under a coordinate system. Due to the addition of the feedforward compensation, the anti-interference capability of the alternating current power grid on asymmetric faults and sudden voltage imbalance is improved; flexible and rapid control of bridge arm energy is realized through an internal current signal of the converter. Abridge arm zero-sequence current suppression link is added, finally, static-error-free tracking control over an alternating-current-side direct-current-side current signal is achieved through a PIR controller, double-frequency components in circulating current and direct-current-side current are filtered out through a PR controller, and the alternating-current-side fault ride-through capacity is greatly improved.

The invention discloses a step-down operation control method for a hybrid MMC flexible direct current power transmission system. The method includes the following steps: determining the step-down coefficient eta on an MMC direct current side and the stable voltage U on an MMC alternating current side according operation requirements; obtaining the alternating current system voltage Us and reactivepower Qv of the MMC alternating current side during step-down operation, obtaining the power factor of the MMC alternating current side, entering the next step if a condition shown in the descriptionis met, and otherwise, returning to the last step; judging the operation conditions of the MMC alternating current side, controlling MMC to absorb a certain reactive power if Us is greater than U, and adjusting the power factor to 1.45 eta; and controlling the MMC to emit a certain reactive power output if Us is less than or equal to U, and adjusting the power factor to 1.45 eta. The control method can be realized by depending on the self and original control capabilities of a control system, so that the problems of the unable voltage-sharing of the bridge arm sub-module of a hybrid MMC flexible direct current power transmission system during step-down operation can be solved, the capabilities of the hybrid MMC to realize step-down operation can be strengthened, and fault ride-through capabilities under the condition of direct current voltage reduction such as direct current line insulation faults can be enhanced.

The invention relates to a current blocking method and device for a direct-current power transmission system fault, a multi-terminal direct-current power transmission system and a storage medium, the method is applied to the multi-terminal direct-current power transmission system, and the system comprises a plurality of sending-end converter stations and a plurality of receiving-end converter stations. Under the condition that a fault occurs in a direct-current power transmission line, a fault current on the direct-current power transmission line is obtained, and a target voltage of a first sending end converter station which enables the fault current of the direct-current power transmission line to be zero is determined according to the fault current and a preset reference current; and after the first sending-end converter station is controlled to output the target voltage, a switch between the direct-current transmission line and the first sending-end converter station is controlled to be switched off, and under the condition, the current of the second sending-end converter station flows into the first sending-end converter station. According to the method, the fault current can be reduced to zero under the condition that the second sending end converter station does not need to quit operation, so that fault current blocking is realized; and then, the second sending end converter station continues to operate, and the fault ride-through capability of the direct-current power transmission system is improved.

The invention relates to current limiting equipment applicable to bidirectional flow direct current system distributed capacitance configuration. The current limiting equipment comprises an H bridge circuit composed of two diode bridge arms, two switch bridge arms and an intermediate branch circuit; the diode bridge arms and the intermediate branch circuit are respectively formed by connecting power diodes in series; the switch bridge arms are respectively formed by connecting switch elements in series, wherein the switch elements can be conducted unidirectionally and can be turned on and off,a collector, anode or drain electrode end of each switch bridge arm is called as a bridge arm positive pole, and a transmitter, cathode or source electrode end of each switch bridge arm is called asa bridge arm negative pole; the two diode bridge arms share the cathode; the negative pole of each switch bridge arm is connected with the anode of one of the diode bridge arms, and the switch bridgearms share the anode and are connected with an anode of a capacitor; and a cathode of the intermediate branch circuit is connected with a common point of the diode bridge arms, and an anode of the intermediate branch circuit is connected with a common point of the switch bridge arms. One of the common point of the diode bridge arms and the common point of the switch bridge arms is connected with adirect current bus, and the other one of the two common points is connected with a direct current circuit.

Disclosed is a converter system of a switch reluctance motor. When the switch reluctance motor is used as a generator for operation, a first capacitor is used as an exciting power supply; charging ofthe first capacitor can be realized in the power generation stage; by adjusting the duty ratio of a first switching tube, the power generation voltage value can be adjusted flexibly to satisfy requirement of the system; when the switch reluctance motor is used as a motor for operation, the same set of current conversion circuit is adopted, and energy regeneration capability is also achieved; and the whole system is simple in structure, low in cost, high in reliability, and can be applicable to medium and small-sized switch reluctance generator application systems and driving systems under various loads.

The invention provides a reactive power coordination control method and system for a wind power plant, and particularly relates to the field of wind power plant control, and the method comprises the steps: firstly, determining the first reactive power of a reactive power compensation device according to a power grid dispatching instruction when a power grid system is in a transient fault state, and performing first-stage reactive power compensation on the power grid system according to the first reactive power until the power grid system is in a steady-state operation state, so that the characteristics of high response speed and high speed of the reactive power compensation device are fully utilized, and transient faults can be quickly processed; and secondly, when the power grid system is in the steady-state operation state, determining second reactive power of the reactive power compensation device and third reactive power of the target wind turbine generator, and performing second-stage reactive power compensation on the power grid system in the steady-state operation state by using the second reactive power and the third reactive power, therefore, the dynamic reactive power reserve of the wind power plant can be greatly improved, and the fault ride-through capability of the wind power plant can be greatly improved.

The invention belongs to the field of wind power protection, and particularly relates to an improved doubly-fed induction wind generator fault ride-through protection circuit. The improved doubly-fed induction wind generator fault ride-through protection circuit comprises current-limiting circuits a, bypass circuits a, current-limiting circuits b and bypass circuits b, wherein one current-limiting circuit a is in parallel connection with one bypass circuit a, three groups of circuits in the above parallel relationship exist, one ends, those are, three phases of input ends U1, V1, and W1 are respectively connected with three phases of windings of a doubly-fed induction motor rotor in the doubly-fed induction wind generator, the other ends, those are, three phases of output ends U2, V2 and W2 are connected with three phases of AC output ends of a rotor-side converter in a doubly-fed induction wind generator converter structure; and three groups of current-limiting circuits b exist either in a delta connection or in a star connection, and leading-out wires are respectively connected with the above three phases of input ends U1, V1 and W1 through corresponding bypass circuits b. The problem that the doubly-fed is out of control in the case of traditional crowbar protection under most voltage fault conditions, and the transient characteristics and the fault ride-through ability of the doubly-fed induction wind generator can be improved.

The invention relates to a valve control overvoltage-overcurrent cooperative protection method and system for a flexible direct current converter valve, and relates to the field of direct current transmission, and the method comprises the steps: obtaining a voltage-current operation capability curve of a sub-module in the flexible direct current converter valve during unlocking operation; obtaining the maximum voltage of each current unlocking operation based on the voltage-current operation capability curve, and calculating a voltage-current protection constant value curve of a sub-module in the flexible DC converter valve based on the maximum voltage of each current unlocking operation; and each sub-module controller performs overvoltage protection by using a dynamic overvoltage protection constant value according to the real-time operation current of the bridge arm and the voltage-current protection constant value curve of the sub-module. The constant value of overvoltage protection is dynamically adjusted according to the magnitude of the current in the operation process, the constant value of overvoltage protection is high when the current is small, the constant value of overvoltage protection is low when the current is large, the risk of overvoltage protection action locking of the converter valve under the alternating-current and direct-current fault of the system can be reduced, and the fault ride-through capacity is improved.

The invention discloses a converter valve bridge arm submodule with an overvoltage suppression function. The converter valve bridge arm submodule comprises a power circuit and an overvoltage suppression circuit, the source electrode of the first power device is connected with the drain electrode of the second power device, and the first bypass switch is connected in parallel with the second power device and the connection port of the converter valve single-bridge arm submodule; the anode of the first lightning arrester is connected with the drain electrode of the first power device and one end of the DC capacitor and one end of the voltage-sharing resistor, and the cathode of the first lightning arrester is connected with the anode of the second lightning arrester. The negative electrode of the second lightning arrester is connected with one end of the DC capacitor, one end of the voltage-sharing resistor and the source electrode of the second power device. And the second bypass switch and the third power device are connected in parallel with the second lightning arrester. By adding the overvoltage suppression circuit, the overvoltage stress of the converter valve equipment under the in-station extreme fault working condition and in the alternating current system fault ride-through process is effectively reduced, the alternating current system fault ride-through capacity and the in-station extreme fault endurance capacity of the flexible direct current converter valve equipment are improved, and the large engineering application potential is achieved.

The invention discloses a method for controlling a photovoltaic grid-connected inverter. The method comprises: obtaining output voltage and output power of a photovoltaic cell at preset moment; according to variation trends of the output voltage and output power, performing iterative computation on an output current set value, until an output current reference value of a maximum power point tracking (MPPT) control module at a maximum power point of the photovoltaic cell is obtained; according to the output current reference value, calculating to obtain a current set value of a current inner loop, finally, based on a proportional resonance (PR) control strategy, realizing maximum power point tracking and photovoltaic inverter grid connected. Through the variation trends of the output voltage and output power of the photovoltaic cell, iterative computation is directly performed on the output current set value, and finally the current set value of the current inner loop is obtained. Compared with the prior art, voltage outer loop control is not needed, the method can track the maximum power point more rapidly and accurately, and simplifies a photovoltaic grid-connected inverter control system, and photovoltaic grid-connected fault through capability is improved, so as to ensure safe operation of a power grid.