128 results about "Diode rectifier" patented technology

The invention discloses a hybrid direct current transmission power coordination control device and a control method and equipment thereof, and relates to the technical field of offshore power generation, and the hybrid direct current transmission power coordination control device comprises a diode rectifier unit and a first modular multilevel converter which are connected with an offshore wind plant, the sending-end converter station is used for converting alternating current generated by an offshore wind plant into direct current and outputting the direct current; the second modularized multi-level current converter is connected with the diode rectifier unit and the land power grid and is used for restoring the direct current into the alternating current and transmitting the alternating current to the land power grid; and the control module is connected with the first modular multilevel converter and is used for controlling the DC voltage of the first modular multilevel converter based on the fluctuation power according to the transfer relation between the active power and the DC voltage of the sending end converter station, so that the higher requirement of the rated capacity of the MMC in the related technology is met, and the reliability of the MMC is improved. And the engineering construction cost is increased.

A power converter (100) for converting multi-phase AC grid input power (GIV, GIC) to DC output power. For allowing efficient, cost-effective, easy installable, and reliable power supply to a DC power consumer with high power requirements, it includes at least one phase block (106A, 106B), each having at least two separate converter single-phase string arrangements (1), each of them including an individual active rectifier portion (10), including a H-bridge with semiconductor switches (12), for rectifying single-phase AC input power (SInV, SInC) to intermediate DC power and an individual DC / DC converter (20). The latter includes an inverter portion (30), having a H-bridge with semiconductor switches (32), for inverting the intermediate DC power to first intermediate AC power (PAC1) with an elevated frequency (f1), a transformer (40, 240) for transforming the first intermediate AC power (PAC1) to second intermediate AC power (PAC2, PAC2A, PAC2B), and a passive diode rectifier (50, 150, 250), including a diode bridge (51), for rectifying the second intermediate AC power (PAC2, PAC2A, PAC2B). The disclosure further discloses a hydrogen production facility (200) with an electrolyzer stack (20) and such a power converter (100).

The invention discloses a method and a device for suppressing harmonic instability of a new energy grid-connected system, electronic equipment and a storage medium. The method comprises the following steps: acquiring basic data of a diode rectifier in the new energy grid-connected system; constructing a time domain model of the diode rectifier according to the basic data; converting the diode rectifier time domain model into a diode rectifier frequency domain model based on a harmonic linearization algorithm; constructing a frequency domain small signal model according to the diode rectifier frequency domain model and the diode rectifier direct current side filter inductance parameter; constructing an alternating current side impedance model and a direct current side impedance model according to the frequency domain small signal model and the leakage inductance parameters of the diode rectifier transformer; generating the resonant frequency of the new energy grid-connected system according to the AC side impedance model and the DC side impedance model; and adjusting a direct current side filter inductance parameter of the diode rectifier according to the resonant frequency. According to the invention, the harmonic stability of the grid-connected system can be improved.

This invention discloses a multiplexing configuration method and apparatus for a diode phase-shift rectifier power transmission system, relating to the field of power electronics technology. The method involves acquiring the topology diagram and rectification operating parameters of the diode rectifier unit in the diode phase-shift rectifier power transmission system. Based on the rectification operating parameters and a preset power frequency cycle coefficient, the DC-side output current of the diode rectifier unit is determined. Harmonic characteristic analysis is performed using the DC-side output current and the diode rectifier unit topology diagram to obtain the total harmonic distortion (THD) function corresponding to the diode phase-shift rectifier power transmission system. Based on preset harmonic distortion limits and the THD function, the target multiplexing number of the diode phase-shift rectifier power transmission system is determined. This invention solves the technical problem that existing technologies do not fully utilize the operating parameters of the diode phase-shift rectifier power transmission system to analyze the multiplexing number, thus reducing the reliability of offshore power transmission platforms.

The invention discloses a self-aligned anode ultra-wide bandgap semiconductor diode rectifying device on a diamond high-thermal-conductivity substrate and a preparation method thereof, the device comprises a gallium oxide epitaxial wafer on the diamond substrate, one end of the upper part of the gallium oxide epitaxial wafer is provided with an ion implantation region, and a cathode electrode is prepared above the ion implantation region; an anode electrode is prepared at the other end above the gallium oxide epitaxial wafer on the diamond substrate, the ohmic contact resistance of the cathode electrode and the gallium oxide epitaxial wafer on the diamond substrate is reduced by the ion implantation region, and the anode electrode and the gallium oxide epitaxial wafer on the diamond substrate form Schottky contact; the preparation method comprises the following steps: preprocessing a gallium oxide epitaxial wafer on a diamond substrate; ion implantation; preparing a cathode electrode and an anode electrode; and performing self-aligned anode etching and in-situ annealing to finally form the gallium oxide self-aligned anode diode on the diamond. According to the invention, the breakdown voltage of the device is improved while the preparation process steps of the device are simplified.

The invention relates to the technical field of direct current collecting and sending out, and particularly provides a new energy direct current collecting and sending out system and a control method thereof, and the system comprises a new energy station, a network construction type energy storage device, a distributed diode rectifier, a direct current circuit breaker, a direct current power transmission line, and a controllable commutation current converter. The alternating current of the new energy station is rectified by a distributed diode rectifier, then is subjected to direct current collection, and is sent to a receiving end alternating current power grid through a direct current power transmission line; a direct-current circuit breaker is arranged between the direct-current output end of the distributed diode rectifier and the direct-current power transmission line; and the receiving-end alternating-current power grid adopts a controllable commutation current converter to invert direct current of the direct-current power transmission line into alternating current. The technical scheme provided by the invention is flexible in design, easy to maintain, high in capacity and voltage grade expansibility, good in economical efficiency, good in networking flexibility, suitable for island or weak network new energy collection grid connection and long-distance transmission scenes, wide in application scene and outstanding in advantage effect.

The invention relates to the technical field of rectifier bridges, in particular to a low-loss rectifier bridge circuit, which comprises a power supply AC1, a power supply AC2, a power supply cathode, a filter capacitor C1, two groups of high-end driving switches with the same structure and two groups of low-end driving switches with the same structure, the high-end driving switch comprises a transistor V1 and a transistor V4, the low-end driving switch comprises a transistor V2 and a transistor V3, the transistor V1 and the transistor V3 are connected with a power supply AC1, and the transistor V2 and the transistor V4 are connected with a power supply AC2. The rectifier bridge has the advantages that the voltage drop loss is reduced by about 50% compared with that of a pure diode rectifier bridge under the same condition; the rectifier bridge has an anti-backflow function, and can solve the problem of backflow current of a pure MOS tube rectifier bridge. Compared with a PMOS (P-channel Metal Oxide Semiconductor) tube, an NMOS (N-channel Metal Oxide Semiconductor) tube has the advantages of lower conduction impedance, low price, abundant model selection, simple circuit and low cost.

The utility model discloses a generator control device, a gas generator system and an aircraft, the generator control device comprises an automatic control unit, a sensing unit and a rectification unit, the generator is connected with a turbine of a turbojet engine through a main shaft, and the generator is connected with electric equipment. The automatic control unit is connected with an oil pump of the turbojet engine, electric equipment, the sensing unit and the rectifying unit, the sensing unit comprises a rotating speed sensor connected with a main shaft, the rectifying unit comprises a diode rectifier bridge and a buck-boost converter, the generator is connected with the diode rectifier bridge, and the diode rectifier bridge is connected with the buck-boost converter. And the buck-boost converter is connected with electric equipment. The power supply can stably output electric energy according to the requirements of electric equipment, ensures that the output voltage is stable, and meets the requirements of the electric equipment.

The invention relates to a brushless motor with balance ring diodes. The brushless motor comprises a housing, a stator assembly, a rotor assembly, a rotary transformer and a rectifier. The stator assembly is disposed within the housing and includes a stator winding disposed on a stator core. A rotor assembly is also positioned within the housing with an air gap separating the rotor assembly from the stator assembly. The rotor assembly includes a rotor shaft, a rotor winding, and a balance ring. A resolver is positioned within the housing and includes a primary coil and a secondary coil. The rectifier includes a plurality of diodes positioned on a balance ring. A rectifier is electrically connected between the secondary coil and the rotor winding.

The invention discloses a wind power generation and energy storage integrated system based on an open winding motor and a control method of the wind power generation and energy storage integrated system. The system comprises an open winding permanent magnet synchronous wind driven generator, a controller, an energy storage device, a machine side converter, a network side converter, a three-phase diode rectifier bridge, a capacitor, a three-phase power grid and a filter. Compared with a traditional direct-drive type permanent magnet synchronous wind power generation system, the wind power generation system has the advantages that the structural characteristic of double-end feed of the open winding motor is utilized, the capacity of the system for absorbing wind energy can be brought into full play, and the problem of low electric energy quality caused by intermittent wind power generation and generated power fluctuation is solved. The invention can effectively reduce the cost of the open winding permanent magnet synchronous wind power generation system, improve the energy utilization rate, reduce the system control complexity and improve the power quality of the power grid.

The utility model discloses a three-phase diode rectifier bridge module, particularly relates to the technical field of three-phase diodes, and comprises a heat dissipation box, one side of the heat dissipation box is hinged with a box door, one side of the box door is fixedly provided with a sealing strip, the surface of the heat dissipation box is provided with a sealing groove, the sealing strip is clamped with the sealing groove, and a heat dissipation mechanism is fixedly arranged in the heat dissipation box. The heat dissipation mechanism comprises a mounting plate arranged in the heat dissipation box, a heat conduction plate is fixedly arranged at the top of the mounting plate, a three-phase rectification module is fixedly arranged at the top of the heat conduction plate, a mounting groove is formed in the mounting plate, and a plurality of fins are arranged in the mounting groove; one end of each fin sequentially penetrates through the mounting plate and the heat dissipation box and extends to the outside of the heat dissipation box, and circulating water pipes are fixedly arranged on the two sides of the three-phase rectification module. According to the utility model, the contact area between the heat conduction plate and the three-phase rectification module can be increased, so that the heat dissipation effect is enhanced, and the overall heat dissipation effect is improved through multi-surface heat dissipation.

The application relates to the technical field of urban rail transit power supply, in particular to an enhanced bidirectional converter with a built-in rectifier and a control method thereof. The enhanced bidirectional converter comprises an axial double-column four-winding transformer, a switch assembly, a first rectifier assembly and a second rectifier assembly, and first and second thyristors. The input end of the axial double-column four-winding transformer is connected with a power grid, and the output end of the axial double-column four-winding transformer comprises multiple taps; the switch assembly comprises multiple switch pieces, and the switch states of the multiple switch pieces correspond to the current operation mode of the enhanced bidirectional converter with a built-in rectifier; one side of the first rectifier assembly and the second rectifier assembly is connected with the switch assembly, the other side of the first rectifier assembly is connected with the first thyristor, and the other side of the second rectifier assembly is connected with the second thyristor. Thus, by combining the advantages of a diode rectifier and an IGBT-based bidirectional converter, the problems of high cost and large occupation of the prior art and insufficient reliability of a power supply system are solved.

The invention discloses an efficient LLC converter structure inverter which comprises a power switch, a resonant network, a high-frequency transformer and a diode rectifier. The power switch is composed of four switching tubes which are divided into two groups and connected in series, and on-off is controlled to convert direct-current voltage into square-wave voltage. The resonant network is combined with an adjustable resonant inductor, a capacitor and an excitation inductor, dynamic working parameters are obtained through voltage sampling and PI feedback adjustment, the resonant inductor is connected with a bias winding, and bias current is applied to change magnetic resistance; harmonic waves of the square wave voltage are eliminated through a resonance network, and fundamental frequency sine waves are output; the high-frequency transformer integrates a magnetic core, a primary side / secondary side coil and an air gap in a single magnetic structure; the diode rectifier converts alternating voltage output by the secondary side of the high-frequency transformer into direct current, outputs smoothing voltage of a filter capacitor, and reduces ripple waves; by optimizing the resonant network and the high-frequency transformer, a circuit soft switching technology is realized, so that the loss in an energy transmission process is reduced, and the overall efficiency of the inverter is improved.

This invention belongs to the field of high-voltage direct current (HVDC) transmission in power systems, specifically relating to a method, equipment, and medium for AC fault ride-through control at the sending end of a new energy source transmission system via a DRU-HVDC. When an AC fault occurs at the sending end, the grid-side converter of the new energy power station exits the active, reactive, and voltage loops, retains the inner current loop, and switches to maximum current output mode, locking the frequency to the rated value. Simultaneously, the receiving-end converter station exits the DC voltage outer loop, retains the inner current loop, and controls the DC current according to preset commands. During the fault duration, the diode rectifier station remains on and transmits maximum active power. After the fault is cleared, the output current of the new energy power station is reduced to the rated value, and then the power and voltage control loops are restored; the receiving-end converter station resumes constant DC voltage operation. This invention achieves maximum power control through preset commands. By controlling and switching between the new energy power station and the receiving-end converter station, the DRU is effectively maintained on, improving the active power transmission capacity and system recovery speed during faults.

The invention discloses a rectifier-diode-free single-inductor boost energy recovery circuit and a control method thereof, and relates to the technical field of electric energy conversion circuits. The circuit topology comprises a switching tube S1, a switching tube S2, an inductor L, a diode D1, a diode D2 and an output capacitor Co. One end of the alternating current input side is connected with the drain electrode of the switching tube S1, the positive electrode of the output capacitor Co and one end of the load RL; the source electrode of the switching tube S1 is connected with one end of the inductor L and the cathode of the diode D1; the negative electrode of the output capacitor Co is connected with the positive electrode of the diode D1, the other end of the load RL and the positive electrode of the diode D2; the other end of the AC input side is connected with the drain electrode of the switch tube S2, and the source electrode of the switch tube S2 is connected with the other end of the inductor L and the cathode of the diode D2. According to the rectifier-diode-free single-inductor boost energy recovery circuit, by completely eliminating a diode rectifier bridge, energy loss is reduced, and the circuit structure is simplified.

The invention discloses a high-voltage and low-voltage direct-current dual-output three-stage generator system and a design method. The system comprises a three-stage generator and a controller. The three-stage generator is composed of a permanent magnet auxiliary exciter, a main exciter, a main motor, a rotary transformer and a rotary rectifier. The controller comprises a voltage regulating circuit, a thyristor rectifier bridge, a diode rectifier bridge, a control circuit, a power generation control relay and a current sensor. The main motor is provided with a low-voltage three-phase winding and a high-voltage three-phase winding which respectively meet the requirements of low-voltage direct current and high-voltage direct current. According to the invention, the exciting current of the exciting winding of the main exciter is regulated through the voltage regulating circuit, so that the low-voltage direct-current voltage is stabilized at an expected voltage value; by means of phase-controlled rectification control, the output high-voltage direct-current voltage is stabilized at an expected voltage value, meanwhile, the switching frequency which is the same as the output electric frequency of the generator is adopted for power generation and voltage stabilization of the thyristor rectifier bridge, and the thyristor rectifier bridge has the advantages of being low in loss, low in high-frequency ripple frequency spectrum component, weak in high-frequency conduction and radiation interference, high in power density and the like.

The present invention relates to the field of photovoltaic power generation wireless energy transmission devices, in particular to a photovoltaic power generation wireless energy transmission system and a supporting transmission method. It aims to solve the problem of low conversion efficiency of photovoltaic power generation wireless energy transmission in the prior art. The present invention successively includes a photovoltaic side circuit, a wireless energy transmission transmitting circuit, and a wireless energy transmission receiving circuit along the energy transmission direction; wherein, the photovoltaic side circuit includes a photovoltaic module and a synchronous boost DC-DC converter module, the wireless energy transmission transmitting circuit includes a full-bridge inverter circuit module and the first half of an LCC-S resonant compensation mechanism; the wireless energy transmission receiving circuit includes the second half of the LCC-S resonant compensation module, a diode rectifier circuit module, a synchronous buck DC-DC converter module, and an electrical load. The advantages are as follows: the conduction loss of the freewheeling diode is greatly reduced, thereby obtaining a higher energy conversion efficiency.

A D-mode GaN transistor synchronous rectifier of the present invention includes a power switching module, a peak detection module, and a gate driver module. The peak detection module stores energy when the negative end of the secondary side winding of the power converter is at a high voltage. The power switching module includes a first switch and a D-mode GaN HEMT as a second switch connected in series. The energy is provided to the module gate of the power switching module through the gate driver module to keep the first switch turned on. The gate driver module conducts the module gate and the module source when the positive end of the secondary side winding is at a low voltage, such that a clamp circuit pulls the gate-source voltage of the second switch below threshold and turns it off. The synchronous rectifier replaces conventional diode rectifier, having lower conduction loss and response ringing.

The present invention discloses a method for suppressing overvoltage in the sending-end grid of a hybrid offshore wind power bipolar flexible direct current (DC) system. For a hybrid offshore wind power bipolar flexible direct current (DC) system in which the sending-end negative-pole converter uses a diode rectifier, the present invention achieves system overvoltage suppression in the event of a sending-end grid fault through coordinated control of the sending-end positive-pole MMC converter, the receiving-end negative-pole MMC converter, and the receiving-end positive-pole MMC converter. Compared with existing solutions, the control method proposed in the present invention can suppress overvoltage levels to a limited extent in the event of a sending-end grid fault, ensuring the safe and stable operation of the system, and has good application prospects.

The application discloses a high-voltage direct-current converter topology and a control method thereof, and belongs to the technical field of power generation, power transformation or power distribution. The topology is composed of a high-voltage side filter inductor, a three-phase MMC inverter circuit, a three-phase leakage inductor, a three-phase transformer, a three-phase diode rectifier circuit, a medium-voltage side filter inductor and a medium-voltage side filter capacitor. The topology structure of the application can realize higher reliability, lower cost and smaller size by the relatively mature high-voltage side modular structure and the medium-voltage side diode series connection technology. By precisely controlling the three-phase current to be a positive-negative half-cycle symmetrical trapezoidal current, reliable commutation of the three-phase rectifier diode is realized, and meanwhile, smooth direct-current is synthesized on the high-voltage side and the medium-voltage side, so that the operation efficiency of the converter and the port power quality are significantly improved, and the filter size is reduced.

This invention relates to a triple-multiplier auxiliary circuit for a series-type 12-pulse rectifier, belonging to the field of power electronics technology. It solves the problems of existing pulse multiplier circuits used in the DC side of series-type 12-pulse rectifiers, which suffer from large turns ratios in the primary and secondary windings of the auxiliary transformer, resulting in significant leakage inductance and poor harmonic suppression. Furthermore, the large turns ratio and the presence of numerous diodes in the multiplier circuit also contribute to its complex structure and increased manufacturing difficulty. This invention's triple-multiplier auxiliary circuit, by adjusting the turns ratio of the primary and secondary windings of each auxiliary transformer, allows the auxiliary diodes D... f1 and auxiliary diode D f2 The conduction times of the two diodes are 1 / 3 or 1 / 4 of their respective input voltage cycles, enabling the first diode rectifier bridge and / or the second diode rectifier bridge to operate simultaneously or alternately, thereby achieving a pulse multiplication of 3 times. This invention is mainly used to achieve pulse multiplication.

The application provides a DRU-LFAC system and a wind turbine generator network type control and black start control method, and relates to the technical field of wind power generation. The offshore wind farm is a permanent magnet direct drive full power wind turbine generator, low frequency alternating current is sent to the onshore back-to-back converter through a low frequency side subsystem, the onshore back-to-back converter converts the low frequency alternating current into high frequency alternating current and sends the high frequency alternating current into an onshore power grid, the onshore back-to-back converter comprises a twelve-pulse diode rectifier unit and a modular multilevel converter, and a filter is used for reactive power compensation. The DRU-LFAC system has active power-voltage coupling characteristics and reactive power-frequency coupling characteristics. The application solves the problems that the low frequency side power characteristics of the current DRU-LFAC system are different from those of the traditional power system and cannot be effectively analyzed, the current traditional wind turbine generator control strategy is not applicable to the DRU-LFAC system, and the offshore wind farm cannot be started through a conventional process due to the unidirectional conduction characteristics of the DRU.

A brushless electric machine includes a housing, a stator assembly, a rotor assembly, a rotary transformer, and a rectifier. The stator assembly is arranged within the housing and includes a stator winding provided on a stator core. The rotor assembly is also positioned within the housing with an airgap separating the rotor assembly from the stator assembly. The rotor assembly includes a rotor shaft, a rotor winding, and a balance ring. The rotary transformer is positioned within the housing and includes a primary coil and a secondary coil. The rectifier includes a plurality of diodes positioned on the balance ring. The rectifier is electrically connected between the secondary coil and the rotor winding.

The invention discloses an offshore wind power DR-MMC direct current sending-out converter and a control method thereof, and efficient wind power direct current sending-out is realized through a structure that a diode rectifier (DR) is connected with a direct current side of an auxiliary converter in parallel and an alternating current side is connected with a grid through a transformer. The auxiliary converter is composed of a high-voltage series submodule branch (HVSB), a low-voltage three-phase series modular multilevel converter (LV-SC-MMC) and an LC filter, the LV-SC-MMC adopts a three-phase modular full-bridge series structure, each phase comprises four bridge arms, and the alternating current side is in triangular connection through three single-phase transformers. According to the control method, variable-amplitude high-frequency voltage (the amplitude is dynamically adjusted along with a fundamental component) is injected into an LV-SC-MMC bridge arm, on the premise that the number of sub-modules is not increased, the peak value / valley value of the bridge arm voltage is not changed, and meanwhile power balance control is completed by using the superposition characteristic of the high-frequency voltage on the direct current side and combining HVSB voltage adjustment. The device effectively reduces the number of sub-modules, guarantees the quality of AC-side electric energy, and is suitable for offshore wind power low-cost and compact DC transmission scenes.

The invention discloses a hybrid offshore wind plant black-start method based on a DRU-HVDC sending-out system, and belongs to the technology of a power transmission system due to the economical efficiency and the reliability of the power transmission system. In order to solve the problem that a control strategy of a DRU-HVDC power transmission system based on a diode rectifier unit is still challenged in the black-start process of an offshore wind plant, the invention aims to solve the black-start problem of an offshore wind plant low-frequency alternating current collection and direct current sending-out system adopting the DRU-HVDC and realize stable grid connection and mixed operation of wind turbine generators after starting. The control method comprises the steps that a switchable control strategy is provided, undisturbed switching between a GFM operation mode and a GFL operation mode is supported, after starting, the system can stably operate in the mixed mode of the GFM operation mode and the GFL operation mode, and a reliable black-start and mixed operation solution is provided for an open-sea wind power plant without synchronous power supply support.

The application discloses a topology structure and a control method of a bipolar composite offshore converter station, belongs to the technical field of offshore power transmission and distribution, and aims at solving the problems of large volume, complex structure and poor system reliability of the existing offshore wind power. The bipolar composite offshore converter station comprises a positive pole and a negative pole; the positive pole adopts a half-bridge modular multilevel converter topology structure, the negative pole adopts a diode rectifier topology structure, the two topology structures are connected in parallel at an alternating current side and are connected in series at a direct current side, and a direct current connection point is used as a grounding pole to form a symmetric bipolar structure. The topology structure of a shore converter station comprises: the positive pole and the negative pole both adopt a half-bridge modular multilevel converter topology structure. The control method comprises the following steps: when a direct current of the grounding pole increases from zero, an alternating current voltage rated value of the offshore converter station is added with a fine adjustment amount, the added value is used as a given value of a d-axis voltage ring of a wind turbine, the direct current of the grounding pole is kept as zero, power balance control of the positive pole and the negative pole is realized, and the application is used for the offshore converter station.

The invention relates to the technical field of offshore wind plants, and discloses an electric energy transmission system, method, device, medium and product of an offshore wind plant, the electric energy transmission system of the offshore wind plant comprises a wind plant bus, an offshore sending end converter station, an onshore receiving end converter station and a power grid; the wind power plant bus is used for performing electric energy transmission with a power grid; the offshore sending end converter station comprises a diode rectifier module and an offshore side modular multilevel converter module which are connected in parallel; the diode rectifier module comprises four diode rectifier units which are connected in parallel; and the offshore sending end converter station is used for monitoring whether a target diode rectifier unit with a fault exists in the four diode rectifier units, and if yes, the target diode rectifier unit is controlled to be disconnected, so that other diode rectifier units transmit electric energy. According to the invention, the four diode rectifier units are configured, the other four diode rectifier units continue to operate when a fault occurs, and the electric energy transmission capability of the system is guaranteed.

The application discloses a kind of hybrid offshore wind power bipolar flexible transmission system power coordination control methods.For sending end negative converter adopts diode rectifier hybrid offshore wind power bipolar flexible transmission system, by adjusting the active power flexible distribution between bipolar by negative MMC DC bus voltage of receiving end.Compared with the existing method, the scheme can coordinate the power distribution between bipolar, maintain the stable operation of offshore ac grid, and has good application prospect.

The invention provides an offshore wind power plant direct current sending-out system and method, in a black start stage of the system, a diode auxiliary current converter and an auxiliary current converter of a shore converter station, or a diode in anti-parallel connection with a main current converter and the auxiliary current converter form a low-voltage black start loop which is connected with a shore alternating current power grid; the shore alternating current power grid provides starting energy for the network-forming reactive power compensation device and the offshore wind power plant; in a power path transfer stage of the system, transferring the low-voltage black-start loop to a power transmission path formed by the diode rectifier and a main converter of the shore converter station; and in the steady-state operation stage of the system, an alternating-current voltage of the common connection point is established by the network-forming reactive power compensation device, so that the offshore wind plant transmits rated power through the diode rectifier. Compared with a modular multilevel converter, the diode rectifier is small in size, so that the construction cost economy of the offshore platform is better.

The invention provides a partial-capacity medium-voltage flexible interconnection device and a fault current-limiting control method, and belongs to the technical field of medium-voltage power distribution network flexible interconnection, and the device comprises a power frequency isolation transformer, a power flow transfer module, a fault protection module, and a fault current-limiting module formed by connecting a diode rectifier bridge and a thyristor in parallel. During normal operation, the power frequency isolation transformer provides isolation to ensure that the power flow transfer module does not cause loss due to generation of leakage current, and meanwhile, a thyristor SCR1A of the fault protection module is turned off to ensure normal power flow adjustment of the series converter module; when a power grid line breaks down, devices of the series module are all locked, meanwhile, the thyristor SCR1A is rapidly switched on so as to bypass the series module, the thyristor SCR2A of the fault current limiting module is switched off, and the diode rectifier bridge is connected to the line in series and blocks fault current. The device overcomes the defects that a traditional device is high in cost and needs complex protection, gives consideration to efficiency and compactness, and is suitable for low-cost flexible power flow control of the medium-voltage power distribution network.