Offshore wind power failure condition phase-shifting energy storage and consumption combined control system and method

Abstract

The application belongs to the technical field of power electronics, and provides a phase-shifting energy storage and consumption combined control system, method and system for offshore wind power fault conditions, which comprises two bridge arms and an energy dissipation unit, the two bridge arms are connected in parallel, and the two ends of the two bridge arms are connected in parallel on a DC bus; each bridge arm comprises a valve string formed by a plurality of energy storage units connected in series and a bridge arm inductor connected in series with the valve string, and is used for storing redundant power; the two ends of the energy dissipation unit are connected to the valve string and the bridge arm inductor of the two parallel bridge arms, respectively, and the energy dissipation unit is used for consuming redundant power. The application comprehensively considers the advantages of the energy storage and consumption system, realizes the fault ride-through of the offshore wind flexible direct current transmission system and the absorption and reuse of redundant power, and can reduce the volume of a single energy storage or consumption device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power electronics, and particularly relates to a phase-shift type energy storage and consumption combined control system and method for offshore wind power fault conditions. BACKGROUND

[0002] With the transformation of global energy structure to low carbonization, offshore wind power, as an important part of clean and renewable energy, is accelerating the expansion to the deep sea area. However, the traditional alternating current transmission technology is limited by transmission distance, capacity and voltage level, and it is difficult to adapt to the requirements of large-capacity and long-distance transmission of offshore wind power. The flexible direct current transmission technology is superior to alternating current transmission in economy and reliability due to its small loss, long transmission distance and no need for reactive power compensation, and is widely used in the field of offshore wind power transmission.

[0003] When the offshore wind power is transmitted through the flexible direct current transmission system in the steady state, the direct current system voltage remains stable, that is, the active power output by the wind farm and the active power connected to the land grid are always balanced. However, when the land alternating current grid fails, the power output by the wind farm cannot be completely transmitted to the alternating current grid, and the redundant power generated will charge the equivalent capacitor of the direct current system and the internal capacitor of the converter, thereby causing the direct current system voltage to rise and endangering the stable operation of the system. To realize the fault ride-through of the flexible direct current transmission system during the grid side fault, the redundant power in the system needs to be eliminated. Reducing the output power of the wind farm to balance the output and grid-connected power of the wind farm is a direct and effective way, but it has the disadvantages of high communication delay and slow response speed. At the same time, compared with the alternating current system, the direct current system has small inertia, and when the direct current system fails, the fault propagation is more rapid and the impact on the system is more serious. Therefore, it is difficult to meet the requirements of fault ride-through by directly reducing the output power of the wind farm when the fault occurs. Another common method is to introduce energy consumption devices on the direct current side, that is, to convert the redundant power generated in the system into heat energy by configuring equivalent loads, so as to suppress the rise of the direct current system voltage. Although this method can balance the power in a short time, it has the problem of low energy utilization rate, and is accompanied by the design of a large heat dissipation structure, resulting in increased overall equipment cost and system space occupation, and high engineering implementation difficulty. SUMMARY

[0004] The purpose of the present application is to provide a phase-shift type energy storage and consumption combined control system and method for offshore wind power fault conditions, to solve the problems of low energy utilization rate and high cost in the prior art.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] In a first aspect, the present application provides a phase-shifting energy storage and consumption combined control system for offshore wind power failure conditions, comprising two bridge arms and an energy dissipation unit, the two bridge arms being connected in parallel, and the two ends of the two bridge arms being connected in parallel on a DC bus;

[0007] Each bridge arm comprises a valve string formed by a plurality of energy storage units connected in series and a bridge arm inductor, the valve string and the bridge arm inductor being connected in series, for storing redundant power; the energy dissipation unit is connected between the valve string and the bridge arm inductor of the two parallel bridge arms, and the energy dissipation unit is used for consuming redundant power.

[0008] Further, the energy storage unit comprises a half-bridge module, a filter inductor L, a capacitor and an energy storage battery, the half-bridge module comprises an upper switch tube S1 and a lower switch tube S2, the upper switch tube S1 and the lower switch tube S2 are complementary to be turned on, and the energy storage battery and the filter inductor L are connected in series and connected in parallel with the capacitor.

[0009] Further, the upper switch tube S1 and the lower switch tube S2 are insulated gate bipolar transistors IGBTs with anti-parallel diodes

[0010] Further, the energy dissipation unit comprises a switch tube S r , a switch tube S r ' , an LC series resonance network, a bridge diode rectifier module, a filter capacitor and a power dissipation resistor, one end of the switch tube S r is connected between the valve string and the bridge arm inductor of one bridge arm, the other end is connected to one end of the LC series resonance network, the other end of the LC series resonance network is connected to one end of the bridge diode rectifier module, the other end of the bridge diode rectifier module is connected to one end of the switch tube S r ' , and the other end of the switch tube S r ' is connected between the valve string and the bridge arm inductor of the other bridge arm; the bridge diode rectifier module has a filter capacitor and a power dissipation resistor connected in parallel in sequence.

[0011] Further, the LC series resonance network comprises an inductor L r and a capacitor C r , and the inductor L r and the capacitor C r are connected in series.

[0012] Further, the switch tube S r , the switch tube S r 'It consists of two inverted series switching transistors, and is an insulated gate bipolar transistor (IGBT) with an anti-parallel diode.

[0013] Furthermore, the bridge diode rectifier module has a structure of multiple diodes connected in series.

[0014] Secondly, this invention provides a method for joint control of energy consumption by phase-shifting energy storage under offshore wind power fault conditions, comprising the following steps:

[0015] During energy storage, the two reverse-connected switching transistors are kept off at the same time, and the energy dissipation unit is equivalent to an open circuit. No current flows through the power dissipation resistor. In this state, the charging and discharging power of the battery is controlled by changing the number of energy storage units inserted into the circuit.

[0016] When two reverse-connected switches are closed simultaneously, the energy dissipation unit is activated, simultaneously storing and dissipating power. The AC voltage across the energy dissipation unit transfers energy to the power dissipation resistor through a series LC resonant network.

[0017] Furthermore, when the energy storage unit has the ability to fully absorb the system's redundant power, it only operates in the power storage state; if the redundant power exceeds the maximum energy storage capacity, it switches to the power hybrid absorption state and simultaneously closes the two reverse-connected switches in the energy dissipation unit to absorb the excess energy through the power dissipation resistor.

[0018] Furthermore, before the energy dissipation unit starts and stops, the phase shift angle is... θ Set to 0, and simultaneously increase the number of negative pulses in the modulation wave of the energy storage unit. k Set to 1.

[0019] Compared with the prior art, the present invention has the following technical effects:

[0020] The application provides a phase-shifting energy storage and consumption combined control method for offshore wind power flexible direct current transmission fault conditions, which comprehensively considers the advantages of energy storage and consumption systems, realizes offshore wind power flexible direct current transmission system grid side fault ride-through and absorption and reuse of redundant power, and can reduce the volume of a single energy storage or consumption device.

[0021] The application also provides a phase-shifting energy storage and consumption combined control system for offshore wind power fault conditions, which solves the problems of low energy utilization rate and high cost in the prior art through the collaborative design of two parallel bridge arms and an energy dissipation unit. The system comprehensively utilizes the characteristics of energy storage and consumption systems, realizes efficient absorption and reuse of redundant power of offshore wind power flexible direct current transmission system during grid side fault, and reduces the volume and cost of a single energy storage or consumption device. The system stores redundant power by using a valve string composed of multiple energy storage units in series during a slight fault or suppresses power fluctuation in a steady state, and quickly puts into an energy dissipation unit during a serious fault to realize mixed absorption of excess energy through an LC series resonance network and a power dissipation resistor, and can decouple and regulate energy storage and consumption power, thereby improving the flexibility of control and the reliability of the system. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A phase-shifting energy storage and consumption integrated topology structure applied by the application;

[0023] Figure 2 A power storage state diagram of the phase-shifting energy storage and consumption integrated topology structure applied by the application;

[0024] Figure 3 An energy storage unit structure diagram in the phase-shifting energy storage and consumption integrated topology structure applied by the application;

[0025] Figure 4 A carrier phase-shifting modulation principle diagram applied by the application;

[0026] Figure 5 Modulation wave optimization principle diagram proposed by the present application;

[0027] Figure 6 Phase-shifted waveform principle diagram proposed by the present application;

[0028] Figure 7 Energy storage-energy consumption combined control method block diagram proposed by the present application;

[0029] Figure 8 Energy dissipation unit low-voltage stress start-up shutdown strategy diagram proposed by the present application. DETAILED DESCRIPTION

[0030] The present application is further described below in conjunction with the accompanying drawings:

[0031] Example 1, please refer to Figure 1 The present application provides a phase-shifted energy storage and consumption combined control system for offshore wind power fault conditions, including two bridge arms and an energy dissipation unit, the two bridge arms are connected in parallel, and the two ends of the two bridge arms are connected in parallel on the DC bus;

[0032] Figure 1 Cell1, Cell2…CellN are all energy storage units, each bridge arm includes a valve string formed by a plurality of energy storage units connected in series and a bridge arm inductor, the valve string and the bridge arm inductor are connected in series, and are used for storing redundant power; the two ends of the energy dissipation unit are connected to the valve string and the bridge arm inductor of the two parallel bridge arms, respectively, and the energy dissipation unit is used for consuming redundant power.

[0033] The phase-shifted energy storage and consumption combined control method for offshore wind power flexible transmission fault conditions described in the present application is based on the phase-shifted energy storage and consumption integrated topology. The main circuit of the phase-shifted energy storage and consumption integrated topology is composed of two parallel bridge arms and an energy dissipation unit, the two ends of the bridge arms are connected in parallel to the DC bus and bear the voltage of the DC system. Each bridge arm is composed of a valve string formed by N energy storage units connected in series and a bridge arm inductor; the energy dissipation unit is composed of two reverse series connected switch tubes, an LC series resonance network, a bridge diode rectifier module, a filter capacitor and a power dissipation resistor, and the two ends of the energy dissipation unit are connected to the valve string and the bridge arm inductor of the two bridge arms, respectively. Among them, a plurality of diodes in series is used to replace a single diode in the bridge diode rectifier module to withstand higher voltage.

[0034] Example 2: This invention provides a phase-shifting energy storage and energy dissipation combined control system for offshore wind power fault conditions. This system is based on a phase-shifting energy storage and energy dissipation integrated topology. The main circuit of this integrated topology consists of two parallel bridge arms and an energy dissipation unit. Each bridge arm consists of a valve string (N energy storage units connected in series) and a bridge arm inductor. The energy dissipation unit consists of two anti-tandem switching transistors, an LC series resonant network, a bridge diode rectifier module, a filter capacitor, and a power dissipation resistor. The two ends of the energy dissipation unit are connected between the valve string and the bridge arm inductor of the two parallel bridge arms, respectively.

[0035] The energy dissipation unit includes a switching transistor. S r Switching transistor S r ' LC series resonant network, bridge diode rectifier module, filter capacitor and power dissipation resistor, switching transistor S r One end is connected between the valve string and the bridge arm inductor of one bridge arm, and the other end is connected to one end of an LC series resonant network. The other end of the LC series resonant network is connected to one end of a bridge diode rectifier module, and the other end of the bridge diode rectifier module is connected to a switching transistor. S r ' One end, the switching transistor S r ' The other end is connected between the valve string of another bridge arm and the bridge arm inductor; the bridge diode rectifier module is connected in parallel with a filter capacitor and a power dissipation resistor.

[0036] LC series resonant network includes inductor L r and capacitor C r Inductor L r and capacitor C r Series connection.

[0037] Switching transistor S r Switching transistor S r ' It consists of two inversely connected series switching transistors, and is an insulated-gate bipolar transistor (IGBT) with an anti-parallel diode. The bridge diode rectifier module has a structure of multiple diodes connected in series.

[0038] The energy storage unit consists of a half-bridge module connected in parallel with an energy storage battery connected in series with an inductor.

[0039] Both the switching transistors in the half-bridge module and the switching transistors in the energy dissipation unit are insulated-gate bipolar transistors (IGBTs) with anti-parallel diodes.

[0040] Each diode in the bridge diode rectifier module is composed of multiple series to withstand a larger input voltage.

[0041] The storage of redundant power and the suppression of power fluctuation are realized through the energy storage units in the two bridge arms.

[0042] The hybrid absorption of redundant power is realized through the energy storage units in the two bridge arms, the two anti-series connected switch tubes in the energy dissipation unit, the LC series resonance network, the bridge diode rectifier module, the filter capacitor, and the power dissipation resistor.

[0043] The voltage across the power dissipation resistor is doubled by improving the modulation waveform.

[0044] The voltage stress on the anti-series connected switch tubes is reduced by improving the start-up and exit strategies of the energy dissipation unit.

[0045] Embodiment 3, refer to Figure 1 and Figure 2 The present application provides a phase-shifted energy storage and dissipation combined control method for offshore wind power fault conditions, comprising:

[0046] Figure 2 Cell1, Cell,2…CellN in the middle are energy storage units. When the phase-shifted energy storage and dissipation integrated topology only stores energy, the two anti-series connected switch tubes are kept open at the same time, and the energy dissipation unit is equivalent to an open circuit, with no current flowing through the power dissipation resistor. At this time, each bridge arm is only left with N energy storage units in series with the bridge inductor Lp, and this circuit state is called power storage state. In this state, the charging and discharging power of the battery is controlled by changing the number of energy storage units inserted into the circuit. Figure 1 At this time, this circuit state is called power hybrid absorption state, and the alternating voltage across the energy dissipation unit transfers energy to the power dissipation resistor through the series LC resonance network.

[0047] Referring to Figure 3 The energy storage units of the phase-shifted energy storage and dissipation integrated topology are composed of half-bridge modules and energy storage batteries in parallel with series filter inductors L. Among them, the upper and lower switch tubes of the half-bridge module are complementary to each other. When the upper switch tube S1 is closed, the main circuit is connected with the capacitor and the energy storage battery in the energy storage unit, and at this time the energy storage battery participates in power exchange; when the lower switch tube S2 is closed, the energy storage unit is bypassed and does not participate in power exchange.

[0048] Referring to Figure 4 Taking three energy storage units in each bridge arm as an example, in the power storage state, the two valve strings use the same phase carrier phase modulation, and the equivalent output voltage of the bridge arm is vs The frequency is three times the output voltage frequency of the energy storage unit, and its amplitude is in the range of 3. V c With 2 V c The voltage fluctuates between intervals, at which point the voltage across the bridge arm inductor... v Lp Peak value is V c .

[0049] refer to Figure 5 Taking three energy storage units in each bridge arm as an example, by superimposing a negative pulse into the modulation wave of each energy storage unit, the equivalent output voltage of the bridge arm is increased. v s The amplitude is in 3 V c and V c The voltage fluctuates between intervals, at which point the voltage across the bridge arm inductor... v Lp Peak-to-peak value is 2 V c And so on, assuming the number of negative pulses in the voltage modulation wave of each energy storage unit is... k The voltage across the bridge arm inductor v Lp Peak value is kV c Therefore, it can be seen that by changing the modulation wave of each energy storage unit, the voltage across the bridge arm inductor can be adjusted. V c This represents a doubling of the order of magnitude.

[0050] refer to Figure 6 Input voltage of the energy dissipation unit v in equal to the voltage across the inductor of bridge arm 2 v Lp2 Subtract the voltage of bridge arm 1 inductor v Lp1 Its waveform is a three-level waveform, with voltages of respectively. kV c , 0, - kV c By changing the phase shift angle θ The magnitude of the value can change the duty cycle of each level in the three-level voltage, thereby changing the voltage across the power dissipation resistor.

[0051] refer to Figure 7 The current system status is determined by whether the DC system voltage exceeds the limit (1.05 pu).

[0052] If the DC system voltage does not exceed the limit, the system is considered to be operating normally, and the wind farm's power is entirely transmitted to the AC power grid. Because the wind farm's power output is volatile, the grid-connected power will fluctuate accordingly, affecting the power quality on the grid side. Therefore, energy storage units are used to suppress this fluctuation. Since the two bridge arms are identical, they absorb or generate the same power. The difference between the actual measured power and the wind farm's rated power is calculated, and half of this difference is divided by the DC system voltage to obtain the reference current that the energy storage unit in the bridge arm needs to inject into the DC system. This reference current is then subtracted from the sampled actual current and used by a PI controller to generate a modulated wave of the valve string voltage. After multiple phase-shift modulation (PS-PWM), the signal for the switching transistor in each energy storage unit is generated.

[0053] If the DC system voltage exceeds the limit, a grid-side fault is considered to have occurred, and the wind farm's output power cannot be fully absorbed by the grid, resulting in a certain amount of redundant power. In this case, if the redundant power can be completely absorbed by the energy storage unit, the DC system voltage can be stabilized within a safe range, and there is no need to activate the energy dissipation unit; that is, the two reverse-connected series switches are simultaneously disconnected. However, when a severe grid-side fault occurs (such as a three-phase ground fault), the redundant power cannot be completely absorbed by the energy storage unit. This unabsorbed redundant power will cause the DC system voltage to continue to rise. In this case, the energy dissipation unit needs to be activated simultaneously to further dissipate the excess redundant power; that is, the two reverse-connected series switches are simultaneously closed. Therefore, the excess voltage is first subtracted from the reference voltage, and the redundant power of the system is calculated by the PI controller. If the redundant power is small, power storage is used for absorption. The redundant power is subtracted from the actual power absorbed by all energy storage units, and the reference current value of the valve string is calculated by the PI controller. This reference current value is then subtracted from the actual current of the valve string, and the PI controller generates a modulation wave of the valve string voltage, which is then used to generate the signal for the switches in the energy storage unit via PS-PWM. If the redundant power is large, the energy dissipation unit is activated. The reference value of the valve string current is calculated by subtracting the maximum absorbed power in the power storage state from the sum of the input power of all energy storage units and then using a PI controller. At this point, since the charging and discharging power of the two valve string energy storage units is coupled with the power dissipation resistor, decoupling control is required. Figure 1 The voltage and current directions shown are reference directions, and the total power flowing into this phase-shifted energy storage integrated topology is shown in Equation (1).

[0054] (1)

[0055] There are two bridge arms, each with a valve string. The two bridge arms are designated as the first bridge arm and the second bridge arm. The valve string on the first bridge arm is called the first valve string, and the valve string on the second bridge arm is called the second valve string. the power absorbed by the first valve string, the power absorbed by the second valve string, the power dissipated on the power dissipation resistor, the voltage of the DC system, the current on the first valve string, the current on the second valve string;

[0056] The total power absorbed by the valve strings is given by equation (2).

[0057] (2)

[0058] where, is the voltage on the first valve string is the voltage on the second valve string.

[0059] The power dissipated on the power dissipation resistor is given by equation (3).

[0060] (3)

[0061] where, is the input current of the energy dissipation unit.

[0062] With equations (1)-(3) together, the total power absorbed by the valve strings can be rewritten as equation (4).

[0063] (4)

[0064] Further, equation (4) can be simplified as equation (5).

[0065] (5)

[0066] Therefore, by controlling the inner loop current trackers of each valve string, the first valve string tracks the current , and the second valve string tracks the current , the valve strings can track the total power From equation (5), it can be seen that the tracking value of is offset by in equation, and thus the energy storage power and energy dissipation power are decoupled. As shown in Figure 5 , the reference value of the valve string current is subtracted from , respectively, and then the PI controller generates the modulation wave of the valve string voltage.

[0067] The difference between the redundant power of the system and the maximum power that the power storage state can absorb is the power that needs to be consumed on the power dissipation resistor. The reference voltage across the power dissipation resistor can be obtained by knowing the resistance value of the power dissipation resistor. The phase shift angle is calculated by the PI controller after the difference between the power dissipation resistor reference voltage and the actual voltage θ Meanwhile, the number of negative pulses in the modulation wave is obtained by the rounding function of the power dissipation resistor reference voltage and the capacitor voltage k In the PS-PWM, the carrier of the second valve string is phase shifted relative to the carrier of the first valve string θ by the angle, and one negative pulse is superimposed in the modulation wave of each energy storage unit k , and finally the control signals of the switching tubes of the energy storage units of the two valve strings are generated.

[0068] Reference Figure 8 Before the energy dissipation unit is started, the phase shift angle θ is set to 0, and the number of negative pulses in the modulation wave of the energy storage unit is set to 1 k , so that the series switch S r , S r ' The voltage on both sides is minimum, only one capacitor voltage V c , and the voltage stress is lowest S r , S r ' is closed, and then the phase shift angle θ ref and the number of negative pulses in the modulation wave are controlled according to the output of the controller k ref . Before the energy dissipation unit is turned off, the phase shift angle θ θ is set to 0, and the number of negative pulses in the modulation wave of the energy storage unit is set to 1 k , so that the series switch S r , S r ' The voltage on both sides is minimum after the turn-off, realizing the on-off control of the low-voltage switch on the high-voltage energy dissipation unit.

[0069] The above only describes the preferred embodiments of the present application, and does not use any limitation on the technical solutions of the present application. Those skilled in the art should understand that without departing from the spirit and principles of the present application, the technical solutions can also be modified and replaced in several simple ways, and these modifications and replacements also belong to the protection scope covered by the claims.

Claims

1. A method for combined energy consumption control of phase-shifting energy storage under offshore wind power fault conditions, characterized in that, A phase-shifting energy storage and energy dissipation joint control system based on offshore wind power fault conditions, the system includes: two bridge arms and an energy dissipation unit, the two bridge arms are connected in parallel, and the two ends of the two bridge arms are connected in parallel to the DC bus. Each bridge arm includes several valve strings and bridge arm inductors formed by energy storage units connected in series. The valve strings and bridge arm inductors are connected in series to store redundant power. The two ends of the energy dissipation unit are respectively connected between the valve strings and bridge arm inductors of two parallel bridge arms. The energy dissipation unit is used to consume redundant power. The method includes the following steps: During energy storage, the two reverse-connected switching transistors are kept off at the same time, and the energy dissipation unit is equivalent to an open circuit. No current flows through the power dissipation resistor. At this time, the charging and discharging power of the battery can be controlled by changing the number of energy storage units inserted into the circuit. When two reverse-connected switches are closed simultaneously, the energy dissipation unit is activated. Both the energy storage unit and the energy dissipation unit absorb energy. The AC voltage across the energy dissipation unit is transferred to the power dissipation resistor through the series LC resonant network. When the energy storage unit has the ability to fully absorb the system's redundant power, it only operates in the power storage state; if the redundant power exceeds the maximum energy storage capacity, it switches to the power hybrid absorption state and simultaneously closes the two anti-series switches in the energy dissipation unit to absorb the excess energy through the power dissipation resistor. Before the energy dissipation unit is started and turned off, the phase shift angle is... θ Set to 0, and simultaneously increase the number of negative pulses in the modulation wave of the energy storage unit. k Set to 1.

2. The method for combined control of phase-shifting energy storage energy consumption under offshore wind power fault conditions according to claim 1, characterized in that, The energy storage unit includes a half-bridge module, a filter inductor L, a capacitor, and an energy storage battery. The half-bridge module includes an upper switch S1 and a lower switch S2, which are complementary in conduction. The energy storage battery and the filter inductor L are connected in series and then in parallel with the capacitor.

3. The method for combined control of phase-shifting energy storage energy consumption under offshore wind power fault conditions according to claim 2, characterized in that, Both the upper switch S1 and the lower switch S2 are insulated gate bipolar transistors (IGBTs) with anti-parallel diodes.

4. The method for combined control of phase-shifting energy storage energy consumption under offshore wind power fault conditions according to claim 1, characterized in that, The energy dissipation unit includes a switching transistor. S r Switching transistor S r ' LC series resonant network, bridge diode rectifier module, filter capacitor and power dissipation resistor, switching transistor S r One end is connected between the valve string and the bridge arm inductor of a bridge arm, and the other end is connected to one end of an LC series resonant network. The other end of the LC series resonant network is connected to one end of a bridge diode rectifier module, and the other end of the bridge diode rectifier module is connected to a switching transistor. S r ' One end, the switching transistor S r ' The other end is connected between the valve string and the bridge arm inductor of another bridge arm; a filter capacitor and a power dissipation resistor are connected in parallel on the bridge diode rectifier module.

5. The method for combined control of phase-shifting energy storage energy consumption under offshore wind power fault conditions according to claim 4, characterized in that, LC series resonant network includes inductor L r and capacitor C r Inductor L r and capacitor C r Series connection.

6. The method for combined control of phase-shifting energy storage energy consumption under offshore wind power fault conditions according to claim 4, characterized in that, Switching transistor S r Switching transistor S r ' It consists of two inverted series switching transistors, and is an insulated gate bipolar transistor (IGBT) with an anti-parallel diode.

7. The method for combined control of phase-shifting energy storage energy consumption under offshore wind power fault conditions according to claim 4, characterized in that, A bridge diode rectifier module is a structure consisting of multiple diodes connected in series.

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