Energy storage and energy consumption cooperative control system and method for fault of flexible DC power transmission network side

Abstract

The invention belongs to the technical field of power electronics, and discloses an energy storage and consumption cooperative control system and method.The system comprises an energy storage module and an energy consumption module, the energy storage module and the energy consumption module are connected through an energy consumption path switching tube, and the energy storage module is connected with a flexible direct current transmission network bus; the method is used for storing and consuming surplus power of the bus of the flexible direct-current power transmission network. By finely modulating the N submodules which are connected in series, the flexible coping capacity of the submodules under different working conditions is shown. When the power system is in a transient stage, the sub-modules can respond quickly, and redundant electric energy is converted into chemical energy to be stored, so that the system power is effectively balanced, and overload of a power grid is prevented. And when the system enters steady-state operation, the sub-modules can release the stored energy according to the demand of the power grid, or the power supply stability and quality are ensured through fine adjustment of the electric energy quality, and the demand of a user for high-quality electric energy is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics and relates to a coordinated energy storage and energy consumption control system and method for a flexible direct current transmission network side fault. Background Art

[0002] Offshore wind power has the advantages of not occupying land resources, being less affected by terrain factors, and having stable wind speeds, and has broad development prospects. However, the transmission of electricity through AC submarine cables faces the problem of reactive power loss, which is not conducive to the development of wind power in the deep sea. Flexible DC transmission technology is based on voltage source converters (VSCs), which have the advantages of independent regulation of active and reactive power, no commutation failure problems, and no need for reactive power compensation. It has been widely used in offshore wind power transmission.

[0003] When offshore wind power transmitted by flexible direct current is in steady-state operation, the active power of the wind farm at the sending end and the onshore power grid at the receiving end are balanced. However, when a short-circuit fault occurs on the grid side, the voltage on the grid side drops, which in turn reduces the active power absorbed by the grid side. Since the converter station of the offshore wind farm cannot sense the grid-side fault in time, the output power of the wind farm remains unchanged, which leads to power imbalance between the sending end and the receiving end. The surplus active power will cause the DC voltage to increase, and in severe cases, the system will be shut down. In order to achieve fault ride-through of the system when there is a grid-side fault, it is necessary to reduce or absorb the surplus power that occurs when there is a grid-side fault. One method is to rely on communication lines to reduce the output power of the wind farm, but the communication system has the disadvantage of high latency, and the wind turbine has a large inertia, making it difficult to respond to the need for fault ride-through in time; another method is to connect energy-consuming devices in parallel at both ends of the DC line, convert the surplus power into heat energy through energy-consuming resistors, and dissipate it, thereby maintaining the voltage stability of the DC line. However, the consumed surplus power has the problem of energy waste, and the energy-consuming device needs to be equipped with a large heat dissipation device, which occupies a large area. Summary of the invention

[0004] The object of the present invention is to provide a coordinated energy storage and energy consumption control system and method for a flexible DC transmission network side fault, so as to solve the above-mentioned problems.

[0005] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides an energy storage and energy consumption coordinated control system for a fault on the side of a flexible DC transmission network, comprising an energy storage module and an energy consumption module, wherein the energy storage module and the energy consumption module are connected via an energy consumption path switch tube, and the energy storage module is connected to a busbar of the flexible DC transmission network, and is used for storing and consuming surplus power of the busbar of the flexible DC transmission network.

[0006] The energy storage module is a bipolar structure, each pole includes a plurality of energy storage sub-modules and a bridge arm inductor, and the plurality of energy storage sub-modules are connected in series and then connected in series with the bridge arm inductor to ground.

[0007] Furthermore, the energy consumption module includes a resonant network, a diode rectifier bridge, a filter capacitor and an energy consumption resistor, and the resonant network, the diode rectifier bridge, the filter capacitor and the energy consumption resistor are connected in series.

[0008] Furthermore, the energy storage submodule includes a half-bridge module, an inductor and an energy storage battery, and the half-bridge module is connected in parallel with the energy storage battery in series with the inductor.

[0009] Furthermore, the switch tube of the half-bridge module and the switch tube of the energy consumption path are both insulated gate bipolar transistors with anti-parallel diodes.

[0010] Furthermore, the energy consumption module is connected between the energy storage submodule and the bridge arm inductor through an energy consumption path switch tube.

[0011] Furthermore, one end of the energy consumption path switch tube is connected to the bridge arm inductor Lp, and the other end is connected to the resonant network.

[0012] Furthermore, the resonant network is an inductor and a capacitor connected in series.

[0013] In a second aspect, the present invention provides a control method for an energy storage and energy consumption coordinated control system for a fault on a flexible DC transmission network side, comprising the following steps: By real-time detection of the DC bus voltage switching control state, when the DC bus voltage is within a safe range, the wind farm energy fluctuation is supplemented and the power quality is adjusted through N series-connected energy storage submodules; When the DC bus voltage exceeds the safety range, the surplus power is stored through N series-connected energy storage submodules; When the surplus power is greater than the upper limit of the energy storage system absorption, the surplus power is stored and consumed simultaneously through N series-connected energy storage sub-modules, resonant networks, filter capacitors, and energy-consuming resistors.

[0014] Furthermore, the capacitor voltage of the energy storage submodule controls the charging and discharging of the parallel energy storage batteries in the submodule by controlling the number of submodules put into operation at the same time.

[0015] Furthermore, in steady state, the fluctuation of the output power of the wind farm is detected and absorbed or supplemented by utilizing the energy storage state.

[0016] Furthermore, in the energy storage and consumption state, N series-connected submodules are simultaneously switched on or off, and the series voltage of the submodules is equivalent to a two-level voltage, and the output voltage amplitude is adjusted by changing the frequency of the two-level voltage.

[0017] Compared with the prior art, the present invention has the following technical effects: The present invention provides a system that integrates energy storage and energy consumption functions, which can effectively manage the surplus power of the busbar of the flexible DC transmission network. The bipolar structure design of the energy storage module improves the reliability and flexibility of the system and can cope with power flows in different directions. The design of the energy consumption module allows the surplus power to be safely consumed when necessary to prevent grid overload or equipment damage.

[0018] The design of the energy storage submodule enables each submodule to independently control charging and discharging, improving the flexibility and response speed of the system. The combination of the half-bridge module and the inductor provides effective protection for the energy storage battery to prevent overcharging or over-discharging.

[0019] Using an insulated gate bipolar transistor (IGBT) with an anti-parallel diode improves the efficiency and reliability of the switch. The anti-parallel diode provides reverse conduction capability, helping to maintain system stability when the direction of power flow changes.

[0020] The flexible connection between the energy consumption module and the energy storage submodule enables the system to quickly switch the working mode according to actual needs. The control of the energy consumption path switch tube provides precise control of the energy consumption module input and output.

[0021] The location design of the switch tube in the energy consumption path allows the surplus power to be efficiently transferred to the energy consumption module. The design of the resonant network helps to achieve a smooth transition and consumption of power during the energy consumption process.

[0022] The series inductor and capacitor form a simple but effective resonant network for absorbing and releasing energy during the energy consumption process. The design of the resonant network helps to reduce the voltage and current fluctuations during the energy consumption process and improve the stability of the system.

[0023] The present invention also provides a real-time control strategy based on the DC bus voltage, so that the system can automatically adjust the working mode according to the state of the power grid. Under different working conditions, the system can respond flexibly to ensure the stable operation and power quality of the power grid.

[0024] When the surplus power exceeds the upper limit of the energy storage system's absorption, the system can simultaneously start the energy storage and energy consumption functions to effectively prevent the grid from overloading. The energy storage submodule controls the charging and discharging of the parallel energy storage batteries in the submodule by controlling the number of submodules put into operation at the same time; in steady state, it detects the fluctuation of the wind farm's output power and absorbs or supplements it using the energy storage state. By controlling the number of submodules put into operation at the same time, the system can accurately adjust the charging and discharging state of the energy storage battery. In steady state, the system can automatically adjust the energy storage state according to the fluctuation of the wind farm's output power to maintain the stable operation of the grid. This control strategy improves the flexibility and response speed of the system, and helps to meet the challenges of wind farm energy fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1A schematic diagram of the integrated topological structure of energy storage and consumption used in the present invention; Figure 2 A schematic diagram of the structure of the energy storage and energy consumption integrated topology neutron module used in the present invention; Figure 3 A schematic diagram of the energy storage state structure of the energy storage and energy consumption integrated topology used in the present invention; Figure 4 This is a block diagram of the energy storage state control strategy proposed by the present invention; Figure 5 This is a block diagram of the energy storage and consumption state control strategy proposed by the present invention. DETAILED DESCRIPTION

[0026] Related term explanation: IGBT: (Insulated Gate Bipolar Transistor) Insulated Gate Bipolar Transistor, a power semiconductor device; PS-PWM: (Phase-Shift Pulse Width Modulation) Phase-Shift Pulse Width Modulation is a modulation method used in power electronics and power conversion technology; PI: Proportional-Integral Controller, is a linear controller widely used in industrial control systems.

[0027] The technical solution of the present invention will be described clearly and completely below with reference to the accompanying drawings: Example 1, please refer to Figure 1 The present invention provides an energy storage and energy consumption coordinated control system for a fault on the side of a flexible DC transmission network, including an energy storage module and an energy consumption module. The energy storage module and the energy consumption module are connected via an energy consumption path switch tube. The energy storage module is connected to the bus of the flexible DC transmission network and is used for storing and consuming surplus power of the bus of the flexible DC transmission network.

[0028] The energy storage and energy consumption integrated topology is a bipolar structure, and each pole is composed of N series energy storage sub-modules, a bridge arm inductor, an energy consumption path switch tube, an LC resonant network, a diode rectifier bridge, a filter capacitor and an energy consumption resistor.

[0029] The submodule is composed of a half-bridge module and an energy storage battery with a series inductor connected in parallel.

[0030] The switch tubes in the submodule and the switch tubes in the energy consumption path are both insulated gate bipolar transistors IGBTs with anti-parallel diodes.

[0031] By connecting N series energy storage submodules, the surplus power can be stored and the power quality can be adjusted.

[0032] Through N series-connected energy storage submodules, resonant networks, filter capacitors, and energy-consuming resistors, the storage and consumption of surplus power are simultaneously achieved.

[0033] Embodiment 2, the present invention provides a coordinated energy storage and energy consumption control system for a fault on the flexible DC transmission network side, specifically comprising: The energy storage module and the energy consumption module are connected through the energy consumption path switch tube, and the energy storage module is connected to the flexible DC transmission network busbar, mainly used to store and consume the surplus power of the flexible DC transmission network busbar. The energy storage module is designed as a bipolar structure, each pole contains several energy storage sub-modules connected in series and a bridge arm inductor L connected in series with it. p .

[0034] In the energy storage module, each energy storage submodule consists of a half-bridge module, an inductor, and an energy storage battery. These components are connected in parallel with the energy storage battery with the inductor in series. In particular, the switch tube of the half-bridge module and the energy consumption path switch tube both use IGBTs with anti-parallel diodes. This design improves the flexibility and reliability of the system.

[0035] The energy consumption module includes the resonant network LC, the diode rectifier bridge, and the filter capacitor C o And the energy dissipation resistor R o , these components are connected in series. The energy consumption module is connected to the energy storage submodule and the bridge arm inductor through the energy consumption path switch tube. The specific connection method is: one end of the energy consumption path switch tube is connected to the bridge arm inductor L p The other end is connected to the resonant network LC. The resonant network LC is composed of a series inductor L s and capacitor C b Composition, such a design helps to achieve efficient transfer and consumption of energy.

[0036] The energy storage and consumption integrated topology is a bipolar structure, each pole consists of N series sub-modules CELL1---CELL1N, bridge arm inductor L p , energy consumption path switch tube S r (S r '), LC resonant network, diode rectifier bridge, filter capacitor C o And the energy dissipation resistor R o composition.

[0037] The series submodules (CELL1 to CELLN) are connected in series to form a chain structure with voltage superposition. Each submodule may contain energy storage elements such as capacitors or batteries to provide a stable voltage output.

[0038] Bridge arm inductance L p Connected to one end of the series submodule chain and connected to the energy consumption path switch tube Sr (or S r '). Inductor L p Its main function is to limit the rate of change of current, thereby smoothing the current waveform and reducing the impact of current fluctuations on the system.

[0039] Energy consumption path switch tube S r and S r 'Respectively connected to the bridge arm inductor L p The two sides of the switch are connected to the LC resonant network. These switch tubes are used to control the flow path of energy and realize the transmission and dissipation of energy through switching actions.

[0040] The LC resonant network consists of an inductor L and a capacitor C, which are connected to the energy-consuming path switch S. r (S r ') and the diode rectifier bridge. This network uses the resonant characteristics of inductance and capacitance to achieve power conversion and transmission at a specific frequency.

[0041] The diode rectifier bridge consists of four diodes connected between an LC resonant network and a filter capacitor C o The function of the rectifier bridge is to convert AC power into DC power and provide a stable DC voltage for subsequent filtering and energy consumption processes.

[0042] Filter capacitor C o Connected between the output end of the diode rectifier bridge and the energy dissipation resistor R o The main function of the filter capacitor is to smooth the DC voltage waveform after rectification, reduce voltage fluctuations and ripples, and improve the stability of the output voltage v0.

[0043] Energy dissipation resistor R o Connect the filter capacitor C o The other end is connected to the rest of the circuit. The main function of the energy dissipation resistor is to dissipate excess energy, prevent voltage rebound and circuit overvoltage, and thus maintain stable operation of the circuit.

[0044] refer to Figure 2 The energy storage and energy consumption integrated topology submodule is composed of a half-bridge module and an energy storage battery connected in parallel with a series inductor Lb. When the upper switch tube S1 is closed and the lower switch tube S2 is disconnected, the submodule capacitor and the energy storage battery are in the input state; when the upper switch tube S1 is disconnected and the lower switch tube S2 is closed, the submodule capacitor and the energy storage battery are in the bypass state.

[0045] The half-bridge module contains two key switch tubes, namely the upper switch tube S1 and the lower switch tube S2. These two switch tubes are connected to the upper and lower ends of the circuit respectively to control the flow direction of the current.

[0046] When the upper switch tube S1 is closed and the lower switch tube S2 is open, the current can flow to the load through S1. At this time, the sub-module capacitor and the energy storage battery are in the engaged state, and jointly participate in the energy transmission and storage of the circuit.

[0047] When the upper switch tube S1 is disconnected and the lower switch tube S2 is closed, the current flows to the load through S2. At this time, the sub-module capacitor and the energy storage battery are in bypass state, the capacitor is isolated, and the energy storage battery works independently.

[0048] The inductor Lb is connected in series with the energy storage battery to smooth the current and store energy in the circuit. One end of the inductor is connected to the output end of the half-bridge module, and the other end is connected to the load.

[0049] Capacitor C is connected in parallel at the output end of the half-bridge module to store and release electrical energy to maintain the stability of the output voltage. Vx It is the voltage value of capacitor C. In the switched-on state, capacitor C participates in the energy transmission and storage of the circuit together with the energy storage battery.

[0050] The energy storage battery is connected in series with the inductor Lb and in parallel with the capacitor C (controlled by the half-bridge module). In the on state, the energy storage battery and the capacitor C work together; in the bypass state, the energy storage battery works independently.

[0051] The switch tubes in the submodule and the switch tubes in the energy consumption path are all IGBTs with anti-parallel diodes.

[0052] refer to Figure 3 , when the energy consumption path switch tube S r (S r ') is disconnected, the energy-consuming branch is removed, and only N submodules are left in series with the bridge arm inductor Lp. This circuit state is called the energy storage state. r (S r ') When closed, the energy consumption branch is connected to the energy storage state circuit, refer to Figure 1 As shown, this circuit state is called energy storage and consumption state.

[0053] In the energy storage state, the submodule capacitor voltage can be changed by modulating the number of submodules switched on and off, and then the charging and discharging of the energy storage battery can be controlled; in the energy storage consumption state, N series-connected submodules are switched on or off at the same time, and the series voltage of the submodules is equivalent to a two-level voltage. Due to the existence of the LC resonant network, changing the frequency of the two-level voltage can change the amplitude of the output voltage, thereby changing the energy consumption power of the energy consumption resistor. At the same time, the submodule capacitor voltage can be changed by controlling the number of submodules switched on at the same time, thereby controlling the charging and discharging of the parallel energy storage batteries in the submodules.

[0054] refer to Figure 4 : Signal_1: System status indication signal. Signal_1 = 0 indicates that the system is operating normally; Signal_1 = 1 indicates that the system is in a fault state.

[0055] P wind and P wind_ref : P _wind : Actual output power of wind farm.

[0056] P _wind_ref : Rated power of wind farm.

[0057] The difference between the two reflects the fluctuation of wind farm power.

[0058] V dc and V dc_ref : V dc : Actual DC bus voltage.

[0059] V dc_ref : DC bus reference voltage, set to 1.05 pu (the unit is usually voltage unit).

[0060] V dc With V dc_ref The comparison is used to determine whether the system is in a safe operating state.

[0061] P bat and P bat_ref : P bat : Actual power of energy storage system.

[0062] P bat_ref : Reference power of energy storage system.

[0063] In the fault state, P bat_ref It is used to indicate the surplus power that the system needs the energy storage system to absorb.

[0064] I ref and I: I ref : Reference current of energy storage system.

[0065] I: Actual current of the energy storage system.

[0066] I ref It is calculated based on the system status and is used to control the current of the energy storage system.

[0067] PI controller: Used to adjust errors and generate reference waves for submodules.

[0068] PS-PWM: Multiple phase-shifted pulse width modulation is used to generate control signals for sub-module switch tubes.

[0069] Submodule sorting and voltage balancing: Sub-module capacitor voltage sorting and voltage balancing ensure sub-module voltage stability.

[0070] Submodule switching signal: The signal controlling the switch tube of the submodule is used to realize the switching of the submodule.

[0071] Principle explanation Normal operation status (Signal_1 = 0): The system detects the DC bus voltage V in real time dc , if V dc , within the safety range (1.05 pu), the system operates stably.

[0072] At this time, the power absorbed by the grid side is equal to the power output by the wind farm, and the system maintains power balance.

[0073] By detecting the actual output power P of the wind farm wind With rated power P wind_ref The difference between the wind farm power and the wind farm power fluctuation value is obtained.

[0074] Use energy storage systems to supplement or absorb this fluctuation value, maintain constant grid-side absorption power, and improve grid-connected power quality.

[0075] Divide the wind farm power fluctuation value by the DC bus voltage V dc , get the current reference value I of the energy storage system ref .

[0076] I ref After subtracting the actual current I of the energy storage system, it is adjusted by the PI controller to generate the reference wave of the submodule.

[0077] After the reference wave is modulated by PS-PWM and the capacitor voltage of the sub-module is sorted and balanced, a signal of the sub-module switch tube is generated to control the switching of the sub-module.

[0078] Fault status (Signal_1 = 1): If the DC bus voltage V _dc If it exceeds the safety range (1.05 pu), it means that a ground fault has occurred on the grid side and there is surplus power in the system.

[0079] At this time, an energy storage system is needed to absorb the surplus power.

[0080] The actual DC bus voltage V dc With reference voltage V dc_refThe surplus power P of the system is obtained after calculation by the PI controller. bat_ref .

[0081] Make surplus power P bat_ref Divide by the DC bus voltage V dc , get the current reference value I_ of the energy storage system ref .

[0082] The subsequent process is the same as the normal operation state, that is, I_ ref After subtracting the actual current I of the energy storage system, it is adjusted by the PI controller to generate the reference wave of the sub-module, and after PS-PWM modulation and sub-module capacitor voltage sorting and balancing, the signal of the sub-module switch tube is generated.

[0083] By real-time monitoring of parameters such as the DC bus voltage and wind farm output power, and calculating the current reference value of the energy storage system according to the system status, and then going through steps such as PI controller and PS-PWM modulation, the signal of the sub-module switch tube is finally generated, thus achieving power balance and fault handling of the wind farm grid-connected system.

[0084] When the circuit is in the energy storage state, the DC bus voltage is detected in real time. If the DC bus voltage is within the safe range (1.05pu), pu represents the per-unit value, indicating that the system is running stably. At this time, the power absorbed by the grid side is equal to the power output of the wind farm, and the system maintains power balance. Since wind power generation is volatile, the output power of the wind farm is unstable. Therefore, by detecting the actual output power of the wind farm and subtracting it from the rated power of the wind farm, the fluctuation value of the wind farm power can be obtained. Using the energy storage state to supplement or absorb this fluctuation value can maintain the constant power absorption on the grid side and improve the quality of grid-connected power. Therefore, the wind farm power fluctuation value is divided by the DC bus voltage to obtain the current reference value of the energy storage system. After subtracting it from the actual current of the energy storage system, the PI controller generates the reference wave of the submodule, and after multiple phase-shift modulation PS-PWM and submodule capacitor voltage sorting and equalization, the signal of the submodule switch tube is generated. If the DC bus voltage exceeds the safe range, it means that a grounding fault occurs on the grid side, and the system has surplus power, resulting in an increase in the DC bus voltage. At this time, the energy storage state needs to be used to absorb the surplus power. The actual DC bus voltage is subtracted from the reference voltage, and the system surplus power is calculated by the PI controller. The surplus power is divided by the DC bus voltage to obtain the current reference value of the energy storage system. The reference wave of the sub-module is then generated by the PI controller after subtracting it from the actual current of the energy storage system. After multiple phase-shift modulation PS-PWM and sub-module capacitor voltage sorting and balancing, the signal of the sub-module switch tube is generated.

[0085] refer to Figure 5 : V dc: Actual DC bus voltage, indicating the DC voltage value in the current system.

[0086] V dcref : DC bus voltage reference value is the DC voltage value that the system expects to maintain.

[0087] P ref : The system's surplus power, that is, the portion of actual power that exceeds system demand.

[0088] P bat_max : The maximum power that the energy storage system can absorb, indicating the maximum surplus power that the energy storage device can handle.

[0089] P R_ref : The power that needs to be consumed by the energy dissipation resistor. When the surplus power exceeds the absorption capacity of the energy storage system, this part of the power will be consumed through the energy dissipation resistor.

[0090] V R_ref : The reference voltage across the energy dissipation resistor is the key parameter for controlling the power of the energy dissipation resistor.

[0091] V R : Actual voltage of energy dissipation resistor, indicating the current working voltage of energy dissipation resistor.

[0092] f: The frequency of the two-level voltage, used to control the charge and discharge rate of the submodule capacitor.

[0093] Submodule capacitor reference voltage: It is an important parameter for controlling the submodule switch tube signal and is used to maintain the stability of the submodule capacitor voltage.

[0094] If the enabled energy storage state can absorb all the surplus power, the DC bus voltage can be stabilized within a safe range, and there is no need to start the energy consumption device. When a serious fault occurs on the grid side and the surplus power is greater than the upper limit of the energy storage system, the surplus power that cannot be absorbed will cause the DC bus voltage to continue to rise. At this time, it is necessary to simultaneously activate the energy consumption branch to further absorb the excess surplus power. Figure 1 Topology, when the surplus power is greater than the upper limit of the energy storage system absorption, the energy consumption path switch tube S is closed r With S r 'Input into energy consumption branch. Figure 5 As shown in (a), the actual DC bus voltage is subtracted from the reference voltage, and the surplus power of the system is calculated by the PI controller; Figure 5 As shown in (b), the surplus power of the system is subtracted from the maximum power that can be absorbed by the energy storage state to obtain the power that needs to be consumed by the energy dissipation resistor. If the resistance value of the energy dissipation resistor is known, the reference voltage across the energy dissipation resistor can be obtained; Figure 5As shown in (c), the energy-consuming resistor reference voltage is subtracted from the actual voltage and the frequency of the two-level voltage is calculated by the PI controller. The maximum power absorbed in the energy storage state is subtracted from the sum of the input powers of all batteries and the submodule capacitor voltage reference value is calculated by the PI controller. In order to reduce the large switching stress caused by the simultaneous switching of submodules, a quasi-square wave modulation strategy is adopted so that there is a slight phase shift difference when adjacent submodules are switched. The quasi-square wave with a frequency of f and the submodule capacitor reference voltage are input into the NLM link, and then the submodule capacitor voltage is sorted and balanced to generate the signal of the submodule switch tube.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. The energy storage and energy consumption coordinated control system for the fault of the flexible DC transmission network side is characterized by: It includes an energy storage module and an energy consumption module, which are connected via an energy consumption path switch tube, and the energy storage module is connected to the flexible DC transmission network busbar, and is used for storing and consuming the surplus power of the flexible DC transmission network busbar; The energy storage module is a bipolar structure, each pole includes a plurality of energy storage sub-modules and a bridge arm inductor, and the plurality of energy storage sub-modules are connected in series with the bridge arm inductor and grounded.

2. The energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 1 is characterized in that: The energy consumption module comprises a resonant network, a diode rectifier bridge, a filter capacitor and an energy consumption resistor, and the resonant network, the diode rectifier bridge, the filter capacitor and the energy consumption resistor are connected in series in sequence.

3. The energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 1, characterized in that: The energy storage submodule includes a half-bridge module, an inductor and an energy storage battery. The half-bridge module is connected in series with the inductor and then connected in parallel with the energy storage battery.

4. The energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 3 is characterized in that: The switch tube of the half-bridge module and the switch tube of the energy consumption path are both insulated gate bipolar transistors with anti-parallel diodes.

5. The energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 1, characterized in that: The energy consumption module is connected between the energy storage submodule and the bridge arm inductor through an energy consumption path switch tube.

6. The energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 1, characterized in that: One end of the energy-consuming path switch tube is connected to the bridge arm inductor, and the other end is connected to the resonant network.

7. The energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 1, characterized in that: The resonant network is an inductor and a capacitor connected in series.

8. A control method for the energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to any one of claims 1 to 7, comprising the following steps: By real-time detection of the DC bus voltage switching control state, when the DC bus voltage is within a safe range, the wind farm energy fluctuation is supplemented and the power quality is adjusted through N series-connected energy storage submodules; When the DC bus voltage exceeds the safety range, the surplus power is stored through N series-connected energy storage submodules; When the surplus power is greater than the upper limit of the energy storage system absorption, the surplus power is stored and consumed simultaneously through N series-connected energy storage sub-modules, resonant networks, filter capacitors, and energy-consuming resistors.

9. The control method of the energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 8, characterized in that: The energy storage submodule controls the charging and discharging of the parallel energy storage batteries in the submodules by controlling the number of submodules put into operation at the same time.

10. The control method of the energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 8, characterized in that: In steady state, the fluctuation of wind farm output power is detected and absorbed or supplemented by energy storage.

11. The control method of the energy storage and energy consumption coordinated control system for a fault on the flexible DC transmission network side according to claim 8, characterized in that: In the energy storage and consumption state, N series-connected submodules are simultaneously switched on or off, and the series voltage of the submodules is equivalent to a two-level voltage. The output voltage amplitude is adjusted by changing the frequency of the two-level voltage.

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