MMC converter valve and method for realizing AC / DC fault ride-through based on energy consumption submodule

Abstract

The present invention relates to the field of high-voltage direct current transmission, aiming to provide an MMC converter valve and method for achieving AC-DC fault ride-through based on energy-consuming sub-modules. The present invention is based on the topological structure of a conventional MMC converter valve. Between the arm inductor of each arm and the midpoints of the upper and lower arms, M energy-consuming sub-modules that are serially connected in sequence and have the same structure are provided. Each of the energy-consuming sub-modules includes a main current-carrying branch, an energy-consuming branch, and a bypass circuit connected in parallel. In the main current-carrying branch, a semi-controlled switching device T1 and its freewheeling diode D1 are reversely connected in parallel, and then reversely connected in series with a fully-controlled switching device T2 and its reverse freewheeling diode D2. The energy-consuming branch includes an energy-consuming resistor R d , and the bypass branch includes a bypass switch K. The present invention integrates AC fault ride-through and DC fault ride-through into the topology of the MMC converter valve, improving the integration degree of the protection scheme; it can effectively smooth the voltage fluctuation during AC fault ride-through and improve the stability during AC fault ride-through.

Description

Technical Field

[0001] The present invention belongs to the field of high-voltage direct current transmission, and in particular is an MMC converter valve and a control method thereof for realizing AC / DC fault riding based on an energy-consuming submodule and applied to a high-voltage flexible direct current transmission system. Background Art

[0002] In order to meet the electricity demand of the rapid economic and social development and meet the requirements of clean emissions and environmental protection, a large number of wind power, photovoltaic and other new energy units have been connected to the power grid in recent years. The high-voltage flexible direct current transmission system has the advantages of high energy conversion efficiency, low transmission line loss, and meeting sensitive direct current loads, and has therefore been widely used.

[0003] Modular Multilevel Converter (MMC, this topology usually exists in the form of a converter valve in the field of high-voltage power transmission, hereinafter referred to as a converter valve) is a new type of multilevel converter topology. Compared with traditional two-level or three-level VSC, it has the characteristics of flexible voltage level control, low harmonic content, and low switching loss. It has been widely used and studied in the field of high-voltage direct current transmission and high-voltage power change. However, if a DC short-circuit fault occurs in the system, its fault characteristics are short duration, rapid current rise, and high overcurrent peak. If it is not suppressed, it will damage the power electronic equipment inside the transmission system. For example, if an AC short-circuit fault occurs on the AC side of the converter station at the receiving end of the high-voltage direct current transmission system, the power transmission capacity of the transmission system itself will further decrease with the voltage; and the transmission power of the sending station cannot be adjusted in a short time, and the surplus power between the sending and receiving ends will force the DC bus voltage to increase. When the voltage rises to the protection threshold of the transmission system, the transmission system will trigger the protection threshold to cause the system to lock and stop operation. Therefore, it is necessary to use appropriate equipment to dissipate the surplus power in the case of an AC short-circuit fault.

[0004] The protection equipment of the high-voltage flexible direct current transmission system in the prior art has a single function, and is mostly used to meet the requirements of characteristic protection. That is, high-voltage flexible direct current transmission requires the purchase of two sets of equipment for DC protection and AC short-circuit fault protection. For example, the DC protection equipment adopts a DC circuit breaker or a hybrid MMC, and the energy-consuming device protection adopts DC chopper and other solutions. Among them, the DC circuit breaker and the hybrid MMC solution require a large number of fully controlled IGBT devices in series and parallel, which is expensive. In addition, in the existing AC fault crossing technology, the energy-consuming device used will bring additional DC bias voltage at the time of input and removal, which further causes large fluctuations in the DC bus voltage; when the voltage fluctuation exceeds the threshold set by the protection system, the DC transmission system will be locked, which also causes the failure of AC fault crossing.

[0005] Therefore, proposing a new AC / DC fault ride-through technology is of great significance for solving the above technical problems and achieving better economic benefits of high-voltage flexible DC transmission systems. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and propose an MMC converter valve and a control method thereof for achieving AC / DC fault ride-through based on an energy-consuming submodule.

[0007] To solve the technical problem, the solution of the present invention is:

[0008] Provided is an MMC converter valve for realizing AC / DC fault ride-through based on an energy-consuming submodule. The topological structure of the converter valve is composed of three-phase six bridge arms, and each phase includes two upper and lower bridge arms; wherein the common point of the three-phase bridge arm is used as a DC port connected to a DC system, and the midpoint of the upper and lower bridge arms is used as an AC port connected to an AC system; each bridge arm includes a bridge arm inductor and N MMC submodules connected in series in sequence and having the same structure, where N≥1;

[0009] Between the bridge arm inductance of each bridge arm and the midpoint of the upper and lower bridge arms, M energy-consuming submodules with the same structure are arranged in series, M≥1; the energy-consuming submodule includes a parallel main current branch, an energy-consuming branch and a bypass loop; in the main current branch, the half-controlled switch device T1 and its freewheeling diode D1 are reversely connected in parallel, and then reversely connected in series with the fully-controlled switch device T2 and its reverse freewheeling diode D2; the energy-consuming branch includes an energy-consuming resistor R d , the bypass branch includes a bypass switch K.

[0010] As a preferred solution of the present invention, the MMC submodule is a half-bridge power module, including two switching power devices with built-in reverse diodes and a capacitor.

[0011] As a preferred solution of the present invention, the half-controlled switch device T1 of the energy consumption submodule is a thyristor, and the fully-controlled switch device T2 is a three-terminal semiconductor switch device IGBT.

[0012] The present invention further provides a control method for realizing AC / DC fault ride-through based on the aforementioned MMC converter valve, wherein the MMC converter valve is connected to a high-voltage flexible DC power transmission system;

[0013] Under normal operation, only the main flow branch of the energy-consuming submodule in each bridge arm is in the on state and is connected in series in the bridge arm loop of the MMC converter valve; since the bypass switch K is disconnected and the energy-consuming resistor R d With relatively higher resistance, the current in the bridge arm loop does not pass through the energy-consuming branch and the bypass loop;

[0014] When an AC / DC short circuit fault or an AC side short circuit fault occurs, the switch is switched to only the energy-consuming branch connected in series in the MMC bridge arm loop, and the energy-consuming resistor R d Consume energy; define this action as putting the energy-consuming submodule into operation;

[0015] When the fault-through submodule itself fails, the bypass switch K in the bypass branch is turned on to remove the submodule from the operation state.

[0016] As a preferred solution of the present invention, when a DC short circuit fault or an AC side short circuit fault occurs, the half-controlled switch device and the fully-controlled switch device on the main current branch receive the fault signal and execute the action of shutting down the circuit, and the bypass switch K remains in the open state; the fault current is transferred to the energy consumption branch, and the energy consumption resistor R is used to d Limit the impact current amplitude after a DC short circuit fault occurs, or use energy dissipation resistor R d Consume the surplus power of the transmission system caused by the grounding fault on the AC side; when the fault is cleared and the flexible DC transmission system is restarted, reconnect the semi-controlled switching devices and the fully controlled switching devices, so that the main current branch is turned on and connected in series in the bridge arm circuit of the MMC, and the energy-consuming sub-modular MMC converter valve returns to normal operation.

[0017] As a preferred solution of the present invention, when an AC side short circuit fault occurs, by controlling the number of MMC submodules in the MMC converter valve, the DC bus voltage fluctuation caused by the energy-consuming submodule is adjusted to be smooth; specifically, the following contents are included:

[0018] When an AC short circuit occurs and the energy-consuming submodule is put into operation, the freewheeling effect of the bridge arm inductance will bring about a DC bias voltage U dc1 ; In the MMC converter valve, the bridge arm current I arm At the positive zero crossing moment, some MMC submodules in the bridge arm are cut off to adjust the DC bias voltage U dc1 ;

[0019] The bridge arm current I arm In the reverse case, the energy-consuming submodule is put into operation, and the turn-off action of its fully controlled switch device will bring about a reverse voltage bias U bias , the bias voltage U needs to be balanced by adjusting the number of MMC submodules put into use bias ;

[0020] When the AC short circuit fault ends, the removal of the energy-consuming submodule will cause a DC voltage bias U dc2 ; The number of MMC submodules needs to be increased by adjusting the DC voltage bias U dc2 To balance the DC bus voltage.

[0021] As a preferred embodiment of the present invention,

[0022] When adjusting the DC bias voltage U dc1 When the number of MMC submodules N to be removed is determined as follows sm1 :

[0023] (4)

[0024] When adjusting the reverse bias voltage U bias When the number of MMC submodules N put into operation is confirmed as follows sm2 :

[0025] (6)

[0026] When adjusting the DC bias voltage U dc2 When the number of MMC submodules N to be added is determined as follows sm3 :

[0027] (8)

[0028] In the above formulas, roundup() is the upward rounding function; U dc1 U is the DC bias voltage brought by the energy-consuming submodule; bias is the bridge arm current I arm When the energy-consuming submodule is put into operation in the reverse condition, the reverse bias voltage caused by the turn-off action of its fully controlled switch device; U dc2 To remove the DC bias voltage brought by the energy-consuming submodule; U sm is the rated voltage of the capacitor in the MMC submodule.

[0029] The present invention also provides a computer device, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor executes the aforementioned MMC converter valve control method for achieving AC / DC fault crossing based on the energy-consuming sub-module.

[0030] The present invention also provides a computer-readable storage medium, characterized in that the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the aforementioned MMC converter valve control method for realizing AC / DC fault crossing based on the energy consumption sub-module.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) Compared with the prior art in which AC and DC protections require different protection design schemes, the scheme of the present invention integrates AC fault ride-through and DC fault ride-through into the topology of an MMC converter valve, thereby improving the integration of the protection scheme of the high-voltage DC transmission system.

[0033] (2) The present invention can effectively smooth the voltage fluctuation of the high-voltage flexible direct current transmission system during AC fault riding, and improve the stability of the high-voltage flexible direct current transmission system during AC fault riding.

[0034] (3) Compared with the prior art, the present invention does not need to use different corresponding protection devices for AC and DC protection at the same time; only one MMC converter valve topology is used to achieve AC and DC fault riding at the same time, which can effectively reduce the procurement cost of the DC transmission system protection solution.

[0035] (4) Compared with the prior art, the present invention can effectively smooth the voltage fluctuations during AC fault riding of the high-voltage flexible DC transmission system, avoid triggering the protection threshold and causing the fault riding failure, and improve the stability of the high-voltage flexible DC transmission system during AC fault riding.

[0036] (5) Compared with the power electronic topology in the prior art, the present invention uses thyristors as part of the switching elements in the main current branch, which can further reduce the device cost of the protection device.

[0037] (6) The topological scheme of the present invention is concise and the functions are clear; the operation logic is simple and the parameters of the internal components are easy to design. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The topological structure of the MMC converter valve for realizing AC / DC fault ride-through based on the energy-consuming submodule in the present invention.

[0039] Figure 2 This is the operating logic of the MMC converter valve under AC / DC short circuit conditions.

[0040] Figure 3 It is the corresponding operation logic when the energy-consuming submodule needs to be cut off due to a fault.

[0041] Figure 4 is the DC bus voltage of the HVDC transmission system under AC fault ride-through.

[0042] Figure 5 The voltage bias introduced when the energy-consuming submodule is put into operation.

[0043] Figure 6 This is a schematic diagram of the change in the number of MMC sub-modules put into use.

[0044] Figure 7This is the DC bus voltage condition when an AC fault is not applied to the control strategy of the present invention.

[0045] Figure 8 The DC bus voltage condition when an AC fault is crossed after the control strategy of the present invention is adopted. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0047] 1. Topological structure description of MMC converter valve

[0048] Figure 1 It is a topological structure of an MMC converter valve based on an energy-consuming submodule for realizing AC / DC fault crossing in a high-voltage flexible DC transmission system. The topological structure of the converter valve is composed of three phases and six bridge arms, each phase including two upper and lower bridge arms; wherein the common point of the three-phase bridge arm is used as the DC port connected to the DC system, and the midpoint of the upper and lower bridge arms is used as the AC port connected to the AC system; each bridge arm includes a bridge arm inductor and N MMC submodules connected in series in sequence and with the same structure, N≥1; between the bridge arm inductor of each bridge arm and the midpoint of the upper and lower bridge arms, there are M energy-consuming submodules connected in series in sequence and with the same structure, M≥1; the energy-consuming submodule includes a parallel main current branch, an energy-consuming branch and a bypass loop; in the main current branch, the half-controlled switch device T1 and its freewheeling diode D1 are reversely connected in parallel, and then reversely connected in series with the fully-controlled switch device T2 and its reverse freewheeling diode D2; the energy-consuming branch includes an energy-consuming resistor R d , the bypass branch includes a bypass switch K.

[0049] Among them, the MMC submodule can be a half-bridge power module, including two switch power devices with built-in reverse diodes and a capacitor. The half-controlled switch device T1 can be a thyristor, and the fully controlled switch device T2 can be a three-terminal semiconductor switch device (IGBT). In each bridge arm, the number of MMC submodules and energy-consuming submodules connected in series, as well as the selection of capacitors and switch devices, are determined by technicians based on the actual situation of the high-voltage flexible DC transmission system.

[0050] 2. Description of the control method of MMC converter valve

[0051] Based on the topological structure of the above converter valve, the present invention proposes an MMC converter valve control strategy for achieving AC / DC fault ride-through. The problem to be solved for DC short-circuit fault is to limit the amplitude of the impact current, and the problem to be solved for AC short-circuit fault is to deal with the rapid dissipation of surplus power. However, in essence, both can be achieved by limiting the current amplitude and consuming energy through energy-consuming damping. In view of the analysis of the above two types of faults, the present invention proposes the following Figure 2 The MMC converter valve control logic is shown.

[0052] First, under normal operation, only the main flow branch of the energy-consuming submodule in each bridge arm of the MMC converter valve is in the on state and is connected in series in the bridge arm circuit of the MMC converter valve; since the bypass switch K is disconnected and the energy-consuming resistor R d With relatively higher resistance, the current in the bridge arm loop does not pass through the energy-consuming branch and the bypass loop.

[0053] When an AC / DC short circuit fault is detected in the HVDC transmission system, a blocking signal is immediately sent to the controllable devices on the main flow branch in the MMC converter valve (i.e., thyristor T1 and IGBT T2 connected in reverse series). After receiving the fault signal, thyristor T1 and IGBT T2 shut down the main flow loop. Since the bypass switch K remains in the open state, the AC / DC short circuit fault current is forced to transfer to the energy consumption branch. The energy consumption resistor R d Incorporated into the MMC bridge arm loop. Among them, for DC faults, the energy dissipation resistor R d The impulse current amplitude of DC short circuit fault is limited; for AC fault, the energy dissipation resistor R d Consume the surplus power between the transmitting and receiving ends to maintain the stability of the high-voltage flexible DC transmission system. After waiting for the AC / DC short-circuit fault to be cleared, restart the high-voltage flexible DC transmission system and turn on the switching devices (i.e. turn on the thyristor T1 and IGBT T2), and re-enter the MMC converter valve to normal operation.

[0054] The operation logic for the energy-consuming submodule failure is as follows: Figure 3 As shown. When an energy-consuming submodule in the MMC converter valve needs to be removed due to its own fault, it only needs to close the bypass switch K in the bypass loop. Since the resistance in the bypass loop is the lowest, the current will be conducted through it, so the fault-crossing modular device can be removed from the loop to prevent it from affecting the normal operation of the high-voltage flexible DC transmission system converter station.

[0055] In the actual application process, different AC and DC fault conditions may occur due to differences in loads and lines in the power grid. Relevant technical personnel in this field can decide which energy-consuming submodule on the bridge arm to use and how many energy-consuming submodules to use based on the actual fault situation based on knowledge accumulation, learning ability and operating experience. This part of the content does not belong to the core innovative content of the present invention, so it will not be repeated.

[0056] 3. Based on the MMC converter valve with modular design of energy-consuming sub-modules, the present invention can also realize a smooth control strategy for DC bus voltage fluctuations in the case of AC fault ride-through.

[0057] For ease of understanding, this embodiment is constructed in the PSCAD simulation software Figure 1The topology and control model of the MMC converter valve is shown in Figure 1. The specific parameters are shown in Table 1. The simulation results of the control process are shown in Table 1. Figures 4 to 8 shown.

[0058] Table 1 Simulation parameters of HVDC transmission system based on energy consumption submodule

[0059]

[0060] like Figure 4 As shown in FIG. 1 , in the case of AC fault ride-through, the DC bus voltage fluctuation can be divided into the pre-fault stage, the energy-consuming submodule input moment, the fault ride-through stable stage, and the energy-consuming submodule removal moment.

[0061] (1) When an AC short circuit fault occurs in the HVDC transmission system, it is detected that the DC bus voltage exceeds the protection threshold (for example, the threshold is set to 1.05 times the rated voltage), and the energy-consuming submodule is put into operation. However, since the bridge arm inductance inside the converter valve has a freewheeling effect, the current remains near the rated operating point when the energy-consuming submodule is put into operation. Therefore, the input of the energy-consuming submodule will bring about a DC bias voltage:

[0062] (1)

[0063] Among them U dc1 is the DC bias voltage brought by the energy-consuming submodule, I arm is the bridge arm current, R diss is the energy dissipation resistor R d Introduced energy dissipation damping.

[0064] In actual operation, the bridge arm current I arm is the sum of the DC component and the AC component:

[0065] (2)

[0066] Among them I dc The DC current transmitted by the HVDC transmission system, I ox It is the AC current corresponding to the AC side of the HVDC transmission system.

[0067] Since the AC components in the upper and lower bridge arm currents are in opposite phases, the AC voltage biases generated when the energy-consuming submodule is put into operation cancel each other out. Therefore, the voltage bias brought about by the energy-consuming submodule when it is put into operation is mainly concentrated on the DC component, that is, the DC bias component U introduced dc1 for:

[0068] (3)

[0069] In order to reasonably offset this voltage component, it is necessary to adjust the number of MMC submodules put into the converter valve bridge arm:

[0070] (4)

[0071] Where N sm1 is the number of MMC submodules to be removed, roundup is the upward rounding function, U sm is the rated voltage of the capacitor in the MMC submodule.

[0072] In actual situations, since some of the switching devices used in the energy-consuming submodules are semi-controlled devices (such as thyristors), they must wait until the bridge arm current passes zero in the positive direction before they can be reliably put into operation. Therefore, it is necessary to collect the current I of each bridge arm of the converter valve in real time. arm , when I arm When the positive zero crossing moment occurs, the number of internal bridge arms of the converter valve is immediately cut off. sm1 MMC submodule, thereby smoothing the DC bias voltage U brought by the energy-consuming submodule dc1 .

[0073] (2) Since some of the switching devices in the energy-consuming submodule are fully controlled devices (such as IGBT), although they can be reliably switched on when the bridge arm current is reversed, the fully controlled switching devices will bring about a reverse bias voltage U when they are switched on. bias :

[0074] (5)

[0075] Because U bias The component is negative. In order to reasonably offset this component, the number of MMC sub-modules invested needs to be adjusted:

[0076] (6)

[0077] Where N sm2 The number of MMC submodules put into operation.

[0078] (3) When the AC short circuit fault ends, removing the energy-consuming submodule will bring about a DC bias voltage U dc2 :

[0079] (7)

[0080] Therefore, it is necessary to increase the number of MMC submodules N put into the converter valve bridge arm. sm3 To balance the DC bus voltage, the adjusted high-voltage transmission system is restored to normal operating levels and AC fault ride-through is achieved.

[0081] (8)

[0082] Figure 5 The voltage offset U introduced when the AC fault ride-through device is put into operation is shown. dc1 , U bias , U dc2 .

[0083] Figure 6 The number of internal MMC submodules in the bridge arm of the high-voltage transmission system is shown. In order to balance the voltage bias U dc1 , U bias , U dc2 , the number of MMC submodules switched in the HVDC transmission system needs to be adjusted, and the number of MMC submodules switched N is changed for different voltage biases. sm1 、N sm2 、N sm3 .

[0084] Figure 7 The situation where the control strategy proposed by the present invention is not adopted is shown. Figure 8 The situation with the control strategy proposed in the present invention is shown. By comparison, it can be seen that when the control strategy proposed in the present invention is not adopted, the DC bus voltage fluctuation range is 517kV~701kV (0.8.pu~1.095.pu). Since the lowest voltage is already lower than the protection threshold of the high-voltage DC transmission system, it will trigger the DC system undervoltage protection, which will lead to a failure of crossing. If the control strategy proposed in the present invention is adopted, the voltage fluctuation range can be effectively balanced at 635kV~702kV (0.99.pu~1.095.pu), avoiding the protection threshold being triggered to cause the fault crossing failure, and improving the stability of the high-voltage flexible DC transmission system during AC fault crossing.

[0085] Therefore, the energy-consuming sub-modular MMC converter valve applied to the high-voltage flexible DC transmission system provided by the present invention can effectively improve the integration of the protection system of the high-voltage flexible DC transmission system, reduce the cost of the protection device, and effectively smooth the voltage fluctuation during the AC fault crossing of the high-voltage flexible DC transmission system, and improve the stability of the high-voltage flexible DC transmission system during the AC fault crossing, which is of great significance for promoting the rapid development and safety assurance of the flexible DC transmission system.

Claims

1. A method for realizing AC / DC fault ride-through using an MMC converter valve, characterized in that: This method utilizes the MMC converter valve based on the energy-consuming submodule; The topological structure of the MMC converter valve is composed of three phases and six bridge arms, and each phase includes two upper and lower bridge arms; wherein the common point of the three-phase bridge arm is used as the DC port connected to the DC system, and the midpoint of the upper and lower bridge arms is used as the AC port connected to the AC system; each bridge arm includes a bridge arm inductor and N MMC sub-modules connected in series in sequence and with the same structure, N≥1; between the bridge arm inductor of each bridge arm and the midpoint of the upper and lower bridge arms, M energy-consuming sub-modules connected in series in sequence and with the same structure are arranged, M≥1; the energy-consuming sub-module includes a parallel main current branch, an energy-consuming branch and a bypass loop; in the main current branch, the half-controlled switch device T1 and its freewheeling diode D1 are reversely connected in parallel, and then reversely connected in series with the fully-controlled switch device T2 and its reverse freewheeling diode D2; the energy-consuming branch includes an energy-consuming resistor R d , the bypass branch includes a bypass switch K; The method specifically comprises: Connecting the MMC converter valve to a high-voltage flexible direct current transmission system; Under normal operation, only the main flow branch of the energy-consuming submodule in each bridge arm is in the on state and is connected in series in the bridge arm loop of the MMC converter valve; since the bypass switch K is disconnected and the energy-consuming resistor R d With relatively higher resistance, the current in the bridge arm loop does not pass through the energy-consuming branch and the bypass loop; When an AC / DC short circuit fault or an AC side short circuit fault occurs, the switch is switched to only the energy-consuming branch connected in series in the MMC bridge arm loop, and the energy-consuming resistor R d Consume energy; define this action as putting the energy-consuming submodule into operation; When the fault-through submodule itself fails, the bypass switch K in the bypass branch is turned on to remove the submodule from the operation state.

2. The method according to claim 1, characterized in that The MMC submodule is a half-bridge power module, comprising two switch power devices with built-in reverse diodes and a capacitor.

3. The method according to claim 1, characterized in that The half-controlled switch device T1 of the energy consumption submodule is a thyristor, and the fully-controlled switch device T2 is a three-terminal semiconductor switch device IGBT.

4. The method according to claim 1, characterized in that When a DC short circuit fault or an AC side short circuit fault occurs, the half-controlled switch device and the fully-controlled switch device on the main current branch receive the fault signal and execute the action of shutting down the circuit, and the bypass switch K remains in the open state; Transfer the fault current to the energy dissipation branch and use the energy dissipation resistor R d Limit the impact current amplitude after a DC short circuit fault occurs, or use energy dissipation resistor R d Consume the surplus power of the transmission system caused by the grounding fault on the AC side; when the fault is cleared and the flexible DC transmission system is restarted, reconnect the semi-controlled switching devices and the fully controlled switching devices, so that the main current branch is turned on and connected in series in the bridge arm circuit of the MMC, and the energy-consuming sub-modular MMC converter valve returns to normal operation.

5. The method according to claim 1, characterized in that When a short circuit fault occurs on the AC side, the DC bus voltage fluctuation caused by the energy-consuming submodule is adjusted to be smooth by controlling the number of MMC submodules in the MMC converter valve. Specifically, the following contents are included: When an AC short circuit occurs and the energy-consuming submodule is put into operation, the freewheeling effect of the bridge arm inductance will bring about a DC bias voltage U dc1 ; In the MMC converter valve, the bridge arm current I arm At the positive zero crossing moment, some MMC submodules in the bridge arm are cut off to adjust the DC bias voltage U dc1 ; The bridge arm current I arm In the reverse case, the energy-consuming submodule is put into operation, and the turn-off action of its fully controlled switch device will bring about a reverse voltage bias U bias , the bias voltage U needs to be balanced by adjusting the number of MMC submodules put into use bias ; When the AC short circuit fault ends, the removal of the energy-consuming submodule will bring about a DC voltage bias U dc2 ; The number of MMC submodules needs to be increased by adjusting the DC voltage bias U dc2 To balance the DC bus voltage.

6. The method according to claim 5, characterized in that When adjusting the DC bias voltage U dc1 When the number of MMC submodules to be removed is determined as follows N sm1 : （4） When adjusting the reverse bias voltage U bias When the number of MMC submodules put into operation is confirmed as follows N sm2 : （6） When adjusting the DC bias voltage U dc2 When the number of MMC submodules to be added is determined as follows N sm3 : （8） In the above formulas, roundup() is the upward rounding function; U dc1 U is the DC bias voltage brought by the energy-consuming submodule; bias is the bridge arm current I arm The reverse bias voltage caused by the turn-off action of the fully controlled switch device when the energy-consuming submodule is put into operation in the reverse condition; U dc2 To remove the DC bias voltage brought by the energy-consuming submodule; U sm is the rated voltage of the capacitor in the MMC submodule.

7. A computer device, characterized in that: include: At least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor executes the MMC converter valve control method for realizing AC / DC fault ride-through based on an energy-consuming submodule as described in any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the MMC converter valve control method for achieving AC / DC fault ride-through based on an energy-consuming submodule according to any one of claims 1 to 6.

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