195 results about "Dc fault" patented technology

The invention discloses an alternating-current and direct-current fault protection method of a hybrid commutation converter valve and related equipment thereof, and relates to the technical field of high-voltage direct-current power transmission. The method comprises the steps of obtaining an AC voltage of an AC side, a target trigger angle of a hybrid commutation converter valve and a DC current of a DC side, and determining an extinction angle margin risk factor and a volt-second area margin risk factor according to at least one of the above, the extinction angle margin risk factor being used for representing a commutation success margin, and the volt-second area margin risk factor being used for representing a target trigger angle of the hybrid commutation converter valve; the volt-second area margin risk factor is used for representing the commutation driving capability; determining a commutation failure risk index based on the extinction angle margin risk factor, the volt-second area margin risk factor and the prediction confidence factor; and when the commutation failure risk index is abnormal, controlling and triggering the hybrid commutation converter valve to enter a corresponding commutation enhancement mode or an active turn-off mode based on the commutation failure risk index. According to the embodiment of the invention, active intervention can be carried out before the commutation failure is caused by the AC / DC fault, so that the commutation failure can be fully resisted.

The invention relates to a direct current fault ride-through method, a direct current fault ride-through device, direct current fault ride-through equipment and a medium. The method comprises the following steps: switching a control mode of network-forming type energy storage into an alternating-current voltage control mode or a direct-current control strategy, carrying out coordinated control on devices in a multi-terminal direct-current collecting and sending-out system, clearing fault current, and clearing the fault current by utilizing an active step-down control strategy or the direct-current control strategy at the same time. According to the method, measures such as additional direct current circuit breakers are not needed, control is flexible and easy to achieve, the multi-terminal direct current collecting and sending-out system after fault clearing is controlled to be recovered by judging the operation state of the multi-terminal direct current collecting and sending-out system, and safe and stable operation of the multi-terminal direct current collecting and sending-out system is facilitated.

The present invention provides a hybrid direct current transmission system and a control method thereof, which belongs to the field of power electronics. The system includes: the rectifier side circuit adopts a heterogeneous series topology structure, the high-voltage valve group adopts LCC to withstand high voltage levels, and the low-voltage valve group adopts MMC to establish and maintain the voltage stability of the grid connection point; the inverter side circuit adopts a distributed connection, wherein the high-voltage valve group adopts LCC, the low-voltage valve group adopts three parallel MMCs, and multiple inverters are distributedly connected to different AC circuits. The rectifier side is composed of LCC and MMC in series, and the inverter side is composed of three parallel MMCs and LCC in series that are distributedly connected to different AC circuits. In this way, the system can provide voltage support for the energy base, has AC and DC fault ride-through function, prevents phase change failure, and improves system stability. In addition, the distributed access method can also achieve flexible power distribution.

The invention discloses a fault detection method of an eddy current sensor, a related device, equipment and a medium, and the method comprises the steps: sampling a first AC signal and a second AC signal outputted by the eddy current sensor, and obtaining sampling data; based on the sampling data, determining whether the eddy current sensor has a target fault; wherein the target fault comprises at least one of a DC fault and an AC fault; under the condition that the eddy current sensor has a direct current fault, at least one of the first alternating current signal and the second alternating current signal is changed into a direct current signal from an alternating current signal; when the eddy current sensor has an alternating current fault, at least one of the first alternating current signal and the second alternating current signal becomes an abnormal alternating current signal. Through the mode, the fault type of the eddy current sensor can be detected, the fault reason and the fault position of the eddy current sensor can be quickly determined during maintenance, and the maintenance efficiency of the eddy current sensor is improved.

The invention relates to a high-voltage direct-current power transmission technology, and aims to provide a direct-current fault ride-through method and device based on energy-consuming damping and a circuit breaker and a medium. The method comprises the following steps: reducing the AC side voltage of a converter valve, and transferring a fault current to an energy consumption damping module in the MMC converter valve, so that an electromotive force enters a new steady state stage; the direct current fault current is gradually reduced, the direct current circuit breaker executes breaking operation, and a direct current fault point is completely isolated from the high-voltage flexible direct current power transmission system; a control strategy when the MMC converter valve operates normally is recovered, the energy consumption damping module is cut off step by step, and the MMC sub-module is put into operation at the same time, so that the high-voltage flexible direct-current power transmission system is stably transited to the normal operation state. Impact and damage risks of fault current on system equipment can be effectively reduced, and safe and stable operation of the system is guaranteed; a direct-current circuit breaker with a smaller capacity can be adopted, so that the purchase cost of equipment is remarkably reduced; the system stability can be kept under the fault condition, and the power supply reliability is improved.

The present invention discloses a method for self-clearing DC faults in a new energy island power grid transmission system. The sending end adopts a constant AC voltage and frequency control strategy, and there is only one receiving end that adopts a constant DC voltage control strategy, while the remaining receiving ends adopt a constant active power control strategy. At the same time, each pole of the flexible DC converter station at the sending end real-time detects the DC current flowing out of this pole, and each pole of the flexible DC converter station at the receiving end real-time detects the DC current flowing into this pole. After detecting the occurrence of a DC fault, the DC fault is automatically cleared according to their respective control strategies, and the energy balance of the sending end island is achieved in cooperation with the AC energy consumption at the sending end. It solves the technical problems of coordinated control between flexible DC and new energy, power surplus, and self-clearing of DC faults on the DC side, and improves the power regulation ability and system stability of the new energy island power grid transmission system.

The invention discloses a flexible direct-current power transmission system and a fault ride-through method and system thereof. The flexible direct-current power transmission system comprises a main control module, and a new energy sending-out system, an alternating-current energy consumption device, a sending-end converter, a direct-current circuit breaker, a receiving-end converter and a receiving-end alternating-current power grid which are connected in sequence, the direct current circuit breaker is deployed on a direct current power transmission line between the sending end converter and the receiving end converter, and the receiving end converter is a modular multi-level converter formed by cascading a plurality of half-bridge sub-modules with damping branches; the main control module is in communication connection with the half-bridge sub-modules, the direct-current circuit breaker and the alternating-current energy consumption device and used for controlling the damping branches of the half-bridge sub-modules in the running state, the direct-current circuit breaker and the alternating-current energy consumption device to act when a direct-current fault occurs so as to restrain direct current and adjust direct-current voltage to be within a set voltage range. Therefore, no-locking fault ride-through is completed. According to the invention, high-reliability and low-cost DC fault ride-through can be realized.

The invention provides a direct-current boost collection converter of an offshore wind power full-direct-current sending-out system, and the converter can quickly suppress residual direct-current fault current, so that quick direct-current fault isolation is realized by utilizing a direct-current switch. And the fault clearing time is obviously shortened from about 500ms to below 14ms, so that rapid system recovery is realized. The working principle of the topology under the conditions of normal operation and direct-current fault is elaborated, and enhanced power equalization control is provided, so that direct-current voltage and current equalization among sub-modules of the topology is realized. In addition, after interleaving control is adopted, the number of direct-current reactors of the topology is remarkably reduced. A simulation result verifies the effectiveness of the hybrid DC / DC converter and the control scheme thereof in the aspects of blocking fault residual current and promoting direct current fault ride-through by using the DCS.

The invention relates to the technical field of high-voltage direct-current transmission, and particularly provides an LCC-full-bridge MMC series light HVDC converter station control method, which comprises the following steps: a rectification side of a power grid commutation converter adjusts direct-current power through an outer ring and an inner ring adopts linear trigger angle control to generate a trigger pulse; transformer tap adjustment is supplemented; on the basis of the established stable direct current system, an inversion side selects a minimum trigger angle as a control signal by coordinating three control rings of a turn-off angle, direct current voltage and direct current to form a control system; the full-bridge modularized multi-level converter is switched to a power grid following and network construction control mode according to power grid conditions; and when a direct current fault is detected, setting the trigger angle of the commutation converter of the power grid to be 90 degrees and switching the full-bridge modular multi-level converter to an STATCOM mode, thereby realizing direct current fault ride-through without locking the converter. According to the invention, direct-current fault rapid ride-through of the non-locking converter is realized.

The invention relates to the technical field of direct-current transformer high-voltage side fault identification and ride-through, and discloses a direct-current transformer high-voltage side fault identification and ride-through method and system, and the method comprises the steps: obtaining a first parameter of a high-voltage side of a target direct-current boosting transformer; acquiring a first fault feature according to the first parameter; the first fault feature is used for identifying a direct-current boosting transformer high-voltage side fault type; and presetting a fault ride-through strategy, and if the first fault feature of any fault type is obtained, starting the fault ride-through strategy. According to the invention, reliable identification and fault ride-through of the DC fault of the collection system can be realized by using the local measurement information of the DC transformer, the method is not influenced by photovoltaic output, the accuracy and efficiency of fault identification are improved, a new idea and method are provided for fault diagnosis of the DC boosting transformer, and the fault diagnosis efficiency of the DC boosting transformer is improved through a control and protection cooperation mode. The accuracy and efficiency of fault recognition are improved, and a new thought and method are provided for fault diagnosis of the direct-current boosting transformer.

The invention relates to the technical field of power system fault simulation, and discloses a DC fault simulation method for a medium-voltage DC system, and the method comprises the steps: constructing an equivalent circuit containing line distribution parameters, and representing the transmission characteristics of resistance, inductance and capacitance per unit length, a linear mathematical model of arc voltage and arc length is established based on arc discharge experiment data, a dynamic resistance curve is generated in combination with an arc length time increase function, an initial value and a change rate of dynamic resistance are extracted as characteristic parameters, and a mapping relation table of the characteristic parameters with metallic short circuit and mild / severe arc faults is established. And according to a target fault type, matching a dynamic resistance parameter, injecting the dynamic resistance parameter into an equivalent circuit, solving a differential equation containing a time-varying resistor, and outputting a high-fidelity DC fault current signal. The method solves the problem that static resistance simulation cannot reproduce arc dynamic characteristics, and significantly improves the accuracy of fault simulation.

The invention provides a medium-voltage direct-hanging multi-level energy storage grid-connected direct-current fault isolation method and device. The method comprises the following steps of: establishing corresponding protection partitions on a phase arm, a bus section and a battery cluster, configuring a polarity controllable blocking sub-module capable of being inserted with reverse voltage on the phase arm, and respectively configuring direct-current circuit breakers on the bus section and the battery cluster; generating a criterion set based on the measured value, and performing consistency voting on the criterion set to obtain a direct current fault determination result and a partition positioning result; when a fault is determined, issuing modulation and zero setting, and calculating a reverse equivalent voltage according to the change rate of the phase arm current and the target current to trigger the insertion of a polarity controllable blocking sub-module; selectively driving a corresponding direct current circuit breaker to be switched on and off according to a partition positioning result, or splitting a fault phase arm; and after selective switching-off is completed, outputting an isolation state to a grid-connected control unit of the energy storage grid-connected system. According to the invention, millisecond-level robust fault discrimination, partition selective isolation, cooperation of current limiting and on-off can be realized, and the removal range is narrowed.

The embodiment of the invention provides a method and a system for adjusting the capacitance value of a half-bridge sub-module. The method comprises the following steps: acquiring an initial capacitance value of a capacitor meeting steady-state operation voltage fluctuation constraint and dynamic response time constraint; obtaining a resistance value range of a resistor in the damping branch under the multi-condition constraint; wherein the multi-condition constraint comprises a current limiting condition constraint of the flexible direct-current power transmission system based on the initial capacitance value when a direct-current fault occurs, and a transient stability condition constraint of the flexible direct-current power transmission system when an alternating-current fault occurs; based on the resistance value range, obtaining an introduced transient voltage fluctuation range of the capacitor through simulation; obtaining a selectable capacitance value range in which the capacitance meets the transient operation condition constraint corresponding to the introduced transient voltage fluctuation range; and replacing the initial capacitance value with the capacitance value in the optional capacitance value range to obtain a target capacitance value of the capacitor. According to the invention, the engineering cost of the flexible DC power transmission system can be reduced on the basis of realizing AC / DC fault non-locking fault ride-through.

The invention discloses a fault power loss cooperative calculation method and system for a DC power transmission system of a parallel converter topology, and electronic equipment. The method comprises the following steps: establishing communication between a stability control device and DC control and protection equipment of the DC power transmission system; the stability control device judges that the fault-caused locking of the current converter comprises fault-caused locking of the current converter on the side, fault-caused locking of the current converter on the opposite side and locking faults of double sets of crashed fault-pole current converters on the basis of a signal sent by the direct-current control and protection system; according to the direct current pole control mode, whether the sound current converter has the power conversion capability or not when the intra-pole single current converter breaks down is judged, and the direct current fault power loss amount is calculated based on the maximum transmittable power of the remaining sound current converter after the fault. According to the method, the problem of inaccurate fault power loss calculation under complex working conditions of opposite-side single converter locking, bipolar control crash and the like is solved, the effect of accurately calculating the fault power loss amount is achieved, and the method is of great significance to fault analysis, reliability evaluation and safe and stable control of the parallel converter topology direct-current power transmission system.

The application discloses a DC line single-end fault ranging method and system with self-calibration capability, and belongs to the technical field of DC line fault positioning. The technical problem to be solved is that the anti-interference capability of a DC fault ranging technology is weak, parameter drift cannot be calibrated, double-end synchronization is required, and engineering implementation is complex. Technical scheme points are as follows: an excitation signal is injected into a fault line through an H-bridge circuit unit, an H-bridge output voltage and a line port voltage after an external calibration inductor are synchronously collected, and a line fault loop current zero-crossing moment is detected; at the zero-crossing moment, two groups of voltage equations are used to solve an external calibration inductor calculation value in real time, the inductor calculation value is compared with a nominal value to obtain an inductor correction coefficient, online self-calibration of the line inductor is realized; and based on the calibrated line inductor, fault discrimination and distance calculation are completed in combination with a relationship between a port voltage and a current slope.

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.

The application discloses a method for controlling hybrid MMC sub-modules to clear DC short-circuit fault current. The method detects the real-time size of AC voltage, calculates the bridge arm voltage according to the principle of limiting AC current change and not affecting the speed of DC fault current clearing, and determines the number of improved sub-modules (sub-modules capable of providing counter electromotive force, such as full-bridge sub-modules) in each bridge arm according to the bridge arm voltage. Compared with the conventional method of directly locking all sub-modules to clear DC fault current, the application reduces the bridge arm current during the DC fault current clearing process, alleviates the overvoltage of the improved sub-modules, limits the influence on the speed of DC fault clearing, and improves the safety of the hybrid modular multilevel converter during the process of clearing DC fault current.

The present application relates to the technical field of power system stability control, and is a steady-state voltage control method and system for reducing transient voltage instability risk of a new energy collection station, the method comprising: establishing a new energy collection station bus transient voltage model of a new energy sending end power grid after a DC bipolar blocking fault; setting a new energy collection station transient voltage instability limit of the new energy sending end power grid after the DC bipolar blocking fault; and setting a steady-state voltage control threshold for reducing the transient voltage instability risk of the new energy collection station bus based on the new energy collection station bus transient voltage model. The present application can achieve the purpose of reducing transient voltage instability risk by controlling the steady-state operating voltage of a high-proportion new energy sending end power grid without increasing dynamic reactive power compensation equipment. The present application is used to solve the problem of transient voltage instability caused by new energy off-grid of a new energy collection station of a DC sending end power grid after a DC fault due to excessively high transient voltage caused by excessively high steady-state operating voltage of the power grid.

The application discloses a DC fault ride-through method of a sea-land integrated DC system of offshore wind power based on a fast communication link, and the method comprises the following steps: when a DC fault occurs, the voltage drop speed and the voltage drop amplitude of an onshore converter station are obtained; when the voltage drop speed is lower than a voltage drop speed threshold value and the voltage drop amplitude is lower than a voltage drop amplitude threshold value, a fan energy consumption input instruction is sent to an offshore converter station, so that the offshore converter station transmits the fan energy consumption input instruction to each communication forwarding device through a bidirectional ring network optical fiber channel, and then the fan energy consumption input instruction is transmitted to corresponding fan energy consumption devices by the communication forwarding devices, so that the fan energy consumption devices absorb the fault surplus power according to the fan energy consumption input instruction; wherein the time from the issuance of the fan energy consumption input instruction from the HVDC side to the start of the fan energy consumption device is not greater than the maximum allowable delay duration.

The invention discloses a DC fault current analysis and calculation method suitable for multi-type MMC converters, and the method comprises the steps: determining the topology type of an MMC converter related to a fault line, and collecting core parameters; constructing an RLC series unified equivalent circuit model of the MMC, and correcting the RLC series unified equivalent circuit model based on the topology type to obtain an equivalent circuit correction model; and determining a DC fault current based on the equivalent circuit correction model. According to the method, a technical architecture of'unified modeling + differential correction 'is constructed, multiple types of MMC converters are abstracted into an RLC basic equivalent model, local parameter correction is carried out only for fault characteristic differences of different topologies, and the tedious process of repeated modeling is effectively avoided; meanwhile, converter active current limiting strategies such as locking and negative input control are considered in the modeling process of fault current analytical calculation, the model architecture has good expansibility, various control strategies can be flexibly fused, and deep fusion of the electromagnetic transient process and the control process is achieved.

The invention relates to the technical field of high-voltage direct-current power transmission, discloses a hybrid cascade direct-current fault disturbed coordination system based on a turn-off current source converter, and belongs to the technical field of high-voltage direct-current power transmission. A receiving-end high-end power grid commutation converter is replaced by a turn-off current source converter, and an active energy consumption mechanism of a lightning arrester is combined, so that control cooperation is realized; a main branch of the turn-off current source converter is formed by connecting a thyristor and a full-control device in series, and an auxiliary branch is connected with a metal oxide lightning arrester in parallel. When a fault occurs, the control unit actively turns off the main branch IGBT, the fault current is switched to the auxiliary branch, the lightning arrester is utilized to establish a reverse commutation voltage and rapidly discharge energy, and the direct current and voltage fluctuation of the low-end MMC is inhibited. The method has the advantages that the commutation failure risk is eliminated, the MMC locking probability is reduced, and the energy loss is reduced, the hybrid direct-current power drop during the fault period is reduced, and the method has remarkable engineering application value.

The application discloses a kind of hybrid line DC fault ride-through control method, device and system, belong to flexible HVDC transmission technology.The DC fault ride-through control method of the application, first, the actual DC current corresponding to DC line in flexible HVDC transmission system is monitored, and the actual DC current in abnormal target line is obtained;Then according to the actual DC current corresponding to target line, the DC reference voltage corresponding to target line is adjusted to fault ride-through voltage reference value, to control the DC current corresponding to target line to be set value of fault ride-through;Finally, in the case where the actual DC voltage corresponding to target line satisfies preset recovery condition, the DC reference voltage corresponding to target line is restored to preset reference voltage value.The DC fault ride-through method of the application is fast in response speed, can also reduce the influence on output power, reduce power loss, improve the stability and reliability of flexible HVDC transmission system operation.

The present invention provides an MMC semi-full bridge submodule topology, and the present invention relates to the technical field of modular multi-level converters. The present invention improves the connection mode between the internal switch device and the capacitor of the SFBSM by adding a small amount of power devices, and proposes a semi-full bridge submodule topology structure. The improved ISFBSM has the capabilities of DC fault ride-through, capacitor voltage balance and negative level output. The present invention proposes an improved semi-full bridge submodule topology structure with DC fault ride-through, capacitor voltage self-balance and negative level output capabilities. By adding a fast fault clearing module, the DC fault clearing speed of the SFBSM is doubled, the number of output levels is increased, and the control flexibility of the system is improved. In addition, combined with the characteristics of the submodule capacitors running in parallel, the ISFBSM can be independent of additional control means, and the problem of submodule capacitor voltage balance can be solved simply through the hardware topology structure.

The invention provides a low-conduction-loss direct-current circuit breaker with a fault type judgment function and a judgment method, and belongs to the field of circuit fault detection. In order to solve the problems that in an existing hybrid high-voltage direct-current circuit breaker, the conduction loss of a load commutation switch is high, and a circuit device does not have the fault type discrimination capability, the direct-current circuit breaker comprises a load branch, a multifunctional branch, a main breaking branch and an energy absorption branch. The discrimination method comprises the following steps: in a normal operation mode, a load branch is conducted; the capacitor pre-charging mode operates in parallel to charge the capacitor C; when the circuit is short-circuited, a thyristor turn-off mode is entered, and the T1 is turned off; and entering a load commutation mode, converting the fault current to a main breaking branch, introducing an energy absorption branch, and entering an energy absorption mode. And injecting a controlled RLC oscillation current, analyzing current waveform characteristics to judge a direct current fault type, and performing reclosing or maintenance of the circuit breaker according to the analyzed direct current fault type.

The invention provides a direct-current fault arc extinguishing system, which is applied to a direct-current power grid and comprises a magnetic core module with an air gap, a driving module and a control module, and the driving module is connected with the magnetic core module and the control module; the magnetic core module is used for reconstructing and generating reverse voltage based on fault current in the direct-current power grid; and the control module is used for acquiring fault current at a first sampling frequency, determining a current change rate based on the first sampling frequency and the fault current, determining a control strategy for the air gap when the current change rate is greater than or equal to a preset threshold value, controlling the driving module to adjust the air gap based on the control strategy, and changing the magnetic coupling strength of the magnetic core module. Therefore, the reverse voltage is controlled to reach a voltage arc extinguishing threshold value. The magnetic coupling strength of the magnetic core is changed by dynamically adjusting the air gap, accurate control over reverse voltage is achieved, stable arc extinguishing voltage output is maintained when fault current fluctuates, and the action reliability of an arc extinguishing system is improved.

The invention provides a quantitative evaluation method and system suitable for the voltage supporting capability of multiple types of reactive power equipment, and a storage medium. By setting alternating current and direct current faults, grid-connected point data of different reactive power devices are obtained; based on the dynamic characteristics of the reactive power equipment and factors affecting the power grid strength, a reactive power equipment voltage supporting capacity multi-index evaluation system considering the two aspects of the reactive power equipment and a power system is provided; constructing a cooperative game combination weight optimization model by adopting a deviation minimization principle, and calculating the weight of each index; proposing a construction method of a central point mixed sine whitening weight function, and carrying out gray fixed weight clustering evaluation on the voltage supporting capability of the multi-type reactive power equipment; and finally, verifying the accuracy and universality of the method provided by the invention based on PSASP simulation. According to the method, the influence of the dynamic characteristics of the reactive power equipment on the voltage supporting capacity is considered, and the index system is more comprehensive, the index weighting is more reasonable and the evaluation result is more credible based on the improved grey whitening weight function fixed weight clustering evaluation.

The invention discloses a direct-current fault clearing method and device for a multi-terminal flexible direct-current sending-out system, a direct-current circuit breaker can quickly act to cut off a fault current within several milliseconds, the system can only isolate a fault line, and the system keeps running in a non-fault area; the grid-side converter station, the load-side converter station and the alternating-current energy consumption device are matched to perform direct-current voltage reconstruction and power recovery, and the load-side converter station can be quickly restarted after a fault is cleared, so that the power supply reliability is improved; the technical problems that a direct current fault clearing mode of an existing multi-terminal flexible direct current sending-out system can cause system shutdown and cannot meet the direct current fault rapid isolation requirement are solved.

The present application relates to the field of high-voltage direct current transmission, and aims to provide a topology of bridge arm integrated current-limiting energy-consuming device, a converter valve and a coordinated control method. The topology is a modular MMC architecture of three-phase double bridge arms, which comprises a plurality of MMC sub-modules connected in series in the upper bridge arm, and a current-limiting energy-consuming device composed of a plurality of current-limiting energy-consuming sub-modules connected in series in the lower bridge arm; the current-limiting energy-consuming sub-module comprises a sub-module main power unit and a sub-condition energy-consuming unit, the latter at least contains two energy-consuming units adapted to different fault conditions, and each contains an energy-consuming resistor and an adaptive condition switching device. The present application integrates the functions of direct-current fault current limiting and alternating-current fault energy consumption in the same integrated device, realizes integrated protection of AC and DC faults, does not need to configure multiple sets of separate equipment, and solves the problem of functional redundancy of the traditional scheme. Redundant configuration can be reduced, hardware cost is reduced, system size is reduced, and operation and maintenance complexity is simplified; the risk of device overvoltage breakdown is avoided, and the service life of the equipment is improved.

The invention discloses a fault processing method and device, a flexible direct current system and a storage medium, and relates to the technical field of system control. The method is applied to a flexible direct current system comprising a hybrid MMC, and comprises the following steps: when an MMC direct current fault occurs, obtaining a direct current side fault current and a fault voltage in real time; judging whether a first preset condition is met or not according to the fault current and the fault voltage; if yes, performing locking control on the MMC to realize fault isolation; otherwise, continuously judging whether a second preset condition is met according to the fault voltage; if yes, negative voltage control is carried out on the MMC, and fault ride-through is realized; otherwise, controlling the MMC to work normally; in the fault ride-through process, whether a third preset condition is met or not is judged according to the fault current; if yes, zero-voltage control is carried out on the MMC so as to recover normal work of the MMC; otherwise, performing locking control on the MMC to realize fault isolation. The invention provides a rapid and reliable flexible direct current fault processing method on the system level.