714 results about "High voltage direct current transmission" patented technology

The invention relates to the field of high-voltage direct-current power transmission, and aims to provide an MMC converter valve and method for realizing alternating-current and direct-current fault ride-through based on an energy consumption sub-module. On the basis of a topological structure of a conventional MMC converter valve, M energy consumption sub-modules which are sequentially connected in series and are the same in structure are arranged between a bridge arm inductor of each bridge arm and the midpoint of an upper bridge arm and the midpoint of a lower bridge arm, and each energy consumption sub-module comprises a main through-flow branch, an energy consumption branch and a bypass loop which are connected in parallel; in the main through-current branch, the half-controlled switching device T1 is reversely connected in parallel with a fly-wheel diode D1 of the half-controlled switching device T1, and then is reversely connected in series with the full-controlled switching device T2 and a reverse fly-wheel diode D2 of the full-controlled switching device T2; the energy consumption branch comprises an energy consumption resistor Rd, and the bypass branch comprises a bypass switch K. According to the invention, alternating current fault ride-through and direct current fault ride-through are integrated into the topology of the MMC converter valve, so that the integration level of the protection scheme is improved; voltage fluctuation during alternating-current fault ride-through can be effectively smoothed, and the stability during alternating-current fault ride-through is improved.

The invention discloses a fan inertia support evaluation and control method considering power grid inertia space-time distribution. Based on wide area measurement system data, a power grid inertia space-time distribution model is constructed, inertia contribution characteristics of different areas are analyzed, and the influence of extra-high voltage direct current transmission on inertia distribution is considered. And calculating the inertia response power of the fan, quantifying the support contribution of the virtual inertia of the fan based on the frequency change rate and the regional equivalent inertia, and establishing an inertia support efficiency evaluation index system. A dynamic feedback control strategy is put forward, a reinforcement learning or adaptive gain adjustment method is adopted in combination with the real-time distribution condition of the inertia of the power grid, the virtual inertia control parameters of the fan are optimized, and the response accuracy is improved. Based on a wide-area coordination optimization method, a fan inertia support scheduling strategy is optimized, and the system frequency stability is improved. The method can effectively improve the frequency supporting capability of the new energy power grid, improves the new energy consumption level, enhances the operation safety of the power grid, and is suitable for a high-proportion new energy grid-connected smart power grid.

The present application provides a reactive power feedback control-based control method for a commutation failure in a hybrid cascaded high-voltage direct-current power transmission system, a storage medium and an electronic apparatus, and particularly relates to a reactive power feedback control-based control method for a commutation failure in a hybrid cascade high-voltage direct-current power transmission system. The method mainly comprises the following steps: acquiring power data of a hybrid cascaded high-voltage direct-current power transmission system; calculating the reactive power supply of an inverter-side MMC-end alternating-current system, the reactive power supply of an inverter-side alternating-current filter, and the reactive power supply of an inverter-side LCC-end alternating-current system; solving a reactive power control instruction of an inverter-side MMC converter; and, on the basis of a critical voltage, determining whether to implement the reactive power feedback control-based control method for a commutation failure in the hybrid cascaded power transmission system. The method can effectively reduce the probability of commutation failures in hybrid cascaded power transmission systems, thus guaranteeing safe and stable operation of large-scale power grids.

The invention relates to the technical field of photovoltaic grid connection, and particularly provides an active support control method and an active support control device for transient voltage of a transmitting end power grid of an LCC-HVDC (line commutated converter high voltage direct current power transmission) system, and the active support control method and the active support control device for the transient voltage of the transmitting end power grid of the LCC-HVDC system. Comprising the following steps: correcting an output voltage phase of a synchronization link in a virtual synchronous generator control strategy based on active power and frequency output by a network construction type photovoltaic converter, and correcting an output voltage amplitude of a voltage amplitude link in the virtual synchronous generator control strategy based on a measured value of a sending end power grid voltage; and using the virtual synchronous generator control strategy to control the network construction type photovoltaic current converter in the LCC-HVDC system containing the network construction type photovoltaic current converter. According to the technical scheme provided by the invention, the stability of photovoltaic access to the weak power grid can be improved, and the reactive power output by the converter can be automatically adjusted after the transient voltage of the sending-end power grid occurs due to the commutation failure of the LCC-HVDC system, so that the transient voltage is effectively supported, and the phenomenon of reverse adjustment of the reactive power is prevented.

The invention provides a power grid cable real-time current detection method and system, and the method comprises the steps: carrying out the multi-frequency-band synchronous collection of the current of a cable shielding layer for a high-voltage DC power transmission system with multiple loops laid in parallel, and obtaining the time-space information data; an electromagnetic coupling transfer function is calculated based on the data, and an electromagnetic coupling coefficient matrix is constructed, so that near-end cross induction current is separated to obtain a real current signal; establishing a cable dispersion model by using a real current signal, and performing fault feature recognition by combining a time domain criterion, a frequency domain criterion and time-frequency joint entropy analysis; and finally, calculating a credibility index by combining the temperature gradient and the electromagnetic environment parameters, correcting a preliminary judgment result and generating a protection control signal. According to the method, the near-end cross induction current and the real fault current can be effectively distinguished, the problem that the protection system of the multi-end high-voltage direct current system operates by mistake or does not operate in the power-on transient period is solved, and the reliability of the system is improved.

The invention discloses a high-voltage direct current transmission converter thyristor fault identification method based on reliability evaluation. The method comprises the following steps: constructing a stress-degradation-life mapping relation model through a stepped temperature-voltage cooperative stress test; establishing a three-stage Wiener degradation model, and predicting a critical failure point in combination with a dynamic threshold jump mechanism; an FPGA + CPU heterogeneous computing platform is adopted to execute an EM-MCMC joint estimation algorithm in parallel, and parameter updating is accelerated through assembly line MCMC sampling; designing a dynamic correction factor optimization reliability index based on the buffer layer parameters; constructing a dual-channel LSTM network to extract degradation features and generate a dynamic failure threshold value; a converter topology is reconstructed through a graph neural network, and fault positioning and damage grading are realized in combination with a three-level early warning mechanism. According to the method, fault identification is carried out through combination of multi-stress coupling modeling and a dynamic threshold value, the real-time performance is improved through a heterogeneous computing architecture, the false alarm rate is reduced through combination of a dynamic correction and topology reconstruction technology, and accurate identification and operation and maintenance decision support of the thyristor fault are realized.

The invention relates to a controllable turn-off converter valve for a high voltage direct current (HVDC) system, each converter valve arm comprises a valve arm voltage-sharing device and a plurality of cascaded controllable turn-off converter modules, and each controllable turn-off converter module comprises an assembly voltage-sharing device and a plurality of cascaded controllable turn-off converter assemblies. Each controllable turn-off current conversion assembly is configured to comprise at least one voltage-sharing circuit and at least one controllable switching device, and two ends of each controllable switching device are provided with one voltage-sharing circuit in parallel. Therefore, the controllable turn-off converter valve can realize voltage sharing at each level, the requirement of the controllable turn-off converter valve on the consistency of controllable switching devices is reduced, a large number of controllable switching devices can be connected in series in the same converter valve arm, and reliable conversion of extra-high voltage direct current transmission at the voltage level of + / -800 kilovolts and above is realized. The problem of commutation failure of the extra-high-voltage direct-current type converter valve is solved, and safe and stable operation of a power system is ensured.

The present disclosure provides a method for controlling the receiving-end alternating-current (ac) fault ride-through of the hybrid cascaded high-voltage direct-current (hvdc) transmission system. According to the method, a line commutated converter (lcc) on the rectifier side determines the occurrence of a receiving-end ac fault based on a change in an electrical quantity of its dc port, and quickly reduces the dc voltage on the rectifier side by increasing the firing angle, so as to quickly suppress an overcurrent. The mmcs on the inverter side, which use the constant active power control, correct the outer-loop active power reference values to transmit as much active power as possible, thereby reducing the surplus power of the receiving-end system and suppressing an overvoltage for submodule capacitors of the mmcs.

The invention relates to the technical field of high-voltage direct-current transmission, and discloses a reactive power support control method and system for a CLCC converter under an alternating-current fault, in order to fully explore the power support potential of the CLCC, the method comprises the following steps: firstly, starting from the forced commutation process of the CLCC during the fault period, analyzing that the trigger angle and the power have the multi-quadrant regulation and control capability; secondly, a direct current operable range and a trigger angle regulation and control range are determined; a power operation domain in the range is established; then, determining a trigger angle compensation amount and a control mode by taking no influence on active power transmitted to a receiving end alternating current system as a target; according to the method provided by the invention, the direct-current voltage and the direct-current transmission power of the inverter side during the alternating-current fault period can be kept unchanged, the voltage drop of the converter bus during the alternating-current fault period can be reduced, and the quick and stable recovery of the alternating-current voltage is facilitated.

The invention discloses a pressure sensor zero drift compensation method and system for a high-voltage direct-current converter valve cooling system, and relates to the technical field of monitoring and calibration of high-voltage direct-current transmission equipment. The method comprises the following steps: constructing a multi-factor coupling drift model taking temperature, vibration frequency and electromagnetic interference intensity as inputs; environment parameters and pressure signals are collected in real time, and reference pressure signals are collected regularly; short-term dynamic compensation is realized based on model prediction and reference deviation correction; updating the model through incremental learning according to the drift trend; and real-time monitoring and abnormal early warning are carried out. The system comprises a multi-parameter acquisition unit, a data processing unit, a reference pressure generation unit and a communication unit. According to the method, shutdown calibration is not needed, the compensation precision is improved by 75% or above, the calibration period is prolonged to 12 months, meanwhile, the method has the abnormal diagnosis and standby compensation functions, measurement continuity is guaranteed, compatibility is high, industrial popularization is easy, and the method is particularly suitable for being used in a complex environment.

The invention discloses a method and a device for tracing a commutation failure fault of a high-voltage direct-current power transmission system, and the method comprises the steps: taking three electrical quantity signals, namely an alternating-current voltage, a direct-current current and a direct-current voltage, of an inversion side of the high-voltage direct-current power transmission system as source data when the commutation failure occurs; extracting an optimal fault feature of the source data by adopting a fault feature extraction model and a feature screening algorithm based on feature density; and finally, in combination with a commutation fault detection model and the optimal fault characteristics, obtaining a fault type causing commutation failure of the high-voltage direct-current power transmission system. Through the above design, fault tracing of the commutation failure can be realized, and in the tracing process, the optimal fault features are extracted by using the machine learning model and the feature screening algorithm based on the feature density, so that interference of human subjective experience on feature extraction can be reduced, and the effectiveness of fault tracing is improved; therefore, the method is very suitable for large-scale application and popularization.

The invention discloses a method for quantitatively evaluating the immune level of subsequent commutation failure of an AC-DC hybrid system, and the method comprises the steps: carrying out the analysis of the transient process of the system based on the transient reactive dynamic characteristics of the AC-DC hybrid system on the basis of achieving the cross-regional power transmission through a high-voltage DC power transmission technology; the essential relation among the electrical quantities in the transient process is obtained; and deducing an online evaluation index GCFII for reflecting the immune level of the subsequent commutation failure of the system in combination with known system parameters and electrical signals acquired by the PMU. According to the method, the influence of the direct current control mode is considered by obtaining the online evaluation index GCFII, and real-time updating can be carried out along with the change of system operation parameters, so that the requirements of real-time performance and accuracy can be met, a theoretical basis is provided for power grid construction and operation of operation personnel, and safe operation of a power grid is effectively ensured.

The invention provides a series-parallel high-voltage direct-current power transmission system transient state control method suitable for sending-end alternating-current faults, and belongs to the technical field of power systems. The method comprises the following steps: constructing a direct-current power safe operation boundary of an LCC converter station by combining LCC rectification side safety constraint and LCC inversion side commutation failure risk constraint conditions; constructing a commutation failure suppression strategy model of VSC and LCC cooperative control; and by using the commutation failure suppression strategy model, after a sending end alternating current fault occurs and is eliminated, controlling and suppressing the commutation failure of an LCC inverter station by using a control strategy of VSC dynamic reactive compensation and LCC trigger angle adaptive adjustment cooperation, and completing commutation suppression of the series-parallel high-voltage direct-current power transmission system. According to the invention, the problem of commutation failure caused by a sending end alternating current fault intensified by the interaction influence of conventional high-voltage direct current and flexible direct current is solved.

The invention relates to an HVDC commutation failure risk prediction method considering an optimal CFPREV, belongs to the technical field of commutation failure defense of a high-voltage direct-current transmission system, and aims to predict the commutation failure risk of an LCC-HVDC system under the control of the optimal CFPREV and judge whether the system can suppress the commutation failure only by changing the size of a trigger angle after a fault occurs. And a support is provided for the investment of an off-station commutation failure defense device. In the implementation process, an inverter station trigger angle under the CFPREV limit effect is calculated through real-time measurement data in the operation process of the high-voltage direct-current power transmission system, then the commutation failure risk under the optimal CFPREV control is predicted based on the commutation area theory, and the change of direct current under the CFPREV effect is considered in the calculation process, so that the prediction accuracy is improved. And the reliability of prediction results is ensured.

The invention provides an extra-high voltage hybrid DC power transmission control system and method, and the system comprises a controller which is used for transmitting fault control trigger pulse control information to a hybrid converter when a transmitting end AC fault occurs; the hybrid converter is used for reducing the injected active power and the output direct-current power when the extra-high voltage direct-current power transmission line is in a normal operation condition; based on the state of the ultra-high-voltage direct-current power transmission line in the normal operation working condition, the full-bridge sub-module in the ultra-high-voltage direct-current power transmission line is controlled to output negative voltage, and short-circuit fault current is suppressed. And the turn-off current source type current converter is used for triggering an internal lightning arrester to generate a commutation voltage when a receiving end AC fault occurs, and carrying out commutation by combining the power grid voltage with the commutation voltage. According to the system, a hybrid converter is adopted at a sending end, active power and reactive power of the sending end are flexibly regulated and controlled, and negative voltage is output to suppress short-circuit fault current when a direct-current short-circuit fault occurs; and when the receiving end has an alternating current fault, reliable commutation can still be ensured.

The invention provides a current source type hybrid direct-current power transmission system based on an injection type power grid commutation converter, and relates to the field of high-voltage direct-current power transmission, and the system comprises a rectification station which at least comprises a thyristor-based power grid commutation converter and is used for converting alternating current into direct current; the inverter station at least comprises an injection type power grid commutation converter and is used for converting the direct current output by the rectifier station into alternating current; and the control module is used for controlling the operation of the rectifier station and the inverter station based on the trigger time sequence constraint, and has the advantages of completely inhibiting the commutation failure and reducing the loss.

The invention provides a wind power high-voltage direct-current power transmission system, and belongs to the technical field of power transmission. The system comprises an intelligent wind driven generator, a modular converter station, an intelligent temperature monitoring direct current transmission line, a power grid friendly intelligent inverter station, and an intelligent regulation and control system integrating real-time data analysis, dynamic control and fault self-diagnosis. Through a maximum power point tracking algorithm and a self-adaptive control strategy, the system optimizes the wind energy conversion efficiency. The intelligent regulation and control system predicts wind power output by using a deep learning model and a random forest algorithm, dynamically adjusts voltage and current, and quickly responds to power grid demand changes. In addition, the system can quickly position and isolate faults, start a standby path and ensure continuous power supply. By adopting the wind power high-voltage direct-current power transmission system, the intelligent level of wind power high-voltage direct-current power transmission is improved, and the power transmission efficiency and the system stability are enhanced.

The invention discloses a high-voltage direct-current line EM lightning arrester valve plate shunting non-uniformity test system and method, and belongs to the technical field of lightning arrester performance test.The method comprises the steps that S1, a high-voltage direct-current power transmission system simulation model is established, and the discharge current of an EM lightning arrester under the severe working condition of single-pole line short circuit is evaluated based on the high-voltage direct-current power transmission system simulation model; adopting square-wave pulse approximate discharge current, and determining the total amplitude and square-wave pulse width of long-wave discharge current of the EM lightning arrester; s2, applying the square wave pulse to the tested EM lightning arrester resistor discs through a shock wave test platform, and testing the current magnitude and the total current of each resistor disc of the EM lightning arrester under the working condition; the total amplitude and the square wave pulse width of the preset square wave pulse are the same as the total amplitude and the square wave pulse width of the long wave of the discharge current of the EM arrester; and S3, according to the current of each resistor disc and the total current, calculating a current non-uniform coefficient and the current range of the resistor discs. According to the invention, the current distribution non-uniformity of the multi-column parallel lightning arrester can be tested and evaluated more reasonably and comprehensively.

The invention relates to the technical field of high-voltage direct-current transmission, and discloses a split type on-load tap-changer mechanical clamping stagnation fault detection method and system, and the method comprises the steps: judging whether a switch switching module has transition resistance loss or not based on first current data; gear switching delay time and a gear shifting instruction response state in the gear switching process are collected; acquiring second current data of the converter transformer at a plurality of gear switching point monitoring positions, and judging whether the switch switching module has the condition that the mechanical frictional resistance exceeds the standard to cause the short-circuit current peak value to exceed the limit or not based on the second current data; acquiring third current data of the converter transformer in the operation module, and comparing and analyzing the third current data to obtain a fault mode classification result of the switch switching module; and performing cooperative processing on the fault mode classification result and the gear shifting instruction response state to obtain a target alarm signal. According to the invention, accurate identification and timely protection of mechanical clamping stagnation faults can be realized in a complex and changeable operation environment.

The invention discloses a machine learning-based ultra-high-voltage direct-current transmission locking fault diagnosis method and system, and the method comprises the steps: obtaining various electrical quantity change data of each network node before and after a fault, screening out feature electrical quantities and feature nodes from the electrical quantity change data, and forming fault feature data; extracting a fault occurrence time point and a frequency component from the fault feature data through wavelet transform, constructing a fault signal model, and judging a fault position by adopting an extreme point detection method; constructing an input sequence according to the extracted fault occurrence time point and frequency component, and constructing a convolutional neural network model; expanding the input sequence into a time feature matrix, redistributing the weight of each feature in the time feature matrix by adopting a channel attention mechanism, and performing weighted average on the input time sequence of each time step length in the time feature matrix by adopting a time attention mechanism to obtain an improved convolutional neural network model; and training the improved convolutional neural network model, and extracting fault features of extra-high voltage direct current locking to complete fault diagnosis.

According to the converter valve waste heat digital comprehensive analysis model and method, working parameters of a converter valve are monitored in real time, a physical mechanism and a data driving method are combined, and a hybrid modeling system is constructed for waste heat model building and dynamic correction. A multi-scale data fusion framework is adopted to carry out data processing and mode recognition, the accuracy of model prediction is evaluated through a residual analysis mechanism, and future temperature rise prediction is carried out. According to the method, a dynamic knowledge graph is constructed based on a digital twin platform, multi-dimensional report contents including a cooling system upgrading scheme, a valve tower inspection period adjustment strategy and the like are generated, and data traceability is ensured through block chain evidence storage. According to the method, the requirements of a current converter valve waste heat analysis method for real-time monitoring and accurate prediction are improved, a feasible mode for real-time monitoring and accurate prediction of converter valve waste heat is provided, the accuracy of equipment working state feedback and fault prevention measures is ensured, and the stability of a high-voltage direct-current power transmission system is further ensured.

The invention relates to the technical field of power transmission systems, in particular to a high-voltage direct-current power transmission receiving end tap switch control method, system and device and a medium. An initial tap switch gear is selected from the tap switch gear interval, and the lowest steady-state alternating current system voltage is determined based on the initial tap switch gear; calculating a minimum valve side ideal no-load direct-current voltage according to the minimum steady-state alternating-current system voltage; according to the minimum valve side ideal no-load direct-current voltage and the minimum direct-current resistance, the minimum steady-state direct-current voltage value of the sending end is calculated; calculating the maximum steady-state direct-current voltage value of the sending end based on the maximum alternating-current system voltage and the maximum direct-current resistance; and carrying out iterative adjustment on the tap switch gear based on the lowest steady-state direct-current voltage value of the sending end and the highest steady-state direct-current voltage value of the sending end to obtain an optimal target gear of the tap switch. According to the invention, the optimal control of the tap switch gear is realized, the action times of the tap switch are effectively reduced, and the stability and reliability of a power transmission system are improved.

The invention relates to a commutation method of a high-voltage direct-current transmission commutation system and the high-voltage direct-current transmission commutation system. The commutation method comprises the following steps: detecting an output current of a commutation module, and obtaining a reference current corresponding to a first direction; the output current of the commutation module is adjusted according to the output current and the reference current, so that the commutation module performs current commutation from the second direction; the first direction and the second direction are opposite directions. According to the embodiment of the invention, the output current of the commutation module can be adjusted according to the output current of any commutation module and the reference current feedback corresponding to the first direction, so that the power flow inversion can be realized by performing current commutation on the output current of the commutation module; according to the embodiment of the invention, power inversion can be realized without a direct current voltage polarity inversion mode, and a control mode for performing power flow inversion control by adopting the commutation module can be simplified.

The invention relates to the technical field of high-voltage direct-current transmission, and particularly provides an overvoltage threshold self-adaptive adjustment protection method and device for an IGCT (integrated gate commutation current transformer), and the method comprises the steps: obtaining the real-time terminal voltage of a sub-module of a hybrid commutation current converter and the operation condition of the IGCT in the sub-module; and adjusting the overvoltage protection threshold of the IGCT in the sub-module of the hybrid commutation converter based on the real-time terminal voltage of the sub-module of the hybrid commutation converter and the operation condition of the IGCT in the sub-module. According to the technical scheme provided by the invention, a fuse can be omitted, the operation reliability of the converter valve is improved, the technical blank of related protection strategies of the lightning arrester of the hybrid commutation converter valve assembly is filled, and a reference basis is provided for the design of an engineering control protection system.

The invention provides a health state depth feature extraction method for key components of an extra-high voltage direct current transmission converter valve, and belongs to the technical field of extra-high voltage transmission equipment.The health state depth feature extraction method comprises the steps that firstly, different fault state models are constructed through PSCAD simulation, data are collected, and dimension reduction processing is conducted on multi-source heterogeneous data through principal component analysis; and establishing a time sequence sliding window mechanism to calculate data characteristic parameters. And then temperature features are extracted based on a thyristor junction thermal diffusion mechanism equation, deep feature extraction is performed by using a multi-head self-attention enhanced bidirectional long-short-term memory network, multi-source data such as infrared temperature measurement and ultraviolet discharge are fused, and abnormal feature representation is calculated through an isolated point feature evaluation function. And finally, constructing a feature vector space containing electrical features, temperature features, isolated point features and multi-component correlation features, outputting complete health state feature representation, and providing a basis for state evaluation and fault prediction of the converter valve.

The invention discloses an ultra-high voltage direct current transmission system fault intelligent analysis method and system based on a domestic artificial intelligence large model framework, and a storage medium, and belongs to the field of electric power system artificial intelligence fault diagnosis. According to the method, multi-source heterogeneous fault data are accessed and standardized and aligned, the processed data are input into a domestic artificial intelligence large model adapted by knowledge in the electric power field, and the model is utilized to perform multi-modal feature fusion and intelligent analysis, so that automatic identification and accurate positioning of fault types are realized; and an analysis report and a disposal strategy are automatically generated. The system comprises a data input module, an intelligent analysis module and a decision output module, and the intelligent analysis module performs feature extraction and recognition by adopting a CNN-Transform hybrid neural network and realizes fault positioning based on a knowledge graph and a graph neural network. According to the method, full-process automatic intelligent analysis from data access to decision output is realized, and the efficiency, the accuracy and the engineering landing capability of fault diagnosis are remarkably improved.

The invention discloses an SVG converter valve parameter configuration method and device. The method comprises the steps that the capacity and rated working voltage of a converter valve are determined according to the basic function requirement of an SVG; according to the capacity and the rated working voltage of the converter valve, determining the type and the rated working voltage of each sub-module, and combining third harmonic injection and harmonic suppression to determine the number of the sub-modules; determining the capacitance value of the sub-module and the parameters of the bridge arm reactor according to the volatility of the capacitance voltage of the sub-module in the steady state and the harmonic suppression requirement; according to overvoltage and overcurrent characteristics of the SVG, the number of sub-modules, capacitance values and bridge arm reactor parameters are optimized; and according to overvoltage characteristics of the SVG after parameter optimization, determining lightning arrester configuration, and obtaining converter valve parameter configuration of the SVG. The method is suitable for extra-high voltage SLCC direct current power transmission system design, and the system design efficiency and standardization can be effectively 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 invention relates to the technical field of extra-high voltage direct current transmission, and particularly provides a topological structure of a controllable commutation converter valve control system and an operation method thereof, and the topological structure comprises a main branch trigger monitoring case and an auxiliary branch trigger monitoring case. The main branch trigger monitoring case is used for completing optical signal interaction on the main branch of the CLCC based on a trigger signal corresponding to the main branch in the received trigger signals, and forwarding a trigger signal corresponding to the auxiliary branch in the received trigger signals to the auxiliary branch trigger monitoring case; and the auxiliary branch trigger monitoring case is used for completing optical signal interaction with the auxiliary branch of the CLCC based on the received trigger signal corresponding to the auxiliary branch. According to the technical scheme provided by the invention, synchronous triggering and time-sharing turn-off functions of the thyristors and the IGBTs are realized, and valve control systems of the LCC and the CLCC can be compatible.

The invention discloses a high-voltage direct-current power transmission grid-connected system stability control method and system, and relates to the technical field of power system control, and the method comprises the following steps: collecting the numerical information of a high-voltage direct-current power transmission system, and calculating the numerical information to obtain a receiving end output d-axis current reference value and a receiving end output q-axis current reference value; calculating a d-axis current control value through the d-axis current reference value, and then obtaining a d-axis modulation signal; calculating a q-axis current control value through the q-axis current reference value, and then obtaining a q-axis modulation signal; and performing grid-connected current control according to the d-axis modulation signal and the q-axis modulation signal, and driving a receiving-end converter of the high-voltage direct-current power transmission grid-connected system. According to the method, the new energy side output impedance remodeling can be realized without introducing an additional device, the dynamic performance of the high-voltage direct-current power transmission system is not influenced, and the stability of the high-voltage direct-current power transmission grid-connected system is improved.