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

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 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 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 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 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 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 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 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.

A control method for suppressing an overvoltage of the receiving end hybrid modular multilevel converter with full-bridge submodules and half-bridge submodules (F / HMMC) under the fault at the receiving-end alternating-current (AC) system of the hybrid high-voltage direct-current (HVDC) transmission system. After a short-circuit fault occurs in a receiving-end AC) system of the hybrid HVDC transmission system, an AC voltage drop is generated, and the effective voltage of the receiving-end AC bus at the current time is measured. Because the hybrid modular multilevel converter (MMC) is capable of actively decreasing the DC voltage for operation, on a premise of ensuring that its output current is always within a rated current range, a control manner of setting the reference DC voltage and making the reference DC voltage not greater than the effective voltage of the AC bus enables receiving end power to be sent out, thereby suppressing an overvoltage of the receiving-end F / HMMC.

An electric tool battery replacement device is characterized by comprising an alternating current-direct current conversion box (1), a voltage reduction box (2), an alternating current input line (3) and a high-voltage direct current transmission line (4), the alternating current input line (3) is connected to the input end of the alternating current-direct current conversion box (1) so as to be connected with an alternating current power supply, the high-voltage direct current transmission line (4) is connected between the output end of the alternating current-direct current conversion box (1) and the input end (2) of the step-down box (2), and the output end of the step-down box (2) is connected with an electric tool (5); a rectifying circuit is arranged in the alternating current-direct current conversion box (1) and is used for rectifying alternating current into direct current; and a direct-current voltage reducing and stabilizing circuit is arranged in the voltage reducing box (2) and is used for reducing high-voltage direct current into low-voltage direct current and outputting the low-voltage direct current in a voltage stabilizing manner. According to the utility model, rectification boost and DC voltage reduction output are completed in two parts (i.e., the AC-DC conversion box and the voltage reduction box), and a high-voltage DC power transmission principle is adopted, so that the loss caused by a line is reduced, and the utilization rate of energy is improved.

The invention discloses a new energy system frequency domain modeling and equivalent circuit order reduction analysis method, and relates to the technical field of new energy power system modeling and stability analysis. The method is used for solving the problems that in an existing frequency domain modeling means, the automation degree of data acquisition is low, fitting precision and stability are poor, equivalent circuit universality is poor, and order reduction analysis is not systematic. The method comprises the following steps: acquiring system frequency domain response data based on disturbance injection; constructing a system rational function model by adopting an improved vector fitting algorithm; and then model order reduction is realized through state space modeling and an SVD-based balanced truncation method, and response consistency and stability analysis is carried out in a frequency domain and a time domain. The method can be widely applied to modeling analysis of new energy equipment such as wind power equipment, voltage source converters and high-voltage direct-current power transmission equipment, and has the advantages of being high in automation degree, high in modeling precision, good in visualization, clear in structure, suitable for simulation and control design and the like.

The embodiment of the invention discloses a commutation failure detection method, the method is applied to a high-voltage direct-current power transmission system, the high-voltage direct-current power transmission system comprises a converter valve, and the method comprises the following steps: collecting a valve current time sequence signal in a commutation process, the valve current time sequence signal is a current value sequence of the converter valve continuously changing along with time; presetting a time delay parameter; reconstructing a valve current time sequence signal into a three-dimensional phase space trajectory based on the time delay parameter; deriving the three-dimensional phase space trajectory, and determining an instantaneous torsion rate and an instantaneous curvature in a commutation process; substituting the instantaneous torsion rate and the instantaneous curvature in the commutation process into a preset two-dimensional elliptic discriminant; and determining whether commutation failure occurs or not according to whether the discriminant is true or not. According to the method, a two-dimensional ellipse discriminant is adopted to perform joint discrimination on the torsion and the curvature, so that the method has higher sensitivity and reliability, and misjudgment and missed judgment can be effectively avoided.

The invention discloses a hybrid cascade system commutation failure suppression method caused by sending end faults, and belongs to the technical field of high-voltage direct-current power transmission systems. The invention aims to provide the method for suppressing the commutation failure of the hybrid cascade system caused by the sending-end fault, which comprises the following steps of: monitoring the deviation between a direct current instruction value and an actual value in a system fault recovery period in real time, and dynamically adjusting a rectifier-side trigger angle instruction according to the deviation so as to control the direct current recovery rate and amplitude. According to the method, the dynamic recovery characteristic of the sending-end bus voltage and the constant direct-current voltage control effect of the inversion-side MMC are combined, and key influence factors of commutation failure are systematically analyzed; a commutation failure suppression strategy based on a rectification side additional trigger angle is provided. According to the method, the influence of the phase dynamic change of the alternating current bus voltage at the rectification side and the constant direct current voltage effect of the MMC at the inversion side on the commutation failure in the fault recovery process is fully considered, and reference is provided for safe and stable operation of the hybrid cascaded high-voltage direct current power transmission system.

The invention belongs to the technical field of ultra-high voltage direct current power transmission, and discloses a test system and method of a converter valve thyristor voltage detection board card, and the test system comprises a test cabinet and a test tool. An industrial control system is integrated in the test cabinet to set test parameters and criteria, an electric control unit loads an excitation source, an acquisition display unit acquires test data and presents the test data in an oscillogram, and a test tool fixes a tested board card. The industrial control system outputs a control instruction to drive the electric control unit to apply system test excitation, the actual working condition of the thyristor is simulated, and meanwhile, the acquisition and display unit automatically captures multichannel signal data; data are transmitted to the industrial control system through the electric control unit, and the board card performance is automatically analyzed and a test report is generated in combination with a preset criterion. By adopting the system, the problems of insufficient function verification, low test efficiency, vulnerable equipment, poor data accuracy and large manpower occupation are solved, efficient and lossless automatic test is realized, the test reliability is improved, and the operation process is simplified.

The invention relates to the technical field of extra-high voltage direct current transmission system control, in particular to a single-phase tripping processing method and system for a last circuit breaker of an incoming line of a current converter, and the method comprises the steps: exiting a protection mechanism of the last circuit breaker of the incoming line of a target current converter when only a single circuit breaker operates at the incoming line side of the target current converter; after a single-phase tripping fault occurs in the last circuit breaker of the incoming line of the target converter, reducing the current DC power of the extra-high voltage DC power transmission system according to a set power drop-back rate, and stopping DC power adjustment until the current DC power reaches the sum of the overload upper limit values of all the other converters except the target converter; and distributing the transmission power of the target converter to all the remaining converters until the transmission power of the target converter reaches the minimum transmission power threshold, stopping the target converter, and disconnecting the final circuit breaker of the incoming line of the target converter. According to the invention, the impact of direct-current locking on a power grid is effectively reduced.

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 provides an MMC in-valve fault detection method and device based on IGCT submodules, and relates to the technical field of high-voltage direct current transmission, and the method comprises the steps: continuously obtaining the bridge arm voltage of each bridge arm of an MMC converter, the capacitor voltage of each submodule in the corresponding bridge arm, and the switching state of each submodule; for each bridge arm, based on the bridge arm voltage of each bridge arm and the on-off state of each sub-module, determining a theoretical capacitance voltage of each sub-module through a preset time domain analysis model, the time domain analysis model being used for representing a mapping relationship between the capacitance voltage of each sub-module and the bridge arm voltage when each sub-module is in different on-off states; and calculating a correlation coefficient between the actually measured waveform of the capacitor voltage of each sub-module and the corresponding theoretical capacitor voltage, and if the obtained correlation coefficient is lower than a preset correlation coefficient threshold, determining that the sub-module has a fault. According to the invention, the fault detection efficiency and precision based on the MMC sub-module are effectively improved.

The present application relates to the technical field of high-voltage direct-current power transmission, and provides a restart method and control device for a direct-current line fault of a high-voltage direct-current power transmission system. When a ground fault occurs in a direct-current line, the restart method comprises: at a first restart stage, controlling a faulty direct-current pole to be restarted; when the restart frequency is reached but the restart is still not successful, if a dual direct-current pole power command value is greater than the maximum deliverable power of a non-faulty direct-current pole, at a second restart stage, adjusting the dual direct-current pole power command value to be the maximum deliverable power of the non-faulty direct-current pole, and controlling the faulty direct-current pole to be restarted. The controlling the faulty direct-current pole to be restarted comprises: controlling at least one current converter at each of two ends of the ground fault to continue to operate, and determining direct current reference values of the converters; on the basis of the direct current reference values and within a deionization time, controlling the direct current of the converters to be equal or the difference to be smaller than a first current threshold, or controlling the direction current of the converters to be zero; and increasing the direct-current voltage and / or the direct-current power of at least one converter within a restart time.

The invention provides an alternating-current parallel hybrid converter type direct-current power transmission system and a control method and device, and relates to the technical field of high-voltage direct-current power transmission. The AC parallel hybrid converter type DC power transmission system includes: a first AC parallel hybrid converter and a second AC parallel hybrid converter, the first AC parallel hybrid converter and the second AC parallel hybrid converter each including: a current source converter including a six-pulse bridge circuit; the voltage source converter and the current source converter are connected in parallel on the alternating current side; one side is connected with the alternating current side of the voltage source converter, and the other side is connected with an alternating current system. According to the alternating-current parallel hybrid converter type direct-current power transmission system, 6k + / -1 harmonic waves are filtered out through a voltage source converter, a six-pulse bridge circuit is directly adopted in the high-voltage direct-current power transmission system, the converter structure of the high-voltage direct-current power transmission system is simplified, operation flexibility is improved, and the capacity of suppressing commutation failure is achieved.

The utility model relates to the technical field of extra-high voltage direct current transmission equipment, in particular to a GIS basin-type insulator particle motion device based on photon counting measurement, which comprises a power supply unit, a partial discharge-free transformer, a measuring unit, a recording unit, a counting unit and a data acquisition control unit, the power supply unit is used for providing excitation voltage of an initial DC / AC excitation volt level, and is connected with the non-partial-discharge transformer to amplify the excitation voltage and then is connected with the measurement unit. The measuring unit is used for measuring a GIS basin-type insulator sample to be measured; the recording unit is used for recording the movement process of the to-be-tested GIS basin-type insulator sample particles in a time period from a static state to a movement starting state; the device is simple in structure and convenient to use, is not affected by electromagnetic noise and vibration noise during traditional partial discharge measurement in use, is higher in particle detection sensitivity compared with a traditional partial discharge detection device, and can realize online detection of GIS basin-type insulator particle motion.