1974 results about "Voltage drop" patented technology

A low voltage ride through control method for a grid-forming inverter based on dynamic internal potential adjustment comprises the following steps: detecting a voltage per unit value of a grid-connected point in real time, and comparing the voltage per unit value with a threshold value to judge a voltage drop event and trigger low voltage ride through control; dynamically calculating active and reactive power reference values through a reactive compensation equation and an active current limiting equation according to the voltage amplitude and the power reference value before falling during the ride-through period; inputting the active reference value into a virtual rotor motion equation to generate a reference phase, and outputting a phase reference signal in combination with a dual-mode phase compensation controller; superposing the reactive reference value with the reference voltage through a reactive voltage regulating ring to generate a voltage amplitude reference signal; synthesizing an internal potential according to the phase and the amplitude reference signal, and obtaining an inductive current reference value through virtual impedance control and current amplitude limiting; and finally, a driving signal is generated through the current inner loop controller and the modulation module. According to the invention, overcurrent can be effectively inhibited, rapid reactive power support is provided, and synchronous stability and smooth transition in a fault period and a recovery process are ensured.

The invention discloses a converter collaborative current limiting method based on adaptive virtual impedance and a power loop, and the method comprises the steps: firstly building an equivalent impedance model of a converter and a power grid, analyzing the steady-state and transient characteristics of fault current, and extracting key parameters for current limiting design; when it is detected that the voltage drop of the grid-connected point exceeds a threshold value, a self-adaptive virtual impedance link is automatically put into use, and virtual resistance and reactance values are dynamically calculated according to the variation amplitude of voltage or current, so that the virtual resistance and reactance values are proportionally adjusted along with the fault degree; and when the system voltage returns to normal, the virtual impedance automatically quits, and the control continuity is ensured. Then, the active and reactive power reference values are dynamically corrected according to the voltage drop depth, a power reference signal matched with the voltage amplitude is generated, it is guaranteed that power output does not exceed the limit, and the voltage supporting capacity is improved. Finally, real-time current-limiting control of the converter and stable operation of the system are realized on the premise of not switching the control mode through the synergistic effect of the virtual impedance ring and the power ring. The method has the advantages of being high in response speed, excellent in current limiting effect, good in control continuity and the like, and is suitable for fault current limiting and voltage support control of the grid-forming converter.

The invention relates to the technical field of industrial process control, and discloses an intelligent optimization control method of an alkaline water hydrogen production system, which comprises the following steps: a controller synchronously acquires real-time voltage, current and temperature data of an electrolytic bath; theoretical reversible voltage is calculated according to a Nernst equation, ohm voltage drop is eliminated, and a bubble additional impedance value representing the bubble coverage degree is analyzed; performing differential processing on the change rate of the bubble additional impedance value to generate a flow feed-forward control instruction, combining a feedback control instruction based on temperature deviation to synthesize a target rotating speed instruction, and driving an alkali liquor circulating pump to adjust the flow speed; according to the method, the bubble impedance observation model is constructed, so that zero-delay sensing and decoupling control over the state of bubbles in the electrolytic cell are achieved, hysteresis of single temperature feedback is eliminated, and the problems of actuator saturation and model aging drifting are solved.

The present application provides a method and system for predicting the remaining service life of an IGBT device, comprising: simulating an IGBT device power cycle aging experiment, collecting conduction voltage drop historical data on the basis of the experiment, and respectively obtaining a model parameter empirical value and a model parameter estimated value on the basis of the conduction voltage drop historical data; constructing a first state weight on the basis of the current operation state, and performing smooth adjustment on the model parameter estimated value on the basis of the model parameter empirical value and the first state weight to obtain a parameter correction result; and establishing a state transition equation on the basis of the parameter correction result, and predicting the remaining service life of an IGBT device on the basis of the state transition equation. Use of the present application can improve the accuracy of prediction of the remaining service life of the IGBT device.

The invention discloses a main station big data-based low-voltage transformer area topology hierarchy identification method and system, and the method comprises the steps: constructing a multi-dimensional voltage feature vector through the voltage time sequence data, collected by a main station side, of a transformer area general meter and a user ammeter, and forming an electrical feature matrix through feature extraction; and on the basis, judging the station area affiliation and the phase line affiliation of the user electric meter through similarity calculation. Then, generating a stable consensus cluster based on multi-time window clustering and the copolymerization matrix, and mapping the cluster into a virtual electric meter box node; constructing a minimum spanning tree and carrying out directionalization to obtain an initial radial topological structure; further introducing an electrical consistency criterion based on correlation of voltage drop and subtree current, performing multi-candidate structure optimization on the preliminary topology, and finally obtaining an optimal transformer area topology hierarchical structure consistent with a physical rule; high-precision automatic identification of the low-voltage transformer area topology can be realized without manual participation, and effective support is provided for digital operation and maintenance of a power distribution network.

The invention relates to the technical field of power distribution fault positioning, in particular to a power distribution single-phase earth fault positioning method and device based on multi-source information fusion. The device comprises a data acquisition module, a fault line selection module, a grading emergency module, a fault positioning module and a parameter optimization module. According to the method, the zero-sequence current is monitored in real time, the dynamic change curve is generated, the fault line is accurately identified in combination with amplitude and phase characteristics, electrical parameters, environmental factors and load importance are fused to carry out comprehensive risk assessment and start a hierarchical response mechanism, and the fault point of the fault line is accurately positioned by adopting a voltage drop method. And the monitoring frequency and the decision threshold value are adaptively adjusted according to the fault characteristics and historical data, so that response lag and insufficient precision of a traditional fault positioning method are avoided, full-flow intelligent management from fault detection, accurate positioning to parameter self-optimization is realized, the accuracy and efficiency of fault processing are improved, and safe and stable operation of a power grid is ensured.

The invention relates to the technical field of motor control, and discloses a voltage compensation stable management system for a vortex oscillator motor, and the system comprises a detection unit which is used for collecting a bus current signal; the processing unit is used for performing differential operation on the bus current signal to determine a current change rate, judging that a load sudden change working condition is entered when the current change rate exceeds a preset threshold value, and further querying a load response coefficient according to a preset feature table and calculating a voltage compensation increment; and the driving unit is used for adjusting the phase shift angle of the excitation voltage according to the voltage compensation increment. According to the invention, by identifying the load working condition in real time and executing feedforward compensation, the instantaneous voltage drop caused by load switching is eliminated, the voltage steady-state characteristic of a motor driving link is maintained, the rotation speed fluctuation is effectively inhibited, and the dynamic response capability of the system under the variable load working condition is enhanced.

The invention relates to the technical field of micro-grid control, and provides an island micro-grid distributed control method, system and device and a storage medium. Comprising the following steps: performing voltage compensation gain and frequency compensation gain calculation based on droop control output of each distributed power generation unit, droop control output of all neighbor distributed power generation units, and a voltage dynamic tracking error and a frequency dynamic tracking error which are obtained by calculating a microgrid global recovery target to obtain secondary adjustment output; and after corresponding items in the droop control output and the secondary regulation output are summed to generate comprehensive reference output, voltage synthesis is carried out according to the comprehensive reference output to obtain voltage regulation output for output control of a corresponding inverter. Based on a distributed regulation and control mechanism for cooperatively calculating the compensation amount of each power generation unit by using neighbor information and a global recovery target, the dynamic response speed and the power distribution precision can be improved, voltage drop and frequency deviation caused by load disturbance are effectively eliminated, and rapid recovery is realized.

The invention relates to the technical field of fuel cell control, and discloses a control method of a hydrogen fuel system controller, which comprises the following steps: in response to a system shutdown instruction, controlling a DC / DC converter to maintain operation and request a preset scavenging current, and consuming residual reaction gas in a flow channel and a pipeline by using an electrochemical power generation reaction in an electric pile; meanwhile, hydrogen-cut air-down operation is executed, and the average single voltage of the electric pile is collected in real time; when it is monitored that the average monomer voltage is reduced to be below a preset anti-corrosion safety threshold value, the DC / DC converter is controlled to be disconnected, and mechanical purging is started. A time sequence interlocking mechanism of electrochemical energy depletion and mechanical purging is established, a high-potential retention path in the shutdown process is blocked from the physical and chemical source, and the safety of the shutdown is improved. Reverse polarity corrosion caused by a hydrogen-air interface effect is avoided, and the service life of the galvanic pile is prolonged.

The invention discloses a doubly-fed induction generator fault detection method combining a sliding-mode observer and a bilateral cumulative sum algorithm, and the method comprises the following steps: designing a doubly-fed induction generator rotor current sliding-mode observer based on the combination of a novel reaching law and a doubly-fed induction generator state equation; carrying out stability and convergence analysis on the designed novel reaching law by adopting a Lyapunov stability theory; and the fault detection method of the doubly-fed induction generator is designed in combination with the optimized bilateral accumulation sum algorithm. A rotor current sensor fault, an input interference voltage fault, a voltage drop fault and a stator turn-to-turn short circuit fault are introduced. The rotor current tracking performance of the designed sliding-mode observer under different doubly-fed induction generator faults is verified by using a residual value obtained by comparing a doubly-fed induction generator rotor current value estimated by the sliding-mode observer with an actual rotor current output value; and meanwhile, the reliability of the designed doubly-fed induction generator fault detection method based on the optimized bilateral cumulative sum algorithm is verified. The doubly-fed induction generator fault detection method combining the sliding-mode observer and the bilateral cumulative sum algorithm has the advantages of being high in tracking precision and accurate in fault state characterization, meanwhile, weak fault features can be effectively converted into digital signals to be output, and faults of the doubly-fed induction generator are detected.

The invention discloses a lithium iron phosphate battery anomaly detection method, electronic equipment and a storage medium, and relates to the technical field of battery health management. The method comprises the following steps: acquiring a voltage value and a temperature value of each single battery in a battery cluster every unit time interval, determining a voltage drop rate for any single battery in the battery cluster based on the voltage values of the single battery at the first moment and the last moment in the first unit time, and correcting the voltage drop rate in combination with the temperature value at the last moment. When it is detected that the corrected pressure drop rate is larger than the preset threshold value in the second unit time, the last moment of the second unit time serves as the starting moment, and if the corrected pressure drop rates of all unit time in the first preset time period are all larger than the preset threshold value, the second unit time serves as the starting moment; and if yes, determining an initial voltage entropy value based on the voltage value of each single battery obtained in the last second unit time. According to the invention, the voltage drop rate and the initial voltage entropy value are combined, so that the anomaly detection of the lithium iron phosphate battery is realized.

The invention discloses a distributed dynamic time sequence monitoring circuit and a self-adaptive adjusting system, which comprise a plurality of monitoring units deployed in different IR voltage drop hot spot areas of a chip, each monitoring unit is configured as a delay chain, and the delay of the delay chain is determined by the local power supply voltage and temperature of the area where the monitoring unit is located. The delay variation is equal to the delay variation of the longest key path determined by simulation; the input end of the dynamic aggregation unit is connected with the monitoring unit, and the dynamic aggregation unit is used for comparing delays of all the input signals and outputting the input signal with the longest delay; a central monitor including a configurable delay pad circuit for providing a reference delay; the input end of the delay gasket circuit is connected with the output end of the dynamic aggregation unit, and the delay of the input signal with the longest delay and the reference delay are summed to obtain the total delay of the virtual key path for the real-time longest key path delay of the mirror image chip. According to the invention, non-intrusive monitoring can be realized, and all possible IR voltage drop hot spot areas can be fully covered.

The invention discloses a global cooperative control method and system for unbalanced fault ride-through of a multi-terminal DC power grid, and the method comprises the steps: constructing a fault detection model based on the positive sequence voltage drop depth and the negative sequence voltage size of the AC side of each converter station, automatically judging an unbalanced fault, and carrying out the fault detection when the fault is detected. Calculating the maximum allowable active current based on a fault station unbalanced current control model to carry out current limiting control on the converter station; and carrying out output power adjustment on the DC voltage deviation of the non-fault station based on the non-fault station power cooperation model. Asymmetric fault ride-through is carried out by using a constrained and optimized current instruction generation algorithm, and the capacity of a converter is dynamically and accurately distributed and utilized in a limited manner, so that the voltage support capability of a fault alternating-current power grid is maximized, and globally optimized adaptive power distribution is realized; the power of the non-fault station is calculated and distributed in a centralized manner and is dynamically adjusted according to the real-time available capacity, so that the self-adaption and global optimization of the running state change of the power grid are realized, and the fault handling toughness and reliability of the power grid are improved.

The invention relates to the technical field of power distribution lines, in particular to a power distribution line abnormal line loss analysis and treatment method and system, and the method comprises the following steps: synchronously extracting real-time monitoring data and historical data based on a power distribution line network, carrying out the data alignment and data cleaning, screening features associated with current leakage and voltage drop, and carrying out the analysis and treatment of the abnormal line loss of the power distribution line. Comprising load change rate and temperature fluctuation. According to the invention, through application of real-time and historical data analysis, the detection and management efficiency of the abnormal line loss of the distribution line is improved, the accuracy of data processing is improved through synchronous extraction and data alignment, early recognition of abnormal modes is allowed, the possibility of energy loss and unplanned power failure is reduced, and through adoption of Fourier transform and wavelet transform, the detection efficiency of the abnormal line loss of the distribution line is improved. According to the method, abnormal signals are accurately recognized, the analysis capability of the signals is enhanced, the accuracy of abnormal detection is improved, fault positioning and maintenance plan making are effectively optimized through combination of the GIS system, and the pertinence and efficiency of maintenance work are remarkably improved.

An inertia cooperative control method of an integrated optical storage alternating current and direct current hybrid micro-grid comprises the steps that firstly, according to static and dynamic power capacities of energy storage units in direct current sub-grids and allowed direct current voltage deviation, sub-grid equivalent virtual resistance and virtual capacitance are calculated; secondly, RC + R type parallel virtual impedance parameters are distributed according to the power proportion of each energy storage unit, and multi-energy-storage cooperative response power disturbance according to the capacity is achieved; then, a phase angle is generated based on the mapping relation between direct-current side voltage and frequency, an alternating-current voltage amplitude instruction is determined in combination with reactive power droop control and feeder impedance voltage drop compensation, and a dq-axis voltage instruction is generated through virtual impedance compensation; normalized three-phase modulation waves are obtained through voltage-current double closed-loop control and dq / abc coordinate transformation, and six paths of PWM signals are generated to drive an interconnection converter after the normalized three-phase modulation waves are compared with triangular carrier waves. The method does not need to depend on external communication, has the capabilities of autonomous inertia support, voltage and frequency coordinated regulation and reasonable multi-source power distribution, and improves the stability and dynamic response performance of the system under island operation.

A dynamic grid allocation system for power distribution in the development of integrated circuits in the sub-five-nanometer range, wherein the system comprises the following: a placement processor unit configured to receive a synthesized netlist comprising a variety of standard cells and macros, each associated with switching activity data derived from simulation or synthesis activity profiles, and to generate a spatial cell placement arrangement by grouping cells into microzones based on activity correlation, time sensitivity, and connection proximity; a power density calculation unit coupled to the placement processor unit and configured to calculate the local power density and instantaneous current demand for each microzone based on the spatial distribution of switching operations, capacity load, and effective switching frequencies; a dynamic network generation unit coupled to the power density calculation unit and configured to generate a multilayer power distribution network with variable network topology, where the width, spacing, via density and metal layer assignment of the power network are adaptively determined as continuous functions of the localized power density and power demand calculated for each microzone; a topology control processor configured to monitor voltage drop and electromigration data obtained from signoff analyses or predictive models in real time and dynamically adjust the power grid topology parameters to ensure compliance with predefined reliability thresholds for voltage drop and electromigration; a predictive current modeling unit configured to receive historical switching and voltage data, train a predictive model for transient current peaks, and provide predictive power boost instructions to the dynamic grid generation unit before power integrity violations occur; and A feedback synchronization controller is communicatively connected to the placement processor unit and the topology control processor, whereby the feedback synchronization controller continuously exchanges updated power density information and placement constraints, so that cell placement and network topology adapt together in real time, thereby minimizing routing congestion, ensuring a uniform voltage distribution, and guaranteeing compliance with electromigration and IR drop regulations under various activity conditions.

The invention relates to a method. The invention discloses an ATE-based method for batch detection of pseudo soldering and sealing-off of chip packaging bonding, and belongs to the technical field of semiconductors. The method comprises the following steps: aiming at packaged and bonded chips, providing excitation current for each chip to be tested through an ATE test machine, and conducting an ESD (Electro-Static Discharge) diode connected with each pin of the chip; detecting the voltage drop between each pin and the pin GND; and calculating the equivalent resistance to determine whether pseudo soldering or unsoldering exists. The detection method has high practicability, is simple to operate, is very suitable for large-scale application and popularization, and has a certain promotion effect on improvement of a chip packaging test technology, improvement of chip performance reliability and chip packaging inspection.

The invention discloses a variable virtual impedance implementation method and system for a network-building type converter. The method comprises the following steps: acquiring a ratio of a network-side voltage amplitude of the network-building type energy storage converter to a system rated voltage amplitude; when the ratio is smaller than a set threshold value, voltage drop occurs; at the moment, the active power given value is controlled to keep the power angle stable without divergence; meanwhile, a saturation characteristic function is calculated according to the drop amplitude of the grid-side voltage, and the output value of the virtual internal potential is changed based on the saturation characteristic function, so that the virtual impedance value in the control structure is changed, and the current limiting and voltage supporting requirements of the low-voltage ride-through strategy are met. The virtual impedance value can be changed according to different voltage drop degrees, and meanwhile the saturation characteristic is achieved.

The invention discloses a flux linkage tracking full-speed-domain high-precision predictive current control method for a permanent magnet synchronous motor, and the method comprises the steps: sampling a phase current signal, a position signal and a speed signal of the permanent magnet synchronous motor, and obtaining a dq sampling current through coordinate transformation; calculating a predicted current according to the established tracking discrete model; the sinusoidal variation characteristic and the dynamic transient characteristic of the resistance voltage drop are accurately considered in the current prediction and reference voltage calculation stage, and the resistance voltage drop is accurately represented through accurate feed-forward compensation of predicted current and reference voltage; a driving signal of the inverter is obtained through coordinate transformation and space vector modulation, and full-speed-domain high-precision fast-response current prediction control over the permanent magnet motor is achieved. According to the method, the current flow steady state control error caused by the model error is reduced, the current control precision and the dynamic response performance of the permanent magnet synchronous motor in the full-speed domain are effectively improved, and a high-precision model basis is provided for high-precision position-free control and parameter online identification.

The invention relates to an alternating-current trunk line or an alternating-current power distribution network, in particular to a method for improving the stability of a wind power system through combined control of network construction type energy storage and a nine-switch UPQC. The method comprises the following steps: firstly, proposing an active regulation and inertial support control method based on a virtual synchronous machine mechanism for network construction type energy storage; and secondly, by constructing a coordination control framework, dynamic response complementation of the energy storage system and the UPQC under disturbance is realized, so that the overall frequency stability and voltage supporting capability of the system are improved. And finally, building a system model in Matlab / Simulink, setting three typical working conditions of wind power fluctuation, frequency disturbance and serious voltage drop, and carrying out scheme validity verification. Simulation results show that the method can effectively stabilize the wind power output fluctuation, enhance the frequency and voltage support capability, and significantly improve the stability of a wind power system.

The invention belongs to the technical field of power supply, and particularly relates to a photovoltaic power generation energy storage system switching system and a switching method, and the method comprises the steps: building an output trend prediction model and issuing an early warning signal at the initial stage of illumination change, starting the pre-charging and state self-inspection of an energy storage battery in advance, and synchronously carrying out the phase locking and voltage matching preparation of a commercial power side, a real-time monitoring network covering the whole system is constructed before switching so as to evaluate the bus stability, and then grading decreasing of photovoltaic output and synchronous power undertaking of an energy storage battery are executed after the condition is confirmed to be met, so that smooth transition between power supplies is realized. According to the method, the passive response of a traditional system after the voltage drops is avoided, the voltage fluctuation and power supply interruption in the switching process are effectively eliminated, the power supply continuity and the electric energy quality are remarkably improved, and the power utilization experience of a user and the equipment operation safety are guaranteed.

The invention provides an integrated circuit power supply network wiring optimization method, a computer device and a storage medium. The method comprises the steps of performing initial wiring based on initial parameters and constraint conditions; evaluating the connectivity state of the power supply network after initial wiring, if the number of unconnected pins of the power supply network does not meet the set requirement, performing connectivity optimization calculation on the power supply network, and adjusting wiring parameters of the power supply network to enable the number of the unconnected pins to meet the set requirement; the power supply voltage drop state of the power supply network is evaluated, if the power supply voltage drop value under the worst condition is larger than a preset power supply voltage drop threshold value, power supply voltage drop optimization calculation is carried out, and the power supply voltage drop value under the worst condition is reduced to be below the power supply voltage drop threshold value by adjusting wiring parameters of the power supply network; and carrying out wiring on the power supply network based on the finally determined wiring parameters obtained by power supply voltage drop optimization calculation. The computer device and the storage medium can realize the method. According to the invention, the calculation efficiency of wiring optimization can be improved.

The invention discloses a network construction type VSG power grid fault active support cooperative control method, and belongs to the technical field of new energy grid-connected control. According to the method, the power grid voltage is monitored in real time, and a cooperative strategy is dynamically triggered: when the voltage drops below a set value, a cooperative control mechanism is started, including (1) self-adaptive active power adjustment based on a power angle stability margin and dynamic correction of a power instruction value to suppress kinetic energy accumulation of a rotor; (2) voltage tracking type reactive compensation is superposed in a reactive control loop, reactive current is increased in real time according to the drop depth, continuous reactive support is provided, and steady-state overcurrent is restrained; and (3) inputting a virtual resistance inductor, and limiting a transient over-current peak value by suppressing a dq-axis coupling current component. When the voltage is normal, the conventional VSG control mode is maintained. According to the invention, power-reactive power-impedance three-dimensional cooperation is realized, power angle stability, current limitation and voltage support are considered, and the stability and active support capability of the network-forming VSG under the power grid drop fault are significantly improved.

The invention relates to the technical field of power systems, and particularly provides a network construction type energy storage wide and low frequency disturbance suppression method suitable for a weak power grid environment. The method comprises the following steps: constructing an equivalent impedance model, and analyzing RLC resonance impedance matching conditions; constructing a quantitative model of impedance dynamic correlation; designing a multi-parameter adaptive virtual impedance module; constructing a cooperative control architecture of the adaptive virtual impedance and the network construction type energy storage converter; through verification of a continuous voltage drop simulation scene, adaptive adjustment parameters are optimized by adopting indexes of oscillation amplitude attenuation rate and stabilization time so as to ensure a wide and low frequency disturbance suppression effect under a weak power grid, and according to the method, broadband oscillation suppression under the continuous voltage drop scene is realized through adaptive virtual impedance, and dynamic accurate compensation is realized.

The invention discloses a self-adaptive current-limiting control method and related device for a network construction type energy storage converter under a symmetric fault of a power grid, and belongs to the technical field of network construction type energy storage converter control, and the method comprises the steps: constructing a corresponding fault current dynamic response model based on the network construction type energy storage converter under the symmetric fault of the power grid; generating a self-adaptive current-limiting control strategy based on the voltage drop depth of the power grid; wherein the self-adaptive current-limiting control strategy comprises the steps of carrying out overcurrent steady-state component suppression based on a phasor current-limiting method and carrying out overcurrent transient-state component suppression based on a virtual impedance control method, and self-adaptively adjusting a power instruction to meet a system support requirement in a current-limiting process; a fault current dynamic response model is solved through a self-adaptive current-limiting control strategy, a current-limiting control scheme is obtained, it can be ensured that the converter maintains the networking characteristic in the fault period, steady-state and transient overcurrent is effectively restrained, output current is strictly limited within a safety threshold value, and transient stability of a system is maintained.

The invention relates to the technical field of charging switching control, in particular to a dynamic switching system for cooperative work of wireless charging and wired charging, which performs node modeling and edge weight propagation on multiple parameters such as magnetic field intensity, current fluctuation ratio, contact resistance and temperature threshold through a graph neural network. Structured expression and dynamic updating of a nonlinear coupling relation among parameters are achieved, abnormal feature aggregation and channel state characterization are more refined, fuzzy reasoning and weight adjustment are conducted on multiple variables such as power output, the heat growth rate, the voltage drop rate and the energy efficiency ratio through fuzzy logic control, the stability of a channel priority sequence is enhanced, and the stability of the channel priority sequence is improved. Through dynamic detection of power curve intersection points and transition section time sequence calculation, continuous power distribution is converted into a smooth function interval, instantaneous energy abrupt change during switching is reduced, closed-loop correction of multi-period signals is achieved, and the system keeps stable operation and energy efficiency output consistency under high-dimensional parameter disturbance.

The invention relates to the technical field of electric power, and discloses a photovoltaic grid-connected system fault ride-through method based on VSG current limiting control. When it is detected that the PCC voltage is lower than a preset voltage threshold value, the photovoltaic inverter closes power outer loop control, an active current reference value and a reactive current reference value are reconstructed according to the voltage drop depth, it is guaranteed that grid-connected operation of the photovoltaic side is kept in the fault period, and voltage support is provided; a second-order rotor motion equation and an excitation control equation are established in an energy storage converter controller to simulate a synchronous generator, when PCC voltage drop or a power grid fault is detected, dynamically-adjusted virtual impedance is injected into the output end of a VSG according to the voltage drop depth so as to increase equivalent impedance and actively limit the peak value of short-circuit current, and the voltage drop or the power grid fault is detected. And switching the active power reference value into an active power reference value in a fault state and reducing or inhibiting active output, and switching the reactive power reference value into a reactive power reference value in the fault state so as to enhance the reactive power support capability of the energy storage system and maintain the voltage stability of the grid-connected point.

The invention relates to the technical field of power equipment on-line monitoring and fault diagnosis, and discloses a converter transformer bushing end screen voltage abnormity detection device and early warning method.The method comprises the steps that voltage data are collected through a wireless intelligent sensor, soft synchronization and self-adaptive windowing are achieved through a commutation notch feature locking mechanism, and a preprocessing signal is output; topological correlation clustering is executed to construct a virtual health reference, a dynamic residual sequence is extracted through time domain difference, and system side and equipment side features are decoupled; constructing a variational mode decomposition model, and calculating a characteristic entropy value of the intrinsic mode function; and comparing the entropy value with a threshold value, triggering an active impedance disturbance verification mechanism, controlling a sensor to access a load and comparing an actual voltage drop rate with a theoretical voltage drop rate, and determining an insulation degradation or poor contact fault. High-precision synchronization can be achieved without a hardware clock, and the problems that weak fault features are difficult to extract and virtual connection and insulation faults are difficult to distinguish in a high-impedance loop are effectively solved.

The invention discloses an electric energy metering error evaluation method and system for a direct current charging pile, equipment and a medium, and the method comprises the steps: constructing an electric energy disturbance response function based on transient voltage and transient current, and effectively quantifying the transient metering deviation caused by measurement lag, voltage drop, current peak and other factors in the actual operation of the direct current charging pile. Error reconstruction modeling has higher dynamic adaptive capacity and physical rationality, the limitation that in the prior art, the influence of the high-variable-load working condition on metering cannot be reflected is broken through, and the accuracy and timeliness of direct-current charging pile error monitoring are greatly improved. Besides, a standard error is introduced to carry out fitting calibration on a reconstruction error and carry out energy conservation verification, thereby realizing verifiability on a physical level and controllability in engineering implementation, enhancing credibility and authority of an evaluation result, constructing a closed-loop analysis mechanism from error evaluation to metering correction and then to conservation verification, and improving reliability and reliability of the evaluation result. And the closeness and the adaptive capability of the overall error evaluation are 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.