357 results about "Line current" patented technology

The invention discloses a game reinforcement learning-based reactive power dispatching method for an electric vehicle to participate in a power distribution network, and the method comprises the steps: collecting node voltage, line current, electric vehicle charging and discharging states and topological information, and constructing graph attention embedding; generating an initial reactive power regulation action in the multi-agent game reinforcement learning framework, and shaping and updating a strategy gradient through double rewards; the improved particle swarm is initialized according to the updating strategy gradient, and a self-adaptive inertia coefficient is set; iteratively searching according to the node voltage sensitivity, the line reactive margin and the expected convergence step number to obtain an optimized particle swarm; the particle speed is mapped to a main strategy network through online cooperative training, the inertia coefficient is synchronously adjusted, a cooperative optimization strategy is output, a reactive power dispatching instruction is generated, and the algorithm is updated in a closed-loop mode according to real-time feedback. According to the invention, rapid and cooperative reactive dynamic scheduling of an electric vehicle group is realized, and the voltage stability and the electric energy quality are remarkably improved.

The invention discloses an electricity meter terminal temperature anomaly identification method, system and device and a storage medium, and relates to the technical field of intelligent electricity meter monitoring and anomaly detection.The method comprises the steps that currents of a live line loop and a zero line loop of an intelligent electricity meter are sampled, and the deviation rate of the live line current relative to the zero line current is calculated; estimating the temperature of the terminal of the electric energy meter based on the deviation rate and by using the resistance characteristic metering error change trend of the manganese-copper shunt; and when the terminal temperature estimated value of the electric energy meter exceeds a preset threshold value, determining that the temperature of the live wire terminal is abnormal, and recording an alarm event. The method realizes real-time acquisition of current difference characteristics, provides a reliable data basis for subsequent terminal temperature estimation, realizes a method of indirectly reflecting terminal temperature rise through electrical characteristics, ensures that alarm can be triggered and a complete tracing chain can be formed when temperature abnormity occurs, and improves the accuracy of terminal temperature estimation. Therefore, the controllability of the operation safety of the electric energy meter and the completeness of post analysis are improved.

The invention discloses a DC fault arc identification method and device based on a wavelet transform algorithm, and the method comprises the steps: collecting a DC line current signal through a high-bandwidth current sensor, carrying out the digitalization of a signal conditioning circuit and a high-speed ADC, and sequentially carrying out the preprocessing of the elimination of baseline drift through differential filtering and the suppression of specific frequency interference through adaptive notch; performing 3-8-layer multi-scale decomposition on the pure signal by adopting a Daubechies wavelet basis, preferably selecting high-frequency detail coefficients from the first layer to the third layer, and creatively fusing a multi-scale energy entropy representing energy distribution randomness and a time domain kurtosis representing transient impact to form a composite characteristic quantity; a threshold value (threshold value = mean value + adaptive coefficient * standard deviation) is dynamically generated based on sliding time window historical data, the adaptive coefficient is dynamically adjusted according to the load type, the resistive load is 1.8-2.2, and the inductive / capacitive load is 2.5-3.5; and when the composite characteristic quantity exceeds a threshold value and the sample proportion is greater than or equal to 85% within the duration of 0.5-5ms, a tripping execution mechanism is triggered.

An energy conversion device comprises: an electric motor, an electronic control, a traction battery and a controller. The controller is configured to control all bridge arms corresponding to windings of the electric motor, so that the collaboration of driving and battery self-heating is achieved, and the crest and trough of an actual N line current flowing through an N line of the electric motor to counteract or are superposed with the crest and trough of an actual phase current flowing through each phase of winding of the electric motor, thus reducing or increasing the amplitudes of the actual phase current of each phase of winding at the crest and trough, and thereby providing a greater phase current for the electric motor so as to drive the electric motor. Thus, the torque output by the electric motor is greater.

Accurate real-time monitoring of distribution networks becomes increasingly pivotal to ensure reliable and optimal operation of grid. Existing joint parameter-state estimation techniques predominantly focus on transmission systems, making their applicability to distribution systems challenging due to variations in available input data. Furthermore, the joint estimation techniques significantly suffer from computational complexity. Present disclosure provides a method and a system for personalized multi-subject text to image generation. The system first uses lossy Distflow equations and an inverse Physics-Informed Neural Network (iPINN) architecture for learning network voltage dynamics, drift matrix and network bus voltages from real-time bus power injection data and historical voltage data. Thereafter, the system determines a plurality of line parameters from the learnt drift matrix using a least-square optimization technique. Finally, the system calculates line power flows and line currents using the lossy Distflow equations.

The invention discloses a low-voltage distribution area topology identification method, system and device and a storage medium, and the method comprises the following steps: deploying a synchronous measurement unit in a low-voltage distribution area, and obtaining the outgoing line current phasor and voltage phasor data with a synchronous time scale of a whole network; constructing an incoming line and outgoing line current phasor set, and performing adaptive descending sorting according to amplitudes; determining that the nodes corresponding to the incoming line current phasors and the found nodes corresponding to the one or more outgoing line current phasors are in a father-son relationship, and iterating the process until all sets are empty, thereby completing the identification of the topological relationship of the power distribution side; and according to the equipment number contained in the obtained voltage phasor data, determining a meter box connected with the user electricity meters, and then clustering the user electricity meters connected to the same meter box according to the voltage phase angle to obtain the connection phase sequence of each user electricity meter. The problem of key information missing is solved from a data source, and accurate and efficient identification of topology is realized by fusing physical constraints.

The invention discloses a method for monitoring the insulation state of a stator winding of an injection unit based on neutral point harmonic frequency sweeping. The invention provides an active online monitoring method based on harmonic injection for stator winding insulation of a full-power variable-speed pumped storage unit. A common-mode loop is constructed for a motor stator winding of a network side transformer neutral point ungrounded system through a motor neutral point grounded transformer, and therefore online monitoring of the insulation state of a motor stator is achieved. In order to solve the measurement problem of the full-power variable-speed pumped storage unit under the large-current working condition, a neutral point outgoing line current detection technology is adopted. A machine end large current interference area is avoided, monitoring is carried out on the primary side of the grounding transformer, transmission errors are avoided, and the measurement precision and reliability of insulation monitoring signals are remarkably improved. According to the invention, harmonic injection is carried out by avoiding an inherent common-mode component of a unit, a monitorable leakage current signal is enhanced, and the accuracy of insulation equivalent capacitance calculation is ensured.

The invention discloses a self-adaptive droop control method giving consideration to SOC balance and voltage deviation, and the method comprises the steps: constructing an island DC micro-grid system, considering the power distribution principle of SOC balance and energy storage capacity, and setting a distribution factor associated with the SOC and the energy storage capacity for each energy storage device in the system; determining a power deviation function and a voltage deviation function of the island DC micro-grid system associated with the SOC, and obtaining a comprehensive optimization objective function after weighting; the SOC of each energy storage unit, the voltage reference value of the output end of the DC / DC converter and the line current are mutually communicated and exchanged through a consistency algorithm; and optimizing and solving the comprehensive optimization objective function by using an SHADE algorithm to obtain a droop coefficient and a voltage reference value of each energy storage unit converter. According to the self-adaptive droop control method, the droop control parameters can be dynamically adjusted, the problem that a traditional fixed parameter droop control strategy cannot adapt to actual operation conditions is solved, and meanwhile the system stability is improved and the power distribution is optimized.

The application discloses a kind of method and detection system of calculating elevator balance coefficient, comprising: the three-phase voltage value and two-phase current value of three-phase motor are collected, and the voltage phase angle value under voltage resultant vector and line voltage effective value in two-phase αβ coordinates are calculated based on three-phase voltage value and two-phase current value;Current phase angle value and line current effective value under current resultant vector;Elevator car operating speed and elevator car running distance are calculated based on voltage phase angle value;Power factor is calculated based on voltage phase angle value and current phase angle value;Elevator car passes through the moment of elevator balance position based on elevator car running distance, and elevator balance coefficient is calculated based on the running data when passing through elevator balance position.The application calculates the moment of elevator car passing through elevator balance position by three-phase voltage value and two-phase current value and the running distance of elevator car, and elevator balance coefficient can be quickly and accurately calculated based on the running data when passing through elevator balance position.

The invention discloses an electric power system transient stability rapid response control method and system, and relates to the technical field of electric power systems, and the method comprises the steps: collecting a transient harmonic current signal generated by a power grid fault in real time through a harmonic detection unit connected to a DC bus of an energy storage converter, and calculating the phase offset of the transient harmonic current signal; generating a power control instruction through a pre-configured hardware mapping circuit based on the phase offset; acquiring a current differential signal by using a power grid line current sensor, and identifying a path of transient energy flowing to a key unit based on a power grid topological structure; for the path, dynamically forming a virtual high-impedance wall on the target line; and on a consumption path predefined according to the power grid topological structure, controlling the energy storage converter to operate in a current source mode and configuring a reverse power characteristic so as to absorb the energy flow turned by the virtual high-impedance wall.

The invention discloses a power distribution area line loss regulation and control method and system based on light storage cooperation and multi-time scale optimization. Comprising the following steps: data acquisition: acquiring photovoltaic output, energy storage SOC, node voltage and line current data in real time; prediction calculation: predicting photovoltaic and load, and generating regulation and control boundary conditions; optimization decision making: running day-ahead optimization regulation and control and intra-day multi-time scale regulation and control strategies, and generating a regulation and control instruction; and performing control: realizing rapid power adjustment through an energy storage converter and a photovoltaic inverter. A multi-factor coupling line loss model is established, an improved particle swarm algorithm is designed to solve an optical storage scheduling strategy, and data driving and a physical mechanism model are fused to improve prediction precision. And a second-minute-hour collaborative optimization architecture is further constructed, so that rapid voltage stabilization and energy space-time transfer are realized. The method can effectively reduce the line loss rate of the transformer area, and is suitable for the energy-saving and loss-reducing scene of the power distribution network with high-proportion new energy access.

The invention discloses a transformer substation AC power supply residual current detection method and device, and the method comprises the steps: carrying out the vector synthesis of three-phase current data and zero line current data, forming a current difference sequence, exporting a residual current reference curve, and carrying out the fluctuation analysis of the residual current reference curve, and judging the leakage characteristics. After effective leakage features are formed through harmonic elimination, dominant frequency components are locked through frequency spectrum decomposition; calibrating a leakage type identifier according to the dominant frequency component and forming segmented leakage distribution; a deviation degree is formed by means of segmented leakage distribution and residual current reference curve deviation analysis, a correction deviation value is formed through load fluctuation compensation, and a standard exceeding coefficient is formed according to threshold value comparison to detect abnormal nodes to form hidden danger data; establishing a judgment rule based on the hidden danger data and the leakage type identifier to form a detection evaluation index; and executing path tracking on the detection evaluation indexes to form leakage position information, forming a disposal priority through intensity analysis to generate a residual current detection report, and realizing leakage current classification identification and self-adaptive evaluation.

The invention provides a power distribution network acceptance capability assessment method considering EV space-time transfer characteristics, and belongs to the field of electric vehicle acceptance capability assessment, and the method comprises the steps: building a road network-power grid coupling node aggregation model based on EV charging load space-time distribution; a multi-objective optimization evaluation model of the EV load accepting potential of the power distribution network is constructed by taking the maximum electric vehicle charging load accepting capacity of the power distribution network and the minimum network loss cost of the power distribution network as objective functions, and the time sequence optimal power flow of the power distribution network is iteratively calculated; when it is judged that any one of the maximum deviation rate of the node voltage and the maximum overload rate of the line current exceeds an allowable range, the current EV permeability serves as the maximum critical permeability, and otherwise, the current EV permeability is gradually increased; establishing a comprehensive evaluation index system for the acceptance capability of the power distribution network, and comprehensively scoring each index; the invention further provides a power distribution network admitting ability evaluation system. The problem of insufficient acceptance capability evaluation of the power distribution network during large-scale access of the electric vehicles is solved.

The invention discloses an active power distribution network flexible resource collaborative planning method based on an improved CS algorithm, and the method comprises the steps: constructing a planning and operation integrated active power distribution network double-layer optimization model, enabling an upper planning layer to take the minimum annual comprehensive economic cost as a target, optimizing the locating and sizing of a distributed power supply and energy storage, and covering the investment cost, the operation and maintenance cost and the power purchase cost; the lower operation layer generates an energy storage charging and discharging strategy and a power flow scheduling scheme based on a typical day scene by taking minimum network loss and maximization of new energy consumption as targets, guarantees node voltage and line current safety margin through probability constraint, and constructs a multi-resource coordinated planning-operation closed-loop model; and adopting an improved cuckoo search algorithm to carry out iterative solution on the bilayer programming model. And improving a cuckoo search algorithm, combining a particle swarm optimization algorithm with the improved cuckoo search algorithm, converting double-layer multiple targets into a fitness function by adopting a linear weighting method, and solving an optimal planning scheme.

The invention discloses a short-circuit fault current limiter and a control method thereof. The current limiter comprises a capacitor, two IGBT (Insulated Gate Bipolar Translator) modules and four diode groups, when the line has no short-circuit fault, the two IGBT tubes are controlled to be conducted, and line current flows from the first end of the line to the second end of the line through one IGBT module or flows reversely through the second IGBT module; when a short-circuit fault occurs at the first end of the line, the two IGBTs are controlled to be switched off, the line current flows to the first end of the line from the second end of the line through the first diode group, the capacitor and the fourth diode group, and the capacitor is charged to enable the line to present high impedance so as to restrain the short-circuit current; when a short-circuit fault occurs at the second end of the line, the two IGBTs are controlled to be turned off, the line current flows to the first end of the line from the first end of the line through the third diode group, the capacitor and the second diode group, and the capacitor is charged to enable the line to present high impedance so as to restrain the short-circuit current. The short-circuit fault current limiter is high in response speed and low in equipment cost.

The invention discloses a main and distribution collaborative optimization scheduling method and system based on a static safety boundary of a power distribution network, and relates to the field of power system optimization scheduling, and the method comprises the steps: converting a voltage / current safety boundary of the power distribution network into the static safety boundary of the power distribution network through hyperplane linearization; establishing global safety margin indexes of the node voltage and the line current of the power distribution network, and introducing a safety margin weight coefficient to balance the priorities of the node voltage margin and the line current margin; determining margin income based on the global safety margin index and the safety margin weight coefficient, and establishing a dynamic weight adjustment mechanism to update the safety margin weight coefficient; constructing a target function based on the power generation cost of the main power grid, the new energy power abandoning penalty of the power distribution network and the margin income; and obtaining power grid data, and solving the main-distribution collaborative optimization model by using a quadratic programming method and the power grid data to obtain a main-distribution collaborative optimization scheduling scheme. According to the invention, bidirectional power interaction and collaborative optimization of the main power grid and the power distribution network are realized.

The invention discloses an intelligent opening and closing method and system for a reclosing circuit breaker based on an electromagnet, and relates to the field of intelligent control, and the method comprises the steps: monitoring a line current in real time, comparing the line current with a preset threshold value, and carrying out the opening after the overcurrent abnormality is detected. Entering a first time delay stage after opening, comprehensively evaluating the states of the circuit breaker and the circuit, and constructing a dynamic weight index system to calculate an evaluation score; if the score exceeds a threshold value, closing is carried out after time delay is finished, otherwise, an alarm is triggered. And entering a second delay stage after switching on, continuously monitoring the electric parameters and establishing an anomaly judgment mechanism, forming a closed-loop protection process of monitoring, switching off, evaluating, switching on and re-monitoring, and realizing intelligent linkage of overcurrent protection and state self-adaption. The method has the advantages that through real-time line electric parameter monitoring, multi-dimensional state evaluation and an intelligent decision-making mechanism, precise opening and closing of the circuit breaker are achieved, the power supply reliability is improved, the power failure time is shortened, and the misoperation risk is reduced.

The invention discloses an impedance-adjustable series hybrid cascade static synchronous compensator and a control method thereof. The method comprises the following steps: acquiring grid-connected point voltage and load current information, and performing positive and negative sequence component analysis on the grid-connected point voltage and load current information; calculating a compensation line current component with the same size and opposite phase as the positive and negative sequence components of the load current so as to compensate the reactive power and the negative sequence current of the grid-connected point load; zero-sequence injection current used for in-phase active power balance is calculated, and reference operation current of each cascade branch is obtained; calculating the output reactive power of each phase based on the cascade branch voltage of each phase and the reference operation current, calculating the corresponding trigger angle of each phase thyristor under the condition that the adjustable impedance bears all phase voltages and generates all reactive power, and generating a pulse control signal to realize the control of the adjustable impedance; and each phase cascade converter adopts quasi-proportional resonance control to track the reference operation current, and generates a corresponding PWM signal to respectively control each phase cascade converter.

The invention discloses a photovoltaic station island stability control and re-grid-connection method based on energy storage cooperative regulation and control, and the method comprises the steps: carrying out the island detection in real time in a normal grid-connection state, and switching a photovoltaic system from a first working mode to a second working mode if tie line protection trips, so as to reduce the output power of the photovoltaic system; detecting the state of a grid-connected point circuit breaker, if the connection line circuit breaker is changed from closing to opening, executing connection line current detection, and when the connection line current is judged to be smaller than a current threshold value, switching the energy storage system from the first working mode to a second working mode to provide voltage and frequency support for the photovoltaic system; grid-connected detection: judging whether the island voltage, frequency and phase meet grid-connected conditions or not, if not, continuing grid-connected detection, and if yes, reclosing grid connection; and then, firstly switching the energy storage system from the second working mode to the first working mode, then switching the photovoltaic system from the second working mode to the first working mode, and recovering normal operation of the station.

The invention relates to an optically controllable switch (T2) with a sensor element (SE). The sensor element (SE) comprises a carrier material (TM) with crystals and paramagnetic centers (NV). When irradiated with pump radiation (LB), the sensor element (SE) emits fluorescent radiation (FL) that depends on the magnetic flux density B at the location of the sensor element (SE). A conduction current (I LTG ) in an inner line section (LTG +) generates a magnetic field with a flux density B such that, at sufficient current strength, the fluorescent radiation (FL) influences paramagnetic centers (NV1). Preferably, the optically controllable switch (T2) comprises a microelectronically manufactured semiconductor switch having the electronic switching component. Preferably, the respective sensor element (SE) is a respective microstructured sensor element (SE) on the surface of the microelectronically manufactured semiconductor switch and / or in the metallization stack of the microelectronically manufactured semiconductor switch.

The invention discloses a shunting electricity stealing user identification method, apparatus and device, and a medium. The method comprises the following steps: respectively obtaining zero line current values and live line current values of each user in a detected area at a plurality of time points; calculating the absolute value of the statistical value of the zero line current value and the live line current value of each user at each time point; the absolute value of the statistical value of the live-wire current value is greater than a preset threshold value, and the live-wire and null-wire current ratio is smaller than a preset ratio threshold value; calculating the variance of the current ratios of the zero line and the live line of the screened target user at the plurality of time points; and judging whether the target user is a shunt electricity stealing user or a common null line user according to the variance of the null line and live line current ratio of the target user. According to the invention, shunting electricity larceny detection can be realized, shunting electricity larceny users and common null line users can be accurately discriminated, and the accuracy and efficiency of anti-electricity larceny detection can be improved.

The invention discloses a rapid spare power automatic switching device and method suitable for high-proportion distributed power supply access, and the device comprises a local sampling module which is used for collecting a local side bus voltage Ulocal and an incoming line current Ilocal; the switching value acquisition module is used for acquiring the TWJ state of the switch at the side; the communication module is used for communicating with an opposite-side remote transmission device through an HDLC protocol and acquiring opposite-side switch position information Kremote and an opposite-side voltage state Uremote; programmable logic is arranged in the logic processing module, and the logic processing module is used for executing comprehensive judgment logic; and the control output module is used for executing opening and closing operation of the switch according to the instruction of the logic processing module. Compared with a traditional spare power automatic switching technology, the method effectively solves the problems of operation refusal and maloperation caused by access of the high-proportion distributed power supply, and remarkably improves the power supply reliability and the new energy consumption capability.

The invention relates to the technical field of electrical safety, and particularly discloses an arc fault protection method based on a circuit breaker intelligent algorithm, which comprises the following steps: S1, collecting a line current signal in real time, eliminating harmonic interference of a frequency converter from an original signal through an anti-aliasing filter, and converting the original signal into a digital signal; s2, processing the current signal by adopting a three-stage cascade wavelet analysis module, and outputting a dynamic peak-to-average ratio to S4; s3, detecting current disturbance based on a double-slide-rail window, outputting a disturbance positioning mark and a time-frequency feature to S4, judging a disturbance event, and positioning a starting point; s4, receiving the dynamic peak-to-average ratio of the S2 and the disturbance positioning mark and the time-frequency characteristics of the S3, performing path processing according to a characteristic analysis result, and adopting a direct interruption method and an electromagnetic radiation-current frequency domain cross validation method; s5, constructing an electric arc energy accumulation prediction model; according to the invention, the problems of weak arc leak detection, electromagnetic interference maloperation and delay are solved.

The invention discloses an electric energy meter terminal contact fault diagnosis method, system and device and a medium, and belongs to the technical field of power systems, and the method comprises the steps: obtaining the voltage and current of a plurality of electric energy meters in a same electric meter box, and processing the voltage and current; calculating a voltage difference value between every two electric energy meters in the same electric meter box; performing abnormal value detection on the voltage difference value; judging the electric energy meter of which the abnormal frequency exceeds a first preset threshold value and the average voltage is lower than that of other electric energy meters as an arcing contact fault; for the electric energy meter which is not judged to have the arcing contact fault, calculating the resistance value of each electric meter line in the meter box according to the voltage difference value and the line current, and judging the terminal contact state of the electric energy meter which is not judged to have the arcing contact fault according to the resistance value; and outputting terminal contact state diagnosis results of all the electric energy meters. The electric energy meter terminal contact fault diagnosis method realizes accurate classification diagnosis of the electric energy meter terminal contact fault, does not need to depend on the same time point of the load, and can effectively distinguish loose contact and arcing contact faults.

The invention discloses an inter-harmonic source positioning and propagation path tracking method for a multi-terminal flexible direct-current system. The method comprises the following steps: acquiring an electrical main wiring diagram of the multi-terminal flexible direct-current system, alternating-current side frequency of each converter station, rated capacity and voltage; when inter-harmonics are monitored to exceed the standard in the multi-terminal flexible direct current system, acquiring frequency and amplitude data of inter-harmonic components at the ports of the alternating current side and the direct current side of each converter station; determining a direct current side inter-harmonic frequency needing to be tracked by the multi-terminal flexible direct current system, determining an inter-harmonic frequency and amplitude corresponding to an alternating current side of each converter station, and determining a source station generating inter-harmonics in the multi-terminal flexible direct current system; obtaining current intermediate harmonic amplitude data of each direct current line of the multi-terminal flexible direct current system, and realizing propagation path tracking according to the amplitude of direct current side inter-harmonics needing to be tracked in each line. According to the method, inter-harmonic source positioning of the multi-terminal flexible direct current system is realized, and path tracking of inter-harmonics of the multi-terminal flexible direct current system in a direct current transmission network is realized.

The invention discloses a power distribution network distributed photovoltaic and energy storage combined planning method, which comprises the following steps: constructing power distribution network annual average construction cost, power distribution network annual average operation cost, power distribution network annual carbon emission reduction income, network loss, voltage deviation and voltage stability index objective functions according to the structure and operation condition of a power distribution network; forming constraint conditions of power balance, distributed photovoltaic access capacity, distributed energy storage access capacity, node voltage and line current according to the structure of the power distribution network, photovoltaic generator sets accessed to the power distribution network and the quantity and condition of energy storage; normalizing the six objective functions by adopting a fuzzy theory, and converting the six objective functions into a single objective optimization problem; and solving the access node and the installation capacity of the distributed photovoltaic of the power distribution network and the access node and the installation capacity of the energy storage device, which meet the constraint conditions, by adopting an eddy current search algorithm. According to the method disclosed by the invention, the annual average operation cost of the power grid can be reduced, the annual network loss of the power distribution network is lower, and the planning of the power distribution network is more reasonable.

The invention relates to the technical field of power transmission line load regulation and control, in particular to a power transmission line dynamic load regulation and control method suitable for a high-voltage power transmission system. Determining the fluctuation coefficient of the current load of the power transmission line at each moment; obtaining the frequency of the oil field high-voltage power transmission system at each moment, and taking the frequency as the center frequency of a Butterworth filter at each moment; determining the order of a Butterworth filter at each moment by using the numerical value of the fluctuation coefficient, and optimizing the Butterworth filter in combination with the center frequency and the order; and carrying out harmonic extraction on the current signal at each moment by using the optimized Butterworth filter, and carrying out current compensation based on a harmonic component. The precision of power transmission line load regulation and control is improved.

The invention provides a digital twin line protection parameter identification and model updating method and system based on a time domain method, and belongs to the technical field of power system relay protection. Model and calculation complexity are considered, and a line and reactors at the two ends are equivalent to an accurate pi model; solving the accurate pi model capacitance value of the line by using a generalized KCL and a least square method; solving a line current by using the accurate pi model capacitance value; identifying an impedance parameter by using the line current; determining a parameter updating threshold according to the redundancy of the dynamic state equation; residual errors are calculated through the identified line parameters and the state equation; if the residual error is greater than the parameter updating threshold value, not updating the twinborn model; otherwise, updating the twin model. According to the method, the line is equivalent to the accurate pi model, the twin model is constructed according to the identified parameters, the protection criterion is constructed according to the matching degree of the twin model and the actual model, the protection quickness and reliability are improved by using the state estimation redundancy characteristic of the instantaneous value, and the instantaneous parameter identification accuracy is improved.

The invention discloses a medium-voltage voltage regulating circuit, system and method, and belongs to the technical field of medium-voltage power distribution. The medium-voltage voltage regulating circuit comprises a tapped voltage regulating transformer Tr1, a voltage compensation unit, a current compensation unit and a direct-current supporting unit, the self-coupling winding of the Tr1 and the series transformer of the voltage compensation unit are connected in series to a medium-voltage main circuit, the parallel winding of the current compensation unit and the self-coupling winding of the Tr1 share a magnetic core and take the self-coupling winding of the Tr1 as a primary side and a secondary side, and the direct current sides of the power module of the voltage compensation unit and the power module of the current compensation unit are both connected to the direct current supporting unit. Wide-range voltage coarse adjustment is achieved through the Tr1, stepless voltage fine adjustment is achieved through the voltage compensation unit, meanwhile, the topological structure is simplified through the common magnetic core coupling design of the self-coupling winding and the parallel winding of the Tr1, the equipment size, the magnetic loss and the manufacturing cost are reduced, and the stability and reliability of a medium-voltage power distribution system are remarkably improved.

The embodiment of the invention discloses a productivity evaluation method and equipment for a variable-frequency centrifugal pump and a medium, and relates to the technical field of productivity evaluation.The method comprises the steps that operation data of the variable-frequency centrifugal pump in a first time period are collected, and a latest static characteristic curve image corresponding to the variable-frequency centrifugal pump is obtained, so that the operation data of the variable-frequency centrifugal pump in a second time period are obtained through an image recognition algorithm; generating a static characteristic curve numerical table corresponding to the variable-frequency centrifugal pump; according to a predetermined current motor health degree score corresponding to the variable-frequency centrifugal pump, the energy efficiency power parameter calculation factor is dynamically corrected, so that energy efficiency power parameters corresponding to the variable-frequency centrifugal pump are determined based on the motor line voltage and the motor line current in the operation data; the energy efficiency dynamic parameter calculation factor comprises a shaft power calculation factor and an efficiency calculation factor; and the actually-measured flow data, the actually-measured lift data and the energy efficiency dynamic parameters in the operation data are fitted with the static characteristic curve numerical table, and a dynamic characteristic curve numerical table is generated for productivity evaluation.