204 results about "Admittance" patented technology

The invention belongs to the field of stability analysis of a grid-connected system of a grid-building converter, and particularly relates to a grid-building converter grid-connected resonance risk analysis method considering virtual impedance, which comprises the following steps: S1, establishing a three-phase time domain differential equation and simplifying the equation into a single-phase equivalent time domain model; converting into a harmonic state space model of the main circuit; s2, constructing a harmonic state space model of a control system comprising an active power control loop and a reactive power control loop; s3, introducing a virtual impedance control link, and correcting the voltage amplitude reference phasor output by the reactive power control loop; deriving an expression of a modulation signal disturbance phasor; s4, obtaining a complete frequency domain admittance model YGSC of the network construction converter considering the influence of the virtual impedance; an open loop gain TGFM of the grid converter grid-connected system is constructed; and S5, drawing a Nyquist curve based on TGFM, and carrying out resonance risk determination. According to the method, the interaction dynamic characteristics of the network building converter and the power grid under the influence of the virtual impedance can be accurately represented, and the resonance risk of the grid-connected system is evaluated.

The invention relates to a DC power transmission system oscillation suppression method based on a matrix passivity theory. The method comprises the following steps: firstly, establishing a converter admittance matrix under a frequency coupling effect; then, constructing a stability criterion of the direct-current power transmission system based on the admittance matrix of the converter in combination with a matrix passivity theory; and finally, based on the stability criterion of the direct-current power transmission system, adding active damping and passive damping, adjusting corresponding parameters, and suppressing medium-high frequency oscillation of the direct-current power transmission system. The method can solve the problem of dependence on power grid side impedance modeling, constructs the stability criterion of the DC power transmission system by directly analyzing the admittance matrix characteristics of the converter, adapts to the complex situation when the AC grid side operation condition changes, and can completely suppress the medium-high frequency oscillation of the DC power transmission system. An unstable interval of a direct current system is transferred to a high frequency band through active damping, strict stability of the direct current power transmission system in middle and high frequency bands is achieved through passive damping, and the strategy cost is reduced.

The invention discloses a virtual impedance compensation method for permanent magnet synchronous generator constant admittance modeling, and relates to the technical field of electromagnetic transient modeling of permanent magnet synchronous generators, and the method comprises the steps: firstly, carrying out the discretization of a permanent magnet synchronous generator model; secondly, decomposing the equivalent resistance matrix into a time-invariant part and a time-varying part; then, virtual impedance is added to the q axis of the generator model; thirdly, constructing a generator constant admittance model; thirdly, a converter accompanying discrete circuit model is integrated, a complete permanent magnet synchronous generator constant admittance model is formed, and a node admittance equation is established based on the Kirchhoff's current law; and finally, executing electromagnetic transient simulation. According to the method, constant admittance modeling is achieved based on virtual impedance compensation, the requirement for real-time inversion of a time-varying admittance matrix is eliminated, simulation calculation resource consumption is remarkably reduced, small errors are kept under various working conditions, and efficient simulation of a large-scale permanent magnet synchronous generator system is supported.

The invention relates to the technical field of power equipment state monitoring, and discloses a transformer oil paper insulation frequency domain response online monitoring system which comprises an interface protection module, a modulation control module, a servo balance module and a diagnosis reconstruction module. The interface protection module extracts end screen leakage current and provides overvoltage protection; the modulation control module tracks the bus voltage phase and generates broadband modulation excitation voltage; the servo balance module generates a reverse servo current through closed loop feedback, counteracts a power frequency component in a leakage current so as to maintain a virtual ground state of a measurement node, and injects broadband excitation in a superposed manner; and the diagnosis reconstruction module synchronously acquires signals, reconstructs data in combination with time sequence information, calculates equivalent complex admittance by utilizing cross-correlation demodulation, and outputs complex capacitance and a dielectric loss factor. According to the invention, the operating voltage is used as a carrier wave, strong power frequency interference is eliminated through hardware servo, and safe online excitation is realized by matching with phase chopping, so that the difficult problem of weak broadband signal extraction is effectively solved, and combined monitoring and diagnosis are realized.

The invention discloses an SVG multi-working-condition control parameter optimization method and system, and the method comprises the steps: calculating a system stability margin through building a new energy station single-input single-output admittance model without SVG, traversing the working conditions of a new energy station, and positioning a critical stable working condition; setting the operating condition range of the SVG and judging the stability margin of the system after the SVG is accessed to the critical stable condition of the new energy station; and calculating the impedance ratio sensitivity of the SVG-containing new energy station system, and positioning and adjusting the SVG dominant control parameters to meet the system margin target. According to the method, the impedance characteristic change of the SVG under different operation conditions is comprehensively considered, the stability margin of multiple working conditions of the new energy station containing the SVG is improved, and the broadband oscillation risk caused by interaction of the new energy station and the power grid is reduced. The method can be widely applied to wind power, photovoltaic and other new energy stations containing the SVG, a systematic solution is provided for parameter setting and stable control of the SVG in multiple operation scenes, and the stability and working condition adaptability of a new energy grid-connected system are enhanced.

The invention relates to the technical field of radio frequency filters, in particular to a 13GXBAR filter design method based on a lithium niobate film. The Euler angle of the lithium niobate thin film is subjected to simulation setting in finite element simulation software, admittance responses under different cutting angles are obtained, an admittance curve with a large electromechanical coupling coefficient and complete stray mode suppression is obtained, the tangential angle is used for simulating an electrode material, the interdigital logarithm, the interdigital distance, the thin film thickness and the metallization ratio, and an admittance curve with a large electromechanical coupling coefficient and complete stray mode suppression is obtained. The method comprises the following steps of: constructing a plurality of resonators, obtaining impedance of each resonator, obtaining material parameters of the corresponding resonator, constructing a three-dimensional force-electricity coupling model of the lithium niobate resonator, carrying out layout design on the physical model in finite element simulation software through a field-circuit coupling method, and coupling force-electricity-sound multi-physical fields to obtain an S parameter curve of the designed XBAR filter; and whether the S parameter result is consistent with the target is verified, so that the forward design of full-simulation driving is realized.

The invention provides a picoampere-level current measuring device and method with leakage estimation and digital compensation, and the device comprises an electrometer-level operational amplifier and a transimpedance feedback network which are used for converting a measured current into a voltage signal; in combination with a retaining ring conductor driven by a retaining ring buffer and an inner and outer double-layer metal shielding structure, high-resistance node leakage and external interference are remarkably reduced. The digital controller injects 5mV-50mV micro excitation into the retaining ring in a non-sampling window and detects output response so as to estimate input equivalent leakage conductance and perform online compensation; and meanwhile, environment self-adaptive correction is carried out according to a temperature and humidity-leakage admittance model. The system adopts a 24-bit analog-to-digital converter, two-stage zero-drift amplification and multi-point linearity calibration can be switched, picoampere-level current measurement with high precision, low noise and wide dynamic range is realized, and the system is suitable for the fields of high-insulation detection, light current measurement, electrochemical micro-current analysis and the like.

The invention discloses a wind power plant broadband oscillation suppression method and system based on amplitude-phase characteristic remodeling. The method comprises the following steps: respectively establishing a frequency domain impedance model of each wind turbine generator set and performing dynamic order reduction, analyzing amplitude-frequency and phase-frequency characteristics of wind power plant multi-machine parallel coupling based on the order reduction model, determining an interaction rule of a module value and a phase angle, designing additional damping control and active damping control, and determining a wind power plant multi-machine parallel coupling amplitude-frequency and phase-frequency characteristic of the wind power plant multi-machine parallel coupling amplitude-frequency and phase-frequency characteristic. A weak position of a system is positioned based on an s-domain node admittance matrix method, a function is set by taking improvement of amplitude-phase characteristics as a target and optimizing and setting control parameters for a target wind turbine generator corresponding to the position, the optimized parameters are applied to the target generator, and effective suppression of broadband oscillation is realized. According to the application, the broadband oscillation problem caused by high-proportion new energy grid connection can be systematically solved by synergistically remodeling the frequency domain amplitude-phase characteristics of the wind power plant.

The application discloses a universal numerical aggregation method and system for frequency coupling admittance / impedance, and the method comprises the following steps: determining a frequency coupling admittance model of a converter; acquiring complementary frequency sums in the frequency coupling admittance model; splitting an original network of the converter into a first network and a second network corresponding to the complementary frequency sums respectively; connecting the frequency coupling admittance model to the first network and the second network respectively, and generating a first admittance matrix and a second admittance matrix corresponding to the first network and the second network; merging the first admittance matrix and the second admittance matrix into an extended node admittance matrix; and performing coupling frequency admittance calculation on specified network nodes based on the extended node admittance matrix.

The application discloses a harmonic compensation and stability improvement method, system, medium and equipment, filters components of a grid voltage in a two-phase static coordinate system to obtain corresponding fundamental components; subtracts the fundamental components of the grid voltage from the components of the grid voltage in the two-phase static coordinate system to obtain total harmonic components of the grid voltage; filters the total harmonic components of the grid voltage by using multiple band-pass filters to obtain multiple harmonic components corresponding to frequencies; subtracts reference current instructions of an active power filter from the multiple harmonic components, and inputs the result as a new current reference instruction into a current controller; and based on a virtual harmonic admittance method, outputs harmonic compensation currents through current inner loop control in the two-phase static coordinate system to realize harmonic compensation on a nonlinear load with frequency coupling characteristics and suppression of harmonic compensation oscillation. The application can adapt to various complex grid environments and has relatively practical engineering application value.

This invention proposes a simulation method and system for the current response of distribution networks based on multi-frequency coupling effects, belonging to the field of power system modeling and simulation technology. The method includes: obtaining the frequency domain admittance matrix of the distribution network; extracting the same-frequency admittance vector and coupled admittance vector; converting each admittance vector into a transfer function, and then converting the transfer function into a discrete state-space model; preprocessing the voltage input signal using dq transform to reconstruct components at specified frequencies; substituting the preprocessed voltage signal into the discrete state-space model to obtain the current response of each frequency component; solving for the optimal weighting coefficients using an adaptive weighting strategy, and linearly superimposing the current responses to obtain the real-time simulated total current response.

This invention belongs to the field of power system technology and provides a method and system for allocating capacity to grid-connected renewable energy sources under harmonic and stability margin constraints. It obtains impedance models of grid-connected and grid-connected converters, calculates the equivalent impedance of renewable energy power plants, estimates the equivalent impedance of transmission lines, and combines the two impedances to obtain a stability margin evaluation index. It also obtains the coupled harmonic admittance matrices of the grid-connected and grid-connected converters, calculates the coupled harmonic admittance matrices, and calculates a harmonic emission level evaluation index based on the harmonic distortion level at the grid connection point. The stability margin evaluation index and the harmonic emission level evaluation index are used as comprehensive evaluation indices. The allocation range of grid-connected converters is constrained, and within this constrained range, the comprehensive evaluation index for each capacity allocation is calculated. The capacity allocation is determined based on the optimal result of the comprehensive evaluation index. This invention achieves overall optimality of power plant stability margin and grid-connected power quality.

The application provides a transient ground potential rise induced coupling determination method through cable shielding layer, and belongs to the technical field of cable shielding layer.The application establishes a distributed parameter partial element equivalent circuit model of a grounding network, solves transient ground potential distribution by using a finite difference time domain method, obtains equivalent transfer impedance frequency characteristics of a braided shielding layer by using a four-port S parameter vector network analysis method and a variational asymptotic homogenization multi-scale algorithm, solves core line common mode voltage and differential mode voltage by establishing a multi-conductor transmission line equation group, constructs an artificial intelligence prediction model based on a topology perception graph neural network, solves a large-scale sparse admittance matrix by using a multilevel fast multipole method to obtain full network induced voltage distribution, and establishes a quantitative relationship model between ground potential rise and core line induced voltage, so that the technical problems that cable core line induced voltage caused by transient ground potential rise is difficult to accurately predict and effectively suppress are solved.

The invention discloses a method and a device for calculating short-circuit current of an electric power system, a medium and a terminal, relates to the technical field of short-circuit current calculation of the electric power system, and mainly aims to solve the problem that the short-circuit current of a multi-source heterogeneous electric power system cannot be accurately calculated in the prior art. Comprising the following steps: simulating a short-circuit fault in a simulation environment of a target power system, and constructing a non-fault node admittance matrix; calculating an initial current value of each power supply node to obtain an initial system-wide node injection current vector of the target power system, calculating a quotient between the initial system-wide node injection current vector and a non-fault node admittance matrix to obtain a first iteration system-wide node voltage vector of the target power system, and constructing an iteration solution equation; and performing iterative solution on the basis of the iterative solution equation until a preset convergence condition is met, obtaining a full-system node voltage vector after iteration is completed, and calculating the short-circuit current of the target power system according to the full-system node voltage vector after iteration is completed.

The application discloses a kind of new energy power system small disturbance stability evaluation methods based on geometric separation.Method includes: obtaining the geometric characteristics of the equivalent admittance matrix of the admittance matrix transfer function of the network side and the converter side of new energy power system, and then determining whether new energy power system and each converter meet closed loop stability condition by geometric separation method, if meet, then evaluate new energy power system stability.The method of the application supports the stability verification of massive heterogeneous power electronic equipment in a decentralized and modular manner, effectively avoiding the computational complexity caused by the growth of system dimension;At the same time, the proposed geometric separation condition provides a clear and operable guidance for the external characteristic specification of grid-connected equipment and controller design, which helps to achieve "plug and play" and high proportion of safe access of new energy power system.

This invention discloses a method and apparatus for calculating the three-phase asymmetrical short-circuit current in a distribution network considering photovoltaic (PV) power. The method includes: before a fault, using power flow calculations to obtain the node voltage and injected current of each node, including the PV node, during normal operation; equating the power source to a current source and the load to an impedance based on Norton's equivalent; calculating the admittance matrix based on an equivalent circuit model after a three-phase asymmetrical short-circuit fault; and constructing a network equation for the PV short-circuit calculation node impedance suitable for Gaussian iteration; simultaneously establishing nonlinear piecewise expressions for the voltage and current of the renewable energy node; and solving for the current and voltage during a renewable energy fault using an iterative method to obtain the fault short-circuit current. By constructing the admittance matrix and corresponding voltage and current expressions for single-phase-to-ground short circuits and two-phase-to-phase short circuits, and using iterative calculations to derive the final result, the accuracy of the calculation is improved.

The application discloses a power distribution network voltage control region division method and device and electronic equipment. The method comprises the following steps: obtaining power flow information of each node in a power distribution network, and determining a system admittance matrix of the power distribution network according to the power flow information; determining a cut set corresponding to each region in the power distribution network according to the system admittance matrix, the cut set being used for determining a preliminary partition result of the power distribution network; determining a voltage increment matrix corresponding to each node in the power distribution network, the voltage increment matrix being used for reflecting voltage change conditions of each node after a preset value of power change of any node in each node; taking the cut set as clustering prior information, clustering the voltage increment matrix to obtain a target partition result of the power distribution network, the target partition result comprising regions to which each node belongs; and performing voltage partition control on the power distribution network according to the target partition result. The application solves the technical problem of large partition control loss caused by the power distribution network static partition mode in the related art.

The invention relates to the technical field of power distribution cabinet internal harmonic control, in particular to a power distribution cabinet harmonic suppression method based on multi-source data fusion. By extracting amplitude and phase information at each harmonic frequency point, branch equivalent admittance is calculated, and an admittance distribution state is formed; judging an abnormal branch with admittance deviation at each frequency point, and establishing a corresponding relation between the adjustable electrical parameters and the admittance deviation; in the operation process of the power distribution cabinet, the admittance distribution state and the abnormal branch set are periodically updated, the equivalent admittance of the target branch is dynamically adjusted according to the corresponding relation, and the distribution of the harmonic current among the branches is changed; through the method, the harmonic peak value and the multi-node superposition effect in the power distribution cabinet can be actively reduced, online operation under the condition of multi-frequency and multi-node load fluctuation is adapted, harmonic flow direction reconstruction is achieved on the premise that complex filtering or hardware devices are not added, and the electric energy quality and the system stability of the power distribution cabinet are improved.

The application discloses an active arc-extinguishing compensation method and system for single-phase grounding fault, relates to the technical field of power systems, and comprises the following steps: acquiring a theoretical zero sequence admittance of a zero sequence network; collecting bus voltages of the zero sequence network and zero sequence currents of each branch line in the zero sequence network in real time, and obtaining a current zero sequence admittance of the zero sequence network according to the collected bus voltages and the zero sequence currents; judging whether a single-phase grounding fault occurs or not according to the current zero sequence admittance and the theoretical zero sequence admittance of the zero sequence network; and after judging that the single-phase grounding fault occurs, updating a primary current to be injected into a bus of the zero sequence network according to the current bus voltage and the theoretical zero sequence admittance. The application can sensitively identify the single-phase grounding fault and compensate for residual current through the zero sequence admittance of the zero sequence network, can realize arc-extinguishing compensation without knowing which phase of which branch line has a fault, and will not cause short-circuit faults among phases of the zero sequence network.

The invention relates to the technical field of power distribution monitoring, and discloses an electrical equipment operation monitoring system based on intelligent control, and the system comprises a grid structure recognition unit which collects a switch contact signal, and determines a real-time power grid topology model; the short-circuit capacity evaluation unit reconstructs a node admittance matrix by using a real-time power grid topology model, and calculates node equivalent short-circuit impedance; the transient feature extraction unit samples a node transient current signal and extracts a high-frequency transient component sequence; a monitoring fixed value follow-up setting unit determines a mapping relation between node equivalent short-circuit impedance and short-circuit capacity, and a monitoring threshold value is corrected in a follow-up mode; according to the system and the method, a physical coupling mechanism of the monitoring constant value and the power grid rigidity is established, sensitivity mismatch caused by grid structure reconstruction is eliminated, and the sensing capacity of the system to the initial degradation of equipment is enhanced. The transient integral energy of the high-frequency transient component sequence is calculated, and an abnormal operation signal is generated when the transient integral energy deviates from a monitoring threshold value.

The application discloses a kind of AC subway power supply system public connection point power factor calculation method, comprising the following steps: obtaining the line data required for calculating the power factor of the power supply system public connection point, electrical data;The mutual admittance Y de Between electrical node d and e is calculated, the self-admittance Y dd Of electrical node d is obtained, and the admittance matrix of AC subway power supply system node is obtained;The complex power of No.1 and No.2 electrical nodes is calculated, and the power factor of the public connection point of No.1 incoming line and No.2 incoming line is obtained.The application can provide basis for designers to configure the capacity of reactive power compensation device, provide decision support for system operation personnel to input compensation capacity and balance system reactive power, so as to better guarantee the safe and reliable operation of AC subway power supply system.

The invention provides a high-frequency harmonic suppression method, device and equipment for vacuum circuit breakers and a storage medium, each vacuum circuit breaker is provided with a high-frequency harmonic damper, and the method comprises the following steps: collecting power grid voltage and current signals of each vacuum circuit breaker in a preset area, and determining a harmonic state vector according to the power grid voltage and current signals; based on a preset multi-agent environment, calculating a first admittance value of a connected harmonic damper according to the harmonic state vector, and determining a damping action instruction according to the first admittance value; performing multi-round iteration on the damping action instruction according to a preset distributed collaborative architecture to obtain an execution instruction, the execution instruction comprising a second admittance value; modulating a driving signal of the high-frequency harmonic damper according to a second admittance value of the execution instruction so as to enable the high-frequency harmonic damper to output a high-frequency wave blocking signal; and inputting the high-frequency wave-blocking signal into the vacuum circuit breaker to reduce the high-frequency harmonic wave of the vacuum circuit breaker.

The invention provides a stability judgment method for a direct-current bus of a full-power pumped storage unit, and relates to the technical field of hydroelectric power generation. The method comprises the steps that a direct-current bus capacitor is equivalent to two parallel equivalent capacitors, and the pumped storage unit is split into a unit side and a network side with a parallel connection point as a boundary; respectively constructing small signal models of the electrical devices of the two parts; based on each small signal model, respectively constructing a corresponding admittance model, and then constructing a corresponding impedance model; substituting the electrical parameters and the control parameters into the impedance model, and drawing a corresponding Bode diagram; and under the same working condition, if the phase difference at the amplitude intersection point of the two Bode diagrams is less than 90 degrees, the direct current bus does not generate interactive instability under the corresponding working condition, otherwise, the interactive instability occurs. According to the method, the modeling difficulty and model complexity of the full-power pumped storage unit can be effectively reduced, the characteristics of the pumped storage unit can be accurately reflected, and the interaction stability of a power system on a direct-current bus can be judged.

This invention discloses a method and system for measuring the performance indicators of an acoustic logging transducer, belonging to the field of geophysical logging technology. The method derives an admittance circle measurement method using an equivalent lumped system of the transducer; an admittance circle measurement system is constructed based on this method; the electrical parameters of the transducer are measured using this system to obtain the transducer admittance curve and admittance circle diagram; and the transducer's performance indicators are calculated based on these diagrams. This invention provides more accurate measurement results and simplifies the operation of testing the admittance circle and performance indicators of the transducer.

This invention provides a method and system for determining AC section power failure in a converter, belonging to the field of power technology. The method includes: determining the voltage equations of the admittance matrix at the converter station, the intermediate station, and the system station based on the network topology of the DC converter station, the opposite substation, and the downstream substation; then, using the node injection current method, determining the connectivity between the upstream and downstream components of the DC converter station, the opposite substation, and the downstream substation's upstream component and the AC system; and finally, determining the power failure state of the converter and the AC system based on these connectivity states. This invention improves the determination efficiency while ensuring safety and reliability.

The application provides a three-phase imbalance treatment method based on a fuzzy biased particle swarm optimization algorithm. The three-phase imbalance treatment method based on the fuzzy biased particle swarm optimization algorithm comprises the following steps: constructing a four-phase node admittance matrix equation corresponding to three-phase nodes and a neutral node, solving the admittance matrix equation based on the admittance matrix parameters of a circuit system to obtain electrical basic data of nodes of the circuit system; based on the electrical basic data, deducing, converting three-phase imbalance of the circuit system from a current domain to a power domain, and obtaining an evaluation value of three-phase current imbalance; determining a constraint threshold value of the evaluation value based on a preset power quality standard; constructing a target optimization function based on a constraint condition corresponding to the evaluation value; constructing a multi-dimensional constraint comprising a power grid safety constraint, a device operation constraint and a power balance constraint; initializing a plurality of candidate power scheduling schemes based on power supply output data and load data; and based on the constraint threshold value of the evaluation value and the multi-dimensional constraint, iteratively optimizing the plurality of candidate power scheduling schemes to obtain a target scheduling scheme of the circuit system. The application can improve the accuracy of the three-phase imbalance treatment based on the fuzzy biased particle swarm optimization algorithm.

The invention discloses an electromagnetic transient simulation method, system, equipment and medium based on an error compensation variational algorithm, and belongs to the technical field of electromagnetic transient simulation, and the method comprises the steps: obtaining discrete node electrical parameters of a power system, building an electromagnetic transient equivalent model based on the parameters, and building a loss function; preparing a quantum state representing node voltage through the parameter-containing quantum circuit, calculating a function value of a loss function by using a measurement result of the prepared quantum state, and iteratively updating a variational parameter of the parameter-containing quantum circuit by using the function value; obtaining a measurement result of the quantum state enabling the loss function to converge, and obtaining a solved voltage; and calculating a residual error for error compensation by using the target equivalent admittance matrix, the injection current of the node and the solved voltage, correcting the solved voltage by using the residual error, and obtaining the corrected voltage as an electromagnetic transient simulation result at the current moment. According to the method, calculation errors caused by a current noise-containing quantum computer are relieved, and high-precision solving of the linear equation set is achieved.

The application provides a three-phase load cooperative regulation method and system based on smart meter data, and relates to the technical field of load regulation. The method comprises the following steps: collecting three-phase currents of corresponding users through each smart meter; calculating the positive sequence current effective value, negative sequence current effective value and negative sequence current of each three-phase current; combining the positive sequence current effective value and negative sequence current effective value corresponding to each three-phase current to obtain the line energy of the quantitative power distribution area imbalance degree; determining whether the line energy triggers the regulation process based on the gradient field theory, if yes, determining the adjustable negative sequence admittance of the user corresponding to each smart meter to quantify the compensation capacity of each user to the negative sequence current; taking the offset of the negative sequence current as the constraint, calculating the adjustable negative sequence admittance real part and the adjustable negative sequence admittance imaginary part, and uploading the adjustable negative sequence admittance real part and the adjustable negative sequence admittance imaginary part to the dispatching terminal; performing three-phase load cooperative regulation through the dispatching terminal, otherwise, returning to collect the three-phase current again.

The invention discloses an electric energy meter fault positioning method and device based on topology awareness and a medium, and the method comprises the steps: building a gateway electric energy meter node admittance matrix through measuring the internal impedance between electrical terminals of an electric energy meter, carrying out the decoupling analysis of a voltage loop and a current loop through an orthogonal operator, and obtaining a terminal feature vector; and further solving a fault characteristic matrix on the basis of solving the fault diagnosis reference constant and the grounding reference constant so as to realize fault phase selection. Performing optimization on the basis of a phase selection result according to the terminal feature vector to obtain a fault qualitative vector, and performing analysis according to the characteristics of elements in the fault qualitative vector to obtain the exact position and the fault property of the fault. The method disclosed by the invention has the advantages that the potential fault coupling relationship between different loops is revealed, the detection condition of tiny faults is improved, the misjudgment risk caused by the individual difference of equipment is effectively overcome, the hierarchical decision of fault phase positioning, fault property judgment and fault type identification is realized, and the diagnosis accuracy and completeness are improved.

The invention discloses a switch switching initialization method for electromagnetic transient simulation of an energy storage converter, which is suitable for a switching device circuit comprising a power electronic converter and comprises the following steps of: in the electromagnetic transient simulation of the energy storage converter, when a switch state is switched, switching the power electronic converter into a power electronic converter; acquiring a voltage steady-state value and a current steady-state value of the switch in steady-state operation after switching; substituting the voltage steady-state value and the current steady-state value into a constant admittance equivalent switch model, and calculating to obtain a historical current source initial value corresponding to a switch switching moment; a historical current source initial value is used as historical current source input of a simulation step length, and circuit simulation calculation of the step length is executed to eliminate virtual loss and dynamic fluctuation caused by a historical current source iteration convergence process; the method has universality.