340 results about "Phasor" patented technology

A system-side harmonic impedance estimation method and apparatus, and a storage medium and an electronic device. The method comprises: acquiring an h-th harmonic parameter equivalent circuit simplified on the basis of power grid characteristics, h being a positive integer greater than or equal to 2 (S1); on the basis of the h-th harmonic parameter equivalent circuit, establishing a system-side harmonic impedance estimation mathematical model (S2); acquiring amplitude and phase data of a harmonic voltage and a harmonic current at a PCC (S3); dividing the amplitude data of the harmonic voltage at the PCC into several stable intervals (S4); on the basis of the amplitude and phase data of the harmonic voltage and the harmonic current in the several stable intervals, establishing a variable coefficient regression model between a harmonic voltage phasor and a harmonic current phasor (S5); selecting an optimal window width of a kernel function of the variable coefficient regression model (S6); and calculating a system harmonic impedance on the basis of the variable coefficient regression model and the optimal window width (S7).

The invention discloses a current harmonic disturbance suppression method and suppression system for a permanent magnet synchronous motor. The method comprises the following steps: acquiring voltage and current signals of an electrical loop phasor test in the operation of the motor; an inductance identification algorithm based on high-frequency response is adopted, high-frequency excitation signals are injected, current response is monitored, and stator inductance parameters are calculated; constructing a multi-synchronous rotating coordinate system based on the parameter, and decomposing the current signal to obtain each harmonic current component; building a fuzzy full-order sliding mode observer, inputting an inductance parameter, voltage data and a harmonic current component, and dynamically adjusting a sliding mode surface parameter to observe the position and the rotating speed of a rotor; independently controlling each harmonic current adjusting channel under a multi-coordinate system in combination with observation information, and generating a compensation control signal; and the synthesized master control signal is output to the driving circuit. The system comprises six units, and the method and the system can accurately obtain parameters, efficiently decompose harmonic waves, accurately observe states, realize multi-frequency harmonic disturbance suppression, and improve motor operation stability and efficiency.

The invention discloses a power system inertia estimation method based on multi-mode decomposition and reconstruction, and belongs to the technical field of power system inertia identification control, and the method comprises the steps: obtaining a system frequency deviation signal and three-phase voltage and current data in real time; inputting the frequency deviation signal into a signal processing algorithm, extracting a multi-mode oscillation signal, and reconstructing the multi-mode oscillation signal into an equivalent single oscillation mode signal; the frequency change rate of the reconstructed signal is calculated, and the frequency change rate is obtained and analyzed; after a fault occurs, analyzing the moment corresponding to the maximum value of the frequency change rate, and combining power deviation to trigger inertia constant calculation; according to the frequency change rate and the power deviation, calculating a system inertia constant through a dynamic equation at a triggering moment, and converting the system inertia constant into a per unit value; and reconstructing a frequency signal of a non-measurement node by adopting a weighted least square method to finish inertial estimation. Through a synchronous phasor data dynamic decomposition and reconstruction technology, high-precision online sensing of inertial parameters under complex working conditions is realized.

The invention discloses a broadband random power quality adaptive monitoring system, which relates to the field of power grid monitoring and comprises a broadband signal acquisition module, a synchronous phasor measurement module, an edge calculation module, a cloud edge collaborative analysis module and a local traceability module. The broadband signal acquisition module performs high-frequency sampling on a power grid signal and ensures integrity; the synchronous phasor measurement module is used for realizing time synchronization of multiple monitoring points and generating data with time marks; the edge calculation module is used for studying and judging disturbance and early warning through deep learning, and uploading data to the cloud; the cloud edge collaborative platform aggregates data, deduces regional power quality and issues an optimized AI model; the local traceability module quantifies harmonic responsibility and positions a broadband disturbance source. The system innovatively adopts an ensemble empirical mode decomposition and variational mode decomposition parallel strategy, combines a spectrum kurtosis maximization algorithm to determine the number of modes and accurately separate transient and steady components, solves the problem of feature confusion of a traditional method, and realizes the crossing from single analysis to multi-mode fusion research and judgment.

The invention discloses a broadband oscillation risk prediction method and system based on wide-area broadband measurement, and relates to the technical field of wide-area broadband measurement. The method comprises the following steps: firstly, collecting grid-connected point high-frequency synchronous phasor data by using a PMU device at a photovoltaic field station side, and performing filtering and time mark calibration processing to eliminate noise and ensure time consistency; performing spectrum correlation analysis on wide-area multi-station PMU data based on time mark synchronization, screening broadband oscillation candidate features, and transmitting the broadband oscillation candidate features to a scheduling master station prediction network; and finally, inputting the real-time operation parameters of the power grid and historical oscillation sample data into the network, carrying out risk assessment and trend prediction, and assisting broadband oscillation early warning and prevention and control decision. According to the method, efficient fusion of multi-area equipment data is realized, a full-system broadband dynamic monitoring view angle is formed, the oscillation dynamic state is captured in real time, the risk is pre-judged, the broadband oscillation risk caused by new energy power fluctuation and power electronic equipment transient response can be dealt with, and the dynamic monitoring requirement of a novel power system is met.

The invention discloses an energy storage rapid compensation method and system based on track overhead line system voltage fluctuation feature recognition, and relates to the technical field of track traffic traction power supply. The method comprises the following steps: synchronously acquiring voltage and current signals of the overhead line system, and extracting a composite feature vector containing disturbance root attributes and transient change rate; on the basis of the vector, a transient energy vacancy sequence covering the ultra-short-term future is output in real time through a prediction model fusing dynamic phasor analysis and a feedforward neural network; according to the sequence, a cooperative control strategy fusing overshoot and active damping is generated in combination with a proximity compensation principle and a voltage recovery state so as to drive an along-line energy storage unit; the strategy is executed in advance, compensation energy is injected, and finally double closed-loop correction is conducted based on the voltage residual error. According to the method, the problems of response lag, unclear disturbance identification, poor collaboration and lack of adaptive ability in the prior art are solved, and advanced, accurate, collaborative and self-optimized rapid suppression of the voltage fluctuation of the overhead line system is realized.

The invention discloses a low-frequency load shedding method and system based on zero crossing point real-time frequency tracking, and the method specifically comprises the steps: setting a dynamic time window according to the power frequency characteristics of a sensing signal, and removing an abnormal zero crossing point exceeding the dynamic time window; matching a pre-stored harmonic feature library, establishing a mapping relation between a harmonic mode and a phase offset, and performing adaptive phase compensation on a pseudo zero crossing point of the sensing signal; a sensing signal, PMU phasor data and meteorological parameters are input into a three-dimensional convolutional neural network, a cross-modal incidence matrix is calculated through a self-attention mechanism, a future frequency change trajectory is predicted in combination with an LSTM unit, and an optimal load shedding strategy is output; and based on the optimal load shedding strategy, in combination with a forward acceleration criterion and reverse fault locking, executing emergency load shedding according to load importance grading. The technical bottleneck of a traditional low-frequency load shedding device is effectively solved, and the performance and reliability of frequency stability control of the power system are remarkably improved.

The invention provides a three-phase transformer parameter estimation method and device, computer equipment and a medium, and belongs to the field of electrical control, and the method comprises the steps: obtaining synchronous phasor data of a target three-phase transformer; an improved LASSO algorithm is constructed; preprocessing the data through an improved LASSO algorithm; constructing a positive sequence component equivalent model of the target three-phase transformer; based on the positive sequence component equivalent model, determining a correlation among a plurality of circuit parameters of the target three-phase transformer, and determining the plurality of circuit parameters; and estimating structure parameters and magnetic circuit parameters of the target three-phase transformer based on the circuit parameters to obtain corresponding estimation results. Thus, complex specific experiments do not need to be carried out on the target three-phase transformer, on one hand, loss is low, the application range is wide, the parameters of the target three-phase transformer can be comprehensively estimated, on the other hand, better adaptability is achieved for complex conditions such as nonlinear characteristics of the transformer, and parameter evaluation is more accurate.

The invention discloses a broadband oscillation traceability method, device and equipment, a storage medium and a program product, and relates to the technical field of broadband oscillation traceability. The method comprises the following steps: acquiring broadband oscillation voltage and current phasors of an alternating current side and a direct current side of a key node of a power system; based on the broadband oscillation voltage and current phasors of the alternating current side and the direct current side, broadband oscillation active power of the alternating current side and the direct current side is obtained through calculation; calculating a broadband oscillation active power difference value between the alternating current side and the direct current side based on a preset current reference flow direction and the broadband oscillation active power of the alternating current side and the direct current side; and determining whether the key node is an oscillation source or not based on the positive or negative value of the broadband oscillation active power difference value. According to the embodiment of the invention, broadband oscillation traceability in the power system can be efficiently and accurately realized.

The invention discloses a reinforcement learning-based low-voltage power distribution network multi-target collaborative optimization method and system, and the method comprises the steps: S01, taking adjustable equipment of a low-voltage power distribution network as an intelligent agent, and obtaining the historical operation data of a plurality of intelligent agents to form a training data set; step S02, constructing a multi-objective optimization model, and defining a reward function in a phasor form and a multi-objective weight; step S03, performing centralized training on the deep reinforcement learning model, inputting a multi-target weight into a neural network in the training process, performing learning with a maximum accumulated reward according to a reward phasor, and fusing a multi-target weight vector and a Q value vector through a phasor fusion layer; and step S04, acquiring real-time operation data of a plurality of agents in the low-voltage power distribution network, and controlling each agent to act by using a strategy learned by training. According to the invention, multi-target collaborative optimization control can be realized in a distributed photovoltaic large-scale access scene.

The present application belongs to the grid-connected converter technical field, disclose a kind of droop control inverter current-limiting control method and system, the virtual impedance size and active reference value restriction condition when the fault current is equal to current-limiting value are accurately obtained by phasor analysis, virtual impedance-current difference proportional coefficient and active reference value-current difference proportional coefficient are designed considering the most serious situation of current-limiting, proportional increase virtual impedance and reduce active reference value with the change of adaptive current at fault, can meet the current-limiting requirement under different depth grid voltage drop.The current-limiting control method proposed in the present application is adaptive to fault current, without fault detection device, the transient stability of inverter is enhanced due to the reduction of active reference value at fault, and the fault current is indirectly limited by adjusting virtual impedance and active reference value, the voltage source characteristics of droop control inverter are retained, and the system fault ride-through capability is significantly enhanced.

The invention provides a reactive compensation optimization method and system for a mining frequency conversion system, and the method comprises the steps: collecting the multi-dimensional data of the mining frequency conversion system, and carrying out the feature extraction and preprocessing, and obtaining the preprocessing data; the phase fast tracking module accurately obtains phasor parameters according to the preprocessed data, and the phasor parameters serve as input signals and are used for a phase locking ring to achieve phase and frequency locking of the mining frequency conversion system; constructing a multi-parameter fitness function by adopting a particle swarm algorithm, and dynamically calculating and searching an optimal control parameter combination; instantaneous reactive power and harmonic current are detected and analyzed in real time by adopting an instantaneous reactive power detection technology; the instantaneous reactive power and the harmonic current are input into a fuzzy PI controller, and dynamic error compensation is carried out in combination with the optimal control parameter combination; the static synchronous compensator controls output compensation current to complete reactive compensation and harmonic current treatment; compensation verification and feedback are carried out, and the electric energy consumption condition of the mining device is monitored and predicted in real time.

The invention discloses a power grid switching operation anti-misoperation verification method and device based on real-time topology, and relates to the technical field of power grid anti-misoperation, and the method comprises the following steps: collecting the phasor data of target equipment and the real-time active power flow direction of a power grid, constructing a real-time directed topological graph, and extracting a to-be-reconstructed sub-graph associated with an operation instruction of the target equipment; converting the target equipment operation instruction into an impedance correction term, constructing an estimated impedance matrix based on the to-be-reconstructed sub-graph, and calculating a corresponding power flow transfer vector; performing double-layer constraint decoupling on the topological structure of the to-be-reconstructed sub-graph to generate a source flow path chain set; and generating a verification result based on the power flow transfer vector, the source flow path chain set and a preset anti-error rule. The method is used for solving the problems of electrical rehearsal real-time lagging and complex topology anti-error logic confusion in a complex power grid environment.

The present application relates to the technical field of data processing, and particularly relates to a power monitoring method and system for remote electric energy meter, the method comprising: constructing a time series factor graph model with voltage and current phasor as hidden variables and original electric parameter data as observation nodes; performing synchronous compression wavelet transform on current phasors in the electric energy state sequence to generate a time-frequency energy distribution graph and obtain a monitoring feature vector sequence; inputting the monitoring feature vector sequence into a deep auto-encoder pre-trained on normal power consumption working condition data to calculate a reconstruction error, simultaneously calculating a Lyapunov index of the sequence within a preset time window, and obtaining a negative log-likelihood probability according to a pre-established Gaussian mixture model describing the distribution of the index under normal working condition; and weighting and fusing the reconstruction error and the negative log-likelihood probability to generate a comprehensive abnormality index for judging power consumption events. The present application can realize high-precision and low-false-alarm-rate detection of power consumption events.

The invention relates to the technical field of power distribution network monitoring, in particular to a power distribution cabinet line intelligent detection method and system, and the method comprises the steps: collecting node voltage, phasor current and active / reactive power of each power distribution cabinet, attaching a sampling period and a quality identifier, and carrying out the arrangement according to a timestamp; carrying out edge calculation on harmonic waves, flicker, unbalance, missing measurement compensation and initial estimation, and generating a straight-through UDP stream and a storage stream; a real-time interface is aligned and fused with a topology version according to a unified time reference, state estimation is carried out, and a node initial value set is output; s4, according to the initial value and topological modeling node digital twinning (index recovery load), obtaining online parameters through four-stage sub-step discrete + UKF joint estimation; accessing a real-time simulation platform through HiL, and recharging in the same period; a variable damping impedance stable interface is adopted, and when consistency and a threshold value are met, a digital snapshot containing an online parameter, a steady-state quantity and a transient abstract is generated. According to the method, low time delay of measurement alignment, credible state estimation, digital twinborn self-adaption, hardware-in-loop stability and verifiable result release can be realized, so that the fault detection, positioning and evaluation capabilities of the power distribution network are improved.

A technique is disclosed to use time series phasor data to perform real-time dynamic line rating of electric power transmission lines. A variety of techniques are used to generate well-poised solutions to the determination of transmission line parameters from phasor data. Line health information can also be determined from changes to transmission line parameters, such as galloping, icing, vegetation encroachment, imperfect splicing, and conductor corrosion.

The invention relates to the technical field of a power distribution network of a power system, in particular to a fault prediction self-healing power distribution method, which comprises the following steps of: firstly, acquiring equivalent admittance and physical residual by controlled disturbance and synchronous phasor measurement, generating a spectrum-topology co-embedded coordinate and an innovation consistency index, and finishing topology check; fusing the space evidence, the time evidence and the physical evidence, and combining hazard rate evaluation to form a control admission intensity value; executing offset search under the constraint of feasible region prior, action shielding and control barrier, and performing power flow optimization by taking a condition in-danger value as a target to obtain a self-healing operation sequence; and finally, the operation threshold is shaped according to the anti-fact energy margin, complete sequence checking is completed according to the signal sequential logic and the satisfiability model theory, an execution packet is generated, low misoperation is achieved, and safety and rapid recovery can be proved.

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 power systems, in particular to a power grid fundamental harmonic and inter-harmonic detection method and device and a storage medium, and can collect power grid signals, arrange discrete samples into sample vectors, apply a Hanning window to the sample vectors for zero filling DFT, and obtain a frequency index of fundamental waves according to a peak value of frequency spectrum amplitude square; setting a harmonic wave search range according to the frequency index of the fundamental wave, and screening the harmonic waves according to the frequency related threshold to obtain a frequency index set of the fundamental wave and the harmonic waves; calculating a residual error between the power grid signal and the fundamental harmonic reconstruction signal, and calculating a residual error ratio; and performing secondary iteration on the residual error to obtain a TF coefficient corresponding to the inter-harmonic. According to the technical scheme, fundamental wave phasor measurement, harmonic detection and inter-harmonic detection can be completed at the same time, the precision is high, and the detection efficiency is high.

The invention relates to the technical field of data processing, in particular to an electric energy monitoring method and system for a remote electric energy meter, and the method comprises the steps: constructing a time sequence factor graph model with voltage and current phasors as hidden variables and original electric parameter data as observation nodes; performing synchronous compression wavelet transform on current phasors in the electric energy state sequence, generating a time-frequency energy distribution diagram, and obtaining a monitoring feature vector sequence; inputting the monitoring feature vector sequence into a depth auto-encoder pre-trained on normal power utilization condition data to calculate a reconstruction error, calculating a Lyapunov index of the sequence in a preset time window, and calculating the reconstruction error according to a pre-established Gaussian mixture model for describing index distribution under a normal condition. Obtaining a negative logarithm likelihood probability; and carrying out weighted fusion on the reconstruction error and the negative logarithm likelihood probability to generate a comprehensive abnormal index which is used for judging a power utilization event. According to the invention, high-precision and low-false-alarm-rate detection of power consumption events can be realized.

The invention discloses a DG-containing distribution line single-phase earth fault single-end impedance distance measurement method and system, and the method comprises the steps: inputting parameters and DG distribution conditions into equipment, when a distribution network has a single-phase earth fault, enabling the zero-sequence voltage of the equipment to rise, judging the occurrence of the single-phase earth fault, and starting fault distance measurement calculation; using a symmetric component method to calculate sequence components of voltage and current at the bus, the DG access, the load access and the fault point; and on the basis of the sequence components of the voltage and the current of the fault point, the phasor angle difference between the voltage and the current of the line fault is obtained, and the fault distance is calculated according to the phasor angle difference. The method is good in distance measurement effect and has practicability.

The invention discloses a phasor closed optimization control method for secondary harmonic suppression of a direct-current micro-grid, and the method comprises the steps: taking the square of a total harmonic current amplitude as a measurement standard, and searching an optimal harmonic reference phase through a gradient descent method; adjusting the harmonic phase injected into the direct current system by adjusting the phase of the voltage of the alternating current side inverter or changing the harmonic phase generated by the single-phase inverter by adjusting the voltage phase of the single-phase inverter; and an alternating current reference current generating ring is constructed by adopting a bidirectional DC-DC converter in a step-up or step-down mode to ensure that the absorption current and the residual harmonic waves are synchronous in phase, so that the residual harmonic waves are filtered out. According to the invention, under the condition of not damaging the electric energy direct current of the alternating current side, the second harmonic current injected into the direct current micro-grid is reduced, the configuration capacity of the filter is reduced, and meanwhile, the complete absorption of the amplitude and phase difference between the compensation current of the parallel filter and the actual second harmonic current is realized.

The invention discloses an interface method for a VSC direct current system mixed granularity model and an alternating current system electromechanical transient model. The method comprises the steps that a mixed granularity simulation framework is constructed, wherein an electromechanical transient phasor model is adopted on the alternating current side, and a simplified electromagnetic transient instantaneous value model considering electromagnetic characteristics is adopted on the direct current side; the VSC converter adopts a unified equivalent model, and various types of converters are adapted through parameter configuration; a low-voltage side bus of the converter transformer is arranged at the interface position of the simulation framework and the alternating current system; simulation and interaction rules are configured, wherein the simulation step length of each direct-current power grid is independently set; the alternating current system provides port voltage and alternating current control information for the simulation framework, the simulation framework is equivalent to the alternating current system as a power source, and power exchange is realized through the converter station; in one time step calculation of the electromechanical transient state, the simulation framework changes along with the alternating current side information, a historical simulation state is taken back, and direct current side simulation in the alternating current time step is carried out again until the power interaction deviation converges.

Disclosed are a method for distribution of PHASE to monitor the operating state of a power system by using heterogeneous data obtained from measurement of SCADA and a time synchronized PMU and a method for processing defect data in mixed DSE by using same. The method for distribution of PHASE to monitor the operating state of a large scale power system includes the steps of: defining an extended state variable and an extended state variable set for each region; performing a SCADA-based DSE by using a SCADA measurement value for each region and a covariance matrix thereof, and parallelly performing a PMU-based DSE by using a PMU measurement value for each region and a covariance matrix thereof; and mixing the estimation results of the SCADA-based and the PMU-based DSE algorithms so as to perform a phasor-aided normalized residual test and a general normalized residual test.

The invention discloses a power distribution network fault distance measurement method and system based on a positive sequence component, and the method comprises the steps: collecting the three-phase current and voltage data of two sides of a power distribution network line after the fault, and carrying out the preprocessing of the three-phase current and voltage data; converting the preprocessed data into a phasor form, and extracting a positive sequence component of the phasor form data; and calculating two positive-sequence fault voltages corresponding to the preset fault distance based on the positive-sequence component, and determining a fault positioning result according to phase angles and amplitudes of the two positive-sequence fault voltages. According to the method, the positions of real fault points are continuously approached by comparing the positive-sequence components of the fault points calculated at the two ends; considering the influence of the distributed capacitance on the distance measurement result, the distance measurement result is not influenced by transition resistance and unstable arc, and the distance measurement effect is good.

The invention discloses a three-phase alternating-current motor low-harmonic winding design method, which comprises the following steps of: determining the equivalent slot number qe of each pole and each phase of a three-phase low-harmonic winding according to basic parameters of a motor, dividing an area in an iron core slot of the motor into an upper layer, a middle layer and a lower layer, placing a phase coil of the three-phase winding in a single layer, and determining a phase belt distribution table and a winding connection diagram of the winding; according to the principle that slot current is distributed along the surface of an iron core in a sine mode, the numerical relation of the number of turns of all coils in a phase belt is determined, the turn ratio of all the coils is n1: n2: n3... nqe, the symmetry axis of slot electromotive force in the phase belt is determined, the electrical angles of slot electromotive force phasors relative to the symmetry line are respectively alpha1, alpha2, alpha3... alphaqe, and the range of the number of effective series turns of each phase meeting the motor performance is determined; in consideration of the design principle of the minimum harmonic magnetic potential and the limited slot filling rate, the actual number of turns of the coil in the phase belt is N1, N2, N3... Nqe. According to the invention, the third harmonic electromotive force amplitude of each phase of the motor is reduced, and the motor efficiency is improved.

The invention relates to a double-sheath loop interphase short circuit defect detection method based on adjacent sheath current phasor difference, and the method comprises the following specific steps: 1, constructing a circuit network model of a high-voltage cable, and recognizing different types of grounding fault mechanisms; 2, performing simulation to obtain sheath grounding current data, and performing feature extraction on the sheath grounding current data to obtain the amplitude and the phase of the current; step 3, training and testing the extracted current features by adopting a proper machine learning algorithm, and improving the accuracy of fault detection by constructing a classification model; and 4, classifying the newly collected current data by using the trained model, and judging the fault category, thereby taking corresponding maintenance measures in time, and ensuring the safe and stable operation of the cable. The accuracy of fault detection is improved by constructing the classification model, and the efficiency of sheath interphase short circuit maintenance at the present stage is improved.

The invention provides a regional power grid equivalent damping coefficient evaluation method and system based on data collected by a synchronous phasor measurement device, and belongs to the technical field of power system parameter identification. The method comprises the following steps: firstly, selecting a frequency measurement result with relatively high data quality before and after a large disturbance event, and analyzing the influence of a determined component and a noise component of an active unbalance amount on a system frequency dynamic state in the large disturbance event; secondly, performing curve fitting on discrete frequency measurement results, and estimating a frequency response component caused by a noise component effect after a large disturbance event based on a superposition principle; on the basis, the equivalent damping coefficient of the regional power grid is estimated by combining the active power sudden change amplitude caused by the large disturbance event, the occurrence time of the large disturbance event and the inertia coefficient of the regional power grid.

The invention discloses a power grid voltage sag detection method based on improved discrete Fourier transform, and belongs to the field of power quality detection, and the method comprises the steps: S1, converting a three-phase power grid voltage signal under a three-phase static coordinate system (a, b, c) into a two-phase static coordinate system (alpha, beta) through 3s / 2s coordinate transformation; s2, enabling the voltage signal under the coordinate system (alpha, beta) to sequentially pass through a comb filter Gf (z), a resonator # imgabs0 # and an adjustment factor Ga (z) so as to obtain a phasor signal of a positive sequence fundamental frequency component; and S3, calculating the mode length of the positive sequence fundamental frequency component phasor signal to obtain the amplitude of the positive sequence fundamental frequency voltage, and comparing the amplitude with a power grid voltage sag detection threshold to judge whether the power grid voltage sags or not. According to the algorithm provided by the invention, the accurate detection of the voltage sag event of the power grid can be realized under the non-ideal power grid condition of harmonic distortion and three-phase voltage imbalance.

A WMU data analysis system and associated method are for monitoring an electrical power delivery system. The disclosed techniques entail processing synchro-waveform data to classify an event type and estimate, based on an impedance component and the event type, an event location so as to reduce a number of candidate inspection sites in the electrical power delivery system for inspection by a maintenance team.