462 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 an optimized scheduling method and system for post-disaster recovery of a power distribution network, particularly relates to the technical field of power grid regulation and control, and is used for solving the problem that potential grid-connected potential safety hazards cannot be found in advance before grid connection in the prior art. Acquiring real-time electrical parameter data of the island area and the main power grid, and calculating a phase difference and a frequency deviation between the island area and the main power grid based on a phasor measurement algorithm; according to the detected deviation, the output power and the load state of the distributed power supply in the island area are adjusted in real time, so that the electrical parameters of the island area tend to be consistent with the main power grid step by step; analyzing the energy conversion process of the island area and the main power grid, and evaluating the stability margin before grid connection; extracting complex features of the electrical signals by using a multi-scale signal processing technology, and evaluating the complexity of phase signals of the island region and the main power grid in combination with fractal dimension analysis; and on the basis of the stability margin and the signal complexity, the potential hidden danger degree of grid connection is judged, and when the safety condition is met, grid connection operation is allowed to be executed.

The invention relates to the technical field of power system power distribution network protection, in particular to a self-adaptive current differential protection method for a power distribution network with branch loads. Firstly, current data acquisition is carried out, intelligent electric meters are installed at power distribution network nodes, and timestamps are synchronized. Current phasor estimation is carried out, and the current phasor of each node is obtained through data preprocessing, soft threshold processing, wavelet reconstruction and phasor estimation; then, differential current is calculated, and the vector difference between adjacent nodes is determined; and determining an adaptive threshold according to historical fault data and real-time power grid load. The fault is judged by comparing the differential current with a threshold value, and the fault type is recognized by adopting a mode recognition algorithm. And finally, generating a protection decision based on a result, and taking measures of cutting off branches, selecting a protection mode according to a resistor, adjusting load distribution or limiting current and the like for short circuit, grounding, overload and other faults to improve fault detection accuracy, accurately identify fault types, reasonably generate and execute the protection decision and guarantee safe and stable operation of the power distribution network.

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 invention relates to the technical field of power system devices, and provides a multi-channel sampling value consistency correction method and system of a power system device, and the method comprises the steps: carrying out the test grouping of channels of the same type in the device, and appointing a test grouping reference channel; specifying unique reference channels of the same type in the device; specifying a unique reference channel of the device; calculating to obtain first relative values of all channels in the test group; calculating to obtain second relative values of all channels in the same type; calculating to obtain a module value relative value in the third relative values of all channels in the same type; calculating to obtain a phase difference in the third relative values of all channels in the same type; calculating to obtain a relative time difference; storing the third relative value of each channel and the relative time difference of each channel as correction parameters; calculating to obtain a sampling value after consistency correction; and calculating to obtain a phasor value after consistency correction. According to the invention, the problem of inconsistent multi-channel sampling values of the power system device can be effectively solved.

The invention discloses a transformer winding deformation on-line monitoring method based on impedance characteristic identification, and relates to the technical field of transformer winding parameter monitoring method.The transformer winding deformation on-line monitoring method comprises the steps that a T-shaped equivalent circuit of a transformer and the relation between input signals of the transformer and winding parameters are established; the method comprises the following steps: assuming that voltage excitation remains unchanged during normal operation of a transformer, when the temperature of a winding changes along with the change of a load connected to a secondary side and the environment temperature, other electrical quantities of the transformer all change, and acquiring the temperature change of the winding and real-time waveform data of voltages and currents at two ends of the transformer at corresponding moments; a winding resistance value and real-time waveform data of a sampling period are calculated according to winding temperature change, a phasor value is calculated, and parameters of a T-type equivalent circuit of the transformer are identified by using a recursive least square method based on a forgetting factor. On-line monitoring of the operation state of the transformer winding can be realized, the fault of the transformer winding can be found in time, the fault rate of the transformer is effectively reduced, and the service life is prolonged.

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 a quantitative analysis method and related device for the overcurrent capability demand of a network-forming converter, and the method comprises the steps: building a quantitative relation between the minimum overcurrent capability and critical clearing time, which are required for enabling the converter to meet a transient stability target, based on an equal-area rule; based on the voltage and current phasor diagram when the converter reaches the maximum voltage support, establishing a quantitative relation between the minimum overcurrent capability required by the converter to meet the common coupling point voltage support target and the common coupling point voltage; according to the external power grid working condition of the converter and the key parameters of the converter, the minimum overcurrent capacity meeting the transient stability and common coupling point voltage supporting capacity key indexes is calculated based on the quantitative relation, and the maximum value of the minimum overcurrent capacity is obtained to meet the requirement for the transient stability, the voltage supporting capacity and the overcurrent capacity under the given parameters. According to the method, the minimum over-current capability of the required transient stability and voltage supporting capability of the network construction type converter can be calculated, and the cost of the network construction type converter is optimized.

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 harmonic current calculation method and device, equipment and a storage medium. The method comprises the following steps: acquiring power grid parameters after a photovoltaic inverter is connected to a power grid; performing rotation transformation on the power grid parameters to obtain a voltage harmonic phasor under a rotating coordinate system; an equivalent control circuit of the photovoltaic inverter is constructed, a current dq-axis component matrix of a PCC node is obtained based on the equivalent control circuit, and the PCC node is a coupling common point of the photovoltaic inverter and a power grid; the current dq-axis component matrix of the PCC node is converted into a current harmonic phasor matrix with a voltage harmonic phasor as an excitation condition; and performing decomposition calculation on the current harmonic phasor matrix to obtain harmonic current. And calculating the harmonic voltage to obtain a harmonic current, so as to evaluate the operation possibility of the photovoltaic inverter under the distorted power grid under different conditions through the harmonic current.

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.

The invention discloses a method for measuring the power frequency phasor of an urban substation, and the method comprises the following steps: S1, building a mathematical model of a to-be-analyzed component in a power supply system of the urban substation, and inputting a to-be-measured signal component into the mathematical model; s2, fitting the power frequency phasor parameters by using linear Bessel interpolation to obtain a fundamental frequency, an amplitude and a phase; s3, compensating a frequency spectrum negative image through an iteration process by using a fitting result in the S2, and reducing the frequency spectrum leakage of the negative image; s4, constructing an energy threshold inequality, judging whether the ratio of the energy of the inter-harmonic component to the component of the signal to be detected meets a threshold or not according to the result of the S3, and if so, directly outputting the result; and if not, repeating the steps S2-S4 until the threshold value is met.