1056 results about "Utility frequency" patented technology

The invention provides a multi-dimensional electrical equipment insulation analysis and evaluation method, and relates to the technical field of electrical equipment insulation online detection and intelligent diagnosis. According to the method, an electrically isolated direct current detection channel is constructed in a neutral point small resistance grounding system, controllable direct current detection signals are injected, micro direct current leakage response signals are collected, and after zero drift correction, temperature compensation and power frequency ripple suppression are carried out, layered attribution is carried out in combination with primary system topology and an equipment ledger, and a multi-dimensional response matrix is formed. According to the method, environment and working condition normalization is realized through factor rejection and robust pull-back, a mechanism model containing leakage channel equivalent parameters and path constraints is established, multi-working-condition data is fused to calculate equivalent insulation parameters and credibility indication quantity, and a multi-dimensional insulation representation vector is generated. And performing time sequence analysis on the representation vector, extracting degradation and abrupt change characteristics, outputting a health index and a risk level, and realizing quantitative evaluation and intelligent early warning of the insulation state.

The invention relates to the technical field of ground resistance detection, in particular to a single-core cable ground resistance detection method capable of resisting strong power frequency interference. High-frequency signals are injected in a non-contact mode through a coupling type capacitor clamp, background voltage and current signals are collected firstly, and injection frequency far away from power frequency and harmonic waves is selected through Fourier analysis; cancelling background noise by adopting a normalized least mean square adaptive filter to generate an enhanced signal; the signal is down-converted to a base band through digital quadrature demodulation, a Kalman filter estimates the amplitude and the phase in real time, and the state and noise parameters are periodically calibrated through a compressed sensing algorithm; and finally, loop impedance is calculated according to the voltage and current amplitudes and the phase difference to obtain grounding resistance. The method has the advantages of being non-contact, high in safety, strong in anti-interference capability, high in measurement precision and the like, and is suitable for monitoring the grounding state of the cable in a complex electromagnetic environment.

The invention discloses a high-voltage cable operation state on-line monitoring, intelligent early warning and fault positioning system, particularly relates to the technical field of power equipment insulation monitoring, and is used for solving the problems that transient discharge signals generated in the cable insulation degradation process are difficult to effectively capture and accurate fault positioning cannot be realized in the prior art. The method comprises the following steps: collecting transient leakage current signals and traveling wave propagation characteristic parameters, performing phase correlation analysis on leakage current pulses and power frequency voltage to identify discharge types, and performing variational mode decomposition and Hilbert-Huang transform on the signals to respectively extract complexity characteristics and energy distribution characteristics; signal logic conflicts are judged by analyzing similarity and statistical distance among characteristics of a plurality of monitoring points, and collaborative diagnosis is started or traveling wave distance measurement is directly utilized to carry out insulation state evaluation and fault location. And finally, differential early warning levels are generated according to the diagnosis result, and fault line selection and positioning information is output to realize real-time monitoring, intelligent early warning and accurate positioning of the operation state of the high-voltage cable.

The invention discloses a column type distribution transformer winding abnormity detection system and detection method. The detection system comprises a frequency response detection instrument, a signal coupling assembly, an impedance matching module and a data processing module. The frequency response detection instrument is used for outputting a frequency sweep excitation signal and collecting a winding response signal; the signal coupling assembly is used for isolating power frequency voltage and filtering low-frequency interference; the impedance matching module is used for adjusting output impedance and input impedance to realize matching with electrical characteristics of different windings; and the data processing module is used for constructing an equivalent detection loop model, completing frequency response simulation calculation and carrying out frequency domain analysis and anomaly identification on an actually measured response curve. According to the invention, electrified state diagnosis of distribution transformer winding structure abnormity (such as deformation and loosening) can be realized.

The invention discloses an intelligent fault recording and traveling wave distance measurement integrated control method and device, and belongs to the technical field of fault positioning, and the method comprises the steps: collecting the power frequency electric quantity data and high-frequency traveling wave data of monitoring points at two sides of a fault line; calculating a first fault distance estimation value based on the power frequency electrical quantity data, and identifying an initial traveling wave head based on the high-frequency traveling wave data to calculate a second fault distance estimation value; defining an evaluation time period, and calculating a signal-to-noise ratio value in the evaluation time period; and according to the signal-to-noise ratio value, determining the contribution degree of the first fault distance estimation value and the second fault distance estimation value in generating final fault positioning distance calculation, and performing comprehensive processing on the first fault distance estimation value and the second fault distance estimation value in combination with the contribution degree to obtain a final fault positioning distance. According to the invention, the accuracy and reliability of fault positioning are improved, and positioning requirements under different fault conditions and signal environments are met.

The invention relates to the technical field of power system relay protection, and discloses a relay protection device mutual inductor adjustment system and method, and the system comprises a system connection initialization module, a data collection reference data generation module, a power frequency background signal offset module, a pilot frequency current injection error calibration module, and a calibration result verification output module. The method comprises the following steps: initializing sampling frequency of a to-be-calibrated mutual inductor and calibration source output precision of a calibration system, collecting amplitude and phase data of real-time power frequency current of the mutual inductor, generating offset current with equal amplitude and opposite directions through power electronic compensation based on reference data, optimizing offset current parameters through a closed-loop adjustment algorithm, and adjusting the offset current parameters through a closed-loop adjustment algorithm. Power frequency background signal offset is completed, pilot frequency calibration parameters are set, a difference value between a mutual inductor pilot frequency output signal and a calibration source standard signal is extracted by adopting a zero pointing technology, an optimal calibration coefficient is automatically calculated, verification of a calibration result is completed, and accuracy and reliability of the calibration result are ensured.

The invention provides a current transformer dielectric loss anti-interference measurement method based on a variable frequency power supply, and relates to the technical field of power detection, and the method comprises the steps: constructing an excitation channel, collecting a background response signal, recognizing a main interference frequency through combining a frequency tracking algorithm, and dynamically constructing a frequency deviation parameter; generating a pair of non-power-frequency excitation frequency control variable-frequency power supplies to output sine wave excitation signals; excitation voltage and response current signals are synchronously collected to form sampling signals, notch frequency is set according to frequency deviation parameters, main interference is filtered out, and first processing signals are obtained; performing weighting processing by constructing a window function matched with the frequency band characteristic to generate a second processing signal; the complex amplitude and phase information at the target frequency is extracted, the complex impedance is calculated based on the complex current method, the dielectric loss value of the current transformer is finally output, and the anti-interference capability and precision of measurement are effectively improved. According to the invention, the interference in the dielectric loss measurement of the current transformer can be processed, so that the measurement precision is improved.

The invention relates to the technical field of ammeter fault detection, and provides an intelligent ammeter series arc fault detection method, system and device, a medium and equipment, and the method comprises the steps: firstly obtaining an ammeter data set of an intelligent ammeter, which comprises a pre-ammeter voltage, a post-ammeter voltage and a total loop current in a continuous power frequency period, and then carrying out the division through a sliding time window, obtaining a plurality of ammeter data windows; for each window, calculating a voltage difference sequence and a dynamic loss impedance sequence; when the absolute value of the total loop current is smaller than a preset threshold value, determining the current zero-break interval of each power frequency period and the current zero-break time corresponding to the window; determining an arc voltage estimation value according to a voltage difference between non-zero-break intervals in the zero-break interval; and finally, integrating the current zero break time, the arc voltage estimated value and the dynamic loss impedance of each window to judge whether a series arc fault exists, and if so, triggering a protection action. According to the embodiment of the invention, high-reliability identification of the series arc fault is realized.

The invention discloses a construction method and a modulation method of a three-port multi-frequency MMC topology based on bridge arm multiplexing, and relates to the technical field of power electronics. The construction method comprises the steps that sub-modules of a traditional double-bridge-arm MMC are integrated and optimized into a three-bridge-arm structure through a current conversion branch, independent energy interaction of three ports is achieved through an auxiliary bridge arm, multi-frequency operation modes of power frequency, frequency division, direct current and the like are supported at the same time, and therefore the utilization rate of the bridge arm sub-modules is increased, and the energy utilization rate of the MMC is increased. And the overall size and the manufacturing cost of the converter are reduced. Based on three-port multi-frequency coordination control and power balance requirements, a modulation method of the topological structure is provided, a multi-frequency coordination modulation strategy is adopted, frequency offset is performed through an auxiliary bridge arm to reduce cross interference of port frequency, and output waveform quality is improved through multi-objective optimized capacitor voltage balance control. And meanwhile, direct-current side faults are effectively eliminated by means of the auxiliary bridge arm.

The invention belongs to the field of power transmission line parameter measurement, and discloses a live-line testing device and method for mutual inductance line parameters and zero-sequence impedance parameters. The device comprises a double-circuit line simulation module, a pilot frequency excitation module, a power frequency simulation module, a synchronous acquisition module and a signal processing module. The isolation transformer simulates a double-circuit line, the pilot-frequency power supply provides pilot-frequency excitation signals, the measurement unit realizes synchronous acquisition, and the signal processing module performs anti-interference and amplification processing. The method comprises the steps of line simulation wiring, synchronous time synchronization, pilot frequency signal acquisition, parameter calculation and error verification, and pilot frequency parameters are converted into power frequency parameters by using a frequency conversion formula. According to the invention, power frequency interference can be effectively suppressed in a charged environment, high-precision measurement of zero-sequence impedance and mutual inductance parameters of a mutual inductance line is realized by using pilot frequency excitation and Beidou synchronization technologies, the measurement error is remarkably reduced, the safety and reliability are remarkably improved, and powerful technical support is provided for safe and stable operation of a power system.

The invention discloses a bearing electrostatic signal noise reduction method based on VMD-OMP. In order to solve the problem that early fault features are difficult to extract due to the fact that bearing electrostatic signals are easily affected by power frequency interference and environmental noise, a noise reduction technology based on combination of VMD (variational mode decomposition) and OMP (orthogonal matching pursuit) is provided. The method comprises the following steps of: firstly, performing automatic optimization on a modal number and a secondary penalty factor of VMD decomposition by taking an envelope entropy as a fitness function through a grey wolf optimization algorithm to realize adaptive decomposition; and then, screening effective modal components according to the cross correlation coefficient and the kurtosis, determining the optimal sparseness by adopting a saturation value method, respectively reconstructing the components through an OMP algorithm, and finally, directly adding reconstructed signals to obtain a noise reduction result. According to the method, power frequency noise and broadband interference in the bearing electrostatic signal can be effectively suppressed, and the feature definition and the fault recognition capability of the electrostatic signal are improved.

The invention discloses an offshore wind power collecting and sending-out system and method based on a multi-port multi-frequency alternating current and direct current hybrid integrated platform, and belongs to the field of power transmission and distribution of power systems. The system comprises an intermediate-frequency, power-frequency and low-frequency wind power collection subsystem, an offshore integrated platform, a direct-current sending-out submarine cable, a low-frequency sending-out submarine cable, an onshore converter station and an onshore frequency conversion station. The various wind power collection subsystems respectively collect wind turbine generator group outputs with corresponding frequencies and send the wind turbine generator group outputs to the offshore integrated platform; the offshore integrated platform converts intermediate-frequency, power-frequency and partial low-frequency electric energy into direct current and then transmits the direct current to the onshore converter station through the direct-current sending-out submarine cable, and the converter station converts the direct current into power-frequency alternating current; and after being boosted, the other low-frequency electric energy is sent to a land frequency conversion station through a low-frequency sending-out submarine cable to be converted into power-frequency alternating current, so that efficient collection and grid-connected sending-out of multi-frequency wind power resources are realized. According to the invention, the problem that a plurality of independent platforms need to be built in a complex multi-point grid-connected scene in the prior art can be solved.

The invention discloses a power frequency phase adaptive acquisition device, and relates to the technical field of electric power signal measurement, the device acquires electric field data at a gap through an electric field sensor integrated on an edge shell, calculates electric field intensity fluctuation, and generates interference diagnosis information in combination with a preset interference determination threshold value; when the interference diagnosis information shows that effective interference exists, the electric field intensity variable quantity is calculated, a mapping model is established based on a proportionality coefficient obtained through an experiment so as to obtain zero crossing point offset, and the sampling trigger moment of a zero crossing point detection module is corrected; the clock synchronization module calculates a phase difference by taking the corrected trigger moment as a reference, dynamically adjusts a calibration frequency by combining a phase difference threshold value, and outputs a synchronized system clock signal; and the control system takes the synchronized system clock signal as a trigger signal, collects power frequency phase data according to a power frequency period, and stores the power frequency phase data to a database through a transmission unit, thereby realizing high-precision power frequency phase collection.

The invention discloses an isolation type split-phase inverter circuit and a control method thereof. The isolation type split-phase inverter circuit comprises an isolation DC / DC module circuit and a power frequency rectification module circuit. The isolation DC / DC module circuit comprises an input-side full bridge, a three-end transformer and two output-side circuits, an input-side winding of the three-end transformer is connected with a midpoint of a bridge arm of the input-side full bridge, and the input-side full bridge is connected with a filter capacitor C1 in parallel; two output side windings of the three-end transformer are respectively connected with corresponding output circuits through a resonance network circuit, the two output circuits are connected to a power frequency rectification module circuit through filter capacitors C4 and C5, and the negative electrode of the first output circuit and the positive electrode of the second output circuit are connected to form an interface N; the power frequency rectification module circuit comprises a rectification full-bridge circuit, and an interface L1 and an interface L2 are obtained after rectification. Through cooperative control of direct transmission of integrated topology and voltage signals, a complex parameter matching algorithm is not needed, breakthrough in structure simplification, energy conversion efficiency, control convenience, cost control and safety is achieved, and the method is suitable for various power conversion scenes.

The invention relates to the technical field of partial discharge detection, in particular to a partial discharge detection method and system for a high-low voltage switch cabinet, and the method comprises the steps: obtaining electromagnetic wave signals and power system voltage data of each sensor position in real time; acquiring a partial discharge period in each detection window according to the electromagnetic wave maximum value of all the sensors in each power frequency period in each detection window, the distance between the electromagnetic wave maximum value and the voltage wave crest and the voltage wave trough of the power system, and the electromagnetic wave signal difference between the sensors; and according to the dispersion degree of the electromagnetic wave maximum values of all the sensors under each partial discharge period in each detection window, the electromagnetic wave signal frequency domain energy of each partial discharge period and the proportion of the partial discharge period in each detection window, obtaining the existence confidence of each detection window, and judging whether partial discharge exists under the current detection window or not. According to the invention, by analyzing the distinguishing characteristics of the partial discharge and the electromagnetic interference in the electromagnetic wave signals at multiple positions, the detection precision of the partial discharge is improved.

The invention provides an insulating material surface arc ablation resistance simulation method based on magnetohydrodynamics, and belongs to the field of insulating material performance detection. The method comprises the following steps: establishing an insulating material surface arc ablation resistance model; constructing a magnetohydrodynamic control equation set; setting boundary conditions of the model; and iteratively solving the magnetohydrodynamic control equation set through finite element simulation software to obtain a temperature distribution diagram of the insulating material under different arc ablation times, and comparing the temperature distribution diagram with a TGA curve of the insulating material to judge the arc ablation resistance of the insulating material. According to the invention, the power-frequency alternating-current high-voltage arc and the insulating material are used as simulation objects, engineering practice is better met, the surface arc ablation resistance process of any insulating material can be simulated by changing the physical characteristic parameters of the insulating material, and the TGA curve of the material is introduced to judge the arc ablation resistance of the insulating material. And technical support is provided for high-voltage switch equipment insulating material type selection.

The invention discloses a power grid active support control method for an offshore wind power low-frequency power transmission system. Real-time response of low-frequency power grid angular frequency to power-frequency power grid angular frequency is realized by using an onshore M3C converter; the active power response of the low-frequency fan to the angular frequency of the low-frequency power grid is realized by utilizing a low-frequency fan side converter and a grid side converter; through cooperative control of the M3C converter and the low-frequency fan, active support of the offshore wind power low-frequency power transmission system for frequency fluctuation of an onshore power frequency power grid can be realized, the system stability is improved, and the method has a good application prospect.

The invention discloses an offshore wind power frequency conversion gathering and sending control method, device and system based on onshore integration, and belongs to the technical field of power transmission and distribution of power systems, and the method comprises the steps: converting first AC electric energy generated by an intermediate-frequency / power-frequency wind power plant into first DC electric energy through an offshore converter station; the first direct-current electric energy is transmitted to a land integration station through a direct-current submarine cable; second alternating-current electric energy generated by the low-frequency wind power plant is transmitted to the land integration station through a low-frequency alternating-current submarine cable; and converting the second alternating-current electric energy into second direct-current electric energy in the land integrated station, carrying out collection and power frequency conversion on the first direct-current electric energy and the second direct-current electric energy, and transmitting power frequency alternating-current electric energy obtained after conversion to a land power grid. Therefore, by implementing the application, the problem that the electric energy cannot be transmitted at low cost due to the fact that it is difficult to directly send the electric energy of different frequencies out of the system for topological combination in the prior art can be solved.

The invention discloses a rectifier bridge arm fault identification method and system circuit based on multi-characteristic current waveform analysis, and relates to the technical field of rectifier bridge arm fault identification, and the method comprises the steps: collecting a current signal of an AC input side of a rectifier bridge through a current sensor, and obtaining an original current time domain waveform after filtering conditioning; performing period division on the original current time domain waveform based on a voltage synchronization signal, and outputting a positive half-cycle conduction interval and a negative half-cycle conduction interval in each power frequency period; in each power frequency period, performing square integral operation on the current waveforms of the positive half-cycle conduction interval and the negative half-cycle conduction interval to obtain a positive half-cycle energy value and a negative half-cycle energy value, and calculating an energy unbalance degree; and windowing fast Fourier transform is carried out on the original current time domain waveform, amplitudes and phases of third, fifth and seventh characteristic harmonics are extracted to form a harmonic characteristic vector, the vector is matched with a pre-stored bridge arm fault harmonic fingerprint template, and the matching degree of each fault type is obtained.

The invention relates to the technical field of cable insulation detection, and discloses a power cable insulation state evaluation method and system based on multi-dimensional feature fusion, and the method comprises the steps: collecting a high-frequency current signal on a cable grounding wire, extracting a power frequency phase, a discharge amplitude and a pulse frequency band width, and carrying out the normalization processing, thereby obtaining a sample set; calculating a local sparseness adaptive factor of each sample point, and calculating an energy weighted local density of each sample point; calculating the relative distance of each sample point, constructing a decision value, and determining the sample point with the larger decision value as a clustering center; calculating the path transmission reliability of the non-clustering center sample points relative to each clustering center, distributing the sample points with the path transmission reliability meeting a preset condition to the corresponding clustering center, and if the preset condition is not met, marking the sample points as noise; and extracting statistical characteristics according to the separated discharge clusters, and evaluating the insulation state of the cable by using a preset fault diagnosis rule base. According to the invention, the accuracy of cable insulation state evaluation can be improved.

The invention provides a non-power-cut test method for mutual inductance parameters of a power transmission line under excitation of different-frequency signals and a related device, and solves the problems of difficulty in accompanying stop and high safety risk of adjacent lines. The method comprises the following steps: selecting one circuit in the same corridor for power failure, connecting the head end with an induced electricity suppression device, and performing three-phase short-circuit grounding at the tail end; injecting a different-frequency sinusoidal current of 45-55Hz into the power failure line; the synchronous measurement device collects head and tail voltage and current of a running line based on a satellite synchronous clock; extracting pilot frequency signals through two-stage notch filtering and Fourier transform; and different-frequency zero-sequence self-impedance and mutual impedance are calculated and converted into power-frequency impedance. According to the invention, accurate test without power failure can be realized, and safety and power supply reliability are guaranteed.

The invention discloses an intelligent diagnosis system for power utilization abnormal information acquisition, particularly relates to the technical field of power system monitoring, and is used for solving the problems of waveform distortion and broadening caused by transmission line distribution parameters in the long-distance wired transmission process of an existing system. The system collects abnormal characteristic waveform data through a distributed intelligent terminal, selects a characteristic harmonic component in the power frequency voltage of a power line to construct an inherent test signal, extracts the envelope form similarity of a response signal and the test signal through envelope analysis as a first distortion evaluation index, and obtains a second distortion evaluation index after statistical significance judgment. Performing instantaneous frequency stability analysis on the signal with significant distortion to obtain a second distortion evaluation index, and finally generating a corresponding waveform compensation parameter based on double indexes to realize real-time compensation correction; the integrity of the abnormal characteristic waveform in the transmission process is effectively maintained, and the accuracy and reliability of power consumption abnormity diagnosis are remarkably improved.

The invention discloses a high-precision voltage regulating system of a power frequency no-partial-discharge test transformer, and the system comprises a heterogeneous multi-stage power module which is formed by connecting an H-bridge unit group and a matrix converter in parallel, the H-bridge unit group outputs a fundamental voltage component, and the matrix converter compensates a high-frequency harmonic component; the multi-physics field digital twinning unit integrates an electromagnetic field solver, a thermodynamic model and a mechanical deformation simulation module and predicts the multi-physics field coupling state of the insulation system in real time; the dynamic impedance matching network comprises an adjustable inductor array and a digital capacitor bank, and automatically adjusts filtering parameters according to a load impedance measurement value; and the control module is used for deploying a deep learning model and is used for optimizing a modulation strategy and a protection threshold on line. According to the method, the voltage regulation precision and the waveform purity can be improved, the stability under the wide-range working condition is guaranteed, the breakdown hidden danger is recognized in advance through multi-physics field coupling simulation, and partial discharge development is restrained from the source.

The invention discloses a medium-frequency transformer insulation electrothermal aging evaluation method, a test device and a storage medium, and relates to the technical field of power transformers. The medium-frequency transformer insulation electric heating aging test device comprises a function signal generator, a high-voltage power amplifier, a protection and isolation unit, an electric-heat combined aging oven and a detection and monitoring unit. The electrothermal aging evaluation method comprises the following steps: acquiring an aged sample, testing the ultimate tensile strength and polymerization degree of the aged sample, introducing a frequency correction factor to correct an attenuation constant under a power frequency condition, establishing tensile strength attenuation equations under different frequencies, and evaluating the tensile strength of the aged sample. And respectively fitting the maximum value of the accumulated loss rate and the change rate of the accumulated loss rate under different frequencies to obtain a polymerization degree accumulated loss rate improvement formula, and carrying out aging characteristic analysis on the insulation of the intermediate-frequency transformer according to the actual working condition of the insulation of the intermediate-frequency transformer. According to the technical scheme, the blank of medium-frequency transformer insulation electrothermal aging research is filled.

The invention relates to the technical field of offshore wind power transmission, in particular to an offshore wind power low-frequency conversion system. According to the frequency conversion system, a low-frequency energy consumption module consumes redundant electric energy of a low-frequency power distribution module, so that the influence of unstable electric energy input by external large-capacity offshore wind power on the power distribution stability of the low-frequency power distribution module is eliminated, and the low-frequency power distribution module can output stable low-frequency alternating current; meanwhile, the low-frequency alternating current is adjusted to be in the voltage level suitable for the frequency conversion module to conduct electric energy frequency conversion through the low-frequency voltage transformation module, and therefore the frequency conversion module can easily convert low-frequency electricity input by large-capacity offshore wind power into power frequency electricity suitable for being used by electric equipment. And finally, the power output of the frequency conversion module is readjusted to the voltage level suitable for external electric equipment by the power frequency transformation module, so that the unstable electric energy sent by the high-capacity offshore wind power is converted into the electric energy used by the external equipment, and an application example of the low-frequency alternating-current power transmission land frequency conversion station is provided for the field of high-capacity offshore wind power sending.

The invention provides a cable partial discharge monitoring method and system, a program product and a storage medium, and relates to the technical field of electrical variable measurement, and aims to capture a pulse current signal generated during cable discharge, perform time calibration on the discharge pulse current signal, measure the time difference of signals monitored at different positions, and combine the signal propagation speed to determine the partial discharge of a cable. Therefore, the specific position of discharge is locked. In a power frequency period, a PRPD atlas is constructed according to the amplitude and frequency of a discharge pulse current signal and corresponding power frequency phase information, then a statistical moment, phase symmetry and a polarity effect on each coordinate axis are calculated based on the atlas, and feature vectors are formed and input into a preset mode recognition model. And the model outputs a judgment result containing the discharge point position and the specific defect type by comparing with a preset monitoring parameter threshold value for the specific defect type. And direction reference is provided for subsequent maintenance and repair work, blind troubleshooting is avoided, the maintenance and repair efficiency is improved, and the cost is reduced.

The invention relates to the technical field of steel plant air compression, and discloses a steel plant air compression system universal energy-saving and stable air supply control method which comprises the following steps that S1, the total air consumption demand Q of a steel plant compressed air pipe network is monitored in real time; s2, executing a load segmentation control strategy based on the total gas consumption demand Q; s3, loading and unloading operation of the power frequency air compressor and rotation speed adjustment of the variable frequency air compressor are controlled in a coordinated mode through a central energy-saving control unit; and S4, a pressure buffer tank is arranged on an output pipeline of the variable-frequency air compressor and used for stabilizing the pressure of the pipe network. The total air consumption demand Q is divided into two sections, the power frequency machine is started and stopped according to the N + 1 principle, and the frequency converter is supplemented for continuous quantity supplement, so that the system can operate only with the minimum necessary unit in any load scene, energy waste caused by over-start and over-stop in a traditional scheme is avoided, and overall reduction of compressed air production energy consumption is realized.

The invention belongs to the technical field of nuclear power, and particularly relates to a ground capacitance measurement method based on series capacitance and high-frequency signal injection. In order to solve the problem that a traditional signal injection method cannot accurately calculate the ground capacitance level of a power distribution network, the invention provides a ground capacitance measurement method based on a series capacitor and high-frequency signal injection. The leakage inductance of the voltage transformer is accurately measured by injecting the high-frequency signal, so that a resonance point is convenient to find during frequency sweeping, and the resonance point measured during frequency sweeping is more accurate.

The invention provides a traveling wave signal feature extraction and fault identification method and system based on deep learning, and belongs to the technical field of power system fault diagnosis. The method comprises the following steps: deploying a monitoring terminal at a key node of a power distribution network, and collecting power frequency electric field, power frequency current and high-frequency traveling wave current data in real time; judging whether the power frequency electric field, the power frequency current and the high-frequency traveling wave current trigger wave recording or not, and reporting corresponding wave recording data after triggering; preprocessing the reported data; constructing and training a BP neural network model to obtain a traveling wave classification model; inputting the normalized discrete data into the trained traveling wave classification model, and outputting a fault category; if a fault occurs, judging a fault interval according to power frequency electric field change, power frequency current magnitude characteristics and high-frequency traveling wave current wave head polarity; and according to the judged fault interval, using a traveling wave fault distance measurement algorithm to obtain accurate positioning of a fault point of the overhead line. According to the invention, accurate identification and positioning of the power distribution network line fault are realized.

The invention belongs to the technical field of three-phase alternating current / direct current converters, and particularly relates to a SWISS rectifier control method and system for achieving phase compensation and reducing input current harmonics, and the method comprises the steps: obtaining power grid synchronization information through sampling three-phase power grid voltage in real time and carrying out phase locking and coordinate transformation; a d-axis current reference value is generated by adopting a single PI control loop, and a q-axis compensation current is calculated in combination with feedforward compensation based on filter capacitor parameters; an input current reference value is generated through reverse Park conversion and voltage sorting, and after the direct current side inductive current is subjected to power frequency period synchronous moving average filtering, the direct current side inductive current is directly compared with the current reference value to generate a PWM driving signal. The system only needs to collect direct-current side inductance and three-phase power grid voltage, and a grid-side current sensor is not needed. According to the invention, the control structure is simplified, the power factor is improved, and input current harmonics and hardware cost are reduced.