112 results about "Power system oscillations" patented technology

The invention discloses a method for positioning an oscillation disturbance source in a power system. The method comprises the following steps of: acquiring voltage, current, power physical quantity of a plurality of measuring points in a multi-voltage class power grid and meeting the following conditions: 1, whether each measuring point is subjected to low-frequency synchronous power oscillationis monitored in real time, and an oscillation amplitude, a main oscillation mode frequency, main oscillation mode damping, an initial phase of the main oscillation mode and oscillation initial time information are provided; 2, two frequencies in the main oscillation mode of the measuring points which are subjected to low-frequency oscillation accord with the condition that an absolute value of delta f is less than delta Fset; 3, the oscillation initial time of the measuring points which are subjected to low-frequency oscillation has a sequence relationship, and a clear characteristic that theoscillation starting time of measuring points in a low-voltage class power grid is earlier than the oscillation starting time of measuring points in a high-voltage class power grid; and 4, the average frequency fave of the main oscillation mode of each measuring point which is subjected to low-frequency oscillation accords with the condition that fave is more than fmin and less than fmax; and when the conditions are accorded, determining that the power system is subjected to low-frequency oscillation and a local power grid in an area with the earliest oscillation starting time is the oscillation disturbance source.

The invention relates to the field of power system stability research, in particular to a simulation collocation method for an oscillation disconnection device of a power system. The method comprises the steps: A. building a simulation data model; B. building a research failure set; C. performing simulation calculation of power grid stability after failure, obtaining out-of-step characteristics of a power grid, determining an oscillation center, and summarizing oscillation center moving laws; D. performing simulation calculation of acting characteristics of the oscillation disconnection device after the failure, and judging acting correctness of the oscillation disconnection device; E. putting forward a preliminary collocation scheme of the oscillation disconnection device; F. studying coordinating relations among stability control measures; and G. putting forward the final collocation scheme of the oscillation disconnection device by combination with the step C, the step D, the step E and the step F. The simulation collocation method has the advantages of being strong in maneuverability, comprehensive in considered factors and reasonable in scheme, and has high practical value and good market prospect.

The invention belongs to the technical field of the low-frequency oscillation on-line detection and analysis in an electric power system and provides a low-frequency oscillation modal analysis method, which is based on wide area phasor metrical information and an empirical mode decomposition method and can carry out the on-line detection and node homology grouping toward the complex low-frequency oscillation of the electric power system. The modal analysis method not only has strong adaptability to the complex waveforms of non-linearity, non-stationarity or those containing non-periodic constituents, but also can carry out phase comparison toward nonsine or cosinoidal inherent modal curves which belong to the oscillation mode of the same electric power system but are slightly different in frequency and realize the homology grouping of the nodes participating in each oscillation mode, thus obtaining the power conversion relation among the nodes and the position of an oscillation center or interface.

A digital travelling wave protecting method for electric power transmission lines and its relay and protection system is disclosed. The said system is composed of digital travelling wave relays containing hardware and firmed software and high-frequency carrier communication unit consisting of high-frequency transceiver and high-frequency carrier channel-power transmission lines. The said method features that the action results of said relays at both ends of a power transmission-line are compared with each other to judge if there is a failure on the line. Its advantages include fast response (5 ms for relay action and 15 ms for protection action).

The invention provides a method for quickly positioning the oscillating center of an electric system. In application aspects of inhibiting the oscillation of the system, coordinating the disconnection and the like, the accurate position of the oscillating center of the electric system often needs to be known. By the method, only the electric quantity and natural parameters of circuits need to be measured on the spot, the out-of-step oscillating center of the system can be accurately judged at the synchronous oscillation stage of the system, and the out-of-step quick disconnection criterion is realized based on the on-the-spot electric quantity. By the popularization and the application of the method for positioning the oscillating center based on the on-the-spot electric quantity, and the combination of the reliable quick disconnection criterion, the out-of-step disconnection control can be realized quickly, reliably and on the spot, and the method can also be adapted to different operating modes of the system, and realize the coordinating control of a plurality of disconnection devices.

A method of damping power system oscillations includes obtaining an AC measurement signal from a power system location and determining oscillation frequency values in the AC measurement signal. A plurality of single signal components are extracted from the AC measurement signal by subtracting a plurality of processed measurement signals from the AC measurement signal and a damping signal is generated based on the plurality of single signal components. Each of the plurality of processed measurement signals are generated by time delaying the AC measurement signal with a time delay associated with each of the oscillation frequency values other than the oscillation frequency value of the single signal component to be extracted.

A method and system are provided. The method includes collecting, from a plurality of phasor measurement units, a plurality of synchronized phasor measurements from different portions of a power system. The method further includes estimating, by a controller, oscillation modes of the plurality of synchronized phasor measurements. Each estimated oscillation mode specifies, for each of the plurality of synchronized phasor measurements, two or more of an amplitude, a phase, a frequency, and damping coefficients. The method also includes performing, by the controller, a modal analysis of the oscillation modes of the plurality of synchronized phasor measurements to identify critical modes based on critical mode identifying criteria. The method additionally includes constructing, by the controller based on the critical modes, a power system oscillation dampening control signal for controlling a grid-scale storage portion of the power system to dampen one or more oscillations of the power system at any given time.

A system for damping power system oscillation includes a damping device controller for generating a damping control signal to compensate for a plurality of oscillation modes in the power system oscillations and a damping device to generate a damping signal based on a damping control signal. The damping device controller includes a plurality of outer closed loop paths each including an adaptive controller configured to determine an individual oscillation mode from at least one power system measurement signal. Each adaptive controller is further configured to generate an adaptive control signal to shift at least one open loop pole of an inner loop path related to the individual oscillation mode to a closed loop location.

The invention discloses an electric transmission line single-phase earth fault direction discriminating method based on instantaneous sampled values. The electric transmission line single-phase earth fault direction discriminating method includes the steps of measuring fault-phase voltage sampled values, fault-phase current sampled values, fault-phase negative sequence current sampled values and zero sequence current sampled values at the protection installation position of an electric transmission line at sampling moments, calculating whether an electric transmission line single-phase earth fault direction criterion is workable or not through the fault-phase electric component sampled values at the three adjacent sampling moments, and if the electric transmission line single-phase earth fault direction criterion is workable, judging that a single-phase earth fault in the corresponding direction is generated on the electric transmission line. According to the electric transmission line single-phase earth fault direction discriminating method, the electric transmission line single-phase earth fault direction criterion is calculated only through the fault-phase electric component sampled values at the three adjacent sampling moments, a required data window is short, Fourier algorithm operation is not referred, the operation amount is small, and the calculating speed is high; the discriminating result is not influenced by the factors such as electric system oscillation, the fault position, transition resistance and a load current, and the fault direction of an electric transmission line single-phase earth fault is accurately discriminated.

This invention discloses a method for selecting the phase of the high voltage power lines on the basis of the model distinguishing and is used for the phase selecting components during oscillation blocking. It is characterized in that the model distinguishing method is adopted to calculate respectively the distances and the three orders voltages at the failure sites under two failure models, which are the models of the single phase grounding and the double phases short circuiting grounding when a grounding failure occurs, determining the actual phases on which the failure occurs through judging whether or not the three orders voltage meet the boundary conditions under the corresponding failure.

This invention opens a recognizing method basing on the circuit's failure and oscillation of resistance changing regularity, the method includes: judge whether the circuit has failure and whether distance 1 sect and 2 sect have action, if yes then send out jumping switch order; judge (after failure) whether it reach to 0.1 second, if over 0.1, second, then judge whether it is within the time sect tau, whether the resistance change is less than set-default of resistance changing rate DRset(tau), if in the tau time sect the resistance changing value is more than or equal Drset tau, than confirm as electricity system oscillation, thereby closedown easy misoperation (namly should not jump the switch, but take the switch jump out mistakenly, to broaden the power cut scale) distance protection, otherwise open the protection at all time, monitor whether the electricity system is failure, to ensure not having misoperation.

A method of monitoring a high voltage electrical power system is described in which a system acquires measurements the small perturbations in power system parameters, from which are derived the system dynamic characteristics used to determine power transfer limits that take account of power system prevailing conditions. Further, a method is described that can be used to identify the probable source of power system oscillations that can limit secure power transfer.

The invention relates to the technical field of electric power system, A method for coordinate control of damping of multiple interval oscillation mode in a UHV power network is disclosed, Based on the information of multiple weak damping modes and sensitivity of damping ratio, a multi-objective on-line optimization strategy based on mean square error is adopted, and the output of generator set isoptimized by using genetic algorithm, so as to improve the damping of multiple interval oscillation modes and realize the prevention and control of UHV power system oscillation.

The invention discloses a monitoring method and a system of power system oscillation under time lag and loss of wide area measurement data. The method comprises the steps of disturbance start judgment, data correction processing, data substitution processing and state evaluation and analysis. A disturbance start judgment module roughly judges whether a monitored power system has suspected oscillation; for power angle monitoring data of the suspected oscillation, a data correction processing module performs data preprocessing on a sampling value; for power angle monitoring data of data time lag or data loss, a data substitution processing module provides substitution data based on an electric coupling strength relation; and finally, a state evaluation and analysis module analyzes an oscillation mode of the power system by a classic Prony analysis method. The method can effectively improve the monitoring robustness of the power system oscillation, and is high in practicability.

The invention discloses an electric transmission line inter-phase short circuit fault direction discriminating method based on discrete sampled values. The electric transmission line inter-phase short circuit fault direction discriminating method includes the steps of measuring fault inter-phase voltage sampled values, fault inter-phase current sampled values and fault inter-phase negative sequence current sampled values at the protection installation position of an electric transmission line at sampling moments, calculating whether an electric transmission line inter-phase short circuit fault direction criterion is workable or not through the fault inter-phase electric component sampled values at the three adjacent sampling moments, and if the electric transmission line inter-phase short circuit fault direction criterion is workable, judging that an inter-phase short circuit fault in the corresponding direction is generated on the electric transmission line. According to the electric transmission line inter-phase short circuit fault direction discriminating method, the electric transmission line inter-phase short circuit fault direction criterion is calculated only through the fault inter-phase electric component sampled values at the three adjacent sampling moments, a required data window is short, Fourier algorithm operation is not referred, the operation amount is small, and the calculating speed is high; the discriminating result is not influenced by the factors such as electric system oscillation, the fault position, transition resistance and a load current, and the fault direction of the electric transmission line inter-phase short circuit fault is accurately discriminated.

The invention discloses a multimodal synchronous phasor-based power system oscillation tracing method and system. The system comprises multiple multimodal phasor measurement units, a multimodal phasorconcentrator and a multimodal oscillation wide area monitoring/analysis and tracing platform, wherein the multimodal phasor measurement units are used for extracting all oscillation modes for bus voltage and all phases of current of a line, acquiring corresponding phasors, acquiring positive, negative and zero-sequence phasors in each oscillation mode and corresponding complex power and marking asynchronous time scale to obtain phasor data; the multimodal phasor concentrator is used for communicating with the multiple multimodal phasor measurement units and storing the phasor data; and the multimodal oscillation wide area monitoring/analysis and tracing platform is used for receiving the phasor data transmitted by the multimodal phasor concentrator, carrying out resynchronization on thephasor data according to the time scale, the phasor data are stored in a real-time or historical database to realize multimodal tracing. The system can realize accurate power system multimodal oscillation tracing, the physical meaning is clear, online execution is easy and simple to realize.

The invention belongs to the technical field of power systems, and discloses a power system oscillation parameter recognition method and system, a terminal and a storage medium. The method comprises the steps: achieving the separation of signals of different frequency bands through a band-pass filter; utilizing an improved variational mode decomposition (IVMD) method to extract an oscillation mode signal in each band-pass filtering signal; the HTLS algorithm and the adaptive artificial neural network algorithm Adaline ANN are combined to estimate the frequency, the attenuation factor, the amplitude and the phase of the low-frequency oscillation, and unified recognition of the wide-band oscillation is realized. According to the method, oscillation distinguishing, modal extraction and parameter recognition can be effectively carried out on multi-type and wide-band oscillation such as low-frequency oscillation, subsynchronous oscillation and super-synchronous oscillation from the operation data of the power system. The recognition result plays an important role in the aspects of system dynamic stability analysis and control, oscillation source recognition and positioning and the like, and early warning and timely suppression of system oscillation are facilitated.

The invention discloses an oscillation identification system and method of a power system. The oscillation identification system comprises an information collecting and processing module, a sine impedance calculating module and an oscillation identification module which are connected sequentially; the information collecting and processing module collects and calculates power frequency voltage and current, determines whether protection is carried out at the two sides of a line, and starts the sine impedance calculating module if YES; the sine impedance calculating module calculates the integrated sine impedance of the line; and the oscillation identification module determines whether oscillation occurs in the power system, sends a locking signal to a protector if oscillation occurs in the power system, and otherwise, sends a tripping signal to the protector.

The invention discloses a power distribution network grounding fault protection method based on fuzzy measurement fusion criteria. The method comprises the following steps: acquiring a plurality of fault characteristic quantities of a protected feeder line to form a historical sample, and acquiring a sample to be tested according to the same method; clustering and dividing n historical samples into a fault class and a non-fault class by adopting a clustering algorithm; respectively taking membership degree, distance specific gravity measurement and angle specific gravity measurement as similarity measurement criteria, calculating a fault measurement value and a non-fault measurement value of the sample to be tested, and constructing a fuzzy measurement fusion criterion matrix of the sampleto be tested; and taking the fuzzy measurement fusion criterion matrix as a judgment set of a judgment index system, constructing a factor set of the judgment index system by using all similarity metric criteria, presetting the weight coefficient of each element in the factor set, and judging the fuzzy measurement fusion criterion matrix to obtain whether the distribution network to be tested isin fault or not. According to the method, the fault judgment interval is broadened, erroneous judgment caused by factors such as power system oscillation is effectively avoided, and the robustness isimproved.

The invention discloses a phasor-based forced disturbance source locating method for generators, comprising the following steps: S1) selecting a power generating set with power oscillation amplitude exceeding a threshold range according to a power system oscillation warning signal; S2) obtaining the real time measured data of the electrical power, the frequency or speed, the machine terminal current and the excitation current outputted from the selected power generating set; S3) preprocessing the real-time measured data and obtaining a dominant forced oscillation mode, and calculating the corresponding electric fluctuation quantity phasors in the dominant forced oscillation mode; and S4) locating the forced disturbance source for the generators according to the relationship between the corresponding electrical fluctuation quantity phasors of the generators and further determining the control system where the forced disturbance source is located. According to the invention, the method analyzes the relationship between the corresponding electrical fluctuation quantity phasors on two control channels, locates precisely the generator set where the forced disturbance source exists and judges whether the forced disturbance comes from a speed regulating system or an excitation system; this is of great significance to cut off a forced disturbance source quickly and effectively suppress forced oscillation.

The invention discloses a SPDMD-based power system oscillation mode and modal identification method comprising the steps: the energy weight corresponding to each oscillation mode is represented by thetime amplitude coefficient and the oscillation mode and the oscillation modal of high weight are selected out; a matrix formed by the previous N-1 columns of measurement data sequences is converted to calculate the initial amplitude coefficient, the penalty function term is introduced into the Frobenius norm term and the position of the non-zero elements in the initial amplitude coefficient is determined by ADMM, matrix encoding is performed on the initial amplitude coefficient and the value size of the non-zero elements in the initial amplitude coefficient is adjusted by using a pull multiplier method so as to obtain the optimal amplitude coefficient; and the dominant oscillation mode is determined by the correspondence between the non-zero elements in the optimal amplitude coefficient and each oscillation mode, and the collaborative identification and evaluation of the dominant oscillation mode, the dominant participation factor and the homology cluster are completed. The oscillation mode and modal identification of the power system can be realized, and the defect that the DMD algorithm cannot determine the number of the dominant oscillation mode can be overcome.

The invention discloses a method to divide the surge and the short circuit. It is based on the characteristic of the oscillating current envelope line in the electric power system. It finds the relation between the constant component Io and the alternate component Im in the condition of mishandling in the distance protection part because of the oscillating. When the Im >= k2Io, it is the oscillation; In the process of oscillation error, it finds the relation between the Io and the instantaneous component i, when the I >= k1Io, the angle between the power supply potential of the circuit sides is bigger than 75degreewhich is the second criterion. When it feeds the above two criterions, the surge and the short circuit will be divided. The invention can react with the mishandling in the distance protection part because of the oscillating and the short circuit; it is free from the influence that the electric power system circulates condition variety; and it doesn't limit to the system oscillating period, so it can reach the reliable lock by sensing the distance protection which is sensitive to the oscillation.

The embodiment of the invention discloses a method and system for determining a migration law of an oscillation center of a power system. The method comprises the following steps: making three generator sets in the power system be equivalent to three center points as to serve as head ends, wherein any power source is a two-machine system of the tail end; obtaining the lowest point position of a line voltage of the two-machine system, wherein the lowest point position of the line voltage of the system is the position of the oscillation center; and simulating the power system according to the lowest point of the line voltage of the two-machine system and system parameters in the power system to obtain the migration law of the oscillation center. According to the method and system disclosed by the invention, the position of the oscillation center, the power supply potential frequency, the potential amplitude ratio, the line impedance and other system parameters are considered, and meanwhile, the influence of the initial phase angle change of the power supply potential corresponding to the system operation mode before the out-of-step oscillation on the migration principle of the oscillation center of the system is mainly analyzed. The method and system can be adapted to guiding the positioning of the oscillation center, the configuration of an out-of-step disengagement device and parameter setting under a multi-frequency out-of-step scenae of the power grid to ensure the safety and stability of the power system.

The invention provides a multiple-cluster unit PSS (packet switching service) coordination and optimization method for mitigating inside-and-outside correlative coupling. The multiple-cluster unit PSS coordination and optimization method includes (1) establishing an inside-and-outside interconnected power system static power flow model and stable calculation model; (2) scanning small interfering frequency domain characteristic roots, and identifying an outside-area large power system key electromechanical oscillation mode; (3) participating screening and grouping of inside units of the outside large power system key electromechanical oscillation mode; (4) aiming to increasing outside-area key oscillation mode damp, optimizing unit PSS data parameters group by group; (5) performing multiple-cluster PSS parameter comprehensive coordination and optimization; and (6) estimating outside-area key section power transmission capacity improving effects. By the aid of the multiple-cluster unit PSS coordination and optimization method for mitigating the inside-and-outside correlative coupling, inside-area unit PSS can be utilized comprehensively to suppress outside interconnected power system oscillations, large-area-spanned key section power transmission capacity is improved, and safe and stable running level of a power grid is improved.