The invention discloses a method for positioning low-current grounding fault sections of power distribution networks on the basis of transient energy analysis. The method includes steps of determiningpass frequency band ranges of digital filters and configuring a miniature PMU (power management unit) on each node of the power distribution networks; acquiring zero-sequence voltage phasors and zero-sequence current phasors of the various nodes of the power distribution networks by the aid of the miniature PMUs, judging whether faults of systems occur or not according to the zero-sequence voltage phasors and the zero-sequence current phasors of the various nodes, starting to position the faults if the faults occur, reading three-phase current signals recorded by the various miniature PMUs, computing transient zero-sequence currents of the various nodes by the aid of the three-phase current signals, processing the transient zero-sequence currents, computing transient energy of various sections, and determining the fault sections according to the transient energy of the various sections. The method has the advantages that physical meaning of fault features utilized by the method is clear, the method is high in positioning accuracy and reliability for the fault sections of various branch lines, and input of medium resistors connected with arc suppression coils in parallel or installation of signal injection equipment can be omitted.

Method for positioning low-current grounding fault sections of power distribution networks on basis of transient energy analysis

The invention discloses a complex power grid fault location method based on wide-area travelling wave energy and time difference. According to the fault location method, by starting from travelling wave energy generated after failure of a power grid, the influence of line length and bus out-degree on the attenuation of travelling wave energy in the process of transmission in the power grid is analyzed, the three-phase current of each substation after failure is measured, the magnitude of travelling wave energy of each substation is calculated, and thus, a fault section and a fault point are determined. A lot of existing equipment is used in the method. The method requires low real-time performance of data sampling, and is easy to implement. Through analysis of a simulation model built according to actual parameters, the method is not affected by fault phase angle and fault resistance, and is of high accuracy and robustness. The positioning method of the invention is suitable for application in a complex power grid.

Complex power grid fault location method based on wide-area travelling wave energy and time difference

The invention discloses a transient energy protection method for a fault current of a direct current transmission line, and belongs to the technical field of relay protection of a DC distribution network After the DC line fault current characteristics are fully considered, the positive and negative current instantaneous values and the maximum load current are compared; firstly the fault occurrence and the failure type are determined, and then the difference of line current characteristics of different fault types is used to determine the fault type, and finally the fault current transient energy difference and a delay action on the line are used to determine the fault occurrence position; the fault section can be determined quickly and accurately, a reliable action is achieved without theline communication, andthe sensitivity is high; the transient energy protection method is suitable for the line protection of a DC power distribution system, and helps to improve the line protectionof DC power distribution engineering

Transient energy protection method for fault current of direct current transmission line

The invention discloses a method for judging a fault section of a multi-terminal DC transmission system based on polar wave energy. The method comprises the steps of: recording a fault start moment, acquiring electrical quantities in time segments before and after the fault start moment, and calculating aerial mode components of a voltage and a current at a protection installation part by utilizing the electrical quantities; calculating a polar wave value of each sampling point at a designated moment at the protection installation part in the time segments according to the aerial mode components of the voltage and the current; extracting a polar wave wavelet coefficient of each sampling point at an arbitrary layer in the time segments, and calculating polar wave wavelet coefficient energy;acquiring the maximum value of the polar wave wavelet coefficient energy at the protection installation part in the time segments, regarding the maximum value of the polar wave wavelet coefficient energy as a reference sampling point, taking at least one sampling point after the reference sampling point, and calculating a sum of the polar wave wavelet coefficient energy of the reference samplingpoint and the at least one sampling point; and judging the sum of the polar wave wavelet coefficient energy, and determining the fault section as an intra-cell fault if the sum of the polar wave wavelet coefficient energy is greater than a setting value set in advance.

Method and system for judging fault section of multi-terminal DC transmission system based on polar wave energy

The invention discloses a method for detecting a multi-terminal DC(direct current) system fault based on transient high frequency energy, characterized by establishing an analytical expression of a fault component current of a multi-terminal DC system line; obtaining the transient high frequency energy of the current according to the analytical expression of the fault component current; and if thetransient high frequency energy of a line exceeds a preset protection threshold, determining that the line is a fault line. The invention has the following advantages: the threshold setting is easy to be realized, the robustness of the fault detection of the multi-terminal DC system is improved, the sampling frequency is low, and the transition resistance is good.

Method for detecting multi-terminal DC system fault based on transient high frequency energy

The present invention relates to a fault ranging method based on a mode time difference, belonging to the technical field of power system fault protection. According to the method, in a power transmission line, a transformer substation which is connected to a bus is internally equipped with a traveling wave distance measuring device, and when the power transmission line is failed, fault current traveling wave is spread to the bus; the line mode current traveling wave and zero mode current traveling wave generated by a fault point is spread to a measurement end TA1 with speeds v1 and v0, the distance between the fault point and the measurement end TA1 is lf, a wave head time different Delta t is initailized by using the line mode current traveling wave and zero mode current traveling wave detected by the measurement end TA1, and finally the fault distance lf is calculated combined with the ranging theory and line mode current traveling wave and zero mode current traveling wave speeds. According to the invention, the wave head time different is initialized by using the line mode current traveling wave and zero mode current traveling wave of the fault point, and the reliability of the distance measurement is improved.

Fault ranging method based on mode time difference

The invention relates to a busbar protection method based on fault current wavelet decomposition transient energy, and belongs to the technical field of electric power system relay protection When a circuit or a busbar breaks down, transient current of each circuit on the busbar in a short time window after the fault occurs is extracted, fault-containing phase-mode current is taken after phase-mode transformation to perform wavelet transform; a wavelet energy value of each circuit is solved, whether the fault is a busbar fault or not is differentiated through comparing transient current energy of each circuit, and if the fault is a busbar fault, a busbar circuit in which the fault occurs is judged according to a transient high-frequency energy ratio of a connected circuit The busbar protection method can distinguish a circuit fault and a busbar fault reliably, and is not only simple in principle but also reliable and effective

Bus protection method based on fault current wavelet decomposition transient energy

The invention relates to a temporary-state-quantity distance measuring device detection method based on a real-time digital simulation instrument, and belongs to the technical field of power system relay protection The temporary-state-quantity distance measuring device detection method includes the steps that a temporary-state-quantity current signal i and a voltage signal u generated through a simulation model constructed through a simulation model window of the real-time digital simulation instrument are output through an analog signal channel, and amplified through a power amplifier, and the amplified signals are close to signals connected into a temporary-state-quantity distance measuring device during actual running of a power grid; the signals are connected into the temporary-state-quantity distance measuring device, the temporary-state-quantity distance measuring device detects the received input signals, then the signals are fed back to the simulation model in a closed-loop mode through a simulation signal input channel for compensation and adjustment, the fault positions of a power transmission line are determined through the temporary-state-quantity distance measuring device according to the abrupt-change temporary-state-quantity current signal i or a voltage signal u , then the temporary-state-quantity distance measuring device is detected, wave recording of the temporary-state-quantity distance measuring device is started, a fault waveform is recorded and stored, and the fault distance l is output after calculation

Temporary-state-quantity distance measuring device detection method based on real-time digital simulation instrument

The invention relates to a traveling wave single-terminal distance measurement device test method based on simulation data, and belongs to the technical field of electric power system relay protection. As for a power transmission line, a traveling wave distance measurement device is only installed in a transformer substation connected with the side of a bus. A power transmission line model is established through electric power system simulation software according to the actual operation situation of the power transmission line so that different fault types and different fault locations of fault simulation waveforms are acquired; then the edited simulation waveforms pass through a high-power high-speed signal generator to output fault waveforms to the traveling wave distance measurement device; and the traveling wave distance measurement device records the fault waveforms and then calculates the fault distance. If the traveling wave distance measurement device can start, the wave recording starting function is qualified, or the wave recording starting function is unqualified; and distance measurement is performed on the basis of the qualified wave recording function, and the distance measurement result is accurate if the distance measurement result is within the error range, or the distance measurement parameters require to be adjusted or the distance measurement result is unreliable.

Traveling wave single-terminal distance measurement device test method based on simulation data

The invention relates to a chain network external fault location extension method, belonging to the technical field of power system relay protection. The method includes that in the chain network consisting of three ends, a line MN is a cable, a line NP is an aerial conductor, and only a transformer station connected to a bus M is equipped with a traveling wave location device inside, when the power transmission line NP, which is not monitored by the traveling wave location device, has faults, the current traveling wave of the measuring end TA1, close to the bus M side, in a healthy line MN is acquired by the traveling wave location device, the time for the transmission of the initial travelling wave to the TA1 through the healthy line MN and the time for the transmission of the fault point reflection wave to the TA1 through the healthy line MN are respectively recorded, and the time difference Delta t is calculated, and at the end, the fault distance lf is calculated through the combination of the location theory and empirical velocity. According to the invention, one only needs to install a detection device at one end of the chain network, so that the defects of difficult fault location of circuits that are not monitored and high running cost of a double-end travelling wave method are overcome and the construction cost is reduced.

Shu Hongchun

Papers

Fault ranging method based on mode time difference

Bus protection method based on fault current wavelet decomposition transient energy

Temporary-state-quantity distance measuring device detection method based on real-time digital simulation instrument

Traveling wave single-terminal distance measurement device test method based on simulation data

Chain network external fault location extension method