Fast Differential Protection Method Based on Transient Current Waveform Characteristics
A technology of waveform characteristics and transient current, applied in the direction of automatic disconnection of emergency protection devices, emergency protection circuit devices, electrical components, etc., can solve the problems of action speed constraints, small amount of action, reduced sensitivity, etc., and achieve rapid fault selection. Phase, improve the action speed, the effect of fast recognition
Active Publication Date: 2020-06-02
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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Problems solved by technology
Time-domain current differential is sensitive to noise during fault transients and has insufficient reliability; power frequency phasor current differential has strong anti-interference ability, but there are restrictions on the operating speed
On the one hand, the traditional differential protection is greatly affected by the distributed capacitive current on long transmission lines with high voltage levels, and the high setting value makes the sensitivity greatly reduced; In case of short circuit, it is possible that the action amount is less than the braking amount and refuse to move
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Embodiment 1
[0030] The invention proposes a fast differential protection scheme based on transient current waveform characteristics.
[0031] A fast differential protection scheme based on transient current waveform characteristics. This scheme first extracts the transient fault component current at the protection installation on both sides of the transmission line when the fault occurs, and then samples the data on both sides by setting the time scale and using linear interpolation. Carry out synchronous calibration and sum the differential current. On this basis, the least squares-based fitting calculation method is used to extract the main fluctuation frequency of the waveform in the differential current by using the constructed fitting function. Compared with the protection criterion value, it can judge the internal and external faults and identify the fault phase.
[0032] Such as figure 1 As shown, the calculation formula of transient fault component is as follows:
[0033]
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The invention belongs to the technical field of power system fault recognition, and particularly relates to a fast differential protection method based on transient current waveform characteristics. The method comprises the following steps: 1, extracting transient fault component currents at protection installation positions at two sides of a power transmission line when a fault occurs, and solving a differential current; 2, extracting the waveform main fluctuation frequency in the differential current by adopting a least square fitting calculation method; 3, comparing the waveform main fluctuation frequency with a protection criterion value, judging internal and external faults and recognizing a fault phase. According to the invention, the action speed of protection is greatly improved, and the protection circuit still has high sensitivity under a short-circuit fault of a high transition resistor.
Description
technical field [0001] The invention belongs to the technical field of power system fault identification, in particular to a fast differential protection method based on transient current waveform characteristics. Background technique [0002] With the increase of voltage level and transmission capacity in the construction of my country's power grid, the power grid will have a greater impact after the line fault, so the action time of relay protection is required to be faster. Traditional relay protection is based on power frequency, but filtering will slow down the protection action speed and prolong the protection action time, which will cause a contradiction between action speed and reliability. In addition, with the access of inverter-type power supply and the extensive application of flexible AC transmission systems (FACTS) equipment on the line, its fast adjustment performance brings uncertainty to the use of traditional power frequency protection. The fault transient...
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IPC IPC(8): H02H7/26H02H3/26G01R31/08
Inventor 王增平吕哲许琬昱
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)