Waveform correlation-based distance protection method under distributed parameter model

Abstract

The invention discloses a waveform correlation-based distance protection method under a distributed parameter model. The method includes the following steps that: break variable current is adopted as a protection startup component, and whether a fault occurs on a line is judged, and protection is started; waveform correlation coefficients rho 0.6D and rho D of fault voltage and fault component current at 60% and 100% of the line are calculated through utilizing voltage and current sampling values where protection is installed and combining with fault phase selection results when a fault phase is under a power transmission line Bergeron; and whether rho 0.6D and rho D satisfy the expression rho D<=rho 0.6D is judged, if rho 0.6D and rho D satisfy the expression, the fault is an intra-region fault, protection action trips, otherwise, the protection does not act. The method of the invention is based on a power transmission line distribution parameter model, so that the method is not affected by line distribution characteristics; fault voltage and fault component current are utilized to form time domain protection criterions, and filtering is not required, and transition resistance-withstanding ability is strong; and the fault can be judged as long as the waveform correlation coefficients of voltage and current of two points at the tail end of the line are judged, and therefore, calculation amount is small.

Description

【Technical field】 [0001] The invention belongs to the field of relay protection for power system transmission lines, in particular to a time-domain distance protection method under a distributed parameter model. 【Background technique】 [0002] As a basic component of line protection, distance protection plays a vital role in the safe and stable operation of the power system. With the expansion of power system scale, EHV and UHV long-distance transmission lines are increasing day by day, and higher and higher requirements are put forward for the performance of distance protection. [0003] The existing distance protection has the following problems: the centralized parameter model is adopted, and for ultra-high voltage long lines, its distributed parameter characteristics make the measured impedance of the traditional distance protection not proportional to the fault distance, which has a great impact on the accurate calculation of the distance protection; due to the Influen...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a distance protection method based on waveform correlation under a distributed parameter model, to overcome the traditional distance protection adopting a simplified model, which is easily affected by the distributed capacitance of ultra-high voltage transmission lines; the frequency domain protection performance depends on fast and effective The filtering algorithm realizes the extraction of power frequency; and the existing distance protection algorithm requires high sampling frequency, large amount of calculation, and poor resistance to transition resistance.

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