Distributed parameter measurement impedance-based relay protection method for single-phase grounding fault of power transmission line

Abstract

The invention discloses a distributed parameter measurement impedance-based relay protection method for a single-phase grounding fault of a power transmission line. The method comprises the following steps that: fault-phase distributed parameter measurement impedance Zphi,ce is directly calculated by utilizing fault-phase voltage, fault-phase current, fault-phase negative-sequence current and zero-sequence current of a protector mounting position and parameters of the power transmission line; and if the amplitude of the fault-phase distributed parameter measurement impedance is lower than a set impedance value, and a phase angle of the fault-phase distributed parameter measurement impedance is within the range of 45 to 135 degrees, a protector transmits a tripping signal, otherwise the protector does not act.

Description

technical field [0001] The invention relates to the technical field of relay protection of power systems, in particular to a relay protection method for single-phase ground faults of transmission lines based on impedance measurement of distributed parameters. Background technique [0002] Relay protection is the first line of defense to ensure the safe and stable operation of the power grid. Whether it can act accurately and quickly plays a vital role in isolating faults in time and effectively preventing accidents from spreading. Impedance distance protection has been widely used in power system transmission line protection because it is less affected by power system operation mode and structural changes, and can selectively remove various faults in transmission lines instantly, and has a long and stable protection range. However, the premise of traditional ground impedance distance protection is that the ground fault point voltage is zero, and the fault impedance is measur...

AI Technical Summary

Problems solved by technology

In fact, except for artificially constructed short circuits, the voltage at the ground fault point is almost impossible to be zero, and the voltage at the ground fault point will have a serious impact on the measurement of fault impedance, especially for high-impedance ground faults under heavy load conditions, and the measurement error is very large. It is easy to cause the traditional grounding impedance distance protection to malfunction or refuse to operate, which will have a very negative impact on the safe and stable operation of the power grid

EHV / UHV long-distance transmission lines are often also heavy-duty transmission lines, and heavy-load currents will reduce the action sensitivity of impedance distance protection. Therefore, the impact of heavy-load currents of EHV / UHV long-distance transmission lines on the action performance of impedance distance protection can not be ignored

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