Method for implementing earthing distance measurement element based on negative sequence fault current component

Abstract

The invention discloses an implement method of an element for measuring a grounding distance unrelated to the loading current and the grounding resistance, which is based on a negative sequence fault current component. When a high-voltage / ultra-high-voltage / extra-high-voltage has a single-phase grounding fault, the current in a relay location is IPhi, and the voltage is UPhi; the distance from the fault point to the relay location is x; the voltage at the fault point is UPhif; the grounding current is IPhif; and the break current IPhi2 of negative sequence in the relay location is measured. Since the grounding is ohmic, IPhif is in the same phase with IPhif; as for the single-phase grounding fault, since IPhi2 has the same phase angle with IPhif, UPhif has the same phase angle as IPhi2, so as to calculate and obtain a formula of the distance from the fault point to the relay location; since the formula is unrelated to the loading current and the grounding resistance, as a distance protective impedance measuring element, the element has high measuring accuracy, and is not affected by the loading current or the high resistance grounding fault. Theoretical analyses and simulation results show that the proposed principle has very high practicability and computational accuracy.

Description

technical field [0001] The invention belongs to the technical field of power systems, in particular to a method for relay protection, and in particular to a method for realizing distance measurement of line grounding faults. Background technique [0002] Transmission line is the basic equipment for power generation and transmission in the power system, and occupies a very important position in the power system. When the transmission line is faulty, if it cannot be cut off in time or by mistake, it will have a great impact on the main system, and it will easily cause major accidents such as grid splitting and transformer tripping. High-voltage / ultra-high voltage / ultra-high voltage line protection undertakes the important task of power transmission and is an important hub of the power system. They are extremely expensive to manufacture, and once they are damaged due to malfunctions, they will be difficult to repair and take a long time, causing huge direct and indirect losses...

AI Technical Summary

Problems solved by technology

[0003] On high-voltage / ultra-high voltage / ultra-high voltage transmission lines, excessive resistance and load current have a great impact on impedance calculation. Excessive resistance can change the measured impedance, The distance calculation may be inaccurate, it may be shortened or out of range

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