Method for implementing element for measuring distance between phases without relevance to load current and ground resistance

Abstract

The invention discloses an implement method of an element for measuring a phase distance unrelated to the loading current and the fault resistance. When a high-voltage / ultra-high-voltage / extra-high-voltage has a phase fault, the current in a relay location is IPhiPhi, and the voltage is UPhiPhi; the distance from the fault point to the relay location is x; the voltage at the fault point is UPhiPhif, and the current is IPhiPhif; and the break current DeltaIPhiPhi in the relay location is measured. Since the fault is phase-to-phase, UPhiPhif has the same phase as IPhiPhif; and since DeltaIPhiPhi has the same phase angle as IPhiPhif, UPhiPhif has the same phase angle as DeltaIPhiPhi, wherein UPhiPhif is equal to UPhiPhiPhi minus xZ1IPhiPhi, DeltaIPhiPhi and UPhiPhif are changed into plural forms; since DeltaIPhiPhi and UPhiPhif have the same phase angle, the ratio of the imaginary part to the real part of DeltaIPhiPhi is equal to the ratio of the imaginary part to the real part of UPhiPhif, which is shown in formula (II), so as to calculate and obtain the fault distance x unrelated to the loading current and the fault resistance, which is shown in formula (I); since the formula is unrelated to loading current and the fault resistance, the element can be used as a distance protective impedance measuring element. 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 field of power systems, and relates to a method for relay protection, in particular to a method for measuring the distance between lines. 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 to the national economy. In this ...

AI Technical Summary

Problems solved by technology

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

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