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 asss 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 electric power systems, and relates to a method of relay protection, in particular to a method of measuring the distance between phases of lines. Background technique [0002] Transmission lines are the basic equipment for power generation and transmission in the power system, and occupy a very important position in the power system. When a transmission line fails, if it cannot be cut off in time or by mistake, it will have a greater impact on the main system, and it will easily cause major accidents such as grid disconnection and transformer skipping. HV / UHV / UHV line protection is responsible for the important task of power transmission and is an important hub of the power system. They are extremely expensive to build. Once they are damaged due to malfunctions, they are difficult to repair and take a long time, and the direct and indirect losses to the national economy are huge. This puts forward higher requirements fo...

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.

Images