Phase voltage self-calibration method for three-phase overhead transmission lines based on series capacitors

Abstract

The invention relates to a series-capacitor-based self-calibration method for a phase voltage of a three-phase overhead transmission line. On the basis of the spatial capacitive divider principle, the line and the ground are viewed as a large capacitor to carry out voltage dividing and the air is used as an insulating medium. Various stray capacitors, including the capacitor caused by the insulating layer and the capacitor existing at the interphase leads, between the three-phase lines are considered fully and a centralized parameter equivalent circuit is established. A switch capacitor is connected in series at an upper polar plate side and a lower polar plate side and the stray capacitance value to the lead by the upper polar plate is changed by changing the capacitance value; different voltage values are measured at a sampling capacitor and thus all unknown stray capacitor values and to-be-measured voltage values are calculated, thereby realizing self-calibration of the three-phase line phase voltage. The method enables the distributed device requirement of the distributed network to be met and thus is superior to the existing voltage measurement plan.

Description

technical field The invention relates to a method for self-calibrating the phase voltage of a three-phase overhead transmission line based on a series capacitor, which is applied in an overhead line distributed voltage sensor. Background technique With the continuous development of my country's electric power industry, building a strong smart grid has become the future development direction. At present, my country's distribution network has a large number of lines, wide areas and long lines, and the environment is complex and the failure rate is high. The development of low-cost distributed monitoring devices can realize real-time online monitoring and fault location of the distribution network operation status. Operation is of great significance. Distributed and accurate measurement of phase voltage of overhead lines in distribution network is a difficult point. Currently widely used voltage sensors mainly include electromagnetic (PT), capacitive (CVT) voltage transformer...

AI Technical Summary

Problems solved by technology

Traditional PTs are affected by factors such as small capacity, high cost, complex insulation structure, ferromagnetic resonance phenomenon, and leakage inductance distributed capacitance, which gradually do not meet the needs of today's power grids.

CVT is mainly used in power grids above 330kV. It is bulky, expensive, difficult to install, and cannot meet the requirements of low-cost distributed devices.

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