Selection analysis of 500 kV GIS voltage transformer

Abstract

This article analyzes the mechanism of ferromagnetic resonance in 500 kV GIS electromagnetic voltage transformers, the conditions required for resonance to occur, the determination method of resonance type, and the main countermeasures. Based on the excitation characteristics of traditional 500 kV GIS electromagnetic voltage transformers and the excitation characteristics of 500 kV GIS low magnetic density voltage transformers at Qingyuan Pumped Storage Power Station, as well as the circuit characteristics of voltage transformers and their connecting short busbars, high-voltage cables, and overhead lines under various operating conditions such as power station testing, commissioning, and maintenance, the equivalent capacitive reactance of independent systems and the excitation reactance of electromagnetic voltage transformers under typical operating conditions were calculated. Based on the PETERSON curve, the possibility of resonance generated by traditional transformers was analyzed, and the types of ferromagnetic resonance were quantitatively calculated and analyzed. During the contract execution phase, a study was conducted with the equipment manufacturer on the low magnetic density voltage transformer. The calculation result showed that the low magnetic density voltage transformer has outstanding anti saturation ability and will not experience ferromagnetic resonance under all predictable operating conditions.

Keywords

directly grounded system / voltage transformer / ferromagnetic resonance / low magnetic density / operation mode