Title :
Experimental study on the influence of the disconnecting switch operation on CVTs in UHV series compensation stations
Author :
Lingyu Zhu ; Shengchang Ji ; Jinyu Li ; Yuan Liu
Author_Institution :
State Key Lab. of Electr. Insulation & Power Equip., Xi´an Jiaotong Univ., Xi´an, China
Abstract :
In series compensation stations of the UHV AC demonstration project in China, capacitive voltage transformers (CVTs) failed several times during the operation of disconnecting switches (DSs). The reasons for this failure are analyzed in this paper. The stray inductor, the stray capacitor between the platform and ground and the capacitor of the CVT forms a resonant circuit in series compensation stations, causing repeated oscillating overvoltage and impulse current acting on the CVTs during DS operation. A full-scale experiment indicates that the oscillating frequency is approximately 200 Hz and the repeating frequency is approximately 0.5 MHz. The simulation experiment in the laboratory indicates that the partial welding mode and the partial high electric field are the main causes of damage to the CVT element insulation. A mechanism of the insulation damage is proposed, and some suggestions are given based on our results.
Keywords :
electric fields; potential transformers; transformer insulation; CVT element insulation; China; UHV AC demonstration project; capacitive voltage transformers; disconnecting switches; impulse current; overvoltage; partial high electric field; partial welding mode; resonant circuit; series compensation stations; stray capacitor; stray inductor; Capacitors; Circuit faults; Current measurement; Insulation; Strain; Testing; Voltage measurement; Capacitive voltage transformer; disconnecting switch; insulation fault; oscillating impulse current; series compensation;
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on
DOI :
10.1109/TDEI.2015.7076793
