Impulse Generator
Investigation of Load Impact on Output Capability of Impulse Voltage Generators
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Investigation of Load Impact on Output Capability of Impulse Voltage Generators

Wang Haoyang, Sun Wei, Fu Zhengcai, Chen Jian
HIMALAYAL - SHANGHAI - CHINA

Abstract: The entrance capacitance of GIS and HV cable can reach 3000pF in impulse voltage test. It is necessary to improve the output capability of the impulse voltage generators (IVG) which were designed without consideration of large capacitance loads. In this paper, by applying the ATP simulation method, a 15-stage 3000kV IVG with a high-voltage RC-filter at the output terminal for improving output capability is analyzed. The waveform influencing factors including load, total inductance, and equivalent resistance, and the output efficiency are investigated. It is shown that the above improving method can enhance the IVG output capability from 4000pF to 11000pF, with the waveform overshoot being controlled within 10%. In addition, the length limit of HV connecting wire is suggested.

Key Words: impulse voltage generator, load impact, waveform overshoot, waveform adjustment

Introduction
As for high-voltage electric equipments of electric power system, impulse voltage tests must be conducted during the delivery test, and even in the installation site. According to requirements of test standards GB/T 16927.1-1997, regarding full lightning impulse with front time (1.2 ±30%) μs and half-peak time (50 ±20%) μs, the amplitude of relative overshoot should be no less than 5%. The new edition IEC 60060-1 Ed.3.0 stipulates that the amplitude of relative overshoot has to be no less than 10%. The revised draft of GB/T 16927.1 will also be consistent with IEC.