Study on characteristics of local discharge photoelectric signal of typical insulation defects in GIS under impulse voltage
Gas Insulated Switchgear(GIS)is an important substation equipment in the power system.If it fails,it will bring serious losses to the national economy.GIS equipment is subjected to not only power frequency operating voltage during operation,but also to transient impulse voltage.Large transient surges can trigger small defects hid-den under power frequency operating voltage to generate partial discharge.Focusing on the partial discharge signal under the surge voltage can effectively improve the sensitivity of detecting small defects inside the equipment.In re-sponse to this,this article sets up typical insulation defects on physical GIS,and based on optoelectronic integrated fusion sensors,uses ultra-high frequency method and optical measurement method to measure and analyze partial discharge under oscillating impulse voltage.The partial discharge detection results of three typical defects in physi-cal GIS under oscillatory impact indicate that the discharge under sharp defects mainly occurs near the peak of ap-plied voltage.But when the voltage is high,due to the influence of the reverse electric field formed by the space charge,the valley discharge is triggered.The discharge under suspended defects will occur in more discharge cy-cles,mainly at the rising and falling edges of the applied voltage.Some of the discharge amplitudes are larger,and the ultra-high frequency method and fluorescent fiber method can simultaneously detect the discharge pulse.The discharge pulses under surface defects occur sequentially at the rising and falling edges of the applied voltage,and the fluorescence fiber method can only detect very few discharge pulses.
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