Research And System Design Of Multi-point Grounding Live Detection Technology For Transformer Core

Power transformer is the key equipment of electric energy transfer.As a power grid hub with different voltage level,its working status is directly related to the safety and reliability of the power system.The multi core grounding of transformer core and its clamps is one of the reasons for transformer accidents in recent years.And the resulting losses are also serious.Thus it is critical to detect such transformer insulation faults for the grid in time.In view of the objective need of power system to detect the grounding state of transformer core,a live detection system for multi-point grounding of transformer core is designed in this paper.At the least change of the wiring mode of the transformer,it is used as an off-line device to detect the current signal of the transformer bushing.Based on the quantitative mathematical description of the relationship between flux and potential,a mathematical model of the transformer which suitable for analyzing the multipoint grounding current of iron core is established.Based on the Matlab environment,the multi point grounding fault of transformer iron core with "iron yoke and clip short circuit" is simulated.It is found that only by extracting the basic frequency component through Fourier transform,the signal obtain in the field fault detection can effectively eliminate the external noise interference and restore the real fault signal size.The charged detection system uses the piercing Holzer current sensor to extract the current signal of the grounding wire of the transformer core.According to the characteristics of signal source,it carries out the corresponding range automatic conversion and hardware anti-jamming design scheme.The detection device is controlled by PIC single chip microcomputer.The ZigBee communication transmission can be carried out by ad hoc network,and the detection signal is transmitted to the portable PC through the RS232 interface for further analysis.