Study On System Of Multi-parameter Detection In10kv-SF₆Ring Main Unit Outdoor

The fault detection system of ring main unit can ensure ring main unit runningsafely,but detection systems being used mostly aim at Simple Parameter,in which wecan not analysis comprehensively and troubleshoot problems.The fault detection ofring main unit research status in and abord is analysed in the article,which can detectthe leak of SF₆gas,the partial discharge of electric cable and the environmentaltemperature in the ring main unit.The partial discharge of electric cable is detected by the method ofelectromagnetic coupling.The PD signal is acquired by the device of capturecard,which is transmitted to the computer used for waveform display,datastorage,signal de-noising and fault recognition.The way of software and hardwarede-noising are adopted in the article.In the hardware aspect,noise is filter in the fieldof space,ground connecting and interior system through reasonably layout.In thesoftware aspect, proper wavelet threshold is chose through simulation for de-noisingof the system and it turned out that,the signal in effect is mostly kept.To all kinds ofworking conditions,the electromagnetic coupling signals is analysed in time domainand frequency domain,finally,a stable selected frequency band is accepted whilepartial discharge producing.In the base of all the work above,BP neural network apply in the partial dischargerecognition.The feature vector is adopted by the power spectrum integral values ofelectromagnetic coupling signal and gradient descent is used to adjust networkparameters,in which the partial discharge of electric cable is distinguishedsuccessfully. Infrared SF₆sensor produced by the method of NDIR is used for the detection ofSF₆reveal and digital temperature sensor is used for the temperature measurement ofthe ring main unit. The STM32single chip is the core processor of lower computerto acquire and dispose the signal.The display circuit,alarm circuit,keyboard controlcircuit is designed to accomplish the function of display,alarm,control.Thecommunication circuit used RS-485is designed to accomplish the function ofcommunication.The software of labview in the upper computer is compiled torealize the function of SF₆concentration display and temperature value display.It turns out that,through many experiments,the system can identify the PDsignal.meanwhile,the leak signal of SF₆gas and the temperature signal of ring mainunit are monitored availably.The system is significance in the running of ring mainunit with high stability.