Design And Implementation Of Rural Grid Residual Current Fault On-line Monitoring Platform

For a long time,a considerable part of rural areas in China have poor power supply,Outdated transmission lines.Resident' awareness of power consumption is relatively weak,resulting in frequent residual current faults in rural areas.Currently,residual current protection devices are generally used to protect residents' lives and property.but if there is a small amount of residual current in the resident's house and does not exceed the trip threshold of the residual current protection device,this residual current will remain in the cable for a long time and cause the line aging to bring security risks.The device is also not conducive to the rapid positioning of electrician fault repair.To deal with these drawbacks,an on-line residual current fault monitoring platform for rural power grids is designed in this paper,including residual current collectors,data concentrators and WEB background monitoring software.It can quickly capture,upload,and alarm fault currents and supports real-time data query.As a result,the agricultural electrician can quickly locate faults and improve repair efficiency.First of all,this paper introduces the development status of the residual current detection technology and its on-line monitoring platform at home and abroad,sums up the existing shortages of the current monitoring platform,and presents the overall design scheme of the residual current fault online monitoring platform for rural power grids,including residual current collector clusters.,data concentrator and WEB background monitoring software.The advantages and disadvantages of three kinds of residual current transformers for electromagnetic type,Hall type and magnetic modulation type were compared,and residual current acquisition and data processing methods were given.The ZigBee technology and GPRS technology responsible for wireless communication in the monitoring platform were introduced and used.NS-2 simulation analyzed the feasibility and reliability of ZigBee network deployment to rural areas.Then,based on the residual current detection scheme,the hardware design and software design of the residual current collector are realized.The hardware design includes residual current detection conditioning circuit,terminal voltage conditioning circuit,main control chip working circuit,power supply and standby power supply module,ZigBee module,etc.Finally,a PCB circuit board was created based on the schematic diagram.The software design mainly realizes the function of inquiring the residual current and the terminal voltage in real time,the function that the residual current exceeds the threshold value or abnormally uploading the fault data at the terminal voltage abnormally,the data retransmission mechanism function,and the design of the collector and concentrator transmission protocol.In addition,based on the analysis of the data concentrator's needs,its hardware design and software design are given,including the MCU core circuit,touch display module,ZigBee module,GPRS module,SD card storage module,and alarm module,etc.,based on schematic design and production.PCB circuit board.The software implements communication tasks,interactive tasks,and alarm tasks.Through the concentrator,it can query the collector's detection data,historical fault data,and configuration parameters in real time,and realizes the human-machine interaction function and fault data storage functions of the touch display screen.The communication protocol with the WEB background monitoring software is given.Finally,completed the monitoring platform test and field installation trials,including the collector power on/off,detection error,power consumption and functional testing,on the concentrator side data transceiver,real-time data query,historical data query and configuration parameter query test,on-site After installation,the entire monitoring platform was tested through WEB background monitoring software.The test results show that the monitoring platform can quickly and stably detect residual current faults and can send data to the concentrator in time.The concentrator will immediately start the alarm and forward the data to the WEB back-end server,which can meet the rural power grid on the residual current online monitoring demands.