Development Of On-line Monitoring System For Multi-state Quantity Sensing Ring Network Cabinet

As an important part of China’s power supply and distribution link,the current traditional detection method in China has a long detection cycle,which requires operation and maintenance personnel to carry equipment for field testing,and there are many devices and many have not formed a relatively complete system.To solve the above problems,this thesis designs a set of ring network cabinet multi-state quantity sensing online monitoring system,aiming to integrate the traditional ring network cabinet with radio frequency identification,network communication,computer technology,etc.,to realize a variety of electric and non-electric capacity remote online monitoring of ring network cabinet,and ensure the stable operation of ring network cabinet.In order to realize the on-line monitoring of the operating environment and cable operating state of the ring network cabinet,the hardware detection circuit is designed for a variety of electric and non-electric capacity inside the ring network cabinet.In addition,four common local discharge defect models were made,and High Frequency Current Transformer(HFCT)and Transient Earth Voltage(TEV)were designed respectively.The signal conditioning circuit is designed according to the output of three kinds of sensors,which is used to cross-verify the phenomenon of local discharge in the ring network cabinet and calibrate the local discharge power.The continuous existence of local discharge will accelerate the process of insulation deterioration and eventually lead to insulation failure.In order to further study the phenomenon of local discharge,the output signal of HFCT conditioning circuit was denoised and decomposed by variational mode decomposition,and multiple entropies of different modal components and waveform features after decomposition were extracted.The dimensionality of the data was reduced by principal component analysis.After identification by support vector machine algorithm,the average accurate classification rate reached 92%.It has good classification effect.In order to realize multi-dimensional data summary and real-time online diagnosis of the ring network cabinet,this thesis uses Zigbee technology to transmit data wirelessly to the PC of the monitoring station,and processes data packets through Lab View designed upper computer software to give early warning of the ring network cabinet fault,so as to timely repair and replace the equipment.At the same time,the system is installed and tested in the laboratory and the substation,which proves that the system has high detection accuracy and can run stably for a long time.