Research On System For The Power Capacitor Intelligent Monitoring And Fault Diagnosis

In modern power system, reactive power compensation device is closely relatedto stability and economic operation of the power and grid voltage support, HV powercapacitors as the main reactive power compensation equipment, widely used in thegrid. Power Capacitor damaged more often, can’t be repaired, or even explode andcause serious accidents in operation. It takes a risk for power system security andeconomic operation and threat the safety of operating personnel. However, it isdifficult to monitor single capacitor’s electric capacity effectively in the operation andmaintenance. When the capacitor failure occurs, only relying on capacitor protectiondevice movement, this method is an afterthought method, and only reflects the faultinformation of the capacitors. Location the fault capacitor need for detectedindividually.To compensate for the lack of conventional capacitors diagnostic techniques, thispaper proposes to design a power capacitor capacitance intelligent monitoring system,to achieve real-time dynamic monitoring for capacity. Firstly, according to capacitorinternal structure established physical model in a35kv substation, and applyMATLAB/Simulink simulation tool for the capacitor internal fault simulationcalculations, get the corresponding relationship between current flowing through thecapacitor and the changes of capacitance of the fault capacitor; On this basis, wepropose a scene capacitor fault location method, which can eliminate the scenevoltage fluctuations, temperature changes and other disturbances, and can determinethe degree of fault according to the size of the capacitance change.Hardware system is composed of current signal collecting system, data collectionand transmission system and power unit system. The taken and acquisition integratedelement of current signal monitored current flowing through each capacitor, and usetaking power online to provide power for data acquisition and wireless transmissionunit. We designed low-power data acquisition and wireless transmission unit forgetting current signal transmitting by sensor, simultaneously to calculate the RMScurrent. Part of the wireless transmission unit sends the collected data to the centralstation through wireless control unit according to the instruction. Taking into accountthe shape of capacitor and requirements of actual job we integrated the taking energydevice and the current sensor, which meet the installation requirements of the capacitor. Software system is monitoring system of visualization based on theLabVIEW, and the database is based on SQL Server2008, for storing the powerfulreal-time monitoring data.We install and test the system in a substation field and laboratory, confirm thatthe system has strong anti-interference ability and feasibility, stability and accuracy ofthe field operation.