Research On Monitoring System Of Ultra-high Voltage Shunt Capacitor

Shunt capacitor bank on the 110 kV side of ultra-high voltage(UHV)substation is mainly used for reactive power compensation and is an important part of UHV transmission system.Its normal and abnormal operation directly affects the safe operation of UHV substation.Therefore,it is of great practical significance to monitor the shunt capacitor bank on the 110 kV side of UHV substation and obtain its running status in time.A real-time monitoring system of shunt capacitor bank on the 110 kV side of UHV substation is developed based on the deep analysis of various operating conditions of shunt capacitor bank on the 110 kV side of UHV substation.The main work and achievements are as follows:In order to provide the design basis for monitoring system of shunt capacitor on the 110 kV side of the UHV substation,the equivalent circuit of the electric power system is established and MATLAB is used to solve the electric current of the capacitor in the running process and PSCAD/EMTDC model is used to simulate the operation process of the capacitor.The results show that the capacitor current oscillates and contains harmonic components in the two cycles after the capacitor is put into operation.Therefore,the monitoring system of capacitor needs to have the function of harmonic analysis and waveform recording.At the same time the start criteria also needs to be studied in order to start the waveform recording timely and accurately.A monitoring system is developed to monitor the operation status of the shunt capacitors on the 110 kV side of UHV substation in real time.The system provides the basis for further analyzing the operation status of the capacitor by measuring the current signal of single capacitor and detecting and analyzing the power frequency current and harmonic components in the current signal and recording current waveform.The whole monitoring system consists of the data acquisition unit using DSP chip TMSF28335 as the core and the data concentrator unit with ARM chip STM32F103 as the core and industrial computer.The hardware and software algorithms of data acquisition unit and data concentrator unit are designed in this paper.The hardware circuit of the data acquisition unit mainly includes analog conditioning circuit,AD7606 circuit,DSP circuit,EEPROM circuit,wireless communication circuit,real-time clock circuit and power supply circuit.The main circuit of data concentrator unit includes wireless communication circuit,RS485 communication interface circuit and power supply circuit.Based on the modular design idea and the CCS software platform,the software design of each unit is completed using the C language programming.Finally the communication protocol and communication mechanism among the components of the monitoring system are given.