Intelligent Combination Switch For Reactive Power Compensation Capacitance Switching

In alternating-current (ac) power systems reactive power compensationequipment play important role in order to ensure the power quality and improve therate of equipment utilization and capacity of transmission network and reduce theline losses. In the reactive power compensation equipment, capacitance switching isthe main process. The traditional compensation switching, which uses mechanicalswitch, cause inrush current problem and produce harmful impact to the capacitanceand power network. Using the power electronic components is a solution to the inrushcurrent problem, but this will improve the cost of the equipment and operation. Soreactive power compensation solution based on pure power electronic components isonly for those quick switching needed situation. The combination switcher, whichintegrates the power electronic components and mechanical switch, having theadvantages of both. Therefore, it is a very significant work for us to develop thecombination switch. Research process, optimizing the control program.In the thesis, based on the simulation and analysis of switching process of thereactive power compensation equipment, the optimal control strategy and algorithmfor capacitance switching is implemented. The simulation research include: therelations between different closing phase angle and inrush current, the influence ofdifferent phase sequence and zero crossing to the combination switch, and immediateclosing after opening process feature. The analysis and research on the functions ofhardware circuit for open-phase protection, capacitance protection and thyristorprotection in the combination switch are introduced. The hardware circuit, which usesthe PIC16F873A MCU as control unit, and the control system software for thereactive power compensation capacitance intelligent combination switch is introduced.The main component of hardware include: phase sequence and phase-open detectioncircuit, temperature sensor circuit, thyristor and relay control circuit andcommunication module. The intelligent combination switch control system softwareis designed and implement using C language. The control system software mainfunctions include: intelligent switching, fault detection and protection andcommunication modules. The optimum control algorithms as the result of thesimulation analysis are implemented in the control system software and the relatedtests and verifications are done.The intelligent combination switch can perform a fast and high reliabilityswitching, power saving and effectively solve the inrush current problem. The testingand actual running show that intelligent combination switch satisfy the designrequirement, and has good application foreground in the reactive power compensationequipment.