Investigation On Synchronized-switching Capacitor Banks With Phase-control Vacuum Circuit Breaker Based On FPGA

Controlled switch, also called synchronous switch, it can make control strategy to switch based on load character, so the switch could close or open at the optimum phase of power system. Synchronous switch could effectively restrain transient state, protect the insulation, improves the quality of power. At present, synchronous switch is mostly used in capacitor banks’ switching for reactive power compensator. Controlled switch could reduce the surges and overvoltage of closing and increase the interrupting capacity, reduce the contact damage.Synchronous switch includes controller and vacuum circuit breaker. Now, DSP and AVR microprocessor are generally used in synchronous controller. The common grounds of them are excellent computing and signal processing ability. But their real feature and timing control ability is relatively weak and the program of both of the microprocessor is vulnerable to interference. The paper puts forward a synchronous control system based on FPGA, which is more suitable for high-speed and easily computing system. This system has the features of perfect real time, good reliability and flexible structure, which make it appropriate for synchronous control system.Firstly, the paper analysis the strategy of three-phase capacitor banks’ switching for reactive power compensator concisely and makes program verification. On this basis, introduce the hardware of controller which is in core of FPGA minimal system. In the software design unit, accomplish several function modules with Verilog in Quartus ii environment. At last, timing simulation, verification of program function and gate-level delay time are given in this part by using Modelsim software.Synchronous switch is normally working in high current and high-intensity magnetic field environment, which requires high reliability of system. The paper makes EMC design to synchronous switch and improves the anti-jamming ability. The switch has also passed five kinds of anti-interference test. In the last part, the sample of synchronous switch is sent to experimental station and made type test. The result shows that, synchronous switch has effectively restrains the inrush current. The precision of the phase of the switch is within0.55ms, and the control system operates properly. The results of the experiment prove the reliability and practicality of the sample.