Design And Realization Of TSC Reactive Power Compensation Device Based On DSP

The reasonable distribution of reactive power is one of key problems to improve the security and economy of power system and it has always been highly valued by electric power companies. In order to avoid the distance transmission of reactive power and to provide safe, economic, reliable energy to customers, the electric power companies realize reactive power local compensation by reactive power compensation devices. The customer whose power factor is lower than the standard will be fined by the electric power companies and rewarded if their power factor is higher than the standard. So, the improvement of power factor is important to both electric power companies and customers. Thyristor switched capacitor is a high performance-price rate reactive power compensation device. Because of using thyristor instead of mechanical switch, it has quick response speed and can realize accurate control.A kind of TSC reactive power compensation devices is designed and realized in this paper, including hardware design and software design. Hardware design mainly include sampling circuit design, synchronous square wave circuit design, optical fiber isolation and thyristor drive circuit design, thyristor voltage balance circuit design, DSP power supply circuit design and hardware watch dog circuit design. The reliable design of hardware ensures device acquires system parameters accurately, thyristor trigger reliably and DSP operates normally. In the side of software design, a DSP chip named TMS320F28335is used as control chip. In order to make use of its powerful function, it is programmed by C language to realize the accurate calculation of system parameters, the control strategy, the circulate switching of capacitors, the thyristor pulse transmitting and other functions. A composite control strategy with power factor and reactive power is used in this paper to avoid the oscillate switching of capacitors. The trigger pulse of thyristor consists of continuous pulse train and other pulse sent at the time of system peak voltage. The way send trigger pulse can reduce the loss of thyristor gate and ensure thyristor operate reliably.On the base of hardware design and software design, the prototype is made. The test results show that the TSC reactive compensation device based on DSP designed in this paper is effective and reliable. It can follow the change of system parameters accurately and compensate reactive power quickly. Moreover, it does not have the problem of oscillate switching of capacitors and realize the function of circulate switching of capacitors. The strategy of putting capacitors into system at the time of zero voltage can inhibit inrush current effectively.