A PC-DSP-based unified control system design for FACTS devices

This paper presents a practical implementation of a PC-DSP-based unified control system for FACTS. Based on C++ technology, the DOS-kernel-WINDOWS-outface PC system provides real-time monitoring, control, coordination, and protection to the two DSP-based slave subsystems. The PC also works as a testbench to provide online and offline analysis of FACTS devices. Tasks such as real-time data display, data recording and operation mode switching are easier to perform. The DSP-based data acquisition subsystem (DAS) implements real-time signal processing such as digital filtering, space phasor calculation, and system frequency measurement. Combined with its unique synchronous signal generator circuit, the DAS measures the system frequency within 0.01 Hz. The DSP-based PWM control signal generation subsystem (CSGS) is capable of generating the programmable switching signals with adjustable blanking time. Also with its embedded finite state machine (FSM) it can provide unique fault indication and protection for FACTS devices. The unified control system has been successfully used in a scaled UPFC at the University of Missouri-Rolla