A microcomputer controlled static VAr compensator for power systems laboratory experiments

The authors report the development of the laboratory model of a microcomputer-controlled static VAr compensator. The model can be useful for teaching. A control circuit with simple hardware was designed to fire the thyristors whose delay angles were controlled by the programmable interval timer 8253. Simple software strategies of either proportional plus derivative (PD) or proportional plus integral plus derivative (PID) control were introduced. Interactive display facilities help in selecting various control parameters (such as proportional, derivative, and integral constants, reference voltage, etc.) through the keyboard. Some experiments useful for students are proposed and demonstrated by examples and results