A Control System for Static VAr Compensator Based on a Digitally Controlled Oscillator

This article deals with the design, construction, and testing of a new control system for a static VAr compensator. The new control system is based on monitoring reactive power, which is used as the only feedback variable for a digitally controlled oscillator. In addition to synchronizing the static VAr compensator with the AC system, the digitally controlled oscillator also schedules the firing of converter valves in order to achieve the reactive power compensation level required in the AC connection bus. The control system design was initially developed in MATLAB (R) and Simulink (R) (The MathWorks, Natick, Massachusetts, USA), and then a +/- 1-KVAr static VAr compensator experimental prototype was built. The static VAr compensator control system was implemented in a PIC16F877 microcontroller (Microchip Technology Inc., Chandler, Arizona, USA). Computer simulations and experimental results for the static VAr compensator and its control system are presented in the article. Finally, the performance of the proposed static VAr compensator control system was compared with a phase-locked loop control system for a static VAr compensator, and the relevant results are presented.