Development considerations of DSP-controlled PWM VSC-based STATCOM

The paper addresses key issues surrounding the development of static VAr compensators (STATCOM). The STATCOM is based on a conventional six-switch bi-directional voltage-source convertor topology using insulated gate bipolar transistors. The sinusoidal pulse-width modulation technique is used to control the convertor output voltage (amplitude and phase). Three DC voltage control methods and the trade-off between the value of the DC capacitor and the ripple voltage and the system´s transient response time are investigated. The system´s control, incorporating a VAr calculator and synchronisation, is implemented on a digital signal-processing board, to achieve excellent overall performance. Experimental results for both leading and lagging VAr compensation, along with changes between them, confirm the good performance and the flexibility of the developed prototype