Digital Simulation of forty Eight Pulse STATCOM for Reduction of Voltage Instability and Improvement of Power Quality

With the trend of progression of distributed generation within a bulk power system, there is a need to support bus bar voltage by injecting appropriate reactive power, which can also improve the dynamic behaviour of a power system. Static Synchronous Compensators (STATCOMs) is a power electronic based synchronous voltage generator (SVG), which provides embedded control of transmission-line voltage and power flows. The paper represents the internal structure of the forty eight pulse STATCOM-based on two24-pulse GTO-based converters, phase-shifted by 7.5 ° from each other for reduction in THD at the output voltage of the load in power systems. The integration of energy storage with a STATCOM can extend traditional STATCOM capabilities to four quadrant power flow control and transient stability improvement. The proposed model of the STATCOM is connected to a 25kv, 60 Hz system and simulation (in MATLAB) results are presented for demonstrating its steady state and dynamic performance. Fast Fourier Transform (FFT) analysis has also been carried out and the results showing the value of THD within acceptable limit and fast control of the reactive current. Thus the STATCOM shows excellent transient response to step change in the reactive current reference.