Voltage-Sourced Converters in Power Systems

11

Static Compensator (STATCOM)

11.1 INTRODUCTION

In this chapter, we analyze the static compensator (STATCOM).¹ The STATCOM is a VSC system whose prime function is to exchange reactive power with the host AC system. In an electric power transmission system, the STATCOM can be used to increase the line power transmission capacity [1], to enhance the voltage/angle stability [95], or to damp the system oscillatory modes [96]. In a distribution system, the STATCOM is mainly used for voltage regulation [97]; however, it can also supply real power to the loads in the case of a blackout if it is augmented with an energy storage device, for example, a battery storage system. Moreover, the STATCOM may also be employed to balance a distribution network by compensating for load imbalances.

In this chapter, we demonstrate that the STATCOM is a special case of the controlled DC-voltage power port that was introduced in Section 8.6 (Section 7.5 for αβ-frame control). Although this model enables one to analyze different applications of the STATCOM, in this chapter we merely focus on the application of the STATCOM for AC voltage regulation. Even though the STATCOM can also be controlled in αβ-frame, in this chapter we focus on the dq-frame control due to its widespread acceptance in the technical literature. Furthermore, based on a dq-frame platform we are able to formulate and analyze dynamics of the phase-locked loop (PLL). The presented methodology is applicable to most cases where a VSC system ...