Wind farms in weak grids stability enhancement: SynCon or STATCOM?

Abstract

Reactive power compensation is an effective method to enhance stability of a power system. Synchronous condenser (SynCon) and static synchronous compensator (STATCOM) are widely used for reactive power compensation. They have the capability of increasing system stability and efficiency by absorbing or generating reactive power. This paper presents a comparison of SynCon and STATCOM under the condition of zero reactive power injection. The two devices are integrated into a grid-connected type-4 wind farm to examine their effects on system stability. It is found that SynCon is more capable in stability enhancement compared to STATCOM. To explain the difference, we measure the dq-frame admittance frequency-domain responses of the two devices using frequency scans. Vector fitting method is then utilized to convert the admittance frequency-domain measurements to an s-domain model. The s-domain admittance-based eigenvalue analysis further confirms that SynCon is advantageous in stability enhancement. The difference of SynCon and STATCOM can be summarized as SynCon providing a steady-state reactance while STATCOM acting as a current source at steady state.