A New Control Strategy for Distributed Static Compensators Considering Transmission Reactive Flow Constraints

This paper presents a new control strategy for a distributed static compensator (also known as distributed STATCOM or DSTATCOM), configured to regulate the reactive (VAr) flow at a point in a transmission system. This new control strategy takes into account the operating VAr limits of that reactive flow in determining the steady-state output of the DSTATCOM. The new control strategy applies a slow reset regulator (SRR) to slowly bias the VAr set point of the DSTATCOM master controller to maintain its steady-state output within a target bandwidth. The operating result maintains an appropriate VAr reserve level from the DSTATCOM for dynamic events in the system. This paper also presents a new algorithm to calculate the operating constraints of the SRR that reflect the VAr flow at the local or remote point in the transmission system and the allowable VAr thresholds for that flow. These allowable thresholds can be utilized to the full extent to lower the steady-state output of the DSTATCOM, maximize its VAr reserve for dynamic events and reduce equipment and associated system operating losses. Modeling, implementation, and simulation of an engineering project show that the new control strategy and algorithm are functioning properly as expected.