Strategies of voltage controllers in delta-connected H-bridge STATCOMs

This paper presents strategies for a voltage controller in which droop control and var reserve control (an auxiliary controller) are included in delta-connected H-bridge STATCOM. To supply the linear property and load sharing effect, the droop control has been applied to a voltage controller. In addition, the var reserve control has been chosen to enlarge the output margin depending on the dead band range. According to the installation environment, the two auxiliary controllers are chosen. However, the combination control of two auxiliary inputs has not been determined. In this paper, three different control strategies (combination methods) are proposed, and the trajectory of equilibrium point is identified. The three combination methods are implemented from HILS tests.