Probabilistic Worth Assessment of Distributed Static Series Compensators

The deployment of flexible ac transmission system (FACTS) devices, despite miscellaneous benefits and applications, has been restricted mainly due to their large investment costs. Accordingly, the notion of distributed FACTS (D-FACTS) was recently proposed. Distributed static series compensators (DSSCs), as a new member of D-FACTS, are directly clamped to conductors of transmission lines. The possibility of controlling the compensation rate of DSSCs from the control center affords the active control of network power flow. This paper presents a comprehensive reliability model for the DSSC. The model is then reduced and a state-space representation is extracted for a transmission line with a number of DSSCs. To illustrate the worth of DSSC utilization, the increment in the expected interruption cost is computed by using a composite reliability assessment. In the contingency analysis procedure, incorporating the active control of power flow provided by DSSCs makes the optimal load curtailment subproblem nonlinear. In order to linearize the subproblem, a novel set of inequalities is extracted. Numerical analysis on the IEEE Reliability Test System (RTS) is conducted to examine the effect of DSSC on composite reliability indices. The results reveal the effectiveness of proposed models and illustrate that DSSCs enhance the system reliability.