Local power flow based decentralized TCSC controller

This paper describes an optimal TCSC (thyristor controlled series capacitor) control method which can be applied to local lines to suppress power flow deviations based on local information obtained at each bus. The main objective of introducing TCSC is that it can be used for improving the system stabilization along with the existing equipment. However, the practical control method should meet some requirements, such as the clock synchronization between collecting and using information for the control, and it should be applicable to a multi machine system. The proposed method is based on the fact that the location of the contingencies can be estimated from only power flow deviations at local buses which are measured after the disturbance occurs. As the power system has many variables, it is necessary to find the control method which designs an optimal controller for each TCSC. In this paper, to encounter this problem easily, an optimal regulator theory is used. A DC power flow calculation and a generalized inverse matrix are used to make a relation between the state variables and the power flow deviations. The simulations with 4-machine 11-bus system model show the effectiveness of the proposed method. Three different cases, namely without control, central control, and the local control are compared. The proposed method adequately controls the amounts of TCSC which are very close to those of a centralized one. It reflects small frequency deviations compared with that of an uncontrolled method. The improved transient performances of frequency deviations are also shown in the simulation tests.