OUTPUT-FEEDBACK TCSC CONTROLLERS TO IMPROVE DAMPING OF MESHED MULTIMACHINE POWER-SYSTEMS

Methods for co-ordinated design of output feedback damping controllers , for thyristor-controlled series compensators (TCSCs) in a meshed pow er system, are developed in the paper. The locations for installing TC SCs and the co-ordination of TCSC controls are determined by analysing the mode controllability. The analysis of mode observability is used to select the effective output feedback signals local to the TCSC loca tions. The design of controller gains is divided into two steps. First , initial gains for each controller are calculated according to the co -ordination determined by the analysis of the mode controllability. Th ese initial gains are then optimised by using linear programming to sa tisfy the given design criteria, It is shown that, by using this proce dure, the desired damping of the critical modes can be achieved withou t significantly deteriorating the damping of the other modes the stabi lity the power and of system. It is also shown that the prolonged satu ration in the TCSC actuators and the adverse interaction among TCSC co ntrollers can be avoided. The proposed controller design methods are v alidated by a case study.