Improvement of interactions among FACTS controls

Interaction among the FA CTS (flexible AC transmission systems) devices in a multi-machine system can adversely influence the damping properties of in dividual FACTS devices. In some critical cases, it may even amplify power s wings or increase voltage deviations. This paper presents a global tuning m ethod for the FACTS controllers in a multi-machine system. Based on a non-l inear optimization algorithm implemented in a simulation program, the param eter settings of the FACTS controllers involved can be simultaneously optim ized at transient conditions in coping with the non-linear nature of the po wer system. By minimizing a non-explicit target function in which swing cha racteristics between areas are included, interactions among the FACTS contr ols at transient conditions in the multi-machine system are minimized. Two multimachine power systems equipped individually with a TCSC (thyristor-con trolled series compensator) and a SVC (static Var compensator) are applied to demonstrate the efficiency of the proposed tuning procedure. The results obtained from simulations validate the improvement in damping of overall p ower oscillations. The simulations also show that the optimized FACTS contr ollers are robust in providing adequate damping for a range of conditions o n the system.