Hybrid control of a multi‐area multi‐machine power system with FACTS devices using non‐linear modelling

Abstract

Generally, the mathematical formulation of the dynamics governing multi-area power systems with Unified Power Flow Controller (UPFC) is a challenging task owing to the presence of both differential and algebraic sub-systems. The proposed research work attempts to integrate the two subsystems by replacing the algebraic subsystem with a differential approximant that leads to a non-linear system of differential equations. Solution of the proposed model with a properly chosen Lyapunov function produce a nonlinear control signal which damps inter-area oscillations effectively. The non-linear control signal is realised using the backstepping method. Moreover, the new formulation enables utilisation of the law for uncertain parameters using the standard parametric feedback form, such that the advantage of such a controller is unaffected by these parameters. In addition to this major contribution, full utilisation of UPFC, by using a lone multi-variable PI controller which eliminates negative interaction between the controllers, is also achieved. Empirical verification of the proposed approach is done by simulating various scenarios with varying degrees of complexity – from dual area power networks to 39 buses New England system. The results of the experiments indicate the efficacy of the method.