Controllable Parameter Region and Variable - Parameter Design of Decoupling Unified Power Flow Controller

An unified power flow controller (UPFC) is a multi-input and multi-output (MIMO) multivariable controller and dynamic interactions are found among its multiple control functions. Focus of study in this paper is to investigate two cases of UPFC control interactions: (1) interactions caused by inappropriate setting of UPFC controller´s parameters; (2) interactions irrelevant with setting of UPFC controller´s parameters, the case of inherent interactions of UPFC control. The work presented in this paper also reveals that with variations of power system and UPFC operating conditions, controllable parameter region of UPFC controllers moves in its parameter space. At two different operating conditions, there could be no union of the corresponding controllable parameter regions. Hence in this paper, a novel variable-parameter control for UPFC based on artificial neural network (ANN) is proposed, in conjunction with a decoupling design of multi-variable UPFC control that is also based on an ANN decoupling control design