A ROBUST DECENTRALIZED POWER SYSTEM LOAD FREQUENCY CONTROL

Hossein Shayeghi

   This paper presents a new robust decentralized controller based on mixed H₂/H_&infin control technique for the solution of Load Frequency Control (LFC) in a deregulated electricity environment. To achieve decentralization in each control area, the connections between this area and the rest of the system and the effects of possible contracts are treated as a set of new disturbance signals. It is shown that, subject to a condition based on the structured singular value (&mu), each local area load frequency controller can be designed independently so that stability of the overall closed loop system is guaranteed. In order to minimize effects of load disturbances and to achieve desired level of robust performance in the presence of modeling uncertainties and practical constraints on control action the idea of mixed H₂/H_&infin control technique is being used for the solution of LFC problem.This newly developed design strategy combines advantage of H₂ and H_&infin control syntheses and gives a powerful multi- objectives design addressed by the Linear Matrix Inequalities (LMI) technique.To demonstrate the effectiveness of the proposed method a two-area restructured power system is considered as a test system under different operating conditions.The results of the proposed decentralized controller are compared with the conventional PI and pure H_&infin controllers and are shown to minimize the effects of load disturbance and maintain robust performance in the presence of specified uncertainties and system nonlinearities.

Keywords: LFC, decentralized control, restructured power system, mixed H₂/H_&infin control, robust control, LMI

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