Decentralized Load-Frequency Control for Interconnected Power Systems with AC-DC Tie Lines

Most of the Load-Frequency Control (LFC) problems in the literature have been treated as single-objective problems till date. This paper emphasizes the need for a multi-objective approach for the load-frequency controller which satisfies two main objectives, namely, minimum Integral Squared Error (ISE) of the system output and maximum closed loop stability of the system. A new Multi-Objective Evolutionary Algorithm (MOEA)-based design of decentralized load-frequency controllers for interconnected power systems with Governor Dead Band (GDB), ac-dc parallel tie lines, and Superconducting Magnetic Energy Storage (SMES) units, is proposed in this paper. AC-DC parallel tie lines provide asynchronous interconnection of neighboring power systems while the SMES units provide bulk energy storage to share the sudden changes in power requirement in the load. Analysis of a two-area interconnected thermal power system reveals that the proposed controller improves the stability and transient response of the system even in the presence of GDB nonlinearity