Design of MOEA based Decentralized Load-Frequency Controllers for Interconnected Power Systems with AC-DC Parallel Tie-lines

A new design of Multi-objective Evolutionary Algorithm based decentralized load-frequency controllers for interconnected power systems with AC-DC parallel tie-lines, is proposed in this paper. HVDC link is connected in parallel with the existing AC link for stabilizing the frequency oscillations of AC system. The proposed controller fulfills two main objectives, namely, minimum Integral Squared Error of the system output and maximum closed loop stability of the system. The optimal Proportional plus Integral controller, obtained by the proposed design, ensures a compromise between Integral Squared Error criterion and Maximum Stability Margin criterion. The proposed design is implemented on a two area interconnected thermal power system with parallel AC-DC tie-lines. System responses show that the transient performance is improved significantly with increased stability margin.