Optimal Placement of <italic>H</italic>&#x221E; Loop Shaping Damping Controller Using Dynamic Relative Gain Array

Abstract

Low-damping inter-area oscillation is a severe problem for the smooth operation of the interconnected power system. These oscillations are observed due to the bulk power transmission from one area to another through a weak tie line. The power system becomes unstable or even blackout due to such oscillations. Hence, it is necessary to identify these oscillations accurately. This paper deals with the identification of different electromechanical modes and the optimal placement of a damping controller in the power system. Dynamic Relative Gain Array (DRGA) tools are adopted to identify the optical location of the Power System Stabilizers (PSS) to damp out the inter-area oscillations. In a Multiple-Input Multiple-Output (MIMO) system, the DGRA number gives an idea of the interaction of the different control loops. DRGA identified the control loop with the least interaction with others. The parameters of the PSS are optimally determined using a residue-based approach. A loop-shaping (LS) based $H_{\infty }$ controller is also proposed and optimally placed using the DRGA approach for further improving the damping of the inter-area oscillations. The DRGA analysis approach is compared with the model analysis approach like the speed-based residues, and perticification factor analysis approaches. IEEE-39 bus test system is used for verifying the damping performance of the proposed controllers. It is verified from the obtained results that $H_{\infty }$ LS controller is optically placed and the damping of the inter-area oscillations is improved effectively.

Keywords

• Relative gain array (RGA)
• power system stabilizers (PSS)
• low frequency oscillation