Optimal Automatic Generation Control of Interconnected Power System with Asynchronous Tie-lines under Deregulated Environment

Abstract

This article presents the design of optimal automatic generation control regulators for an interconnected power system operating in a deregulated environment. An extra-high-voltage AC transmission line in parallel with a high-voltage DC link is considered as an area interconnection between the two areas. The dynamic model of the power system under consideration is developed by incorporating various types of possible market transaction environments. The designed optimal automatic generation control regulators are implemented, and dynamic system responses for various system states are obtained considering load perturbation in one of the areas. The patterns of open-loop and closed-loop eigenvalues are also determined to ensure system stability with and without optimal automatic generation control regulators. From the investigations carried out in the work, it is inferred that the dynamics performance of the system under consideration has an appreciable improvement when a high-voltage DC link is incorporated in parallel with an extra-high-voltage AC line as an interconnection between two areas as compared to that when only an extra-high-voltage AC line is considered as an area interconnection. The frequency deviations are more in the area in which distribution companies violate the contracts. Moreover, optimal automatic generation control regulators are able to demonstrate the matching of demand with generation under a deregulated environment with different market transactions. The power system model under investigation is marginally stable in open-loop operating mode, while it attains good stability margins in closed-loop mode.