Coordinated agent-based control for online voltage instability prevention

Abstract

In this paper, a new method for online voltage instability control suitable for smart grid application is proposed. The method uses the Maximum Loadability Index to determine the amount of load relief necessary to restore stability. This measure can be determined based on local measurements. The load relief is obtained by: increase of local generation, virtual load shedding via adjusting the Load Tap Changers (LTCs) set-point, intelligent load control and the increase of reactive power compensation from Static Var Compensators. For the local generation, the control of two types is described: for micro Combined Heat and Power (micro-CHP) units and for large synchronous generators. In order to obtain constant power supply from a group of micro-CHPs, a Virtual Power Plant coordination method is proposed. The control of the actuators is outlined, and a method is described to coordinate their actions. Based on simulations it is demonstrated that the proposed method works properly: voltage collapse can be avoided, and voltage stability is restored. A sensitivity analysis is performed to determine the optimal settings of the coordinated controller. Furthermore, the merit of including reactive power control in the proposed control strategy is investigated. Compared to classical controls, such as Under-Voltage Load Shedding and LTCs tap blocking, the method performs better. Copyright © 2013 John Wiley & Sons, Ltd.