DETERMINATION OF STABILITY MARGINS IN SINGLE AREA LOAD FREQUENCY CONTROL SYSTEM HAVING INCOMMENSURATE COMMUNICATION DELAYS DUE TO PLUG-IN ELECTRIC VEHICLES

Abstract

This work investigates the impact of time delays on the stability of a single-area load frequency control (LFC) system that includes plug-in multiple electric vehicles (EVs) aggregators to regulate the system frequency. Communication delays are caused by open communication networks used to transceive control signals. These delays can degrade the performance of the controller leading to undesired system frequency oscillations and may even cause instability if they exceed an upper bound limit known as stability margin. These delays can be commensurate or incommensurate depending upon the nature of the communication network. Hence, it is important to determine stability margins of the single-area LFC system with plug-in EVs aggregators to ensure the stable operation under both types of delays. This study determines the stability margins for extensive proportional-integral (PI) controller gains of the single-area LFC system with plug-in EVs by implementing a simulation approach. The knowledge of stability delay margins makes it possible to appropriately tune the PI controller gains that ensure a stable operation of the LFC system even in the presence of inevitable communication delays.

Keywords

• Load frequency control
• Electric vehicles
• Communication delays
• Stability margins

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