Delay-dependent stability analysis of a two-area load frequency control system with electric vehicles and dynamic demand control

Electric Vehicles (EVs) and Dynamic Demand Response (DDR) applications have become a promising tool for frequency regulation (Load Frequency Control-LFC) in an interconnected system with one or more independently controlled areas. This is due to increasing environmental concerns, gradual depletion of fossils resources and increased penetration of highly variable renewable energy (RE) power generation. Batteries in EVs can increase or decrease faster power output than conventional generators. This fast response characteristic enhances dynamic performance of LFC system. EVs can be used as generators or loads and hence reduce generation/demand fluctuations, and improve frequency response. The real-time DDR applications allow the system to manage the variability of RE sources by adjusting responsive loads contributed for proper balance between generation and loads. The integration of EVs and DDR control loops into LFC system requires a communication network to send control signals to EVs and DDR aggregators. For this purpose, an open distributed communication network is generally used. However, uncertain time delays are observed in such a communication network. These delays can cause instability of power system against an expectation that EVs and DDR applications having fast-response characteristics can improve the LFC performance. Hence, it is important to investigate delay-dependent stability of LFC system enhanced by EVs and DDR loops (EV-DDR-LFC) and to develop robust controller design techniques in the presence uncertainties in system parameters and time delays.The purpose of this project is to investigate the delay-dependent stability of two-area EV-DDR-LFC systems and to design robust proportional-integral (PI) controller. For that purpose, stability delay margins of the EV-DDR-LFC are determined using a simulation approach for different values of EAs and DDR participation factors and PI controller Gains. Results shows that the integration of EAs and DDR loop improves the Stability of the two-area LFC System.