Modeling for operational strategy of flexible ramping capacity in deregulated power system considering EV aggregators participation

The increasing deployment of renewable energy, such as wind, affects the flexibility of electric power system operating due to its inherent variability and uncertainty. To mitigate it, more flexible resources offering auxiliary services are needed for power systems. This paper investigates the potential for electric vehicle (EV) to provide flexible ramping capacity in the real-time market. The proposed model for the strategy of offering ramping products for electric vehicle aggregators is formulated as a bi-level optimization problem. At the upper level, the profit of an EV aggregator is maximized. The economic dispatch model is presented at the lower level, which considers both the energy balance and flexible ramping requirement in context of real-time market. The Karush-Kuhn-Tucker (KKT) optimality condition is used to transform the $bi$-level programming problem into a single objective optimization model. The CPLEX software is used to obtain the optimal solution in the dispatching period. Case studies indicate that the mechanism that electric vehicle aggregators participate in the ramping market can effectively improve economic benefits of power systems.