Event-based optimization for smoothing ramp events in combined Wind-Storage energy systems

Abstract

Ramp events caused by intermittent wind power are increasingly intensifying, seriously threatening the stability and economy of power systems. This paper proposes a novel event-based optimization (EBO) method to smooth the impact of ramp events by balancing energy between wind farms and pumped storage power stations. Firstly, ramp events in wind farms are modeled by using discretization energy within given intervals, which is suitable for the EBO framework. Then, a value function is defined to search the discrete smoothing strategy with event constraints, such as switching operation conditions, the storage capacity of pumped storage, etc. The event-based Q-factor, composed of value functions, is used to search the optimal actions with complicated constraints under a single-stage and multi-stage framework. Finally, a simulation example is developed according to the operation data of an actual wind farm, and the smoothing effect of the strategy is verified by comparing it with the dynamic programming algorithm. Simulation results show that the proposed EBO method can smooth the impact of ramp events by flexibly combining the features of wind farms and pumped storage power stations.

Keywords

• Ramp events
• Combined wind-storage energy systems
• Event-based optimization
• Discrete dynamic system