Power Output Smoothing for Renewable Energy System: Planning, Algorithms, and Analysis

The growing penetration of renewable energy sources in electricity generation will bring challenges to the power grid operations due to the intermittency and fluctuation of renewables. In this article, we employ an energy storage system (ESS) in a grid-connected renewable energy system (RES) to serve the electrical load from the power grid. We study the control algorithms of the ESS to smooth the renewable generation and analyze the tradeoff between the ESS size and the system performance, i.e., renewable utilization and operation cost. We provide performance guarantees of the proposed algorithms and propose an optimization framework to configure the ESS. To analyze the reliability of the RES, an analytical framework using the Markov modulated fluid queue is devised. It is shown in our simulation studies that the devised power output smoothing algorithm outperforms other existing algorithms in terms of operation cost under different sizes of ESSs. We also find that, to satisfy the renewable utilization requirement, the required ESS size blows up with both the amplitude of fluctuation and the intermittency level of the profile gap between the renewable generation and the load.