Levelized Cost of Energy Optimization in Hybrid PV Plants by Energy Storage for Ramp-Rate Control Operation

This paper seeks to optimize the levelized cost of energy of a hybrid PV plant considering the integration of an electrical energy storage system to reduce the costs associated with ramp control penalization. The optimization is performed using a real annual profile from a PV plant. Three different minute-to-minute generation profiles based on historical irradiance data are used for the comparison: the time series model, the Hofmann minute model and the Skartveit and Olseth minute model. It is found that the results from the models can predict similar results to the ones obtained from the real profile, thus being a valuable tool for determining the energy storage size for hybrid PV plants during the planning stage.

I. Introduction

Unfortunately, the energy coming from renewable resources is intermittent. The necessity of a higher-penetration rate of renewable generation is accompanied by some drawbacks due to this unpredictable energy source. The main disadvantages affect voltage, power quality, power flow, protection and active devices [1]. Among renewable generation alternatives, solar photovoltaic (PV) particularly exhibits a very low-inertia characteristic in which the irradiance fluctuation due to cloud passing causes sudden variations in the generated energy. When high-penetration of PV occurs in low-inertia grids, the rapid variations of the generation capability can potentially result in undesired grid voltage and frequency fluctuations [2], [3]. These quick ramp-wise variations in the delivered power to the grid can be smoothed by the integration of energy storage systems (ESS), where batteries have been mainly proposed [3].