Levelling the Photovoltaic Power Profile with the Integrated Energy Storage System

Abstract

The extensive penetration in the energy mix of variable renewable energy sources, such as wind and solar, guarantees boosting of the transition toward a decarbonized and sustainable energy system as well as tackling of climate targets. However, the instability and unpredictability of such sources predominantly affect their plant production. Thus, utility-scale energy storage is required to aid in balancing supply and demand and, as a result, to prevent unbalances that might cause issues at different grid levels. In the present study, the authors’ patented energy storage technology, known as Integrated Energy Storage System (I-ESS), is combined with a 10 MWp solar plant. The PV plant and the I-ESS unit function as a Virtual Power Plant (VPP). The selected VPP management strategy attempts to optimize the daily hours during which the plant supplies steady power output. Numerical simulations show that the VPP plant can effectively smooth the PV peak and manage the power supply. In particular, by the definition of a novel metric expressing the ratio between regular hours of power provided to the grid plus the energy stored in the backup unit and the total number of hours in a year, the results show that the VPP regularity is relatively high in terms of PV output, ranging from a low of 50% in December to a high of 87% in August. Thus, the proposed VPP arrangement seems to be a promising technology for pushing toward the carbon-neutral transition.

Off-Design Analysis of a TES-Based Electricity Energy Storage System

“…To evaluate in future work the advantages in terms of accuracy of using compressors' and turbines' maps instead of simplified models, the I-ESS design parameters are the same as those in the work presented in Ref. [9].…”

“…Unlike FBs, the I-ESS plant is characterised by a longer cycle life, whereas, compared to PTES, the I-ESS layout features a lower complexity. Despite the previously conducted studies demonstrated the feasibility of the I-ESS plant (see, e.g., [7,8]), and its ability to be coupled with a variable renewable-based facility to smooth its variable production (see, e.g., [9]), it is necessary to investigate the off-design behaviour of the system during the discharge phase. This is a critical phase due to the need for fast matching the grid requirements; a fact that forces the I-ESS plant to operate in off-design conditions.…”