PNNL

Abstract

With increasing intermittent renewable generation such as photovoltaics and wind, additional flexibility is required to maintain the instantaneous balance between generation and demand in power systems. Dispatchable assets such as hydropower plants have to respond more often to arrest the imbalance. Responding to load fluctuations and electricity market prices requires increased cycling and ramping of hydropower plants, which results in higher wear and tear, increased degradation, and additional loss of life. This paper studies a hybridization strategy where a hydropower unit is paired with an energy storage systems (ESSs) to increase operational flexibility and mitigate damage on hydro plant. Various models are developed to represent the operation of the hybrid system, quantify degradation effects, and assess economic benefits. In addition, an innovative controller is proposed to disaggregate dispatch signals into separate control set points for ESS and hydropower unit. Case studies were carried out on a real-world hydropower facility to demonstrate the proposed methods and evaluate the hybridization. It was found that the ESS-based hybridization can extend the life of the hydropower plant by 5% on average. The present value of economic benefits from reduced maintenance and deferred investment is computed to be around $3.6 million.