Optimal ESS Investment Strategies for Energy Arbitrage by Market Structures and Participants

Abstract

Despite the advantages of energy arbitrage using energy storage systems (ESSs), the high cost of ESSs has not attracted storage owners for the arbitrage. However, as the costs of ESS have decreased and the price volatility of the electricity market has increased, many studies have been conducted on energy arbitrage using ESSs. In this study, the existing two-period model is modified in consideration of the ESS cost and risk-free contracts. Optimal investment strategies that maximize the sum of external effects caused by price changes and arbitrage profits are formulated by market participants. The optimal amounts of ESS investment for three types of investors in three different market structures are determined with game theory, and strategies in the form of the mixed-complementarity problem are solved by using the PATH solver of GAMS. Results show that when all market participants can participate in investment simultaneously, only customers invest in ESSs, which means that customers can obtain market power by operating their ESSs. Attracting other types of ESS investors, such as merchant storage owners and producers, to mitigate market power can be achieved by increasing risk-free contracts.

Fig. 1. Scheme of ESS ownership and operation for energyarbitrage by market participants

Fig. 2. Two-period model: effects of energy arbitrage usingESS on price and demand in periods 1 and 2

Fig. 3. Two-period model under TOU tariff

Fig. 4. Two-period model under SMP with the assumptionthat ESOs are price-takers

Fig. 5. Welfare changes in CASE 1 according to theamount of ESS for energy arbitrage by the costs ofstoring: (a) welfare changes, and (b) marginalwelfare changes

Fig. 6. Best response functions and Nash equilibrium oftwo customers’ non-cooperative game for CASE 2

Fig. 7. Impacts of risk-free contracts on surplus ofinvestors

Fig. 8. Best response functions of a customer and tensymmetric MSOs and their Nash equilibria according

Table 1. Representative entities

Table 2. Value of market and ESS parameters.

Table 3. Total optimal amounts of ESS investment by each sector by the number of market participants (w =0).