Impact analysis of different operation strategies for battery energy storage systems providing primary control reserve

Abstract

Regarding the supply of primary control reserve (PCR), stationary battery energy storage systems (BESS) are a promising alternative to fossil fuel power plants. They offer the ability to respond fast and precisely to grid frequency deviations and may contribute to reducing the must-run capacity of fossil fueled power plants.In Germany, primary control reserve is traded on a separate auction market with specific regulations, which enable the BESS to use a number of measures to balance its charge level and preserve operability. However, little is known about how the requirements from primary control deployment and the measures to keep the BESS operational during PCR contract periods affect operational parameters of the system. This study investigates the impact of operation strategies on different parameters including energy exchange through schedule transactions, total energy turnover, full cycle equivalents (FCE), and state-of-charge (SOC) distributions in a case study for a 2MWh BESS under the German regulatory framework.The results of this study are key to the economic assessment of BESS providing PCR, to an optimization of BESS operation, and to an estimate of battery aging in this specific application field.Based on battery operation simulations, individual elements of operation strategies are identified and their influence on BESS operational parameters is analyzed in a parameter variation. These elements include the chosen measures for charge level management, the SOC ranges, within which these measures are used, parameters defining the schedule transactions, and the prequalified power rating of the BESS.The results show that the choice of the measures for charge level management, the choice of schedule transaction parameters and the prequalified power rating of the BESS have a major impact on energy exchange through schedule transactions. The choice of the measures for charge level management and the choice of schedule transaction parameters have limited influence on the total energy turnover and the resulting number of FCE. These values are mainly influenced by the system design.