Dynamic partitioning method for independent energy storage zones participating in peak modulation and frequency modulation under the auxiliary service market

With the increasing installed capacity of energy storage and the rapid accelerating process of electricity marketization, grid-side independent energy storage are beginning to generate profit by participating in the ancillary service market and reducing the strain on the grid. Although energy storage are currently involved in only one auxiliary service, their low utilization and low revenue can make it difficult to recover costs quickly. A method is presented in this article for optimizing peak modulation (PM) and optimizing frequency modulation (FM) in the auxiliary services market by dynamically partitioning independent energy storage partitions. This paper focuses on developing a method for secondary power allocation that is combined with two-level nested optimization. For two different markets and two different methods, separate power allocations are required. The outer layer optimization depends on the inner layer optimization results to produce the optimal primary allocated power, and the inner layer optimization is constrained by the outer layer optimization results to produce the optimal secondary allocated power. Additionally, the method can not only be applied to fixed type energy storage, but also to pure PM stations and pure FM stations; this paper also proposes an improved method for energy storage containing two batteries and providing two auxiliary services. According to the results of the study, the proposed strategy has a better economic value as well as better engineering value as compared with a single auxiliary service and two different coordination methods.