Shared hybrid energy storage system optimal configuration in multi-energy microgrid system considering the transformer waste heat utilization: A tri-layer programming approach

Abstract

The shared hybrid energy storage system (SHESS) offers a potential solution to high initial investment costs for multi-energy microgrid system (MEMS) users and satisfies demands of loads with fluctuations across multiple timescales. In this context, this paper focuses on SHESS applied in MEMS. Firstly, a pricing method combining capacity leasing with flow billing is proposed. Secondly, a tri-layer programming approach is constructed to obtain the optimal leased capacities of different types of energy storage (ES). This approach balances the interests of SHESS operators and MEMS users in the upper and middle layers, while considering the response characteristics in the lower layer. Additionally, this paper introduces a transformer waste heat utilization system (TWHUS) to reduce energy costs in MEMS. To facilitate the calculation of waste heat, a three-dimensional finite element model is established to derive a quadratic mathematical model for heat generation power based on the transformer load rate. Finally, simulation results from various comparative experiments demonstrate that: (1) The proposed pricing method reduces the cost of MEMS by 14.92 %. (2) The comparison of operating costs with and without TWHUS shows a 22.64 % reduction in overall costs, confirming the system's economic viability. (3) Comparing different types of ES combinations reveals that a three-type ES combination minimizes operational power fluctuations in SHESS. (4) The proposed combination of algorithms can efficiently and effectively solve complex tri-layer optimization problems. (5) The offered tri-layer programming approach can achieve a more balanced and reasonable leased capacity configuration, with highly efficient, needing only 5 iterations to converge.