关键词: ICEEMDAN, 混合储能系统, 电压波动, 光伏并网, 两阶段规划

Abstract:

To address the safety and stability issues caused by power fluctuations in renewable energy generation and load in regional distribution networks, while considering the coupling of high-frequency and low-frequency fluctuations in renewable energy generation and the coupling of fluctuations on both the source and load sides, this paper proposes a two-stage hybrid energy storage configuration method based on empirical mode decomposition and multi-objective optimization. The proposed framework aims to establish a coordinated optimization mechanism that integrates high/low-frequency fluctuation mitigation with system economic operation and stability. In the first stage model, a moving average filter is used to obtain the power fluctuations that the hybrid energy storage system needs to mitigate. Then, the Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN) is employed to separate the high-frequency and low-frequency components of the minute-level grid-connected power fluctuations. By considering the comprehensive cost of supercapacitors (SC) and the minute-level fluctuations, the optimal noise standard deviation (NSTD) and the boundary number between high-frequency and low-frequency modes are determined to achieve the optimal SC configuration for mitigating the high-frequency minute-level fluctuations in photovoltaic generation. In the second stage model, a multi-objective optimization based on the improved multi-objective particle swarm optimization algorithm is performed to optimize the energy storage system (ESS) capacity in the hybrid energy storage system, aiming to minimize the system's comprehensive cost, power loss, and voltage fluctuations. This approach provides a hybrid energy storage configuration scheme that simultaneously addresses both minute-level and hourly-level fluctuations. The effectiveness and superiority of the proposed method are validated using the IEEE 33-node system. The results demonstrate that, compared to traditional methods, the proposed method can effectively consider the coupling of high-frequency and low-frequency fluctuations at individual nodes and the coupling of low-frequency fluctuations across the system. Specifically, it reduces the minute-level high-frequency grid-connected fluctuations by 91.1%, the average voltage deviation by 10.1%, the maximum voltage deviation by 55.4%, the system power loss by 55.9%, and the system's purchased electricity by 10.88%.

Key words: ICEEMDAN, hybrid energy storage system, voltage fluctuations, photovoltaic grid integration, two-stage configuration