Economic Dispatch in Hybrid Microgrids Considering Time-Varying Voltage-Dependent Load Models

Abstract Renewable energy intermittency, network congestion, voltage fluctuations, and time-varying electricity demand provide operational issues as renewable energy supplies become more prevalent in microgrids. Therefore, coordinated scheduling of conventional production, renewable resources, and battery energy storage is necessary for accurate economic dispatch while specifically taking voltage-dependent demand and network operational restrictions into account. For a hybrid microgrid consisting of diesel generators, photovoltaic (PV) production, wind turbines, and battery energy storage systems (BESS) under time-varying voltage-dependent load conditions, this study creates an economic dispatch framework based on AC optimal power flow (AC-OPF). The cost of diesel generation, curtailment of renewable energy, load shedding, and voltage deviation are all taken into account concurrently by the objective function. A modified IEEE 24-bus test system is used to assess the suggested formulation over a 24-hour operational horizon under various loading and renewable energy availability scenarios. The findings demonstrate that the integration of renewable energy significantly lowers reliance on diesel, operating costs, and locational marginal prices. Additionally, the incorporation of BESS increases operational flexibility, decreases load shedding, and improves voltage control. With a stated total operating cost of Rs 322,387.4, the combined renewable-energy and BESS configuration outperforms the traditional Case 1, which has a total operating cost of Rs 639,162.4. The reduced-load Case 4(b) yields the lowest reported cost of Rs 198,387.2, whereas the increased-load Case 4(c) yields Rs 497,218.3. The findings also show that higher penetration of renewable energy might raise network congestion and decrease fuel usage at the same time due to increased power transmission over limited branches. As a result, the suggested framework offers a physically consistent AC-OPF-based method for coordinating BESS, voltage-dependent loads, and renewable resources in hybrid microgrids while emphasizing the necessity of jointly optimized and uncertainty-aware storage design in subsequent research.