Optimization dispatch method for hydro-wind-solar systems with high proportion of hydro power considering frequency regulation and transmission interface constraints

Abstract

[Objective] This study aims to address the limitations of existing research on the optimal scheduling of hydro-wind-solar hybrid systems, which primarily focuses on energy balance while giving insufficient attention to safety factors such as frequency support and transmission interface constraints. To this end, an optimal scheduling method for hydropower-dominated hydro-wind-solar systems is proposed, incorporating frequency security constraints and transmission interface limits. [Methods] Based on an analysis of the inertia support capability inherent to hydro-wind-solar coupling systems, an optimization model embedding frequency security constraints and transmission capacity constraints is developed. Key indicators such as system inertia constants and primary frequency regulation reserves are quantified through analyzing hydropower start-stop dynamics to evaluate the system's frequency support capacity. Further comparative analysis examines the impact of incorporating transmission constraints on frequency regulation performance. Using data from a southwestern province in China, the proposed algorithm is validated through simulations under multiple scenarios, considering both single and multiple sudden load fluctuations, with and without transmission constraints. [Results] Simulation result demonstrate that across various scenarios, the proposed scheduling strategy effectively ensures that energy output meets load demand. Although the system's overall frequency support capability slightly decreases after incorporating transmission constraints, it still fulfills frequency regulation requirements and mitigates the risk of transmission line overload. [Conclusion] The proposed optimal scheduling method can meet frequency regulation demands under disturbance scenarios, both with and without transmission constraints. It enhances system frequency support capabilities and further ensures system stability and security.

Keywords

high-proportion hydropower / hydro-wind-solar hybrid system / frequency security constraints / transmission interface constraints / optimal scheduling