Day-Ahead and Intra-Day Optimization of Flexible Interconnected Distribution System with Self-Energy Storage Based on the Grid-Side Resource Coordination
Li Yong1, Ling Feng1, Qiao Xuebo2,3, Zhong Junjie1, Cao Yijia1
1. College of Electrical and Information Engineering Hunan University Changsha 410082 China; 2. Electric Power Research Institute of China Southern Power Grid Guangzhou 510663 China; 3. School of Electric and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China
Abstract：The integration of high-permeability distributed photovoltaic (DPV) has introduced new technical challenges for the operation and control of distribution networks. Soft open point (SOP), a typical flexible interconnection equipment that can replace traditional interconnection switches, is capable of accurately controlling power flow between feeders, as well as dynamic reactive power compensation. It provides a new approach to improving the operation level of distribution networks with high-permeability photovoltaics. However, the current cost of SOP remains high, making it necessary to investigate coordinated operating strategies between SOP and traditional grid-side control equipment, and achieve economic and efficient distribution network operations across multiple time scales. Therefore, this paper proposes a day-ahead and intra-day optimization model of flexible interconnected distribution system with self-energy storage based on grid-side resource coordination. Firstly, a multi-time scale optimization control framework is proposed to facilitate the coordinated utilization of multiple grid-side resources within the 'source-network-load-storage' paradigm.In the day-ahead stage, this paper puts forward a long time-scale optimization model that coordinates the active and reactive power considering various devices such as on-load tap changers (OLTC), reactive power compensation devices, interconnection switches, E-SOP, and flexible loads (FL). For the intra-day stage, a comprehensive multi-objective rolling optimization model is presented, which is subsequently transformed into a mixed integer linear programming model through the application of linearization techniques. Moreover, a fuzzy set representing the uncertainties associated with source and load is developed using KL-divergence. The transformation process of the two-stage distributionally robust optimization (DRO) model is proposed, and the solution method based on the column and constraint generation (C&CG) algorithm for the day-ahead stage is provided. The multi-objective intra-day model is solved using the ideal point method. The numerical results demonstrate that, in the day-ahead stage, the coordinated optimization of E-SOP, OLTC, and network reconfiguration proves beneficial in reducing operational costs. Moreover, it is observed that OLTC has a more significant impact on network loss reduction compared to network reconfiguration. Additionally, the utilization of the distributionally robust optimization (DRO) method allows for a balance between economic efficiency and robustness in the day-ahead optimization scheme. During the intra-day stage, the multi-objective optimization results in network loss values and voltage deviations that lie between those obtained from the two single-objective optimizations. This ensures that the distribution network attains improved economic efficiency while maintaining security. The operation strategy for rapid control equipment is optimized at 15-minute intervals. SOP plays a crucial role in swiftly transferring active power between feeders to optimize power flow and voltage distribution within the distribution network. It works in conjunction with SVC to provide reactive power support. Furthermore, energy storage charging/discharging and flexible load (FL) responses also contribute to network loss reduction and enhanced voltage distribution. The following conclusions can be drawn from the study: (1) The day-ahead and intra-day optimization based on the grid-side resource coordination can give full play to the fast and slow regulation characteristics of the grid side control equipment, and improve the operation efficiency of the distribution network. (2) In the day-ahead stage, the total operation cost of coordinated optimization of E-SOP, OLTC and network reconfiguration is about 8.0% lower than that of E-SOP alone. (3) In the intra-day stage, multi-objective rolling optimization can take into account the network loss and voltage optimization, and can obtain more accurate operation strategies of various rapid control equipment. This paper only aims at the coordinated utilization of grid-side resources in the day-ahead and intra-day stage. The next step is to research on the multi-time scale operation optimization of “day-ahead optimization, intra-day rolling and real-time correction”.
李勇, 凌锋, 乔学博, 钟俊杰, 曹一家. 基于网侧资源协调的自储能柔性互联配电系统日前-日内优化[J]. 电工技术学报, 2024, 39(3): 758-773.
Li Yong, Ling Feng, Qiao Xuebo, Zhong Junjie, Cao Yijia. Day-Ahead and Intra-Day Optimization of Flexible Interconnected Distribution System with Self-Energy Storage Based on the Grid-Side Resource Coordination. Transactions of China Electrotechnical Society, 2024, 39(3): 758-773.
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2024, Vol. 39 
