New research on renewable-dominant power systems: Optimizing transmission and storage planning

In the ongoing quest to integrate renewable energy (RE) into power systems, a new study published in Engineering offers valuable insights into coordinated transmission, renewable, and storage expansion planning (TRSEP). The research, led by Qian Yang, Jianxue Wang and colleagues from Xi’an Jiaotong University, presents a novel approach to address the challenges posed by the randomness and volatility of renewable energy sources.

The study emphasizes the importance of adequate transmission capacity and energy storage systems (ESSs) in facilitating the integration of renewable energy into power systems. As renewable energy penetration increases, the need for effective planning strategies becomes more critical. The authors propose a TRSEP model that not only considers the internal loads of the system but also the proportion of renewable energy in tie lines, which is essential for green power trading between systems.

A key innovation in this research is the definition of Renewable Energy Power Flow Density (RE-PFD), inspired by the concept of Carbon Emission Flow (CEF). RE-PFD allows for the tracking of renewable energy transmission paths, distinguishing between internal loads, external loads, and energy losses. This method provides a detailed understanding of how renewable energy is distributed and utilized within a power system.

The TRSEP model developed in this study is designed to cope with the impacts of climate change and achieve renewable energy penetration targets. It includes operational constraints for RE-PFD, ensuring that the model can accurately reflect the proportion of renewable energy in different parts of the system. The model also incorporates investment constraints and operational constraints for units and networks, making it a comprehensive tool for power system planning.

To address the bilinear terms in the proposed model, the authors apply the McCormick method, a technique used to linearize nonlinear programming problems. A customized feasibility correction strategy is designed to ensure that the solutions obtained are feasible. This strategy involves iterative adjustments of key parameters to narrow the feasible region, ultimately yielding a solution that meets all constraints.

The study includes numerical results from case studies using Garver’s six-bus test system, the IEEE-118 test system, and an actual provincial power system. These results demonstrate the effectiveness of the proposed approach in distinguishing the renewable energy transmission path and meeting both internal and external renewable energy requirements. The findings highlight the necessity of constructing ESSs to ensure power system balance and the significant impact of the location of external load buses (ELBs) on planning results.

The research also explores the concept of energy transition areas, where specific requirements for the proportion of renewable energy are set. The results show that different energy transition areas can significantly impact the distribution of renewable energy capacity in the planning results.

This study presents a robust and detailed approach to coordinated transmission, renewable, and storage expansion planning in renewable-dominant power systems. The proposed TRSEP model and the customized linearization correction strategy offer valuable tools for planners aiming to integrate renewable energy effectively and meet green power trading requirements. Future research may focus on optimizing the iterative framework to improve the iteration effect and further enhance the solvability of the model.

The paper “Coordinated Transmission Renewable-Storage Planning in Renewable-Dominant Power Systems Considering Energy Transmission Pathways,” is authored by Qian Yang, Jianxue Wang, Zhiyuan Li, Yao Zhang, Xiuli Wang, Xifan Wang. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.02.014. For more information about Engineering, visit the website at https://www.sciencedirect.com/journal/engineering.