Unit commitment optimization method based on linear approximation of AC power flow

Authors

• Shengbo Ji, College of Electrical Engineering ， Zhejiang University ， Hangzhou 310027 ， China ;Zhejiang Provincial Key Laboratory of Renewable Energy Electrical Technology and Systems ， Zhejiang University ， Hangzhou 310027 ， China
• Jinlong Zhang, State Grid Electric Power Research Institute Co .， Ltd. （NARI Group Corporation ） ， Nanjing 211106 ， China
• Ruipeng Guo, College of Electrical Engineering ， Zhejiang University ， Hangzhou 310027 ， China ;Zhejiang Provincial Key Laboratory of Renewable Energy Electrical Technology and Systems ， Zhejiang University ， Hangzhou 310027 ， ChinaFollow
• Chuangxin Guo, College of Electrical Engineering ， Zhejiang University ， Hangzhou 310027 ， China ;Zhejiang Provincial Key Laboratory of Renewable Energy Electrical Technology and Systems ， Zhejiang University ， Hangzhou 310027 ， China

Keywords

AC power flow, linearization, coordinated active and reactive power optimization, unit commitment, base point-increment

Abstract

To address the conflict between the neglect of reactive power and voltage issues in DC power flow and the complexity of solving accurate AC power flow in traditional transmission network unit commitment，this paper proposes a coordinated active and reactive power optimization strategy based on a linear approximation of AC power flow.First，the AC power flow equations are linearized，transforming the nonlinear unit commitment problem into a Mixed-Integer Quadratic Programming （MIQP ） model.The model is further transformed into a mixed-integer linear programming （MILP ） model through piecewise linearization of the cost function.Second，considering that reactive power and voltage relationships in power systems are not approximately linear over a wide range，a base point-increment method is introduced to improve the accuracy of the linearized model.Finally，case studies are conducted on the IEEE 39-bus and IEEE 118-bus systems.GUROBI is employed to solve the model efficiently，and accurate power flow results obtained using MATPOWER are used to further verify the effectiveness of the proposed method.The results demonstrate that the proposed method achieves coordinated active and reactive power optimization in systems of different scales.The application of the base point-increment method and piecewise linearization of the cost function significantly improves solution performance and provides reliable and efficient unit commitment schedules.

DOI

10.19781/j.issn.1673-9140.2026.04.017

First Page

208

Last Page

222

Recommended Citation

Ji, Shengbo; Zhang, Jinlong; Guo, Ruipeng; and Guo, Chuangxin (2026) "Unit commitment optimization method based on linear approximation of AC power flow," Journal of Electric Power Science and Technology: Vol. 41: Iss. 4, Article 17.
DOI: 10.19781/j.issn.1673-9140.2026.04.017
Available at: https://jepst.researchcommons.org/journal/vol41/iss4/17