A review of research on traction load models and modeling methods for electrified railways

As the electrified railways, especially high-speed railways, continue to expand, the proportion of traction load in overall power load is increasing significantly. Establishing a traction load model is crucial for the design and operation of traction power supply system (TPSS) and the evaluation of impact on power systems. The paper provides an overview of key issues related to traction loads in electrified railways. It systematically summarizes research trends and achievements on traction load characteristics, models, and modeling methods, as well as their comparability and practicality. Firstly, we analyze the electrical and spatiotemporal characteristics of traction loads. Secondly, based on the modeling requirements and application scenarios of traction loads, this paper classifies and compares existing traction load models. Then, we review the current research status of traction load modeling methods, with a focus on deterministic and uncertainty modeling methods for traction loads. The advantages and disadvantages of various traction load modeling methods are analyzed and compared. Finally, it highlights trends in traction load modeling, including traction load forecasting, multi random variable modeling, data-driven approaches, and integration of AI and IoT. This paper presents a comprehensive survey on traction load modeling, current practices, and future outlook, while providing guidance for selecting appropriate traction load models.