Generation mechanism and mitigation measures for multi-source stray current: A systematic review and prospects

To achieve the goal of carbon neutrality, the global installed capacity of renewable energy power system is rapidly increasing, along with the expansion of high-voltage direct current (HVDC) transmission techniques that offer lower power losses. Concurrently, the complexity of environmentally friendly urban rail transit is escalating. However, these developments introduce a significant challenge: stray currents. These currents originate from the grounding electrodes of HVDC systems or through leakage of traction currents from rails into the earth. In addition, the converter and grounding systems of renewable energy system and EV charging and energy storage stations (EVCES) have emerged as additional sources of stray current. Stray currents jeopardize the safety and reliability of power systems by adversely impacting adjacent transformers, buried metallic pipelines, and other components. This review systematically compares the generation mechanisms and conduction paths of stray currents from distinct sources. It further contrasts the key influencing factors for stray currents originating from each source. Different simulation models describing the dynamic distribution of stray currents are evaluated to assess their performance advantages. The strengths, limitations, and applicable source contexts of various mitigation strategies are also examined under a unified source–path–receiver framework. Current research faces critical gaps: the inability to achieve synchronized monitoring between source and affected terminals, mitigation strategies lacking adaptability to changing operating conditions, and the insufficient understanding of stray current from renewable energy system and EVCES, especially regarding converter leakage, grounding coupling, and external propagation paths. Future advancements, leveraging neural networks and frequency-domain analysis, promise to enable precise stray current source identification and facilitate dynamic, multi-terminal collaborative mitigation.