Investigation into the online measurement technique for critical parameters of the on-load tap changer

The on-load tap changer (OLTC), widely used as a voltage regulation device in power systems, requires regular assessment and maintenance to ensure reliable operation and avoid adverse impacts on the power system. These assessments encompass key parameters such as transition waveform, transition time, three-phase synchronization, and transition resistor, along with the operational status of the mechanical structure. However, the maintenance process, typically conducted offline, can diminish equipment efficiency. Moreover, the accuracy of some parameter measurements needs improvement. To bolster equipment reliability and refine detection methods for critical parameters, this study explores online detection techniques for key switching parameters of the OLTC body. This paper proposes a method to identify these key parameters in the switching circuit, using coordinate transformation as the core algorithm. We used a specific vacuum OLTC device for our research, conducted theoretical analyses, developed a simulation model to validate the proposed method for identifying OLTC switching parameters, and further built a test platform to verify the algorithm’s effectiveness. The results show a close alignment between simulation and actual measurement outcomes. Each switching process interval conforms to the manufacturer’s design specifications for the equipment, with the transition resistor parameter calculation accuracy ranging from approximately 95.39% to 100%. Similarly, the tap winding voltage calculation accuracy is between approximately 91.52% and 100%, satisfying engineering requirements and enterprise standard [1]. This method provides a basis for optimizing the measurement of working parameters in OLTC equipment and aims to offer ideas for the next step of prototype development.