一种高压电子式电流互感器在线校验系统

An Online Calibration System for High Voltage Electronic Current Transformers

电子式互感器由于具有数字量输出、测量频带宽等优点而应用的愈加广泛,但由于是新兴技术,与传统互感器相比故障率高,因此需要缩短校验周期。传统校验方式需要线路停电,操作复杂且会造成停电损失。针对这些问题,本文提出一种高压电子式电流互感器的在线校验方法。在线校验时,高精度标准电流互感器和在线操作方式是研究的关键。设计了一种包含钳形铁心和钳形空心线圈的钳形双线圈作为标准互感器,校验时,通过分析比对两种线圈的输出特性,实现钳形双线圈准确度的自动校准,保证了校验系统的精度。在线操作时采用地电位作业法,利用绝缘操作杆将钳形双线圈接入高压母线,操作简单安全。国家高电压计量站检定及现场运行结果证明:该在线校验系统精度可达0.05级。

Electronic transformers are widely used in intelligent substations for their digital output and wide bandwidth. However, as a new technique, its failure rate is higher than that of traditional transformers. So the calibration period should be shortened. Traditional calibration methods need the power to be cut off, which lead to a complicated calibration process and loss of power outage. For this reason, this paper proposes an online calibration method for electronic current transformers. The high accuracy standard current transformer and online operation mode are the key technologies. A combined clamp-shape coil based on clamp-shape iron core coil and clamp-shape air core coil was designed as the standard. By analyzing the characteristics of the two clamp-shape coils, the combined coil can realize self-calibrating. So the accuracy of the system can be guaranteed. Employing the earth potential working method and using insulating rods to connect the transformer to the high voltage bus, the calibration becomes simple and safe. Tests in National Center for High Voltage Measurement and field tests show that the proposed online calibration system has a high accuracy of 0.05 class.