基于LPCT的激光供能电子式电流互感器

介绍的基于铁心、线圈式低功率电流互感器(LPCT)的激光供能高压电子式电流互感器,克服了空心线圈测量精度易受温度和制作工艺影响的缺点.首先描述了LPCT的测量原理和互感器的结构.互感器的一次转换器能够提供两路传感器数据通道,并且具有温度补偿和高压侧采集通道自校正功能,在较宽温度、较大电流范围内保证了极高的测量精度;二次转换器具有数字和模拟接口,可以接受数据并发送命令控制一次转换器,包括同步和校正命令在内的数据信号可以通过同一根供能光纤传送到一次转换器.互感器还提供一些在线监测功能,这种预防性的维护和自检测功能能够提示维护或提出警告,提高系统的可靠性.系统测试表明:具有低功耗光纤发射驱动电路的一次转换器平均功耗在40mW以下;上行光纤中通信波特率可以达到200kb/s,下行光纤中更是高达2Mb/s;系统准确度同时满足IEC6044-8标准对0.2S级测量和5TPE级保护电子式互感器的要求.

A Laser Powered Electronic Current Transformer Based on LPCT

A laser powered electronic current transformer (ECT) for protection or metering purposes based on low power current transformer (LPCT) used in high voltage power system has been developed to overcome the disadvantages of the measuring accuracy of air core coils that can be influenced by temperature and manufacturing technology. The principle of LPCT and the structure of ECT are presented in the paper first. The primary converter includes two primary sensor data channels with active temperature compensation and self-calibration at the high voltage side. This allows even higher accuracy over an extended temperature range and a wide current range. The secondary converter with analog and digital output converts the signal from primary converter and send signal to control the primary converter. Data signals include synchronization and calibration can be transmitted via the same optical fiber that is used to transmit power to primary converter. Some online supervisory functions are also successfully accomplished in this system, and this form of preventive maintenance or built-in test will increase system reliability by giving advance warning and indicating necessary maintenance. The experimental results show that the primary converter together with the improved circuit driving fiber transmitter can work reliably consuming averagely no more than 40mW power. Data signal can be transmitted at baud rate as fast as 200kb/s from the second to the primary converter, and 2Mb/s at the opposite direction. The ECT can meet the accuracy requirement of IEC 6044-8 standard 0.2S class for measuring current transformer and 5TPE class for protective current transformer.