A hybrid optical current sensor for power system metering and protection

This paper proposes a novel design of hybrid optical current sensor (HOCS). A bulk-optic glass sensing head is simplified, which combines with a conventional sampling current transformer (CT) to form the HOCS. In this design, a technique of coefficient adjustment is adopted. Using the stationary outputs of sampling CT to adjust the outputs of bulk-optic sensing head, the transient and stationary performance and long-term stability of the HOCS have been improved effectively. The output interface of HOCS is suggested and introduced for new and existing substations. The test results are given, especially the optical sensing parts. A prototype of HOCS has been designed and constructed. Initial tests show that it meets requirements for power system metering and protection.