Analysis of Influence of Abnormal Fiber-Optical Current Transformer on Double Closed-Loop Control of Converter Valve in Flexible DC Converter Station.

The fiber-optical current transformer (FOCT) is the core measuring equipment of the flexible DC converter station, which affects the operation control of the system. In order to solve the problem of the influence of the abnormal FOCT on the operation of the converter valve being unclear, the common fault modes of temperature and optical path of the FOCT are analyzed in this paper. Then, based on the traditional optical current transformer (OCT) model and considering the influence of temperature parameters on the FOCT, the FOCT dynamic model considering multiple factors is constructed. Finally, the simulation analysis is carried out on the MATLAB 2021b/Simulink platform, and the results show that (1) when the FOCT temperature compensation is abnormal, the transmission power of the converter valve increases with the increase in temperature, but the increase in temperature change is small; (2) when the FOCT light source compensation is abnormal, the light source attenuates, the converter valve active power decreases, and the reactive power increases; and (3) when the optical fiber sensing ring is broken, the transmission power increases and seriously deviates from the preset value (the active power increases by about 87.5% and the reactive power increases by about 90%). It can be seen that the abnormal FOCT in the converter station has a serious influence on the operation of the converter valve. [ABSTRACT FROM AUTHOR]