Study of the entire current differential protection of EHV transmission lines based on electronic transducer

Aiming at these two severe problems OCT faced, temperature excursion and no operating stability that baffled its utility in power system, the adaptive optical transducing principle and the solenoid collecting magnetic field optical path are presented to solve them, after analyzing the open loop mechanism of OCT. According to IEC660044-8, the performance of AOCT is examined roundly applying the standard testing system. The results indicate that under the steady state the measurement precision of the AOCT has already reached class0.2 and under the transient state the maximal peak instantaneous alternating current component error of the AOCT has already reached class1. It can measure the non-periodic component and kinds of AC harmonic component exactly, and it also has no saturation phenomenon. This paper uses Bergeron transmission lines model to set up the entire current differential protection of EHV transmission lines based on the electronic transducers. This algorithm has taken into account of the capacitive current automatically, and can pass over of the compensation of capacitive current. Simulation results confirm that the analysis is correct and the algorithm is reliable, and it is suit to apply into the digital substation.