Research on High Fault-tolerant Control Method for Step Response of Fiber Optical Current Transformer

Flexible DC systems have raised higher demands for the step response of all fiber current transformers, which suffer from issues such as long response time and insufficient bandwidth at high precision and sampling rates. Therefore, targeted methods are needed to improve the step response characteristics and dynamic performance of all fiber current transformers. This article analyzes the fast response characteristics of all fiber current transformers, A core chip fault-tolerant and dual AD acquisition and error correction hardware design based on DSP/CPU and FPGA was proposed. Based on high-speed closed-loop control dynamic response model analysis. Build a DC measurement device error testing system that complies with the GB/T 26216.1-2010 standard. The FOCT prototype has a maximum step response time (rise time and fall time) of no more than $18 \mu \mathrm{~s}$, a signal processing delay of no more than $10 \mu \mathrm{~s}$, a nonstandard 12 byte frame format for the prototype communication protocol, a communication delay of only $6.4 \mu$ s under 40 Mbd baud rate transmission, and a total response time of no more than $40 \mu \mathrm{~s}$. At the same time, it meets the accuracy requirement of 0.2 level and can meet the requirement of less than $60 \mu$ s for flexible DC high-speed control and protection systems.