Abstract:

In order to improve the stability and reliability of DC system and ensure that the short-circuit current can be judged and cut off in time after the failure of DC system,a short-circuit current fast identification device for medium voltage DC(MVDC) system is proposed.The hardware is designed with the dual processor structure of FPGA+AVR as the core of each functional circuit,which realizes the extraction and conditioning of the main circuit current,as well as the communication,human-machine interaction and communication functions between the two processing chips.The software system of the short-circuit currnt identification device is projected respectively using top-down and modular programming ideas for FPGA and AVR.The short circuit current fast identification software system based on DDL algorithm,FIR filter and sampling algorithm is designed.Finally,the rapid and accurate identification of the short-circuit current by the device is verified through experiments,which provides a guarantee for the stable operation of MVDC system.

Key words: DC power girds, short-circuit fast identification, DDL algorithm, FPGA