Operation of offshore wind farms connected with DRU-HVDC transmission systems with special consideration of faults

The diode rectifier unit(DRU)-based high-voltage DC(DRU-HVDC) system is a promising solution for offshore wind energy transmission thanks to its compact design, high efficiency, and strong reliability. Herein we investigate the feasibility of the DRU-HVDC system considering onshore and offshore AC grid faults, DC cable faults, and internal DRU faults. To ensure safe operation during the faults, the wind turbine(WT) converters are designed to operate in either current-limiting or voltage-limiting mode to limit potential excessive overcurrent or overvoltage. Strategies for providing fault currents using WT converters during offshore AC faults to enable offshore overcurrent and differential fault protection are investigated. The DRU-HVDC system is robust against various faults, and it can automatically restore power transmission after fault isolation. Simulation results confirm the system performance under various fault conditions.

高铁GSM网络专网优化和维护经验

文章基于专网优化思路,阐述了中国移动泰安分公司针对时延干扰、功率输出、DRU环路保护、供电和防雷、远程监控、防盗等展开的高铁GSM通信专网优化和维护整改活动,提升了高铁沿线的整体覆盖和通信质量,并改善了设备维护中的监控及时性和运行稳定性。

柯达DR3000机器U型臂故障的检修

柯达DR3000的U型臂经常出现机械故障,经常是由于电位器故障引起的,更换电位器后,要对各项参数进行校准,本文介绍具体的校准步骤。