柔性电磁环网控制保护系统研究与设计

对贵州电网存在大量500/220kV电磁环网运行无法在短期内实施解环的特性，实现开环运行容易降低供电可靠性，合环运行面临潮流控制困难、短路电流超标这一矛盾问题。而系统运行主要是以提高局部电网运行可靠性为目的这一背景。提出了采用柔性直流输电系统安装于电磁环网低压侧通道实现合环运行的方案。利用柔直的不向系统注入短路电流、有功无功可实现独立解耦控制等众多优势。研究了这种方案下柔直的控制保护系统系统方案的基本策略，包括柔性直流输电系统的基本保护策略，基于贵州电网环网的整体控制保护不同控层级的设计原则及设计方案。最后以贵州六枝、普定变的220千伏的电压层级安装柔性直流背靠背装置为仿真研究对象，仿真结果表明：该设计方案可以有效的保护柔直在电磁环网应用场景下的的安全稳定运行。

Research and Design of Control and Protection System for Flexible Electromagnetic Loop Network

In view of the fact that a large number of 500/220kV electromagnetic loop networks in Guizhou power grid can not be operated in a short time, the open-loop operation is easy to reduce the reliability of power supply, and the closed-loop operation is faced with the contradiction of power flow control difficulty and short-circuit current exceeding the standard. The operation of the system is mainly aimed at improving the reliability of local power grid. A flexible HVDC system installed in the low-voltage side channel of electromagnetic loop network is proposed to realize loop closing operation. Many advantages such as injecting short-circuit current into flexible and direct non-directional system, active and reactive power can be used to realize independent decoupling control. The basic strategy of the flexible and direct control and protection system under this scheme is studied, including the basic protection strategy of the flexible HVDC transmission system, the design principles and design schemes of different control levels based on the overall control and protection of Guizhou power grid ring network. Finally, the flexible DC back-to-back device installed at 220 kV voltage level of Liuzhi and Puding transformers in Guizhou Province is taken as the simulation object. The simulation results show that the design scheme can effectively protect the safe and stable operation of flexible direct current in the electromagnetic loop network application scenario.