直流紧急功率支援用于第三道防线的研究

直流系统参与安全稳定控制的研究与应用仍局限于属于第一道防线的预防控制和属于第二道防线的紧急控制，挖掘应用直流系统的运行特性和调控能力是提高交直流电网安全稳定水平的重要技术途径。提出将直流系统具有的紧急功率支援能力作为第三道防线候选控制手段的理念，与常用的低频减载/高频切机等措施协调配合，防止系统崩溃;在监测到电网发生频率低/高异常变化时启动利用直流紧急功率支援功能，从而减少切负荷/机组的控制量。从整定计算和控制装置两个方面，阐述实现直流紧急功率支援参与第三道防线中频率异常控制的初步方案。用实际电网的数据仿真分析直流紧急功率支援参与第三道防线取得的有益效果。联系第三道防线发挥作用的时机特点和直流系统运行控制特性，讨论将直流紧急功率支援作为第三道防线措施应注意的问题，对于构筑技术手段更为丰富的电网安全稳定第三道防线，具有重要参考价值。

A Study on the Emergency DC Power Support as the Third Defense of the Power System

The research and application of the DC system as part of the security and stability control of the power grid has been limited to the preventive control and emergency control, which are referred to as the first and the second defense line. Fully exploring the characteristics and control capability of the DC system is an important technical way to improve the safe and reliable operation of an AC/DC power grid. The concept of using the emergency DC power support capability as the third defense line of a power system is proposed. The coordination and cooperation of the emergency DC power support with the under-frequency-load-shedding and the over-frequency- generation-tripping can be applied to prevent system collapses. When abnormally low/high frequency is detected, the emergency DC power support can be activated to reduce the amount of load shedding or generation tripping. A preliminary design is presented on the control parameter setting calculation and the abnormal frequency control device. The beneficial results of the emergency DC power support as a control measure of the third defense line is validated by simulations based on actual grid operation data.. The issues concerning the use of the proposed concept as the third defense line are discussed in relation to the timing and control characteristics of the DC system. The findings have importance reference value for expanded technical options for the third defense line to support safe and reliable operation of the power grid.