交直流系统动态无功源荷失配机理与暂态电压稳定协调控制研究

Based on the dynamic load, the theoretical results of transient voltage stability focus on AC grid. As a result of this, the theory cannot be applied to AC-DC hybrid transmission mode. This project has being studying dynamic reactive power characteristics in AC-DC hybrid grid, analyzing the modes，factors and mechanism of dynamic reactive power source-load mismatch, and excavating the influence pathways and action mode of source-load mismatch on transient voltage stability. About the factors of dynamic source-load mismatch, a new perspective of studying AC-DC transient voltage stability is proposed based on the time-space characteristics, which include grid topology, operation mode, control strategy and fault condition. About the cascade effect and interactive features of source-load mismatch, an assessment model, which can describe the overall process of the influence of DC control strategy and access mode on transient voltage stability, is also presented. Finally, coordination control strategies are put forward, viewed from enhancing the ability of AC-DC coordination. Deeply studying the mechanism of dynamic reactive power source-load mismatch is the gist of this project, at the same time, acquiring some innovations on assessment model, analytical method and coordination control strategies about transient voltage stability is the objective of this project. The study results are of great theoretical value and practical significance for improving control abilities on AC-DC hybrid grid.

暂态电压稳定的以往解答模式立足于负荷动态，理论成果集中在交流电网，无法全面地适应交直流混联输电模式。本课题全方位研究了交直流混联系统中的动态无功特性，分析了动态无功源荷失配模式、影响因素与作用机理，挖掘了动态无功源荷失配对暂态电压稳定的影响途径、作用方式——围绕源荷失配的影响因素，从电网拓扑结构、运行方式、控制策略与故障条件等方面提出了基于时空特性研究交直流混联电网暂态电压机理的新视角；围绕源荷失配的级联效应和交互特性，提出了交直流混联系统暂态电压评估模型，刻画了故障及恢复后直流控制策略与接入模式对系统暂态电压稳定影响全过程。最后，从增强交直流协调配合能力的角度提出了暂态电压稳定协调控制策略。本课题旨在深入动态无功源荷失配机理，将在暂态电压稳定的评估模型、分析方法、协调控制策略等方面获得创新。本课题研究对提高交直流混联电网的驾驭能力，具有极高的理论价值和现实意义。

电压稳定问题在交直流互联电网中广受关注，对这个关键问题的研究将有助于解决目前密集馈入交流电网的直流系统安全稳定运行。传统的暂态电压稳定机理的解答模式立足于交流电网中的负荷动态，然而却无法全面地适应交直流的输电模式。本课题将立足点放在了直流系统所带来的动态无功变化，分析了直流控制对直流所带来的无功变化特点，以及直流系统对交流电网所体现出的动态无功源荷特性，通过对这类无功动态特性的影响因素、特征刻画以及作用机理分析，提出了交直流互联电网中暂态电压稳定机理，构建了丰富的直流系统及其控制的自定义模型，提出了交直流混联系统暂态电压机理与评估指标。最后，在实际电网中应用指标进行稳定性评价，探讨大容量直流的可能接入模式。本课题从动态无功源荷特性入手，在暂态电压稳定机理与分析方法、稳定水平评价指标、协调控制策略等方面获得创新。本课题研究对提高交直流混联电网的驾驭能力，具有极高的理论价值和现实意义。