基于组合方式的多端柔性直流输电系统控制策略

发布时间：2018-06-29 06:23

本文选题：多端直流 + 电压源型换流器　；参考：《电网技术》2015年06期

【摘要】：分析基于电压源型换流器的多端直流输电系统(voltage sourced converter multi-terminal DC,VSC-MTDC)现有控制策略(电压裕度控制与电压倾斜控制)的特点与不足,提出一种新的基于自律分散思想的控制方法。该方法结合了上述二种控制方法的优点,并相互弥补了各自的缺点。正常运行时,主导站定直流电压控制,辅助站定功率控制。一旦主导站因故障丢失,辅助站能够快速并稳定地切换到定电压控制。由于倾斜特性的引入,各换流站的传输功率始终随直流电压的变化而变化,且保持固定的比例关系。因此直流电压不会因电压裕度的选取而产生不同程度的过调量。此后辅助站将作为多端系统的平衡节点,吸收/发出其余端子的功率差额,使系统重新找到新的运行点(预先设定的最优运行点)。在整个暂态过程中,其余端子能够始终不受扰动的影响而保持正常运行,使扰动对直流系统的影响最小化。文中基于PSCAD/EMTDC分别设计这3种控制器,并对其暂稳态特性进行仿真分析与详细比对。仿真结果表明:组合控制改善了系统的暂态特性,并能够保证系统在扰动前后都始终运行在最优点。
[Abstract]:This paper analyzes the characteristics and shortcomings of the existing control strategies (voltage margin control and voltage tilting control) for multi-terminal DC transmission system (voltage sourced converter multi-terminal DCSC-MTDC based on voltage source converters, and proposes a new control method based on the idea of autonomous dispersion. This method combines the advantages of the two control methods and makes up for each other's shortcomings. In normal operation, the main station constant DC voltage control, auxiliary station fixed power control. Once the main station is lost due to failure, the auxiliary station can switch to constant voltage control quickly and stably. Because of the introduction of tilting characteristics, the transmission power of each converter station always changes with the DC voltage, and maintains a fixed proportional relationship. Therefore, DC voltage will not cause varying degrees of overshoot due to the selection of voltage margin. After that, the auxiliary station will act as the balance node of the multi-terminal system, absorb / issue the power difference of the other terminals, so that the system can find the new operation point (the pre-set optimal operating point). During the whole transient process, the other terminals can always operate normally without the influence of the disturbance, so as to minimize the impact of the disturbance on the DC system. In this paper, three controllers are designed based on PSCAD / EMTDC, and their transient characteristics are simulated and compared in detail. The simulation results show that the combined control improves the transient characteristics of the system and can ensure that the system always operates in the optimal condition before and after the disturbance.
【作者单位】：华北电力大学电气与电子工程学院;
【基金】：国家重点基础研究发展计划项目(973计划)(2012CB215200) 国家自然科学基金项目(51177044)~~
【分类号】：TM721.1

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