基于最优潮流的多端柔性直流输电系统控制策略研究

发布时间：2019-01-12 18:49

【摘要】：多端柔性直流输电是智能电网的重要组成部分,也是当前的研究热点。一方面,为了保证多端柔性直流输电系统的安全稳定运行,需要对其协调控制策略进行深入研究;另一方面,多端柔性直流输电系统的推广应用也需要具备较好的经济性,需要对其网络运行进行优化。本文研究基于最优潮流的含电压源型换流器的多端柔性直流输电系统控制策略,具有一定的理论意义和工程应用价值。本文首先对柔性直流输电系统的结构和原理进行分析,对多端柔性直流输电系统的系统级控制策略和换流站级控制方法进行研究,并根据这些控制策略的特点,利用广义下垂控制方式,实现电压源型换流器控制策略的无缝切换。然后,对多端柔性直流输电系统的最优潮流进行研究,提出了兼顾降低有功网损、减小系统电压偏差及增大系统静态电压稳定裕度的多目标潮流优化模型。在此基础上,提出了基于内点法和NSGA2算法相结合的求解方法,将多目标优化问题分成连续优化和离散优化两部分,能够通过一次运行得到多个Pareto最优解,克服了以往算法中多次运行才能得到一组近似Pareto最优解且结果可能出现不一致的缺陷。最后,将多端柔性直流输电系统的潮流优化结果结合广义下垂控制方式,提出了基于最优潮流的多端柔性直流输电系统控制策略。结合风功率预测数据,利用该控制策略对各换流站控制系数进行周期性的调整,对系统运行进行优化,潮流优化及仿真分析结果验证本文所提方法的有效性和可行性。
[Abstract]:Multi-terminal flexible DC transmission is an important part of smart grid, and it is also a hot research topic. On the one hand, in order to ensure the safe and stable operation of multi-terminal flexible direct current transmission system, the coordinated control strategy needs to be deeply studied. On the other hand, the popularization and application of multi-terminal flexible direct current transmission system also need to have good economy, and it is necessary to optimize its network operation. In this paper, the control strategy of multi-terminal flexible direct current transmission system with voltage source converter based on optimal power flow is studied, which has certain theoretical significance and engineering application value. In this paper, the structure and principle of the flexible direct current transmission system are analyzed, and the system-level control strategy and converter station level control method of the multi-terminal flexible direct current transmission system are studied, and according to the characteristics of these control strategies, The control strategy of voltage source converter is switched seamlessly by generalized droop control. Then, the optimal power flow of multi-terminal flexible direct current transmission system is studied, and a multi-objective power flow optimization model is proposed, which takes into account the reduction of active power loss, the reduction of system voltage deviation and the increase of system static voltage stability margin. On this basis, a solution based on interior point method and NSGA2 algorithm is proposed. The multi-objective optimization problem is divided into two parts: continuous optimization and discrete optimization, and multiple Pareto optimal solutions can be obtained by one run. It overcomes the defect that the previous algorithm can get a set of approximate Pareto optimal solutions and the results may be inconsistent. Finally, combining the power flow optimization results of multi-terminal flexible direct current transmission system with the generalized droop control method, the control strategy of multi-terminal flexible direct current transmission system based on optimal power flow is proposed. Combined with wind power prediction data, the control coefficient of each converter station is adjusted periodically by using the control strategy, and the system operation is optimized. The results of power flow optimization and simulation analysis verify the effectiveness and feasibility of the proposed method.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM721.1

【参考文献】