稳态工况下MMC型STATCOM自适应综合控制策略研究

发布时间：2018-04-18 19:22

本文选题：模块化多电平变换器 + MMC-STATCOM　；参考：《南京航空航天大学》2014年硕士论文

【摘要】：模块化多电平变换器（MMC）作为一种新型的、适用于中、高压功率领域的变换技术，由于其具有的公共直流母线，可以实现四象限运行，同时具有良好的可扩展性与故障冗余性，是电能质量治理如无功补偿（STATCOM）、谐波抑制的有效手段。本文以MMC型STATCOM为研究对象，在多电平电路拓扑结构衍变分析的基础上，采用理论仿真与实验验证相结合的研究方法，重点对MMC-STATCOM自适应综合控制策略进行研究，主要研究内容为：本文深入分析了MMC变换器四象限运行基本工作原理，在仅考虑电压电流基波分量的情况下，给出了MMC变换器交流侧工作特性矢量关系图，并在此基础上，通过对容性无功补偿状态下的MMC子模块电容电压直流分量与交流谐波特性分析，提出了以抑制50Hz脉动为目标的直流侧电容选取方法，并兼顾MMC-STATCOM动态跟踪性能、电流脉动以及输出电流能力等设计指标，选取并设计了合适的桥臂串联电感。本文提出了MMC-STATCOM自适应综合控制策略，主控制器采用直接电流型反馈解耦控制策略，在恒频启动过程和稳态工作阶段自适应选择合适的电容电压平衡控制策略，实现了有功电流isd与无功电流isq的独立控制，而且在装置启动阶段子模块电容电压能够快速响应控制指令，稳态工作阶段输出电流谐波特性高，子模块电容电压平衡性能优异。针对MMC-STATCOM恒频启动控制，对NLM排序均压算法进行优化，使其在变换器恒频启动过程及稳态工作阶段均适用，所提出的直流斜坡电压优化控制策略，在未设置预充电电阻的情况下，有效减小了MMC解锁瞬间的冲击电流，从而简化了装置启动电路。本文深入研究了稳态工作阶段MMC-STATCOM电容电压平衡方法，建立了子模块稳态平均数学模型，通过数学推导，，获得了子模块电容电压的解析表达式，从中揭示了导致子模块电容电压不平衡的原因，仿真结果也进一步验证了子模块数学模型的正确性。本文搭建了±3kVar三相MMC-STATCOM实验平台。实验结果与理论分析以及仿真结果相一致，均验证了自适应综合控制策略的可行性与有效性。
[Abstract]:As a new type of conversion technology, modularized multilevel converter (MMC) is suitable for medium and high voltage power field. Because of its common DC bus, it can realize four-quadrant operation, at the same time, it has good expansibility and fault redundancy.It is an effective means of harmonic suppression for power quality control such as reactive power compensation.This paper takes MMC type STATCOM as the research object, based on the topology evolution analysis of multilevel circuit, adopts the research method of combining the theory simulation with the experiment verification, emphatically carries on the research to the MMC-STATCOM adaptive synthesis control strategy, the main research content is as follows:In this paper, the basic operating principle of MMC converter in four quadrants is deeply analyzed, and the vector relation diagram of AC side operation characteristic of MMC converter is given under the condition of considering only the fundamental component of voltage and current.By analyzing the DC component of capacitive voltage and AC harmonics of MMC submodule under capacitive reactive power compensation condition, a method of selecting DC side capacitance aiming at suppressing 50Hz pulsation is proposed, and the dynamic tracking performance of MMC-STATCOM is taken into account.The current pulsation and output current capacity are selected and designed.In this paper, an adaptive integrated control strategy for MMC-STATCOM is proposed. The main controller adopts direct current-mode feedback decoupling control strategy and adaptively selects the appropriate capacitive voltage balance control strategy in the constant frequency start-up process and steady operation phase.The independent control of active current isd and reactive current isq is realized, and the capacitive voltage of the submodule can respond to the control instruction quickly in the start-up stage of the device. The output current harmonic characteristic is high during the steady state operation, and the capacitor voltage balance performance of the sub-module is excellent.Aiming at the MMC-STATCOM constant frequency startup control, the NLM sorting voltage equalization algorithm is optimized, which is suitable for both the constant frequency start-up process and the steady state operation stage of the converter. The proposed DC slope voltage optimal control strategy is proposed without setting the precharge resistor.The impulse current of MMC unlocking is reduced effectively, thus simplifying the starting circuit of the device.In this paper, the method of MMC-STATCOM capacitor voltage balance in steady working phase is deeply studied, and the mathematical model of steady state average of submodule is established. Through mathematical derivation, the analytical expression of capacitance voltage of submodule is obtained.The reason of the unbalance of capacitance voltage of submodule is revealed, and the correctness of mathematical model of submodule is further verified by simulation results.In this paper, a 卤3kVar three-phase MMC-STATCOM experimental platform is built.The experimental results are consistent with the theoretical analysis and simulation results, which verify the feasibility and effectiveness of the adaptive integrated control strategy.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

【参考文献】