基于MMC的混合电网接口变换器控制策略

发布时间：2018-04-13 23:27

本文选题：混合电网 + 模块化多电平变换器　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：随着化石能源的日渐减少以及利用过程中对环境产生的污染,以可再生能源为基础的分布式发电将会是未来发电领域中的一个重要组成部分。可再生能源具有间歇性和多样性等特点,如果发出的电能直接并入交流电网会影响系统的稳定运行。采用交直流电网并存的混合电网可以很好的对发出的电能进行传输和利用。而不同类型的电网间需要采用变换器进行连接,模块化多电平变换器(MMC)由于其自身的优点,非常适合于中高压、大功率情况下混合电网间的能量传递。本文以混合电网中的模块化多电平变换器为研究对象,首先分析其拓扑结构,并对环流成分进行分析。针对环流谐波抑制问题,本文提出一种基于鲁棒H?控制的MMC电流控制,通过使环流趋于设定值来控制环流各分量的大小,从而能够消除环流谐波中的主要成分,进而使系统运行更加稳定。然后,针对MMC交流侧处于弱电网工况时,电网间能量传输不稳定进而导致系统运行不稳定的问题,提出一种基于虚拟同步发电机(VSG)控制的MMC能量控制。通过对电力系统中同步发电机的转速特性和励磁特性的模拟,设计功频控制器和励磁控制器对交流侧处于弱电网工况的MMC进行控制,使系统在弱电网工况下也能正常运行。接着,针对变换器输出阻抗对系统运行可能产生的影响,对变换器输出阻抗的分析,可以预测系统的稳定性。本文提出一种基于变换器输出阻抗的小信号分析方法,对变换器阻抗、采用锁相环和所提虚拟同步发电机控制时变换器的输出阻抗进行分析。最后,在MMC实验样机平台上,对所提出的控制策略进行实验验证。实验结果表明所提控制策略正确、有效。
[Abstract]:As to the environment and the use of fossil energy is reduced in the process of pollution, will be distributed generation based on renewable energy is a future generation in the field of an important part. Renewable energy has the characteristics of intermittent and diversity, if electricity is directly incorporated into will affect the stable operation of the system using the AC network. Hybrid AC / DC power grid power grid coexistence can be very good for transmission and utilization of electricity. Which require the use of converter to connect different types of grid, the modular multilevel converter (MMC) because of its advantages, is very suitable for high voltage transmission, hybrid power grid energy between high power based on the hybrid power grid. The modular multilevel converter as the research object, firstly analyses the topology structure, and the circulation composition analysis. The harmonic suppression in circulation For problems, this paper proposes a robust H? MMC current control control, through the circulation tends to set value to control the circulation of each component size, which can eliminate the main harmonic components in circulation, and make the system more stable. Then, according to the MMC AC side in the weak power grid operation, power grid energy transmission is not stable and lead to system instability problems, put forward a virtual synchronous generator (VSG) based on MMC energy control. Through the simulation speed characteristic and excitation characteristics of synchronous generator in power system, the design of power frequency controller and excitation controller of the AC side in the weak network condition of the MMC control, the the system can run normally in the weak network condition. Then, in view of the influence of converter output impedance of the system may have the operation, analysis of the converter output impedance of the system can be predicted Stability. This paper proposed an analysis method of small signal converter based on output impedance, impedance converter, phase locked loop and the analysis of the output impedance converter virtual synchronous generator control. Finally, the prototype of the MMC platform, in order to verify the validity of the proposed control strategy. The experimental results show that the proposed control strategy is correct and effective.

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM46

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