MMC型轻型直流输电实验平台研制

发布时间：2018-05-10 18:36

本文选题：模块化多电平换流器 + 控制系统设计　；参考：《湖南大学》2015年硕士论文

【摘要】：基于MMC换流器的模块化多电平直流输电系统(MMC-HVDC)对功率器件的要求低,具有良好的可扩展性,可以方便地扩展到很高的电压等级和功率水平。此外MMC-HVDC采用IGBT等可关断器件,没有换相失败问题,具有更强的可控性和灵活性,在大容量远距离输电、风力发电等清洁能源并网、改善电能质量等方面具有广阔的应用前景,是解决现代电网诸多挑战的重要手段之一。首先,本文详细研究了MMC的数学模型,包括开关模型、平均值模型以及小信号模型,并给出了这些数学模型的详细推导过程。通过引入开关函数,得出桥臂电压、电流状态方程;利用开关周期平均算子,将桥臂状态方程平均化得到开关周期平均模型;在此基础上,推导出MMC换流器的小信号模型。通过仿真和实验分别研究了使用外部电源的逐模块充电方法。针对逐模块充电方法的不足之处,分析了适用于模块化多电平逆变器的交流电源充电方法,并给出了仿真和实验结果。其次,详细研究了MMC换流站控制策略以及子模块电容电压均压控制策略,并依据自动控制理论,给出了控制器参数的详细设计步骤。基于连续数学模型,推导出MMC-HVDC换流站级控制系统结构,并对优化后的双闭环控制系统中相关控制器主要参数的设计方法进行了深入研究。采用前馈-反馈控制和稳态逆模型相结合,使控制系统具有优越的稳态和暂态响应特性。时域仿真结果表明,本文推导的控制系统结构及其参数设计方法应用于MMC型轻型直流输电系统时,系统具有良好的稳态和暂态特性。最后,研制了一套三相模块化多电平逆变器的实验平台。从硬件设计和软件设计两个方面详细介绍MMC实验平台的设计过程。首先给出了实验平台的总体设计思路,重要硬件电路框图和软件流程图。在此基础上研制了一台小功率三相实验平台并对实验结果进行了相应的分析。实验结果证明了本文研究结论的正确性,为后续进一步的研究打下了坚实的基础。
[Abstract]:The modularized multilevel HVDC system based on MMC converter has low requirements for power devices and good scalability, and can be easily extended to high voltage levels and power levels. In addition, MMC-HVDC uses IGBT and other turn-off devices, which has no commutation failure problem, has stronger controllability and flexibility, and has a broad application prospect in connection to clean energy sources such as large capacity long-distance transmission, wind power generation, and improving power quality, etc. It is one of the important means to solve many challenges of modern power grid. Firstly, the mathematical models of MMC, including switching model, average value model and small signal model, are studied in detail, and the derivation process of these mathematical models is given in detail. By introducing the switching function, the voltage and current state equations of the bridge arm are obtained. By using the switching cycle averaging operator, the switching cycle average model is obtained. On this basis, the small signal model of the MMC converter is derived. Through simulation and experiment, the charging method of module by module using external power supply is studied respectively. Aiming at the shortcomings of the modular charging method, the charging method of AC power supply suitable for modularized multilevel inverter is analyzed, and the simulation and experimental results are given. Secondly, the control strategy of MMC converter station and the voltage sharing control strategy of submodule capacitive voltage are studied in detail. According to the automatic control theory, the detailed design steps of controller parameters are given. Based on the continuous mathematical model, the structure of MMC-HVDC converter station level control system is derived, and the design method of the main parameters of the related controller in the optimized double closed loop control system is studied. The feedforward and feedback control is combined with the steady-state inverse model to make the control system have superior steady-state and transient response characteristics. The time domain simulation results show that the proposed control system structure and its parameter design method have good steady-state and transient characteristics when applied to MMC HVDC system. Finally, a set of three-phase modularized multilevel inverter is developed. The design process of MMC experimental platform is introduced in detail from two aspects: hardware design and software design. At first, the general design idea, important hardware circuit block diagram and software flow chart of the experiment platform are given. On this basis, a small power three-phase experimental platform is developed and the experimental results are analyzed accordingly. The experimental results prove the correctness of this study and lay a solid foundation for further research.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM721.1

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