永磁直驱三电平变流器控制策略研究

发布时间：2018-06-11 13:07

本文选题：永磁直驱 + NPC型三电平变流器　；参考：《重庆大学》2014年硕士论文

【摘要】：与双馈式风力发电系统相比，永磁直驱式风力发电系统中风机直接与发电机相连，无需齿轮箱，成本降低，并网控制灵活，风力发电的整体效率得到有效提高，成为风力发电技术的研究热点之一。全功率变流器是直驱风电系统的核心部分，它能够及时将发电机输出的电能输送至电网。随着风电技术的发展，现有风电系统对器件耐压水平和功率等级的要求也越来越高。三电平变流器因其能够降低谐波含量、提高功率等级、改善系统工作效率，在直驱风电系统中应用比较广泛。本论文对基于双NPC型三电平变流器的永磁直驱风电系统继续研究。分析风力机的动力学特性和运行特性，研究桨距角、叶尖速比、风能利用系数和输出转矩等物理特性，绘制出最优功率曲线；在同步旋转坐标轴系中，建立永磁同步电机的数学模型，分析其稳态特性和功角特性；根据SVPWM调制的基本原理，重点研究基于参考电压矢量分解的三电平SVPWM调制算法，用两电平参考矢量和两电平基本矢量共同作用的效果来代替三电平电压矢量的单独作用，达到矢量合成的目的；根据三电平变流器的运行原理，，建立机侧整流器和网侧逆变器的数学模型并推导其电压控制方程；对机侧整流器采用转子磁场定向的控制策略，通过调节定子电流分量对电磁转矩进行控制，从而达到调节发电机转速的目的；对网侧逆变器采用电网电压定向的控制策略，调节网侧电流分量达到对逆变器输出有功功率和无功功率独立控制的目的；重点针对NPC型三电平变流器的固有问题—直流侧中点电位波动进行研究，以调制过程中作用的各个基本矢量为切入点，对产生电位波动的根本原因进行分析，并充分利用作用矢量的冗余状态，提出基于实时电流检测的中点电位平衡控制策略；最后，结合机侧和网侧变流器的控制，建立了永磁直驱风电系统的整体控制策略；采用Matlab软件搭建系统仿真模型，通过仿真验证了控制策略的正确性和有效性。
[Abstract]:Compared with the doubly-fed wind power generation system, the wind turbine is connected directly to the generator in the permanent magnet direct drive wind power generation system, the cost is reduced, the grid control is flexible, and the overall efficiency of wind power generation is improved effectively. It has become one of the research hotspots in wind power generation technology. Full power converter is the core part of direct drive wind power system. With the development of wind power technology, the requirements of the current wind power system for the device voltage level and power level are becoming higher and higher. Three-level converter is widely used in direct drive wind power system because it can reduce harmonic content, improve power level and improve system efficiency. In this paper, we continue to study the permanent magnet direct drive wind power system based on the dual-NPC three-level converter, analyze the dynamic and operational characteristics of the wind turbine, study the physical characteristics of pitch angle, tip speed ratio, wind energy utilization coefficient and output torque, etc. The optimal power curve is drawn, the mathematical model of permanent magnet synchronous motor is established in the synchronous rotation coordinate system, the steady state characteristic and power angle characteristic of permanent magnet synchronous motor are analyzed, according to the basic principle of SVPWM modulation, The three-level SVPWM modulation algorithm based on reference voltage vector decomposition is studied. The effect of two-level reference vector and two-level basic vector is used to replace the three-level voltage vector. According to the operation principle of the three-level converter, the mathematical model of the rectifier and grid-side inverter is established and its voltage control equation is deduced, and the rotor field-oriented control strategy is adopted for the motor side rectifier. By adjusting the stator current component to control the electromagnetic torque to achieve the purpose of regulating the speed of the generator, the grid voltage oriented control strategy is adopted for the grid-side inverter. Regulating the current component of the grid side to achieve the purpose of independent control of the output active power and reactive power of the inverter, focusing on the inherent problem of NPC three-level converter, namely, the fluctuation of neutral point potential at the DC side. Based on the basic vectors in the modulation process, this paper analyzes the fundamental causes of the potential fluctuations, and makes full use of the redundant state of the action vectors, and puts forward the midpoint potential balance control strategy based on real-time current detection. The overall control strategy of the permanent magnet direct drive wind power system is established by combining the control of the converter on the machine side and the grid side, and the simulation model of the system is built with Matlab software, and the correctness and effectiveness of the control strategy are verified by simulation.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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