风电场接入的MMC-HVDC仿真建模研究
发布时间：2018-11-10 14:07
【摘要】：随着风力发电技术的发展，风电场的规模越来越大，而风电具有间歇性、不可控等特性，采用交流输电需要大量无功补偿装置、采用传统直流输电需要投入大量滤波装置而且容易发生换相失败，，研究更适合于风电场的并网方式具有重要意义。基于模块化多电平换流器的柔性直流输电技术具有容量大、独立控制有功无功、稳定交流母线电压、隔离故障和容易构成多端直流系统等优点，非常适合于大型风电场并网，将在其风电并网连接中有广泛的应用。 本文首先对交流输电、高压直流输电、柔性直流输电三种并网输电方式进行了综合比较，并对在风电并网中具有技术优势的柔性直流输电技术的研究现状、工程实例进行了介绍，接着对风电场的低电压穿越技术进行了综述，并介绍本文的主要工作。 分析了模块化多电平换流器（MMC，modular multilevel converter）的拓扑结构、工作原理、调制方法、电压平衡方法的原理。研究了MMC的数学模型，在此基础上分析直接电流控制的内外环控制策略，设计风电场侧和交流电网侧换流器的控制策略。设计风电场向交流系统输送功率的两端MMC-HVDC系统，搭建了鼠笼式异步风力发电机模型和永磁直驱风力发电机模型，利用等值技术形成风电场。进行了从MMC-HVDC的空载启动、风电场并网及风速波动过程的仿真研究。将风电场联接交流电网两端MMC-HVDC系统的启动策略和控制策略应用于多端柔性直流输电系统，设计了两个风电场向交流系统送电的三端直流系统，仿真验证了控制策略的可行性。 对受端交流系统连接点发生不同类型故障的故障特性进行分析，针对三相故障提出了直流侧接耗能电阻的控制方法，维持故障阶段风电场出口的电压稳定；针对不对称故障提出基于负序电压前馈的双序控制方法，抑制故障负序电流分量的影响。最后对MMC-HVDC的隔离干扰能力和本文提出的故障控制策略进行了仿真验证。
[Abstract]:With the development of wind power generation technology, the scale of wind farm becomes larger and larger, and wind power has the characteristics of intermittent, uncontrollable, etc. Traditional DC transmission needs a large number of filter devices and is prone to commutative failure. It is of great significance to study the grid-connected mode which is more suitable for wind farms. The flexible DC transmission technology based on modularized multilevel converter has the advantages of large capacity, independent control of active and reactive power, stable AC bus voltage, isolation of fault and easy construction of multi-terminal DC system. It will be widely used in wind power grid connection. In this paper, three grid-connected transmission modes, namely AC transmission, high voltage direct current transmission and flexible direct current transmission, are firstly compared, and the research status of flexible direct current transmission technology which has technical advantages in wind power grid connection is also discussed. The engineering example is introduced, and then the low voltage traversing technology of wind farm is summarized, and the main work of this paper is introduced. The topology, working principle, modulation method and voltage balance method of modular multilevel converter (MMC,modular multilevel converter) are analyzed. The mathematical model of MMC is studied and the internal and external loop control strategy of direct current control is analyzed. The control strategy of wind farm side and AC power grid side converter is designed. The MMC-HVDC system for transmitting power from wind farm to AC system is designed. The model of squirrel-cage asynchronous wind generator and permanent magnet direct drive wind generator is built. The equivalent technology is used to form wind farm. The simulation study of no-load startup of MMC-HVDC, grid connection of wind farm and fluctuation process of wind speed is carried out. The start-up strategy and control strategy of the MMC-HVDC system connected to the AC power grid are applied to the multi-terminal flexible DC transmission system. The three-terminal DC system of two wind farms to the AC system is designed. The feasibility of the control strategy is verified by simulation. This paper analyzes the fault characteristics of different types of faults in the connection point of AC system at the receiving end, and puts forward the control method of the DC side energy dissipation resistance for the three-phase fault, which maintains the voltage stability of the wind farm outlet in the fault stage. A double sequence control method based on negative sequence voltage feedforward is proposed to suppress the influence of the negative sequence current component of the fault. Finally, the isolation interference ability of MMC-HVDC and the fault control strategy proposed in this paper are simulated and verified.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614
本文编号：2322672
[Abstract]:With the development of wind power generation technology, the scale of wind farm becomes larger and larger, and wind power has the characteristics of intermittent, uncontrollable, etc. Traditional DC transmission needs a large number of filter devices and is prone to commutative failure. It is of great significance to study the grid-connected mode which is more suitable for wind farms. The flexible DC transmission technology based on modularized multilevel converter has the advantages of large capacity, independent control of active and reactive power, stable AC bus voltage, isolation of fault and easy construction of multi-terminal DC system. It will be widely used in wind power grid connection. In this paper, three grid-connected transmission modes, namely AC transmission, high voltage direct current transmission and flexible direct current transmission, are firstly compared, and the research status of flexible direct current transmission technology which has technical advantages in wind power grid connection is also discussed. The engineering example is introduced, and then the low voltage traversing technology of wind farm is summarized, and the main work of this paper is introduced. The topology, working principle, modulation method and voltage balance method of modular multilevel converter (MMC,modular multilevel converter) are analyzed. The mathematical model of MMC is studied and the internal and external loop control strategy of direct current control is analyzed. The control strategy of wind farm side and AC power grid side converter is designed. The MMC-HVDC system for transmitting power from wind farm to AC system is designed. The model of squirrel-cage asynchronous wind generator and permanent magnet direct drive wind generator is built. The equivalent technology is used to form wind farm. The simulation study of no-load startup of MMC-HVDC, grid connection of wind farm and fluctuation process of wind speed is carried out. The start-up strategy and control strategy of the MMC-HVDC system connected to the AC power grid are applied to the multi-terminal flexible DC transmission system. The three-terminal DC system of two wind farms to the AC system is designed. The feasibility of the control strategy is verified by simulation. This paper analyzes the fault characteristics of different types of faults in the connection point of AC system at the receiving end, and puts forward the control method of the DC side energy dissipation resistance for the three-phase fault, which maintains the voltage stability of the wind farm outlet in the fault stage. A double sequence control method based on negative sequence voltage feedforward is proposed to suppress the influence of the negative sequence current component of the fault. Finally, the isolation interference ability of MMC-HVDC and the fault control strategy proposed in this paper are simulated and verified.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614
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