双馈风电变流器的谐振控制技术研究

发布时间：2018-05-09 21:02

本文选题：风力发电 + 双馈感应发电机　；参考：《浙江大学》2014年博士论文

【摘要】：随着风电在电网中所占比重的大幅增加,并网风电机组对电力系统的稳定性影响日益显著。为此,世界各主要风电大国纷纷出台并网导则,对风电机组的运行可靠性作出明确要求。其中,并网导则对风电机组在电网故障条件下的行为约束,被公认为是对风电机组的严峻挑战。该约束的核心要求可概括为,不仅要求风电机组能够“适应”各类电网故障,还要求其具备“支撑”故障电网恢复的能力。从常见电网故障类型角度看,电网电压不平衡、谐波畸变、对称(或不对称)骤升、跌落故障对并网风电机组的危害最为直接、普遍,影响也最为显著。因此,开展该类电网故障下并网风电机组的运行特性研究,并提出相应控制对策,具有十分重要的理论研究和工程应用价值。在此背景下,本文以作为主流机型的双馈型风电机组为研究对象,以谐振控制器的拓展应用为核心,以理论分析、仿真研究和实验验证为手段,深入、系统研究了该类风电机组在电网电压不平衡及谐波畸变、跌落及骤升等常见故障下的行为特征,提出了与并网导则相适应的电网友好型风电机组的改进控制策略。论文的研究重点是：1)广义电网电压不平衡及谐波畸变时DFIG机组的建模分析及谐振控制策略；2)电网骤升故障下DFIG机组的高电压穿越运行技术。论文的主要研究内容和贡献有： 1.系统梳理了谐振控制器在双馈风电变流器应用中的关键问题,为该技术在风电场中的推广应用奠定了理论基础。内容包括：对比研究了三种谐振(R)控制器的常见应用形式,即比例谐振(PR)、矢量比例积分(VPI)和比例积分谐振(PIR)控制器,从对基波、谐波电流的调节能力、计算复杂性和频率自适应能力三个方面归纳了三种控制器的基本特点和适用场合；以PR控制器为例,系统解答了R控制器在工程应用中需关注的三个难点问题,即参数整定、相位补偿和离散化,特别地,提出了一种基于根轨迹法和频域分析法相结合、较完整的基频、多倍频PR控制器参数设计方案；此外还提出了一种基于谐振控制器的电网电压同步信号的检测方法。 2.首次从电网不平衡及含低次电压谐波时DFIG机组的数学建模入手,采用解析表达的形式评估了该类电网故障对DFIG定子(或转子)电流不平衡度、畸变程度以及对瞬时有功、无功功率和电磁转矩的影响；基于所建立的DFIG完整数学模型,提出了改善机组运行性能的谐振控制策略。首先建立了电网电压含5次、7次等低次谐波分量时DFIG的完整数学模型,评估了低次谐波对DFIG定子瞬时有功、无功功率和电磁功率的影响；基于DFIG的建模分析,提出了相应可选控制目标及相应电流指令算法,提出了适应谐波电网工况的DFIG风电机组谐振电流控制方案。 3.将上述建模方法拓展应用到电网电压不平衡且含5次、7次等低次谐波时的复杂电网工况,重构了该类工况下DFIG定子瞬时有功、无功功率和电磁功率的表达,厘清了功率、转矩中各类波动成分产生的根由；并据此提出了电网不平衡且含低次谐波电压时DFIG网侧、转子侧变流器的协同控制方案；基于所建立的DFIG风电机组完整数学模型,从工程应用角度出发,对DFIG转子侧、网侧变流器的电流指令简化和控制结构进行了系统改进、优化,提高了控制策略的工程实用性；首次建立了广义电网谐波条件下DFIG的一般化数学模型,该模型不仅可以用来分析5次、7次等传统电压谐波对DFIG运行性能的影响,也适用于分数次谐波甚至低频振荡危害的评估,具有较强的普适性,实现了本文数学建模思想的升华。 4.系统研究了电网电压骤升、跌落故障发生时DFIG风电机组的暂态响应过程,并结合并网导则要求,提出了DFIG机组的高电压穿越(HVRT)低电压穿越(LVRT)协同控制和保护方案。内容包括：分析了电网电压骤升故障对DFIG风电机组的主要危害,提出了影响DFIG机组HVRT运行能力的主要因素,据此提出了DFIG风电机组实现HVRT的可行性思路；从并网导对风电机组无功电流输出要求的角度,提出了满足DFIG机组HVRT运行的控制和保护策略；系统归纳了DFIG风电机组LVRT运行的技术难点和关键问题,在现有风电机组保护模块基础上,提出了完整的DFIG机组高、低电压穿越协同控制和保护实施方案。 5.研制了一种新型可编程电网故障模拟电源,该电源能够模拟电网电压对称、不对称跌落,三相不平衡,电压谐波畸变,频率漂移,相角跳变,电压幅值波动等多种电网故障,或两至三种故障兼而有之,且故障严重程度、持续时间等参数均可编程调节。与此同时,研发了一套5.5kW双馈风电机组样机,验证了本文所提出的电网电压广义不平衡及谐波畸变下DFIG机组数学模型的正确性、谐振控制策略的有效性,以及DFIG风电机组高电压穿越、低电压穿越协同控制方案的可靠性和稳定性。
[Abstract]:With the large increase of the proportion of wind power in the power grid, the influence of grid connected wind turbines on the stability of the power system is becoming more and more significant. For this reason, the major power countries in the world have issued a grid guiding principle, making clear requirements for the reliability of the operation of the wind turbines. It is recognized as a severe challenge to the wind turbines. The core requirements of this constraint can be summarized as not only that the wind turbines are required to "adapt" to various types of power grid failures, but also to have the ability to "support" the restoration of the power grid. From the perspective of common grid fault types, the voltage imbalance, harmonic distortion, or asymmetry of the electric network, the harmonic distortion, or asymmetry. Rising and falling faults are the most direct and universal damage to the grid connected wind turbines. Therefore, it is of great importance for theoretical research and engineering application to carry out the research on the operating characteristics of the grid connected wind turbines under the fault of this kind of power grid and put forward the corresponding control countermeasures.
Under this background, this paper takes the doubly fed wind turbine as the main model, and takes the expansion and application of the resonant controller as the core, with the theoretical analysis, the simulation research and the experimental verification as the means, deeply and systematically, and systematically studies the common faults of this kind of wind turbine under the voltage imbalance of the power grid and the harmonic distortion, falling and rising. For the characteristics, an improved control strategy for the grid friendly wind turbine is proposed. The key points of this paper are as follows: 1) the modeling and analysis of DFIG unit and the resonant control strategy of the generalized grid voltage unbalance and harmonic distortion; 2) high voltage crossing operation technology under the sudden failure of the power grid. The research content and contribution are as follows:
1. the key problems in the application of the resonant controller in the doubly fed wind power converter are combed, which lays a theoretical foundation for the popularization and application of the technology in the wind farm. The contents include: comparison and study of the common applications of the three R controllers, namely, proportional resonance (PR), vector proportional integral (VPI) and proportional integral resonance (PIR) controller The basic characteristics and applicable situations of the three controllers are summed up from three aspects: the fundamental wave, the harmonic current adjustment ability, the computational complexity and the frequency adaptive ability. With the PR controller as an example, this paper systematically answers three difficult problems that the R controller needs to pay attention to in the engineering application, namely, the parameter setting, the phase compensation and the discretization, especially, Based on the combination of the root locus method and the frequency domain analysis method, a more complete parameter design scheme of the basic frequency and multiple frequency PR controller is proposed. In addition, a method of detecting the voltage synchronization signal of the power grid based on the resonant controller is also proposed.
2. for the first time, starting with the mathematical modeling of the DFIG unit with the unbalanced power grid and the low secondary voltage harmonics, the influence of the power grid fault on the current imbalance of the DFIG stator (or rotor), the degree of distortion, the instantaneous active power, the reactive power and the electromagnetic torque are evaluated by the analytical expression. Based on the complete mathematical model of the DFIG, a complete mathematical model is proposed. A resonant control strategy to improve the operating performance of the unit is given. First, a complete mathematical model of DFIG is established for the voltage of 5 and 7 second low harmonic components. The effect of low harmonic on the instantaneous active power, reactive power and electromagnetic power of the DFIG stator is evaluated. Based on the modeling and analysis of DFIG, the corresponding optional control targets and corresponding electricity are proposed. A current control algorithm for DFIG wind turbines adapting to harmonic power grid conditions is proposed.
3. the above modeling method is extended and applied to the complex network condition when the power grid voltage is unbalance and contains 5 times and 7 second low harmonic. The instantaneous active power, reactive power and electromagnetic power of the DFIG stator are reconstructed, and the root cause of all kinds of fluctuating components in the power and torque is clarified. The coordinated control scheme of the DFIG net side and the rotor side converter in the low harmonic voltage voltage is based on the complete mathematical model of the DFIG wind turbine. From the point of view of the engineering application, the current instruction simplification and control structure of the DFIG rotor side, the net side converter and the control structure are improved, and the engineering practicability of the control strategy is improved. The general mathematical model of DFIG under the condition of generalized grid harmonic is established. This model can not only be used to analyze the influence of the 5, 7 and other traditional voltage harmonics on the performance of the DFIG, but also to the assessment of the damage of fractional harmonic and even low frequency oscillation. It has a strong universality and realizes the sublimation of the mathematical modeling thought in this paper.
4. systematically studies the transient response process of the DFIG wind turbine when the power grid voltage rises suddenly and the falling fault occurs. Combined with the requirements of the grid guidance, the DFIG unit's high voltage crossing (HVRT) low voltage crossing (LVRT) cooperative control and protection scheme is proposed. The contents include the main damage to the DFIG wind turbine by the analysis of the voltage rising fault of the power grid. The main factors that affect the operation ability of the DFIG unit HVRT are put forward. According to this, the feasibility of the DFIG wind turbine to realize the HVRT is put forward. The control and protection strategy for the HVRT operation of the DFIG unit is put forward from the angle of the output requirement of the reactive current of the wind turbine, and the technical difficulty of the LVRT operation of the DFIG wind turbine is attributed to the system. And key problems, based on the existing wind turbine protection module, a complete implementation plan of DFIG unit's high voltage and low voltage ride through cooperative control and protection is put forward.
5. a new programmable power grid fault analog power supply is developed. The power supply can simulate the voltage symmetry, asymmetric drop, three-phase unbalance, voltage harmonic distortion, frequency drift, phase angle jump, voltage amplitude fluctuation and so on, or two to three kinds of faults, and the parameters of the fault severity, duration and so on At the same time, a prototype of 5.5kW doubly fed wind turbine is developed, which validates the correctness of the mathematical model of the DFIG unit under the generalized unbalance of voltage and the harmonic distortion, the validity of the resonant control strategy, the high voltage crossing of the DFIG wind turbine group and the reliability and stability of the co control scheme of low voltage crossing. Qualitative.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM614;TM46

【参考文献】