风力发电并网逆变器控制方法的研究

发布时间：2018-08-12 19:52

【摘要】：随着能源短缺问题的日益严重,风力发电成为了一种重要的发展趋势,并且变速恒频永磁直驱风力发电系统已经成为风电领域里的主力军。目前,其中的双PWM“背靠背”全功率变流拓扑结构得到了广泛的应用,逆变器作为并网发电系统的重要组成部分,其控制策略的研究对提高系统响应速度、提高系统抗干扰能力、对提高电网稳定性和对提高电能质量具有重要的意义。由于并网逆变器在能量转换和传输的过程中起到了很重要的作用,为了能够确保电网的稳定、减少电网谐波畸变、提高电压利用率,本文主要针对风力发电并网逆变器的控制方法进行了深入的研究。以三相电压型PWM逆变器为对象进行研究,分析了逆变器开关管的工作原理,推导了数学模型,并详细的研究了并网逆变器的基于SVPWM调制的双环控制策略和直接功率控制策略两种主要的控制方法,在理论分析的基础上建立了系统仿真模型,仿真验证理论的正确性,并总结了两种控制方法各自的优缺点。首先,总结了风力发电的现实意义、发展和研究现状,对风力发电系统进行方案讨论,确定了永磁直驱型风力发电系统,并采用双PWM “背靠背”变流拓扑结构,通过分析网侧逆变器的电路结构和原理,分别在三种坐标系下推导了相应的数学模型。并对逆变器控制策略的发展现状进行了总体概述,确立了本文的研究方向。其次,设计并采用了电压外环电流内环的双环控制方式,并在详细介绍空间矢量脉宽调制(SVPWM)原理的基础上,讲解了 SVPWM调制的实现过程,仿真验证了基于SVPWM的双闭环控制策略理论的正确性,仿真证明其具有电流波形好,电流谐波畸变低的突出优点,应用效果良好。再次,介绍了直接功率控制策略,对基于电压定向和基于虚拟磁链的直接功率控制原理及实现过程进行详细的分析和讲解,并提出了一种预测直接功率控制算法来改进原有的直接功率控制策略的开关频率不固定的问题,并对预测直接功率控制的原理及作用时间的处理方法进行了细致的研究。最后,在MATLAB/Simulink环境下分别搭建系统仿真模型,仿真结果验证了直接功率控制算法理论分析的正确性。采用的控制方法可以实现优良的并网性能,能够实现单位功率因数运行,并且网侧电流正弦化效果良好,达到了预期设计的并网目的,并分析总结了控制策略的优缺点和适应的情况。
[Abstract]:With the increasingly serious problem of energy shortage, wind power generation has become an important development trend, and variable speed constant frequency permanent magnet direct drive wind power system has become the main force in the field of wind power. At present, the double PWM "back-to-back" full-power converter topology has been widely used. As an important part of grid-connected generation system, the research of control strategy of inverter can improve the response speed of the system. It is of great significance to improve the stability of power grid and improve the power quality by improving the anti-jamming ability of the system. Since grid-connected inverter plays an important role in the process of energy conversion and transmission, in order to ensure the stability of the grid, reduce the harmonic distortion of the power grid, and improve the utilization of voltage. This paper mainly focuses on the control method of grid-connected inverter for wind power generation. The three-phase voltage-source PWM inverter is studied. The working principle of the inverter switch tube is analyzed, and the mathematical model is derived. Two main control methods of grid-connected inverter based on double loop control strategy and direct power control strategy based on SVPWM modulation are studied in detail. The system simulation model is established on the basis of theoretical analysis and the simulation results verify the correctness of the theory. The advantages and disadvantages of the two control methods are summarized. Firstly, the practical significance, development and research status of wind power generation are summarized. The scheme of wind power generation system is discussed, and the permanent magnet direct drive wind power generation system is determined, and the double PWM "back-to-back" converter topology is adopted. By analyzing the circuit structure and principle of grid-side inverter, the corresponding mathematical models are derived in three coordinate systems. The development of inverter control strategy is summarized, and the research direction of this paper is established. Secondly, the double loop control mode of voltage outer loop current inner loop is designed and adopted. On the basis of introducing the principle of space vector pulse width modulation (SVPWM) in detail, the realization process of SVPWM modulation is explained. The simulation verifies the correctness of the theory of double closed loop control strategy based on SVPWM. The simulation results show that it has the outstanding advantages of good current waveform and low current harmonic distortion, and the application effect is good. Thirdly, the direct power control strategy is introduced. The principle and realization process of direct power control based on voltage orientation and virtual flux linkage are analyzed and explained in detail. A predictive direct power control algorithm is proposed to improve the unfixed switching frequency of the original direct power control strategy. The principle of predictive direct power control and the processing method of operation time are studied in detail. Finally, the system simulation models are built in MATLAB/Simulink environment, and the simulation results verify the correctness of the theoretical analysis of the direct power control algorithm. The proposed control method can achieve excellent grid-connection performance, realize unit power factor operation, and the sinusoidal effect of grid side current is good. The advantages and disadvantages of the control strategy are analyzed and summarized.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM614;TM464

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