微电网中多功能并网逆变器的控制策略研究

发布时间：2018-06-13 03:29

本文选题：微电网 + 多功能并网逆变器　；参考：《湖南大学》2016年硕士论文

【摘要】：如今全球能源危机和环境污染的问题日益加剧,充分利用光伏、风力等清洁可再生能源发电是未来电网发展的必然趋势,微电网作为一种分布式电源接入电网的有效手段,逐步引起了广泛的关注。微电网中的并网逆变器是能量传输的关键装置,具有与电能质量治理装置类似的拓扑结构和灵活多样的控制策略,可以主动参与微电网电能质量治理,研究多功能并网逆变器的控制策略,提升逆变器在弱电网下的适应能力,对微电网稳定可靠运行具有重要的意义。本文以微电网中多功能并网逆变器的控制策略为对象,深入研究了多功能并网逆变器的同步锁相环控制方法和不平衡及谐波的补偿策略。主要工作和创新点体现在：(1)在分析同步参考坐标系锁相环的数学模型和动态性能基础上,分别研究了基于二阶广义积分和滑动平均滤波的正负序解耦方法。详细阐述了两种滤波策略的结构、参数选择与动态性能,基于两种滤波方法,分别设计了dq旋转坐标系下的锁相环结构。通过仿真验证,两种正负序解耦方法能够精确地检测电网电压基波的正负序幅值和相位信息,消除了电网电压不平衡和谐波对同步信号检测的影响。其中基于滑动平均滤波的正负序解耦方法结构更加简单、响应速度更快、谐波抑制能力更强。(2)针对微电网中的电网电压不平衡和非线性负载谐波问题,本文提出了一种多功能并网逆变器综合集成控制方法,实现对正、负序下的基波有功、无功及谐波综合控制。首先在电网电压不平衡下,研究了一种正序dq旋转坐标系的电流联合控制方法,实现对正序负序电流的控制,提高系统的响应性能。针对非线性负载谐波问题,提出一种谐波复合补偿控制方法,将6k±1次特征谐波变换成dq旋转坐标系下6k次谐波,旨在降低系统的复杂度。然后对基波、2次纹波和6k次指令电流叠加,通过比例谐振控制器实现综合集成控制。最后通过仿真验证了所提出控制策略的有效性。(3)研制了额定功率为50kW的多功能并网逆变器,并给出实验装置的硬件系统、控制系统和软件系统的设计方案。通过对所开发的样机进行测试,在电网电压不平衡和非线性负载谐波下,所提出的控制策略能有效地抑制逆变器直流侧二次纹波,并能对无功与谐波进行补偿,提高了微电网的电能质量。
[Abstract]:Nowadays, the global energy crisis and environmental pollution are becoming more and more serious. Making full use of clean and renewable energy, such as photovoltaic and wind, is the inevitable trend of the development of power grid in the future. Microgrid is an effective means of connecting distributed generation to power grid. Gradually aroused widespread concern. Grid-connected inverter in microgrid is the key device for energy transmission. It has similar topology structure and flexible control strategy as power quality control device, so it can participate in power quality management of microgrid actively. It is of great significance to study the control strategy of multi-function grid-connected inverter and improve the adaptability of inverter under weak grid, which is of great significance to the stable and reliable operation of microgrid. Taking the control strategy of multifunctional grid-connected inverter in microgrid as an object, the synchronous phase-locked loop control method and unbalanced and harmonic compensation strategy of multi-function grid-connected inverter are studied in this paper. On the basis of analyzing the mathematical model and dynamic performance of phase locked loop in synchronous reference coordinate system, the positive and negative sequence decoupling methods based on second order generalized integral and moving average filter are studied respectively. The structure, parameter selection and dynamic performance of the two filtering strategies are described in detail. Based on the two filtering methods, the phase-locked loop structure in the dq rotating coordinate system is designed respectively. The simulation results show that the two positive and negative sequence decoupling methods can accurately detect the amplitude and phase information of the fundamental wave of grid voltage and eliminate the influence of voltage imbalance and harmonics on the detection of synchronous signals. The method of positive and negative sequence decoupling based on moving average filter is simpler in structure, faster in response speed and stronger in harmonic suppression ability. In this paper, a comprehensive integrated control method for multifunctional grid-connected inverters is proposed to realize the integrated control of active, reactive and harmonic waves under positive and negative sequence. In this paper, a combined current control method based on the positive sequence DQ rotating coordinate system is studied under the unbalanced voltage of the power network, which realizes the control of the positive sequence and negative sequence current and improves the response performance of the system. In order to reduce the complexity of the system, a hybrid harmonic compensation control method is proposed to solve the nonlinear load harmonic problem. The 6k harmonic is transformed from 6k 卤1 characteristic harmonics to 6k harmonics in the dq rotating coordinate system in order to reduce the complexity of the system. Then the fundamental ripple and 6k instruction current are superposed and the integrated control is realized by the proportional resonance controller. Finally, the effectiveness of the proposed control strategy is verified by simulation. The multifunctional grid-connected inverter with rated power of 50kW is developed, and the design scheme of hardware system, control system and software system of the experimental device is given. By testing the developed prototype, the proposed control strategy can effectively suppress the secondary ripple of the inverter and compensate the reactive power and harmonic under the unbalanced voltage and nonlinear load harmonics. The power quality of microgrid is improved.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM464

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