基于虚拟电机模型的分布式发电并网逆变器及电压稳定性研究

发布时间：2019-02-25 20:25

【摘要】：分布式发电(Distributed Generation,DG)以其发电方式灵活、能源利用率高、环境污染小等优点日益成为传统电网的有效补充,并网逆变器作为分布式电源与电网的接口,在并网发电中起着关键作用。本文以并网逆变器为研究对象,提出了abc自然坐标系(Natural Coordinates,NC)、虚拟电机(Virtual Machine,VM)的概念,通过对虚拟电机磁链的准确观测,解决分布式电源接入电网时电压波动和功率因数不高的问题。与传统的电压定向和虚拟磁链定向不同,本文所介绍的方法将逆变桥输出电压的积分直接看作虚拟电机磁链,逆变桥以外的部分看作虚拟电机,于是,虚拟电机部分类似于一台无限大的、由逆变器供电并以同步速恒速运行的同步电机。同时,建立abc自然坐标系下的数学模型,提出了基于虚拟电机模型的分布式发电并网逆变器的自然坐标无功稳压控制策略和准直接功率控制(Quasi Direct Power Control,QDPC)策略。两种方法均在自然坐标系下,通过虚拟电机磁链进行定向,abc三相分相独立控制,实现了有功电流和无功电流的解耦。最后,通过Quaser8+dSPACE的半控制器全实物实验平台进行快速实时验证。实验结果表明,本文所介绍的两种方法在无需任何坐标变换、无需锁相环节、无需交流侧电压传感器的条件下均能有效运行。VM无功稳压控制能够快速、持久的保持交流侧和直流侧电压的稳定；VM-QDPC策略使逆变器运行于负单位功率因数,而且能够在小范围内实现完全无模型控制,克服部分源/荷的不平衡,提高了系统鲁棒性。
[Abstract]:Distributed power generation (Distributed Generation,DG) has become an effective supplement to the traditional power grid due to its flexible generation mode, high energy efficiency and low environmental pollution. Grid-connected inverter is the interface between the distributed power supply and the power grid. It plays a key role in grid-connected power generation. Taking grid-connected inverter as the research object, the concepts of abc natural coordinate system (Natural Coordinates,NC) and virtual motor (Virtual Machine,VM) are put forward in this paper. Through the accurate observation of the flux linkage of the virtual motor, The problem of low voltage fluctuation and power factor when distributed power supply is connected to power grid is solved. Different from the traditional voltage orientation and virtual flux orientation, the method introduced in this paper regards the integral of the output voltage of the inverter bridge as the virtual motor flux linkage directly, and the parts other than the inverter bridge as the virtual motor, so the method introduced in this paper regards the integral of the inverter bridge output voltage as the virtual motor. The virtual motor is partly similar to an infinite synchronous motor powered by an inverter and operated at a synchronous speed and constant speed. At the same time, the mathematical model of abc natural coordinate system is established, and the natural coordinate reactive power stabilization control strategy and quasi-direct power control (Quasi Direct Power Control,QDPC strategy of distributed grid-connected inverter based on virtual motor model are proposed. Both methods are oriented by virtual motor flux and controlled independently by abc three-phase separation in natural coordinate system. The decoupling of active current and reactive current is realized. Finally, the rapid and real-time verification is carried out through the hardware-in-the-loop experiment platform of Quaser8 dSPACE. The experimental results show that the two methods presented in this paper can operate effectively without any coordinate transformation, phase locked link and AC side voltage sensor. Maintain the voltage stability of AC side and DC side for a long time; The VM-QDPC strategy makes the inverter run in a negative unit power factor, and can achieve complete model-free control in a small range, overcome the partial source / load imbalance, and improve the robustness of the system.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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