微电网中基于分布式电源改善电能质量的研究

发布时间：2018-03-27 06:46

本文选题：电能质量　切入点：UPQC　出处：《北京交通大学》2014年硕士论文

【摘要】：针对全世界范围内能源的匮乏、能源利用效率的瓶颈、环境污染问题等,世界各国相继开展微电网的研究。微电网利用分布式发电污染少、能源利用率高、安装地点灵活等优点,是大电网的有力补充和有效支撑。微电网中分布式电源(DG)适当的容量和合理的位置是微电源有效利用和用户安全用电的保障,基于此,本文提出了一种具有低碳环保,高效利用,优质电能质量的微电网结构。针对微电网结构中出现的电能质量问题,本文提出了一种基于改进型UPQC结构的微电网控制策略,其具体结构就是在传统UPQC结构左侧增加了一个动态电压恢复器(DVR),利用它们之间的协调控制来改善微电网中的电能质量问题。本文提出的控制策略分为改进型间接控制和改进型直接控制,其可以有效的补偿主电网电压跌落、过电压、电压畸变和校正电压不平衡度,还可以补偿由微电网中非线性和不平衡负荷带来的谐波电流和不平衡电流问题。并网变流器的拓扑结构是由三相四桥臂构成的,包括串联变流器和并联变流器。在串并联变流器补偿电网电压和电流的同时,不仅解决了串并联变流器耦合带来的干扰,而且实现了微电网合理的功率分配。尤其通过改进微电网公共连接点的UPQC结构(在UPQC左侧增加一个DVR),提出了改进型最小能量电压跌落补偿法,克服了传统补偿算法的缺陷,确保了负载电压的相角不会发生突变,不仅提高了DG补偿电压的能力和范围,而且降低了变流器的容量和成本。在检测环节中,针对电网中电压畸变及不平衡情况,利用比例谐振(PR)调节器对特定次频率的有效跟踪来实现零稳态误差,本文利用了基于谐振式PLL改进型最小能量的检测法,有效地削弱了因电网畸变和不平衡带来的检测干扰。本文提出的微电网控制策略还可以减少微电网并网和孤岛模式转换时对微电网的冲击,在主电网故障清楚后可以实现微电网再次并网。最后针对改进型间接和改进型直接两种控制策略的优缺点,提出了其相应的DG应用场合。采用Matlab仿真,在Simulink里设置了各种工况,仿真实验结果验证了本文提出的控制策略的有效性和优越性。
[Abstract]:In view of the shortage of energy, the bottleneck of energy use efficiency and the environmental pollution in the whole world, countries all over the world have carried out research on microgrid, which makes use of distributed generation less pollution and higher energy efficiency. The advantages of flexible installation location are the powerful supplement and effective support of large power grid. The proper capacity and reasonable position of DGG in microgrid are the guarantee of the effective utilization of micro-power source and the safe use of electricity by users. In this paper, a low carbon environmental protection, efficient utilization, high quality power quality microgrid structure is proposed. Aiming at the problem of power quality in microgrid structure, a new control strategy based on improved UPQC structure is proposed in this paper. Its specific structure is to add a dynamic voltage restorer to the left side of the traditional UPQC structure to improve the power quality problem in the microgrid by using the coordinated control between them. The control strategy proposed in this paper is divided into improved indirect control strategy. Control and improved direct control, It can effectively compensate for voltage drop, overvoltage, voltage distortion and correction voltage imbalance. The harmonic current and unbalanced current caused by nonlinear and unbalanced load in microgrid can also be compensated. The topology of grid-connected converter is composed of three-phase four-leg. Including series converters and parallel converters. While the series-parallel converter compensates the grid voltage and current, it not only solves the interference caused by the coupling of the series-parallel converter, Especially by improving the UPQC structure of the common connection point of microgrid (adding a DVR to the left side of UPQC), an improved minimum energy voltage sag compensation method is proposed, which overcomes the defects of the traditional compensation algorithm. It ensures that the phase angle of the load voltage does not change, which not only improves the capacity and range of the DG compensation voltage, but also reduces the capacity and cost of the converter. In the detection link, aiming at the voltage distortion and unbalance in the power network, the effective tracking of the specific secondary frequency by the proportional resonant PR-regulator is used to realize the zero steady-state error. In this paper, the detection method based on the resonant PLL modified minimum energy is used to detect the zero steady-state error. It effectively weakens the detection interference caused by the distortion and imbalance of the power network. The microgrid control strategy proposed in this paper can also reduce the impact on the microgrid when the microgrid is connected and the islanding mode is converted. After the fault of the main power network is clear, the microgrid can be connected again. Finally, aiming at the advantages and disadvantages of the improved indirect control strategy and the improved direct control strategy, the corresponding DG application situation is put forward. The Matlab simulation is used to set up various working conditions in the Simulink. Simulation results show the effectiveness and superiority of the proposed control strategy.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM761

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