交流微电网的无功功率均分控制策略研究

发布时间：2019-03-29 18:45

【摘要】：摘要：电网的安全稳定和经济运行对国民生产生活具有重要意义。而随着全球能源的短缺以及用电需求的日益增长,以传统的集中式大型电力网络的脆弱性日益凸现,以大机组、大电网、高电压为主要特征的电力系统已难以满足现行用户多样化的供电需求和可靠性要求。鉴于以上问题,分布式发电受到人们的广泛关注。而微电网正是充分利用这些分布式能源的价值和效益,将储能装置、电力电子装置、相关负荷和监控保护汇集而成的一种微型发电系统。相对传统的集中式电力系统,以电力电子装置为接口的分布式电源(Distributed Generation, DG)是交流微电网的核心。当微电网孤岛运行时,由于线路差异导致各DG与公共母线间的阻抗不等,造成各分布式电源输出的无功功率不能均分,从而导致各DG单元产生无功环流,严重影响电能质量和系统的稳定性。因此,如何使负荷在各DG单元间合理的分配,成为微电网的研究热点之一。而负荷功率均分取决于微电网的控制技术。因此,本文对交流微电网孤岛运行时,其并联逆变器的有功和无功功率均分控制策略展开了研究,全文的主要工作可分为如下方面： (1)本文详细分析了系统无功环流产生的机理和影响因素,并对比分析和研究了基于通信、基于下垂思想以及基于通信与下垂思想结合的三类交流微电网无功均分控制技术。 (2)论文在研究了下垂控制机理的基础上,提出了一种改进的下垂控制策略。该方法利用低带宽通信获取各微源的无功功率信息,自适应调节无功电压下垂控制的电压偏置,明显地改善了微电网无功出力的分配精度。 (3)为了减少微电网的通信成本,本文提出了一种基于同步补偿思想的无功／电压下垂控制方法,在传统的无功下垂控制基础上适时地增加无功偏差补偿项和电压恢复补偿项,改善了无功出力分配精度的同时,提高了电压质量。 (4)针对本文提出的两种控制策略,建立了MATLAB/simulink仿真平台,并搭建了基于两台分布式微源并联的实验平台,仿真和实验均验证了上述两种控制策略的有效性和可行性。
[Abstract]:Abstract: the security and stability of power network and economic operation are of great significance to national production and life. And with the global energy shortage and the increasing demand for electricity, the fragility of the traditional centralized large-scale power network has become increasingly prominent, with large units and large power grids, The power system characterized by high voltage is difficult to meet the diversified requirements of power supply and reliability of current users. In view of the above problems, distributed power generation has been widely concerned. Micro-grid is a kind of micro-power generation system, which makes full use of the value and benefit of these distributed energy sources and combines energy storage devices, power electronics devices, related loads and monitoring protection to form a micro-power generation system. In contrast to the traditional centralized power system, the distributed power supply (Distributed Generation, DG) with power electronic device as the interface is the core of AC microgrid. When the microgrid islanding, the impedance between the DG and the common bus is different due to the line difference, and the output reactive power of the distributed power supply cannot be divided equally, which results in the reactive power circulation of each DG unit. It seriously affects the power quality and the stability of the system. Therefore, how to make the load reasonably distributed among the DG units has become one of the research hotspots in the microgrid. The load power sharing depends on the control technology of microgrid. Therefore, in this paper, the active power and reactive power sharing control strategy of the parallel inverter is studied when the isolated island AC microgrid is in operation. The main work of this paper can be divided into the following aspects: (1) in this paper, the mechanism and influencing factors of reactive circulation in the system are analyzed in detail, and the communication-based communication is compared and studied. Based on droop theory and combination of communication and droop, three kinds of reactive power sharing control techniques for AC microgrid are proposed. (2) based on the study of droop control mechanism, an improved droop control strategy is proposed. The method uses low bandwidth communication to obtain the reactive power information of each microsource, and adaptively adjusts the voltage bias of reactive voltage droop control, which greatly improves the distribution accuracy of reactive power output in microgrid. (3) in order to reduce the communication cost of microgrid, a reactive power / voltage droop control method based on synchronous compensation is proposed in this paper. On the basis of traditional control of reactive power droop, the compensation terms of reactive power deviation and voltage recovery are added timely, which improves the precision of reactive power distribution and the quality of voltage at the same time. (4) in view of the two control strategies proposed in this paper, a MATLAB/simulink simulation platform is established, and an experimental platform based on two distributed micro-sources in parallel is built. The effectiveness and feasibility of the two control strategies are verified by both simulation and experiment.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM732

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