【作者】 崔明勇；

【导师】 艾欣；

【作者基本信息】 华北电力大学（北京） ， 电力系统及其自动化， 2011， 博士

【摘要】 随着化石能源的日渐枯竭以及环境污染的日益严重,为了满足日益增长的电力负荷需求,必须充分利用各地丰富的清洁和可再生能源,大力发展分布式发电技术,并将分布式发电供能系统以微网形式接入到大电网并网运行,与大电网互为支撑。由于分布式发电(Distributed generation, DG)具有间歇性、复杂性、多样性、不稳定性的特点,如何优化调度各种分布式发电以保证微网的经济运行,多台DG并联运行时如何抑制环流、合理进行功率分配,以及如何实现分布式发电的并网运行,成为了现代电力工业技术领域新的研究热点。本文针对这些问题进行了深入研究,主要的研究内容如下：(1)考虑到太阳能光伏发电、风力发电的不可调度性,以及其它不同类型、容量的分布式发电所消耗的燃料、效率、运行和维护费用、温室气体的排放水平,建立了综合考虑发电成本与排放成本的微网环保经济运行数学模型。(2)为了满足电力负荷需求,并实现微网的低碳优化运行,综合考虑分布式发电接入前后系统的总线路损耗、节点电压偏差、发电成本、CO2排放量,建立了微网多目标低碳优化运行的数学模型。(3)自治微网中,多台DG并联运行时会在各DG间产生环流。在介绍环流危害及常用的环流抑制措施后,提出了基于主从控制的等电压、等电流、等功率、混合式4种环流抑制策略。仿真结果表明这4种策略均能很好地抑制环流,其中等电流策略效果最佳,等功率与混合式策略次之,等电压策略稍差。(4)为实现自治微网中多台DG的并联运行,满足负载需求、快速响应负载变化以及系统的稳定运行,必须在各DG间合理分配功率。在分析PQ控制与下垂控制的基础上,针对低压自治微网特殊的阻抗特性,提出了基于反下垂控制的功率共享控制策略,实现了各DG间更精准、快速的功率共享控制。(5)分析了常规的并网逆变器直接输出电流控制方法的局限性,结合LCL型三相并网逆变器的数学模型,提出了LCL型并网逆变器的输入-输出反馈线性化控制方法。仿真结果表明该方法可实现逆变器的并网运行,且动态响应快,稳态误差小,无需附加阻尼电阻以保证系统稳定运行。更多还原

【Abstract】 With the gradual depletion of fossil fuels and growing environmental pollution, the clean and renewable energy should be made full use of, and distributed generation (DG) technology should be developed greatly and integrated into large power grid in forms of Microgrid to meet the increasing load demand. Considering the characteristics of DG such as intermittent, complexity, diversity and instability, how to optimal operation of various DG to ensure economic operation of Microgrid, how to restrain circulating current and distribute power when multiple DG units operate in parallel, and how to implement grid-connected operation have been the new research hotspots in modern power industry technology. This paper studies these issues in depth, and the main contents are as follows:(1)Considering the undispatchable characteristics of photovoltaic and wind turbine and different fuel consumption, efficiency, operation and maintenance costs, greenhouse gas emission level of DG with various types and capacity, a novel environmental and economical model of Microgrid which considered generation cost and emission cost all together was presented.(2)In order to meet the load demand and achieve low carbon operation of Microgrid, a novel model of multi-objective low carbon operation of Microgrid was presented, which took the line losses, voltage difference, generation cost and CO2 emission on a whole.(3)Circulating current will be generated in autonomous Microgrid when multiple DG units operate in parallel. The hazards and conventional restrain strategy of circulating current were introduced, and four master-slave control strategies, namely equal voltage control strategy, equal current control strategy, equal power control strategy and hybrid control strategy, were proposed. Simulation results showed that all theses four strategies could restrain circulating current effectively.(4)When multiple DGs operate in parallel, power should be distributed reasonably among all DGs to meet the load demands, respond to demands changes rapidly and achieve stable operation of the system. Based on the analysis of the conventional power sharing control strategies of Microgrid, such as PQ control and droop control, a novel power sharing control strategy based on inverse droop control was proposed, in which the special impedance characteristic of low voltage Microgrid has been taken into account. More precise power sharing among the DGs and rapider dynamic response could be achieved by the proposed strategy.(5)Limitation of the traditional direct output current control method of the inverter was analyzed, the model of the grid-connect inverter with LCL filter and the inverter input-output feedback linearization control method were proposed. Simulation results showed that the proposed control method could implement grid-connected operation of inverter with prompt dynamic respond and little steady state error, and achive stable operation of the system without damping resisters.更多还原