【作者】 刘霞；

【导师】 刘海；

【作者基本信息】 山东大学 ， 控制理论与控制工程， 2018， 硕士

【摘要】 随着化石能源枯竭和环境的恶化,人类社会发展与传统能源产业的冲突日益加剧,迫使传统的电力结构发生改变。在过去的几十年,可再生能源(renewable energy source,RES)的开发利用受到越来越多关注。传统的电力系统由于远距离传输的损耗和热能的散失,其能源利用率很低,同时废气的排放量很高。而规模更小、效率更高、排污量更低的分布式发电(Distributed Generation,DG)能够提高能源的利用率,尤其是风电、光伏、燃料电池及储能技术的飞速发展,为微电网的发展提供了越来越多的可行方案。风力(Wind Power,WP)资源的研究与发展受到各国的普遍重视,已经成为开发利用水平最高的新型能源之一[1]。风力资源自身的波动性和不确定性,决定了其输出功率受地域和气候的影响,使得风力发电的可靠性较低。微型燃气轮机(Micro Gas Turbine,MGT)作为可控电源与风电互补形成联合供电系统,提高了微电网运行的可行性,保证微网在各种工况下的可靠供电。本文首先分析风力机、MGT和储能装置的工作原理并建立其等效数学模型,提出相应的控制策略,然后基于PSCAD/EMTDC平台实现了 WP、MGT和储能系统(Energy Storage System,ESS)的联供系统的仿真,验证所提控制策略的有效性。其次,由于各分布式发电(Distributed Generation,DG)单元以逆变器为接口与交流母线相连,而这些DG之间则存在功率分配等协调控制问题。本文基于多台逆变器并联结构,对比分析两种无通讯线型并联逆变器控制方法:虚拟同步发电机(Virtual Synchronous Generator,VSG)控制和下垂控制。得出如下结论:VSG控制既能模拟同步机稳态下垂特性又能模拟暂态特征,其转动惯量和阻尼项能够改善系统的频率波动,增加微电网的惯性,其动态功率均分性能优于下垂控制。微网应具备并网及孤岛运行能力,并且在两种模式之间可以无缝切换,本文首先分析了现有切换控制策略各自的优点及不足,并提出了基于多主多从微网结构的直接电流控制和下垂控制相结合的控制策略,可以保证由并网模式向孤岛模式转换时负载的电压质量,并且可以提高孤岛模式下微网的可靠性。最后针对包含WP、MGT及储能的联合供电系统,提出合理的运行机理及协调控制策略。在并网及孤岛运行时,通过监测风速变化及蓄电池的SOC状态,制定负荷投切计划,以及各DG的出力大小,提高系统整体的运行效率。更多还原

【Abstract】 With the depletion of fossil energy resources and the deterioration of the environment,the conflict between the development of human society and the traditional energy industry has been intensified,forcing the change of traditional power structure.In the past few decades,the development and utilization of renewable energy sources(RES)has received more and more attention.Although the traditional power system is reliable and controllable,due to the loss of long-distance transmission and the dissipation of thermal energy,the energy utilization rate is very low,and the exhaust gas emission is high.Smaller scale,higher efficiency,and lower discharge capacity has made renewable energy generation possible to improve energy use,especially the rapid development of wind power,photovoltaic,fuel cells,tidal power generation,and energy storage technologies,which have provided more and more feasible solutions for the development of Microgrids.Among the renewable energy sources,the development and utilization of wind power(WP)has received universal attention from all of the countries.WP has become one of the new energy sources with the highest level of development and utilization.Wind resource has obvious volatility and uncertainty,and the output power is greatly affected by region and weather,making the reliability of WP generation low.In order to increase the reliability of wind power generation,it is necessary to add a controllable generation unit or distributed energy storage complements wind power generation to form an combined power supply system.The combination of WP and MGT can ensure reliable power supply of the microgrid under various operating conditions.In this thesis,the working principle and equivalent mathematical model of wind turbine,MGT and battery were analyzed,and WP,MGT and Energy Storage System(ESS)simulation models were built on the PSCAD/EMTDC simulation platform according to the mathematical model of each part.Secondly,because each DG unit is connected to the AC bus via the inverter,there is a problem of coordination control,for example,power sharing among these power sources.Based on the multi-inverter parallel structure,the existing control methods of non-communication parallel inverter were compared and analyzed:the dynamic power sharing performance of Virtual Synchronous Generator(VSG)control method and Droop control.Draw the following conclusions:VSG control is an inverter control method that can simulate the steady state droop characteristics and simulate transient characteristics of synchronous generators.The moment of inertia and damping term of VSG control equations can increase the frequency stability of the system.The microgrid should have the capability of grid-connected and islanding operations,and can transfer seamlessly between the two modes.The respective advantages and disadvantages of the existing control strategies of seamless transfer were analyzed.A combined control strategy of direct current control and droop control method was proposed,which can guarantee the power supply quality of the load when switching from grid-connected mode to islanding mode,and can improve the reliability of the microgrid in islanding mode.A combined method of direct current control and droop control for multi-master and multi-slave architecture is proposed.When the grid is broken,the master DGs can transfer from direct current control to V/f control automatically and the quality of load voltage will not be affected.It also can improve the reliability of islanding mode because of the structure of multiple master DGs.Finally,based on the combined power supply system,the reasonable operation mechanism and coordinated control strategy are proposed.The load switching plan and the output of DG units were formulated according to wind speed and the SOC status of the energy storage system,thus can improve the overall system operating efficiency.更多还原