【作者】 匡洪海；

【导师】 吴政球；

【作者基本信息】 湖南大学 ， 电气工程， 2013， 博士

【摘要】 随着人们对可持续发展和降低环境污染的重视，分布式发电（DG）技术以其独有的环保性和经济性引起人们越来越多的关注。DG中的风能受自然条件的影响不能持续稳定地输出电能，因此风电并入电网势必对电力系统的稳定运行产生影响，尤其在系统发生故障时。由于风电场多处于偏远地区，常接于电网的末端，这会使并网后系统的潮流发生改变，影响电网的稳定性和电能质量。本文围绕分布式风电并网系统产生的暂态稳定及电能质量问题，分别从不同风力电机类型、储能系统、微分进化（DE）算法、同步扰动随机逼近(SPSA)算法、电力系统稳定器(PSS)、自动电压调节器(AVR)以及灵活柔性交流输电系统（FACTS）设备等方面开展了较系统、深入的研究，以探求其更为有效的解决方案。本文的主要研究成果如下：（1）提出基于模糊逻辑控制的超级电容器储能系统（SCESS）和双馈感应发电机（DFIG）相结合的解决方案。为提高能源利用率和改善系统的稳定可靠性，常在DG中加入储能装置，而使用SCESS能够同时控制有功功率和无功功率，故它能补偿功率波动；因模糊逻辑器可以有效应用于非线性系统，它能稳定系统；其次DFIG可以调节无功功率，也可以提高电力系统的暂态稳定性。为此本文提出采用DC-DC降压/升压变换器的模糊逻辑控制和电压源变流器的脉冲宽度调制控制相结合的SCESS-DFIG方案，利用Matlab/Simulink软件对并网系统进行了建模仿真分析。研究结果表明该方案能改善风电并网系统的稳定性和电能质量。（2）提出基于同步扰动随机逼近（SPSA）算法的最大风能功率追踪控制策略。为使风力发电系统在变动风速下，不受外界干扰，易使风力机保持在最大功率点运行，本文提出采用SPSA算法进行风力发电系统最大功率追踪。该算法通过调节电源转换器的工作周期，间接控制风力发电机转速，使风力发电系统在任何风速下皆可运行在最大功率点，从而将最大功率输出至负载，并避免实际运行时使用风力计和转速计。研究结果表明无论风速如何变化，SPSA算法皆能有效提高风力发电系统输出功率，并使叶尖速比和效能指数维持在最佳值附近。（3）提出基于电压源变流器的静止同步补偿器（STATCOM）和基于同步发电机（SG）的PSS相结合的解决方案。STATCOM并联于电网中，相当于一个可控的无功电流源，其无功电流可以快速地跟随负荷无功电流的变化而变化，自动补偿电网系统所需无功功率，对电网无功功率实现动态无功补偿。但当电力系统中没有励磁控制器时，即使增加STATCOM系统也不一定能保持稳定，故可考虑在同步发电机上配置PSS并对其参数进行适当调节。为保证风电并网系统的暂态稳定性和电能质量不降低，本文提出研究使用STATCOM-PSS控制方案来改善并网风电场发出的电能质量和故障穿越能力。研究结果表明STATCOM-PSS控制策略能有效恢复风电并入点故障后的电压，提高风电场的故障穿越能力，改善风电并网系统的暂态稳定性和风力发电机组的电能质量。（4）提出基于微分进化(DE)法的AVR-PSS协同控制策略。为解决风电并网系统的稳定性问题，本文从经济性出发，考虑在风电并网系统的SG中安装PSS。但PSS以牺牲AVR为代价来提供阻尼和振荡稳定性，AVR以牺牲鲁棒性振荡稳定来提供暂态稳定性，因此要获得系统较好电压调节和振荡阻尼，AVR和PSS的同步调节是必需的。为此本文提出利用DE算法来解决SG中AVR和PSS参数的最优调节问题，并利用仿真软件在有、无PSS以及是否使用DE算法的各种情况下对风电并网系统稳定性进行了仿真研究分析，研究结果表明基于DE算法的AVR-PSS的协同调节能改善风电并网系统的稳定性。（5）提出基于DFIG-FMAC-PSS的控制策略。针对含有风力发电的系统，在SG的AVR中安装PSS的解决方案可能不再提供额外阻尼，若装有这些装置的SG被切断来调节风力，其阻尼作用明显丧失。为此本文考虑在DFIG装设PSS，提出了DFIG转子磁链幅值和相角控制（FMAC）加PSS的另一种控制方案。选用DFIG定子电功率作为PSS输入信号，通过调节DFIG转子磁链矢量的幅值和相角对发电机的端电压和输出功率进行控制，对大扰动的情况下的并网系统稳定性研究表明，所提DFIG-FMAC-PSS的控制方案经济可行，其提供电压控制、促进阻尼作用和提高风电并网系统的稳定性等性能均优于比SG加PSS的解决方案。更多还原

【Abstract】 With people placing more attention on sustainable development and reducingenvironmental pollution, distributed generation (DG) technology based on renewableenergy for its unique environmental protection and economical efficiency is attractingmore and more attention. But wind energy among DG is affected by natural conditionsso as to can not output power continuously and steadily, so wind energy generationincorporated into the electric power system will bring a series of issues for its steadyoperation, especially when wind power integrated system is fault. Because of windfarms mostly are in remote areas and often are at the most endings of the grid, it willinevitably make power flow of wind power integrated system change, and has aninfluence on electrical energy quality and stability of the grid.Therefore, several solutions are proposed to improve transient stability andpower quality of wind power integrated system in this dissertation. Distributed windpower integrated system is analyzed systematically and deeply in this dissertation,respectively from these aspects including different type of wind generator, energystorage system, differential evolution (DE) method, simultaneous perturbationstochastic approximation (SPSA) algorithm, electric power system stabilizer (PSS),automatic voltage regulator (AVR) and flexible AC transmission systems (FACTS)equipment, the main research results are as follows:（1）The combined scheme of super capacitor energy storage system (SCESS)based on fuzzy logic control and doubly-fed induction generator (DFIG) is proposed.In order to improve energy efficiency and stability and reliability of system, usuallyenergy storage device is used in DG, using SCESS is able to control active power andreactive power at the same time, so it can compensate power fluctuations; The fuzzylogic controller can be used in the stable system, DFIG can also be used to adjustreactive power and improve transient stability of power system. For this reason, thecombined scheme of fuzzy logic control based on DC-DC step-down/boost converterand voltage source inverter control based on PWM is put forward, modeling andsimulation analysis of the wind power integrated system are done by usingMatlab/Simulink software. The study results show that this scheme can improvestability and power quality of wind power integrated system. (2) The maximum wind power point tracing control strategy based on SPSAalgorithm is proposed. In order to make wind power generation system being freefrom outside interference, and easily operating at maximum power point underfluctuant wind speeds, using SPSA algorithm to track system maximum power isproposed in this dissertation. SPSA algorithm indirectly controls wind turbine speedby adjusting duty cycle of power converter, makes system operate at the maximumpower point under any wind speed, and avoids using anemometer and tachometer inpractical applications. As shown in the simulation results, no matter how wind speedchanges, SPSA algorithm can effectively improve power output of wind powergeneration system, and make tip speed ratio and coefficient power be near optimumvalue.(3) The combined scheme of static synchronous compensator (STATCOM) basedon voltage source converter (VSC) and PSS based on synchronous generator (SG) isproposed. STATCOM is in parallel with the power grid, it is equivalent to acontrollable reactive current source, the reactive current can quickly vary with theload reactive current, it can automaticly compense the required reactive power ofsystem and realize dynamic reactive power compensation for the grid. But when thesystem is without excitation controller, even increases STATCOM, the system may notbe able to remain stable, so it is considered that PSS is installed in SG and itsparameters is adjusted appropriately. In order to ensure that transient stability andpower quality of wind power integrated system is not decreased, usingSTATCOM-PSS scheme to improve power quality and fault through ability of theintegrated wind farm is studied in this dissertation.The research results show thatSTATCOM-PSS can effectively restore voltage after fault at the point of commoncoupling in wind farm, enhance the fault through ability of wind farms, improvetransient stability and power quality of wind power integrated system.(4) The AVR-PSS coordinated control strategy based on DE algorithm isproposed. For solving the stability problem of wind power integrated system, PSSsare installed in SGs from the consideration of economics, but AVR provides transientstability at expense of robust oscillation stability; PSS provides damping andoscillation stability at expense of AVR. So it is necessary through the synchronousadjustment of AVR and PSS to obtain good voltage regulation and oscillation damping,using DE algorithm to solve the optimal regulation problem of AVR and PSSparameters in SG is presented. Under the situation of with or without PSS andwhether using differential evolution algorithm, the stability of wind power integrated system is studied in this dissertation. The research shows that wind power integratedsystem has a good damping effect using AVR-PSS coordinated tuning based on DEalgorithm, it can reduce oscillation of rotor angle difference and improve voltagestability.（5）The control scheme based on DFIG-FMAC-PSS is proposed. For the systemwith a lot of wind power, the solution of PSS being installed in synchronousgenerators may no longer provide additional damping, if synchronous generatorsequipped with these devices are cut off to adjust wind power, and the dampingobviously is lost. Therefore PSS being installed in DFIG is considered, anothercontrol scheme of PSS along with flux magnitude and angle controller (FMAC) usedin DFIG is proposed in this dissertation. Stator power of DFIG is chose as PSS inputsignal, through adjusting rotor flux vector magnitude and phase angle of DFIG tocontrol output power and voltage of generator. Under the situation of largedisturbance, the system stability is researched, this research shows that the proposedscheme is economic and feasible, this scheme is superior to the PSS control schemebased on the conventional synchronous generator for providing voltage control,contributing to damping and improving the stability of wind power integrated system.更多还原