典型风电机组阻尼机理分析及强迫振荡抑制方法研究

发布时间：2017-12-27 23:22

本文关键词：典型风电机组阻尼机理分析及强迫振荡抑制方法研究　出处：《华北电力大学(北京)》2016年硕士论文　论文类型：学位论文

【摘要】：电力系统稳定性是影响着互联电网安全可靠和经济运行的关键。而其中的大规模风电接入给电力系统的安全稳定运行带来了严峻考验,同时大规模风电接入系统后所呈现的复杂现象也日益显现出来。当前学术界和工业界对造成这些频繁出现的稳定性事故还缺乏机理性认识,故大规模风电融入电力系统的稳定原理研究显得日益迫切,此将为新能源电力系统的运行和控制提供科学依据。与常规能源发电比较,风电具有很大的不同,主要表现在：①风电出力随机波动,另有风电机组控制目标为最大程度捕获风能,故风电场出力存在不可调度性,而大规模风电接入电网将引起大面积电网潮流转移,且此转移亦具有不确定性；②对于非同步风力发电机组,其运行特征及转动惯性不同于传统同步发电机组,大量风电机组接入抑或取代常规发电机组(特别是取代安装电力系统稳定器的同步机组)将对整个系统的转动惯量、运行特性和阻尼特征产生影响；⑨由常规同步机组构成的常规电力系统中,同步电源间具有自同步机制,因此发电机组具有自我同步能力,但对于非同步的风电机组来说,由于其同步机制与电网存在主从关系,故并不具备此特征；④较之常规发电机组具有成熟控制系统和较大单机容量,风电机组单机容量小(一般在MW级),风电场群基本由成百上千台风机共同构成,因此随机波动的风速及电网故障将导致风电机组的一系列连锁动作,而这种连锁过程具有随机扩散性,故在风电功率连续随机波动的基础上,大量离散型随机扰动又被引入系统,使得融合了大规模风电的电力系统的动态特征逐渐向随机混成动力学系统的方向靠拢。接入电网的大规模风电导致原来可控可调度的同步电力系统中结合了大量具有随机波动性的新能源电源,这些具有随机波动性的新能源电源使得现代电力系统转变为随机一确定性耦合电力系统。这种耦合电力系统的稳定性问题中含有了大量新挑战,例如：系统的本征结构被大规模风电机组并入所改变,进而电力系统原有的稳定机制亦被改变；风电接入同步系统后的系统平衡点大幅度随机移动问题；随机—确定性电力系统的稳定性分类、定义及其判据；风电接入点和接入规模不同对系统功角、电压、低频振荡的影响原理等,给常规电力系统的稳定理论和方法带来了新的挑战。根据现有研究,由于风电场接入位置、风电穿透率、风机运行工况、励磁系统控制参数不同,同步系统在吸纳风电后功角振荡模式阻尼会产生相应变化,但其原因尚不确定。而对于风电接入电力系统小扰动稳定性分析,基本分析方式为在保证网络潮流分布相等的前提下,以同出力(同有功无功)风电机组替代同步机组,对比替代前后的系统特征变动,得出是否稳定的结论。此类方法具有普适性,但也存在其物理意义不明确的问题,即：虽然可看出风电场对电力系统阻尼影响的结论,但其阻尼成因、阻尼性质和大小及其相应影响因素,则无法给出具有物理意义的机理性解释。此外,由于风速波动的存在导致风电场出力随之波动,在功角振荡模式阻尼被接入的风电机改变的情况下,有可能诱发同步系统功角大幅强迫振荡,危及系统安全稳定运行。因此研究典型风电机组阻尼产生机理,以及风速波动引发的强迫振荡是十分必要的。本文首先论证了双馈风机对于同步系统的阻尼意义,从小扰动方程特征值角度对双馈风机的阻尼成因进行分析。通过研究双馈风机的机电解耦特性,阐明虽然其机械部分与电网呈非耦合状态,但其由于其电磁部分动态过程的存在,双馈风机可以视作电网的阻尼源,即双馈风机的存在会增大系统各模式总阻尼之和,并进一步提出其提供的阻尼将以特定方式分配至系统功角模式上。此理论证明了双馈风场对系统功角振荡阻尼的成因。其次,本文从复阻尼转矩的角度,赋予了风电机组提供的功角阻尼物理意义,即论证了风电机组作为动态原件,其阻尼大小及性质可由其复阻尼转矩向量判别。并且推证了风电机组的励磁控制参数显著影响此复阻尼转矩性质。第三,从强迫振荡角度,论证了风速以特定频率波动时将在同步机中引发功角振荡,并且此振荡程度强弱与风机提供的功角阻尼程度有显著相关。据此提出,可以通过调节风机励磁参数来来抑制同步系统受迫振荡强度。
[Abstract]:The stability of the power system is the key to the safety and reliability of the interconnected power grid and the economic operation. The large-scale wind power access has brought severe tests to the safe and stable operation of the power system. At the same time, the complexity of the large-scale wind power access system is increasingly showing. At present, academia and industry lack rational understanding of these frequent accidents. Therefore, it is increasingly urgent to study the stability theory of large-scale wind power integration into power system. This will provide a scientific basis for the operation and control of new energy power system. Compared with conventional energy generation, wind power is very different, mainly reflected in: random wind power output fluctuation, and wind turbine control objectives for maximum wind energy capture of wind power output, so there is no schedulability, and large scale wind power will cause a large area of power flow transfer and the transfer have uncertainty; for the non synchronous wind turbine, its operation characteristics and inertia is different from the traditional synchronous generator, a wind turbine or generator to replace the conventional access (especially to replace the installation of power system stabilizer synchronization unit) rotary inertia and operation characteristics and damping characteristics of the system impact; the conventional power system to constitute by conventional synchronous generators, synchronous power with self synchronization mechanism, so power unit with self synchronization ability, but for non synchronization The wind turbine, because of the existence of the master-slave relationship between synchronization mechanism and power grid, it does not have this feature; mature control system and large capacity with the compared with the conventional generator, wind turbine capacity small (MW grade), wind farm group by hundreds of thousands of fans together, so the random fluctuation of wind speed and power failure will lead to a series of chain operation of wind turbine, and the linkage process with stochastic diffusion, the wind power based continuous stochastic volatility, a large number of discrete and stochastic disturbance is introduced into the system, the dynamic characteristics of integration of large-scale wind power system gradually move closer to the hybrid dynamical systems random direction. Large scale wind power in power system can be controlled and the original synchronous scheduling in a combination of new energy power supply with a large number of stochastic volatility and stochastic volatility with these new energy power makes the modern power system into a deterministic stochastic coupled power system. The stability problem of this coupling power system contains a large number of new challenges, such as: the intrinsic structure of the system is changed into large-scale wind turbines, stable mechanism and the original power system was also changed; equilibrium wind power synchronization system after greatly with the mobile machine problem; random uncertainty of power system the stability of classification, definition and criterion; wind power access point and the access system of different scale power angle, voltage, low frequency oscillation effect principle, has brought new challenges to the stability theory and method of conventional power system. According to the existing research, due to the different location of wind farms, wind penetration, fan operation and excitation system control parameters, the damping of power angle oscillation mode will change correspondingly after absorbing wind power, but the reason is uncertain. For the wind power system small signal stability analysis, the basic analysis method for distribution network power flow under the premise of ensuring equal, with the same output (with active reactive) wind turbine instead of synchronous generators, change system features between before and after replacement, it is stable. This method is universal, but also has its physical meaning is not clear the problem, namely: although it can be seen that influence of wind farm on power system damping the conclusion, but the damping causes, damping property and size and its influence factors, is unable to give rational physical meaningful explanation. Besides, the output of wind farms will fluctuate due to the presence of wind speed fluctuations. When the power angle oscillation mode is changed, the power angle of the synchronous system will be greatly forced oscillation, which will endanger the safe and stable operation of the system. Therefore, it is necessary to study the damping mechanism of the typical wind turbine and the forced oscillation caused by the wind speed fluctuation. In this paper, the damping meaning of the doubly fed fan for synchronous system is demonstrated, and the damping cause of the doubly fed fan is analyzed by the angle of the eigenvalue of the small disturbance equation. The characteristics of electromechanical decoupling of DFIG, that although its mechanical part and a non grid coupling state, but due to the process of electromagnetic dynamic existence, damping source of DFIG can be regarded as the power grid, the DFIG will increase the system damping and mode, and further it provides damping in a specific way to distribution system power angle model. This theory proves the cause of the power angle oscillation damping of the double fed wind field. Secondly, from the angle of complex damping torque, this paper gives the physical meaning of power angle damping provided by wind turbines. It is proved that the size and nature of the damping of wind turbines can be judged by their complex damping torque vectors. It is also proved that the excitation control parameters of the wind turbine have a significant influence on the complex damping torque properties. Third, from the perspective of forced oscillation, it is demonstrated that when the wind speed fluctuates at a specific frequency, it will cause power angle oscillation in synchronous machine, and the degree of this oscillation is significantly related to the degree of power angle damping provided by the fan. Accordingly, it is suggested that the forced oscillation intensity of the synchronous system can be suppressed by adjusting the excitation parameters of the fan.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM614

【相似文献】