Electromechanical Wave Propagation in Large Electric Power Systems

ECS-9709253索普放松管制和创建大型独立系统运营商(ISO)的结果之一是，要操作的系统的物理规模将大大增加。无论是在面积上还是在电气尺寸上，系统都将变得更大。我们的前提是，在如此大的系统中存在着使用现有模型很难理解的影响，并且可以通过宏观地看待系统来获得有价值的理解。随着公交车的数量达到数万辆，系统的规模以数千英里为单位进行测量，想象一个包含传输、发电和负载的分布式系统是有用的。由故障和设备停运引起的发电机转子机电振荡现象是互联网络运营商面临的最棘手的问题之一。如果保护和控制系统在遇到扰动时不能按设计发挥作用，扰动可能会在整个网络中传播，并使单个发电机或发电机组面临与网络其余部分不同步的危险。如果有足够数量的发电机以这种方式失去同步，则会导致系统断电，并且必须遵循非常昂贵、破坏性和耗时的恢复程序。这些现象通常被称为“暂态稳定”研究，是电力系统规划中最重要的研究课题。研究机电暂态现象的常规技术是耗时的，并导致大量的输出，而且往往很难在全球范围内把握随后的现象的意义。建议从一个完全不同的角度来研究发电机转子的机电振荡问题。包含输电线路、发电机和负载的电力系统被认为是一个连续体。当电力系统横跨整个大陆时，S的这一说法当然是一个合理的推断。在这样做的过程中，我们放弃了与每个机器转子的运动相关的细节。作为回报，我们获得并洞察到由断层和其他随机事件引发的扰动在连续统中传播的机制。当问题以这种方式解决时，我们发现在其他领域发展起来的非常强大的技术(等离子体中的波传播现象)可以提供重要的见解和有用的结果。电力系统工程师很早就认识到机电干扰在电网中以有限的速度传播，并表现出弥散现象。直到最近几年，才有可能在GPS卫星系统的帮助下同时测量转子角度(通过同步相量测量)。利用这些远距离测量，我们有望观察到实际电力系统中的行波现象。初步研究证实，在被视为连续介质的网络上存在机电行波。研究提案确定了这项工作需要扩展的几个重要领域，以便产生可用于设计下一代电网监测、保护和控制系统的结果。

ECS-9709253 Thorp One of the results of deregulation and the creation of large independent system operators (ISO) is that the physical size of the system to be operated will be greatly increased. Systems will be larger both in terms of square miles and in electrical dimension. It is our premise that there are effects in such large systems that are not easily understood using existing models and that valuable understanding can be obtained by taking a macroscopic view of the system. As the number of buses reach tens of thousands and system dimensions are measured in thousands of miles, it is useful to imagine a distributed system with a contimuun of transmission, generation, and load. The phenomenon of electromechanical oscillations of generator rotors caused by faults and equipment outages is one of the most vexing problems facing the interconnected network operators . If the protection and control systems do not function as they are designed to do in the face of a disturbance, the disturbance can propagate over the network, and expose individual generators, or groups of generators to the danger of going 'out-of-step' with the rest of the network. If a sufficient number of generators lose synchronism in this fashion, a system black-out results, and very expensive, disruptive, and time-consuming restoration procedures have to be followed. These phenomena -familiarly knows as 'transient stability' studies-are the subject of the most important investigations in power system planning. The normal techniques for studying electromechanical transient phenomena are time-consuming and lead to voluminous outputs, and very often it is difficult to grasp the sense of the ensuing phenomena on a global scale. The proposal is to study the problem of electromechanical oscillations of generator rotors from an entirely different point of view . The power system with its transmission lines, generators, and loads is considered to be a continuum . When the power system spans entire continents, thi s is certainly a reasonable extrapolation. In doing so, we give up the detail associated with the motion of each machine rotor. In return , we gain and insight into the mechanisms by which the disturbances initiated by faults and other random events propagate in the continuum. When the problem is cast in this fashion, we find that very powerful techniques developed in others fields (wave propagation phenomena in plasma) can be brought to provide important insights and useful results. Power system engineers have long recognized that electromechanical disturbances propagate over the power network with finite speed, and exhibit dispersion phenomena. It is only in recent years that simultaneous measurement of rotor angles (through synchronized phasor measurements) has been made possible with the help of the GPS satellite system. Using these measurements over long distances, we expect to observe the traveling wave phenomena in actual power systems. The preliminary investigations confirm the presence of electromechanical traveling waves on the network treated as continuum. The research proposal identifies several important areas in which this work needs to be extended in order to produce results which could be used in designing next generation monitoring, protection and control systems on power networks.