Electromechanical Wave Propagation in Large Electric Power Systems

ECS-9711102法德克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，设想一个具有传输、发电和负载连续体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，则会导致系统停电，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。我们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。我们认为电力系统及其输电线路、发电机和负载是一个连续体。当电力系统覆盖整个大陆时，这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，我们深入了解了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。其中一位联合首席研究员在这一领域做了大量的研究，据我们所知，这是第一次提出这种跨学科的方法来研究电力系统暂态稳定问题。该团队的另外两名成员在电力系统监测、保护和控制领域有着长期的工作记录，并在计算机继电保护和同步相量测量领域做出了原创性贡献。最后这项技术将对这里提出的想法产生重要影响。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，我们有望在不久的将来观察到实际电力系统中的行波现象。

ECS-9711102 Phadke 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 continuum 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. We propose to study the problem of electromechanical oscillations of generator rotors from an entirely different point of view. We consider the electric power system with its transmission lines, generators, and loads to be a continuum. When the power system spans entire continents, this 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 an 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 other fields (wave propagation phenomena in plasmas) can be brought to provide important insights and useful results. One of the Co-Principal Investigators has done considerable research in this field, and to our knowledge this is the first time that such a cross-disciplinary approach to the study of power system transient stability problems has been proposed. The other two members of this team have a long-standing record of having worked in the fields of power system monitoring, protection and control, and have made original contributions to the field of computer relaying and synchronized phasor measurements. This last technology will have an important bearing on the ideas proposed here. 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 in very near future.