Further Investigation of the Impacts of Cold Load Pickup on Design and Operation of Electric Power Distribution Systems

配电系统长时间停电后恢复供电，由于冷负荷回升，导致负荷远高于正常负荷。除了初始瞬态外，冷负载拾取过程中的负载具有持久组件，可以是正常负载的2到5倍，并且可能持续几个小时。持久的成分主要是由于在循环类型的负载，如空调，冰箱等多样性的损失。由于公用事业公司希望最大限度地利用现有资产，冷负荷采集是配电系统设计和运行中的一个重要问题。1994年，PI从国家科学基金会获得了一项项目的资助（奖励号9311257），从运行和设计的角度研究冷负荷提取对配电系统的影响。研究了配电系统分步恢复的最佳分段顺序的确定技术。此外，还对系统设计进行了研究，以确定系统所需分段器的最优数量和变电站变压器的最优尺寸。在此基础上发表了3篇期刊论文和3篇会议论文。该研究还形成了一名博士生的部分博士论文和一名博士生的完整博士论文。提交该提案的目的是请求为进一步研究冷载取电对配电系统的影响提供资金。具体而言，研究将解决1)变压器负载模型的修改，2)对最优恢复序列的进一步研究，3)在优化问题中包含更好的变压器成本和中断成本模型，4)在优化问题中包含电压降和馈线容量约束，以及5)与冷负载提取模型参数估计相关的问题。本文的研究为将配电自动化集成到配电系统设计中奠定了基础。迄今为止，对配电自动化的讨论大多是从系统运行的角度出发的。然而，由于配电自动化的发展，需要新的配电系统设计方法。新的设计应有效地利用自动化，同时保持系统成本低。随着配电自动化程度的提高，新的设计程序将成为配电系统设计的重要组成部分。由于目前在公用事业中正在发生的变化，这些问题将在未来引起更多的关注。这些变化将导致公用事业环境的重组，在这种环境下，配电公司将被要求更有效地管理其资产。拟议的项目将为研究生提供攻读博士学位的新机会，并接受配电系统领域以及各种数学和计算技术方面的培训。这项研究的结果也将非常有用的PI整合到研究型课程。

ECS-9721447 Pahwa Restoration of power after an extended outage in a distribution system results in load much higher than normal load due to cold load pickup. In addition to initial transients, the load during cold load pickup has an enduring component that can be 2 to 5 times normal load and may last for several hours. The enduring component is mainly due to loss of diversity in the cycling type of loads, such as air conditioners, refrigerator etc. Since utilities would like to utilize the existing assets to the maximum extent, cold load pickup is an important issue in design and operation of distribution systems. The PI received funding for a project (Award Number 9311257) in 1994 from the National Science Foundation to investigate the impacts of cold load pickup on distribution systems from both operation and from design points of view. Techniques for determination of the optimal sequence of sections for step-by-step restoration of distribution systems were investigated. Also, system design to determine the optimal number of sectionalizers and the optimal size of substation transformer needed for the system was investigated. Three journal papers and three conference papers were published based on the research. The research also formed partial dissertation of one Ph.D. student and full Ph.D. dissertation of another student. This proposal is being submitted to request funding for further investigation of the impacts of cold load pickup on distribution systems. Specifically, the research will address 1) modification of the transformer loading model, 2) further investigation of the optimal restoration sequence, 3) inclusion of better models for cost of transformers and cost of interruption in the optimization problem, 4) inclusion of voltage drop and feeder capacity constraints in the optimization problem, and 5) issues related to estimation of the cold load pickup model parameters. The proposed research lays a foundation for integration of distribution automation into design of distribution systems. So far distribution automation has mostly been discussed from the point of view of system operation. However, as a result of distribution automation, new methods of designing distribution systems will be needed. The new designs should utilize automation effectively and at the same time keep the system cost low. As the penetration of distribution automation increases, the new design procedures will become an integral part of distribution system design. These issues will gather more attention in the future due to the changes that are taking place presently in the utility business. These changes will result in the restructured utility environment under which the distribution companies will be required to manage their assets more efficiently and effectively. The proposed project will offer a novel opportunity for a graduate student to pursue the Ph.D. degree and receive training in the field of distribution systems as well as in various mathematical and computational techniques. The results of this research also will be extremely useful for the PI for integration into research-based courses.