Benefits of urban underground power delivery

From the community point of view, there are clear and distinct advantages in having all urban power lines underground. Utility companies, operating in a regulated monopoly status, basically have no incentive to accommodate the public in the matters discussed. In general, citizen groups have been unsuccessful in working directly with the utility companies, though some success has been achieved through court action. Moreover, the limited attempt to generate a successful forcing action through the legislative process was unsuccessful except that the effort provided a large amount of data that had heretofore been unavailable for analysis. The problems remain, however, and the public seems to be becoming increasingly aware of them. The undergrounding of urban power lines as a national policy would generate very significant benefits to the public. These benefits are such that in-depth studies to quantify the cost-benefits and for the development of logical methods for cost sharing are needed, The utility companies have no incentive to sponsor such studies as current laws do not require any consideration of societal costs. A reasonable approach, therefore, would be through state legislative action to open the electric power industry to full retail competition and let the market forces bring about this long overdue improvement. An alternative approach could be for legislatures to require utilities to operate in such a manner as to minimize the aggregate of societal costs associated with urban power delivery     

美国配电网架空线入地改造成本效益分析及对我国的启示

介绍美国开展配电网架空线入地改造的有关情况,综合分析了架空线入地的成本效益,并对我国开展架空线入地改造提出启示和建议。     

Bulk power transmission by superconducting DC cable

It is estimated that the total electric system load in the U.S.A. will increase five- to seven-fold by the year 2000. It is reasonable to assume that the transmission line capacities will also increase at least by the same amount. For energy conservation, future transmission lines must be more efficient than those of today. There will also be mounting public pressure to transmit electric power underground because of increasing awareness of environmental quality. There are considerable research activities to develop new technologies to transmit large blocks of power more efficiently by underground cables. The goal of the DC superconducting power transmission line (SPTL) program at the Los Alamos Scientific Laboratory is to develop such a cable. The DC SPTL has the advantage that it has very high power capability (10 GW and more) and no conductor or dielectric losses. The only “loss” of a DC SPTL is in the refrigeration requirement. It has no systems constraints, such as the stability or reactive compensation requirements of an AC system. The paper discusses the conceptual Los Alamos design, some of the technical problems associated with the development and the approaches to their solution.     

电力系统实用动态安全域及其搜索方法的改进

电力系统动态安全域（DSR）可为电力系统提供更为丰富的安全信息．实现电力系统的在线安全性评估与优化。经过大量的仿真实验发现,应用现有的搜索动态安全域临界超平面方法所得到的结果与理论分析得到的结果存在着很多差异。为此,分析了某些情况下应用现有实用动态安全域搜索程序昕得结果存在偏差的原因,给出其理论上的解释。并通过增加非独立节点（一般选取平衡节点作为非独立节点）约束条件和改进相应的搜索方法解决了出现的偏差问题。完善了实用动态安全域（PDSR）的方法。并在CEPRI-36节点交直流混合系统和太平洋联络线交直流并联输电系统算例上进行了验证,得到了满意的结果。改进后的实用动态安全域及其搜索方法使动态安全域超平面的搜索更加精确,对实际系统更具有指导意义。     

Comprehensive reliability assessment of substation originated outages using the Monte Carlo simulation technique

Power system security and stability has become a major concern for electric power utilities, as power systems become more and more complex and are operated closer to transmission capacity limits. Substations and switching stations are pivotal parts of power systems. Failure events in substations often result in multiple outages of generators, lines, and/or loads in power systems, and affect the security and stability of power system dramatically. The reliability evaluation of substation originated outages is therefore of vital importance. This paper presents the application of a Monte Carlo simulation (MCS) method to the reliability evaluation of voltage step-up substations and switching stations (herein referred to only as substations) in transmission systems. The proposed approach is demonstrated by application to an educational test system designated as RBTS (R. Billinton, S. Kumar, L. Goel, et al., A reliability test system for educational purposes—basic data, IEEE Trans. Power Appar. Syst. 4 (3) (1989) 1238–1244) and some selected sensitivity studies are also presented in this paper. The results of studies provide valuable information for decision-making in power system planning and operation. A comparison between the reliability indices of two groups of overlapping failures obtained from both analytical method and MCS approach shows that the approximate equations of analytical methods have constraints when the component average repair time exceeds certain numerical range. The MCS approach is shown to be more accurate when dealing with the multiple order outages.     

A Wholesale Power Trading Simulator With Learning Capabilities

The U.S. wholesale power market comprises a large commodity market. The growth in power trading is due to the ongoing deregulation policy of the electric power industry. Most deregulation scenarios indicate a further separation of power production from transmission and retailing. The power production is opened to more competition. Unfortunately, the power trading mechanism is not clearly investigated in the level that we can predict a price change in the U.S. wholesale power market. Such a price change in the U.S. wholesale power market is explored from a simulation system with learning capabilities. Using the new intelligence system, we investigate the bidding strategies of traders in the wholesale power market and examine how the price change occurs under different economic and engineering environments.     

交流和直流输电线路的经济比较

为比较交直流输电线路的经济性能,首先指出,在采用可控并联电抗器的条件下,交流输电线路的长度和传输功率不受限制。交、直流输电经济比较的准则为线路长度、传输功率、导线功耗和导线电流密度均相同,因此交流相电压应与双极直流的极地电压相等,从而两者的导线重量和价格相同,线路杆塔总的机械负荷和价格亦大体相同,但直流线路的两侧要求设置十分昂贵的换流站和无功能源,故而直流输电的总费用远比交流高;对远距离输电线路常需与中间系统相连的问题,交流线路只用投入联络变压器,而直流线路则需设置代价高昂的换流站。过去人们常将直流极地电压等同于交流相间电压而作对比,得出≥1000km距离时的直流线路要比交流线路更为经济的不适当结论。由于以上主要原因,欧洲国家(包括俄罗斯)不采用架空直流输电线路。     

A strategic policy framework for advancing U.S. civilian nuclear power as a national security imperative

The U.S. is at an inflection point on nuclear power with much debate revolving around the extent to which markets or policy should be leveraged to sustain nuclear. This has generated concerns about costs, grid reliability and climate. However, the national security implications must also be accounted for. Here, a strategic policy framework is presented as a means for sustaining U.S. nuclear power domestically and expanding U.S. nuclear power abroad as a national security imperative.     

关于发电机承受失步振荡能力的建议

美国一贯的指导思想,认为电源充裕,系统有风吹草动,就把发电机切掉。因而在2003年8月14日美加大停电事故中,一开始失步振荡,很多发电机失步保护动作跳闸,扩大了损失。根据我国多年系统振荡经验指出,一旦系统发生振荡,首先应保持系统的完整性,任何线路和发电机都不应因振荡跳闸,大多数情况下系统都能自动恢复同步,避免四分五裂大停电。但目前在国际和国内的发电机都没有建立承受失步能力的标准,以致发电机失步保护的设计,整定原则很不统一。根据IEC34-3发电机承受出口短路和过热的设计标准,建立发电机承受失部振荡能力的建议,一方面希望得到研究、制造部门的协调;另一方面可作为发电机失步保护设计和整定的依据,达到既保电网又保机组的目的。     

Modeling the value of integrated U.S. and Canadian power sector expansion

The U.S.-Canadian power system has evolved into a highly integrated grid. Cross-border transmission and coordination of system operations create an interconnected power system with combined imports and exports of electricity of greater than 77?TWh per year. Currently, more than 5 GW of new international transmission lines are in various stages of permitting and development. These transmission lines may enable even greater integration and coordination of the U.S. and Canadian systems, which can in turn increase the reliability and flexibility of North America’s electricity grid and help address challenges associated with integrating high levels of variable renewables. Using a version of the National Renewable Energy Laboratory’s Regional Energy Deployment System (ReEDS) model that incorporates Canada, this analysis quantifies the differences in the evolution of the power system under scenarios in which cross-border transmission capacity is restricted to today’s levels, and scenarios in which new transmission is less restricted. These impacts are analyzed under a “business-as-usual” reference scenario and a scenario in which deep cuts in power sector carbon dioxide emissions levels are achieved. A set of key impact metrics is analyzed, including 1) the composition of generating capacity by technology, 2) system costs, 3) wholesale electricity prices, 4) international electricity exports and imports, 5) transmission capacity, and 6) carbon dioxide emission levels. When new cross-border transmission is not allowed, the United States needs additional capacity (primarily natural gas and renewable energy) to meet domestic needs, while total Canadian capacity is lower because less capacity is needed to export to the United States. This effect is amplified under the carbon cap scenario. Impacts vary on a regional basis, largely due to the different relative sizes of the generation portfolio between countries and regions and the relative impact from cross-border electricity trade. The total impact from restricting cross-border trade on carbon emissions and average wholesale electricity prices is limited, due to the relative size of the domestic power systems and the cross-border trade volume. Cross-border transmission capacity is projected to more than double under the unrestricted transmission capacity scenarios, which exceeds the rate of projected domestic transmission capacity additions in each country.     

Need for Change Towards Systems Thinking in the U.S. Nuclear Industry

Until recently, nuclear has been largely considered as an established power source with no need for new developments in its generation and the management of its power plants. However, this idea is rapidly changing due to reasons discussed in this study. Many U.S. nuclear power plants are receiving life extensions decades beyond their originally planned lives, which requires the consideration of new risks and uncertainties. This research first investigates those potential risks and sheds light on how nuclear utilities perceive and plan for these risks. After that, it examines the need for systems thinking for extended operation of nuclear reactors in the U.S. Finally, it concludes that U.S. nuclear power plants are good examples of systems in need of change from a traditional managerial view to a systems approach.      

Deregulation and Nuclear Power Safety: What Can We Learn from Other Industries?

An examination of the U.S. aviation and rail industries and the U.K. nuclear power industry provides evidence that changes associated with deregulation can be expected to create major challenges to the management of safety by the U.S. nuclear power industry and its safety regulators.     

考虑雷电天气的大电力系统可靠性评估

雷电天气会导致输电线路故障率增加,对大电力系统可靠性评估有重要影响。针对不同雷电水平下的输电线路具有不同的故障率,依据地闪密度划分雷电水平区域,分区建立输电线路故障率模型,提出一种基于蒙特卡洛抽样原理,在考虑雷电天气下的大电力系统可靠性评估方法。该方法分别对雷电天气和输电线路进行蒙特卡洛抽样,确定雷电天气状态和输电线路状态,生成确定的系统状态,然后进行大电力系统可靠性评估。最后给出在考虑雷电天气下的大电力系统可靠性评估流程,并通过算例说明雷电天气对电力系统可靠性充裕度指标的影响。     

基于多新息最小二乘算法的电力线路参数辨识

随着电力系统的建设和发展,电网结构日益复杂,由于线路长期运行、周围环境变化等原因导致原有的线路参数模型与实际线路参数存在偏差,从而影响电力系统的实时监控和优化运行。考虑到电力系统输电线路中的数据采集与监控(SCADA)系统量测充足,提出基于多新息最小二乘(MILS)算法的线路参数辨识模型,实现全网线路的准确辨识和校正。首先,利用实时数字仿真(RTDS)系统搭建IEEE 39节点电力系统仿真模型,获得潮流运行数据;然后,在Matlab中进行参数辨识,将辨识结果与RTDS中的线路参数进行对比。结果表明,基于MILS算法的参数辨识结果具有较高估计精度,可作为电力系统可疑线路判断依据。     

A Combined Equivalenced-Electric, Economic, and Market Representation of the Northeastern Power Coordinating Council U.S. Electric Power System

This paper develops a representation of the Northeastern U.S. bulk electric power system, with an emphasis on New York and New England. The representation has two parts: a 36-bus electrical model in PTI-23 format and market data in the form of generator bids and load demands. The market data are distilled from historical data on public web sites. Since the historical data are available on an hourly basis over many years, the representation is quite rich. In addition, this paper includes the mix of generation at each bus in the model so that generation cost (fuel and emissions) and unit commitment constraints can be deduced. The representation is intended to be a test-bed for formulating, simulating and analyzing the combined technical and economic objectives of the changing electric power industry. It is further intended to be a test-bed for comparing methods of simulating electric power systems and electricity markets operating under engineering constraints. It can, for example, be used for power flow, optimal power flow, reliability, market clearing, and other economic studies. The representation as described is intended only for steady-state equilibrium studies and does not account for inter-temporal effects such as unit commitment constraints. It can, however, be extended to account for those effects.      

Using multi-objective optimal power flow for reducing magnetic fields from power lines

Over the past several years, concerns have been raised over the possibility that the exposure to 50/60 Hz electromagnetic fields (EMFs) from power lines, substations, and other power sources may have detrimental health effects on living organisms. As a result of these concerns, some European States, as Belgium, Italy, Switzerland and Estonia, have set limits, which are more stringent then the Council Recommendation making reference to the precautionary principle. This stricter legislation is leading not only to an ambiguous legal situation but, above all, to controversy, delay, and costs increases in the construction of utility lines and facilities. Consequently, a number of techniques for mitigating EMFs associated with power lines have been proposed, but many of them are mainly applicable to future constructions and may not be appropriate for existing transmission or distribution lines due to high implementation cost. From these considerations, the study analyses the feasibility of using optimal power flow (OPF) for limiting EMF levels. The mitigation is obtained solving a multi-objective optimal power flow (MO-OPF) problem with a specific objective function for the EMFs. In order to validate the usefulness of the approach suggested herein, a case study using a modified IEEE 30-bus power system is presented and discussed.     

A not-too-modest proposal for a zero-emission U.S. transmission grid: Inter-regional planning,siting, funding & grid enhancing technologies will be key

Decisionmakers confront initiatives to upgrade the electric power grid in ways that might enable the U.S. to meet its Paris Accord commitment to hold global warming to no more than 1.5 degrees Celsius above pre-industrial levels. To achieve that imperative, those decisionmakers need to commit to inter-regional buildout of the high-voltage electric power grid and more efficient use of the existing grid through deployment of grid enhancing technologies. The authors detail how that can be done and how regulatory obstacles can be overcome.     

各国工频电磁场的限值及其确定的依据

重点评述了一些国家以及国际组织标准中工频电磁场的限值及其确定的依据;介绍了目前普遍接受的低频电磁场模型。各国输电线路工频电磁场限值与暴露时长有关,不同地点限值的不同,对敏感区域额外增加预防性限值。目前工频电场限值较一致,磁场限值差异较大;ICNIRP导则已得到多国认可;对尚未确定长期的工频磁场暴露是否会导致特定种类的癌症及其它非癌症类疾病,需进一步研究以澄清电磁场作用于人体的微观机理。     

Distribution arrester outages caused by lightning backflow current flowing from customer's facility into power distribution lines

Direct lightning strokes are considered to be a main cause of damage to surge arresters on power distribution lines. Recently, lightning performance of distribution lines has been observed using still cameras, and lightning‐caused distribution outages on hilltop areas on the coast of the Sea of Japan have been investigated. This research has shown a possibility that lightning backflow current flowing from customer facilities into distribution lines causes damage to surge arresters on the distribution lines. We have investigated the lightning backflow current flowing from customer facilities into distribution lines as a cause of damage to surge arresters. The main results are as follows: (1) The electric charge of the backflow current flowing into distribution lines is more than 60% of that of the lightning stroke current. (2) If the grounding resistance of the customer's facility is not low, the failure rates of a surge arrester caused by backflow current due to winter lightning is more than 90% of that caused by direct lightning strokes. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 9–20, 1999     

Empirical Analysis of the Impact of 2003 Blackout on Security Values of U.S. Utilities and Electrical Equipment Manufacturing Firms

On August 14, 2003, the U.S. faced the largest blackout in history, which left over 50 million people without electricity in eight U.S. states and part of Canada. This paper investigates the effects of the blackout on the security values of the U.S. electric utilities and manufacturing firms in the electric power equipment industry, using an event study method. The results of this empirical study show that the electric utilities were negatively affected, but the electrical equipment manufacturing firms were significantly, positively affected.