Reliability planning for composite electric power systems

This paper proposes a reliability design approach using network flow technique, genetic algorithms, and Monte Carlo simulation for composite electric power systems. With increased emphasis on reliability design and cost control in electric power system planning and operation, particularly in composite electric power system, we are therefore striving to achieve an optimal reliability design solution under a reliability/cost implemented model. Because the floating-point representation is more efficient than the binary representation in genetic algorithms application, and the former also has more robust operators to locate near optimal solutions in most cases, we will employ the floating-point representation. The proposed method primarily finds out the optimal values of reliability indices for the components such that the objective function composed of interruption cost and installation cost is minimized. The reliability indices adopted include expected demand not served (EDNS) and forced outage rate (FOR). Application of the proposed method is demonstrated using a 23-bus test system.     

基于可靠性成本- 效益分析的电网规划

传统电网规划是以电网的直接投资费用最小为目标来满足一定可靠度的电网规划。电网规划的目的是保证电网的供电可靠性,而没有考虑由于电网的扩展所产生的经济效益,这样规划出的电网并不能获得最佳的社会效益。该文通过引入缺电成本,将可靠性与经济性结合在一起,在此基础上提出了一种新的电网规划成本-效益分析方法与数学模型,该方法将缺电成本作为供电总成本的重要组成部分,并且用缺电成本的大小来衡量可靠性效益的高低,将规划的可靠性成本与可靠性效益统一在对电网的经济性评估上。对规划方案进行了分析和评价,进一步完善了成本-效益分析方     

Asset maintenance planning in electric power distribution network using statistical analysis of outage data

The problems faced by electric power utilities in developing countries today is that the power demand is increasing rapidly whereas the supply growth is constrained by aging generating and distributing assets, scarce resources for constructing new ones and other societal issues. This has resulted in the need for constructing new additional generating plants and a more economic ways of planning and maintaining existing Generating and Electric power distribution assets. System planning and maintenance that is based on reliability – centred asset management approach had been adopted in this paper.Maintenance of critical asset is an essential part of asset management in distribution network. In most Electric utilities, planning for maintenance constitutes an essential parts of asset management. In this paper, an enhanced RCM methodology that is based on a quantitative statistical analysis of outage data Performed at system/component level for overall system reliability was applied for the identification of distribution components critical to system reliability. The conclusion from this study shows that it is beneficial to base asset maintenance management decisions on processed, analyzed and tested outage data.     

Pareto optimality-based multi-objective transmission planning considering transmission congestion

In the deregulated environment, transmission congestion is one major problem that needs to be handled in power system operation and network expansion planning. This paper aims to enhance the transmission system capability and have the congestion alleviated using the multi-objective transmission expansion planning (MOTEP) approach. A system congestion index called the congestion surplus is presented to measure the congestion degree of the transmission system. The proposed MOTEP approach optimizes three objectives simultaneously, namely the congestion surplus, investment cost and power outage cost. An improved strength Pareto evolutionary algorithm (SPEA) is adopted to solve the proposed model. A ranking method based on Euclidean distance is presented for decision-making in the Pareto-optimal set. The effectiveness of both the improved SPEA and the proposed multi-objective planning approach has been tested and proven on the 18-bus system and the 77-bus system, respectively.     

Key issues in integrated resource planning for electric utilities

Integrated resource planning (IRP) is a means for utilities and state regulatory commissions to consistently assess a variety of demand and supply resources to cost-effectively meet customer energy-service needs. The authors review recent progress in IRP and identify the need for additional work by utilities, regulatory commissions, and other organizations. They point out that IRP as a planning and regulatory process can also greatly reduce the uncertainties and risks faced by utilities and state public utility commissions. Such benefits occur because of the diversity of resources considered, public involvement in the planning process, and cooperation among interested parties     

综合考虑可靠性因素的电网规划新方法

电网能否稳定运行的关键在于网架结构,坚强的网架结构来源于合理的电网规划.文章提出了一种将电网的可靠性指标转化为经济性指标,并将其作为目标函数一部分的电网规划新方法.该方法将缺电成本划分为静态和动态成本两部分,使得电网规划的数学模型更加完善,体现更广泛的社会效益,客观上有利于电网防灾.     

风电场对电力系统电源规划风险评估的影响

风电是一种绿色可再生能源,在工业和经济飞速发展的今天,对能源的发展和电力结构的调整起着非常重要的作用。同时风电又具有间歇性、波动性和反调峰特性,对电力系统的风险评估造成了一定的影响。因此在传统电源规划的风险评估中,加入风电场这个不确定因素,考虑风电场对电力系统电源规划风险评估的影响。根据风电场的风速及强迫停运建立了风电场的可靠性模型,在此基础上,将蒙特卡洛模拟技术与最小费用评估模型结合起来,形成了含风电场的最小费用模型,通过算例仿真计算比较不同方案的系统的风险指标,结果表明风电场的容量和位置对系统电源规划风险评估的影响很大。     

Transmission surplus capacity based power transmission expansion planning

A power transmission expansion planning model with consideration of transmission surplus capacity and network load factor is presented. With traditional planning model, some transmission lines will operate on high load factors due to ignorance of the load levels of transmission lines. This may lead to network congestion or degrade the dispatch flexibility of future network. Traditional planning model has put more emphasis on investment cost rather than other aspects such as operation environment, transmission benefit, etc. The transmission expansion planning model in the paper aims to maximize network transmission surplus capacity and optimize network load factor distribution with least investment. Chaos Optimal Algorithm (COA) is introduced to solve this nonlinear integer planning optimization problem for its advantage of stochastic and ergodic searching characteristics. The effectiveness of proposed model and methodology is tested with two typical systems.     

基于双种群入侵性杂草算法的服务型城市综合资源规划

针对服务型城市的产业特性及其相应的电力负荷特点,论述了加快建设以蓄冷蓄热技术为主的移峰填谷类能效电厂的必要性。为解决服务型城市峰谷差大的问题,引入调峰能力约束,建立了同时考虑供应侧传统机组与需求侧能效电厂,以规划期内综合成本最小为目标函数的综合资源规划模型。并且提出了一种改进双种群IWO算法进行优化求解,通过算例验证了模型和算法的有效性。应用该模型可以实现系统总成本最小、减少污染物排放及有效调峰等效果。     

全寿命周期成本电网规划的灵敏度分析模型

在建立电网规划方案的全寿命周期成本模型的基础上,重点研究了可靠性成本的分析计算,提出了一种针对居民用户的需求侧单位缺电成本的求解方法。进一步提出了全寿命周期成本灵敏度分析模型,用于对比不同影响因素对电网规划方案的全寿命周期成本的影响程度。结果显示全寿命周期成本模型能够全面反映配网规划的综合成本,所得的决策方案是真正意义上的最优方案;灵敏度分析模型可以使决策者更好地把握相关因素的影响,有助于方案的选取。     

An electric power purchase strategy for bilateral contracts focusing on reliability of customers

With the introduction of the competitive electrical power market, large‐scale customers can select electric power suppliers. Customers need to consider not only the economical efficiency but also reliability, to decide the amount of electrical power to purchase. This paper develops an economic electric power purchase strategy for customers focusing on reliability. A bilateral contract model expressing electric power suppliers as generators with a forced outage rate is proposed and introduced to assess potential outage risks of the bilateral contract between an electric power supplier and a customer. The outage‐related cost, consisting of potential outage risks and the estimated outage cost, is also proposed and introduced as an index of the reliability on the customer side, and an optimal reliability level of a customer is obtained by using the index. Several numerical examples demonstrate the availability of the proposed electric power purchase decision method and reliability improvement strategies for customers are discussed. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(4): 9–21, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20345     

Implications of a regional resource adequacy program for utility integrated resource planning

Resource adequacy (RA) is the ability of an electricity system to reliably satisfy loads using its available resources. Assessing and maintaining RA is becoming more challenging due to increasing coal plant retirements, penetration of wind and solar resources, reliance on bilateral and market transactions, and emerging technologies. RA evaluation and planning have traditionally been conducted by utilities and overseen by their state regulators using integrated resource planning (IRP) processes. However, the Northwest Power Pool (NWPP) is developing a proposal for a regional RA program in the Western U.S. that would set and enforce capacity obligations for member utilities, and achieve RA more cost-effectively by pooling resources and load profiles from across the region. In this paper, we investigate the policy implications of a regional RA program for existing IRP regulations, with the proposed NWPP RA program as our main object of study. We compile the RA assessment practices of Western U.S. utilities, the proposed NWPP RA program design, and lessons from the historical experience of the Southwest Power Pool’s RA program. Our analysis reveals that the IRP components which would be most heavily impacted by the regional program are RA targets, load forecasts, capacity accreditation factors, and transmission upgrades. We conclude by discussing the policy issues that RA program design and state IRP policy would have to address.     

风电场对发输电系统可靠性影响的评估

建立了基于蒙特卡罗仿真的含风电场的发输电系统可靠性分析模型,该模型不仅考虑了风速的随机性、风电机组强迫停运率及其与气候的相关性,而且计及了输电网络故障率和输电线路有功功率限制.将该模型应用于含风电场的电力系统仿真,按照在满足系统安全约束条件的前提下充分利用风电的原则,对系统进行模拟调度,计算出能反映风电价值的可靠性指标,为风电场的规划与运行提供了重要的参考价值.     

Outage costs quantification for benefit–cost analysis of distribution automation systems

Deregulation of electric power industry has motivated electricity customers to pay more attention in evaluating both the direct cost of electric service and the monetary value of reliable electric service. This movement has been recognized by the utilities and the value-based aspects are introduced into the planning and design of power systems to consider the outage costs. The value of service reliability that can portray and respond to actual utility and customer impacts as a result of power interruptions plays a major role on justifying whether a distribution automation (DA) system is beneficial or not. However, for the value of service reliability, there are a number of factors that can affect it. To exactly evaluate the service reliability value, two formulas for quantifying the customer interruption costs and utility reduced energy revenues associated with power failures are derived in this paper. The customer types, feeder loads, feeder failure rate, number of switch, restoration time, and repair time are taken into account. The proposed formulas can provide an exact estimate in outages costs of a feeder and their computation is simplified and straightforward. The estimated outage costs can then be used to calculate the reliability improvement benefit of DA systems for the system benefit–cost analysis. A practical DA system implemented by Taiwan Power Company is used to illustrate the proposed formulas and the benefit–cost analysis result is presented. Sensitivity analysis is also performed to reduce the effects of benefit–cost analysis parameters on the analysis result.     

风电场的发电可靠性模型及其应用

建立了风电场的发电可靠性模型,介绍了该模型在随机生产模拟和随机潮流分析等方面的应用。该模型考虑了风速的随机变化、不同风电场之间风速的相关性、风电机组的功率特性及其强迫停运率、风电机组的布置和尾流效应以及气温等因素及风电场输出功率的影响,揭示了风电场输出功率的统计规律。     

Optimal CBM of tie lines between control areas in a deregulated environment

In order to keep power supply reliability at a certain level, electric power utilities have a certain amount of reserve capacity. When no generator outage or no unexpected large power demand occurs, however, the reserve capacity is regarded as surplus facility. To reduce the reserve capacity, some margin is reserved in tie lines between utilities. This margin is called the capacity benefit margin (CBM). In this study, a method of calculating optimal CBM in tie line under deregulated environment is described and two kinds of optimal CBM are proposed. As a result, it is shown how the deregulation affects the optimal CBM by using numerical simulation for the IEE Japan West 30 test system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 35– 48, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20654     

缺电成本与可靠性规划的研究

本文研究了缺电成本与可靠性的关系，阐述了确定最佳可靠性的方法，并探讨了基于缺电成本的可行性规划问题。     

城市电网用户停电损失估算及评价方法研究

合理地估算和评价城市电网中各类用户的停电损失,为电力企业在提高城市电网的可靠性水平及应急电源优化配置的投资和决策方面提供依据。在对受停电影响造成的各类用户的经济损失进行分类调查的基础上,以峰荷时刻的停电损失为基准,建立了表示综合用户停电损失和停电持续时间关系的综合用户停电损失函数,用以估算每类用户的综合停电损失。基本计算过程为,根据各类用户的综合用户停电损失函数和停电次数的统计结果,采用停电损失评价率和每次事故停电损失2个指标来评价每类用户的停电损失。采用青岛地区53个重要用户的数据为实际算例,估算并评价了各类用户的停电损失。所得结果表明,所提出的估算和评价用户停电损失的方法,有助于电力企业确定不同可靠性水平下的应急电源优化配置成本。     

基于改进遗传算法的风力－柴油联合发电系统扩展规划

提出基于改进遗传算法的风力-柴油联合发电系统容量扩展规划模型,在满足系统规划和运行等非线性约束条件下,寻求总成本最小的容量扩展方案。在规划总成本中除了计及机组建设的投资费用和运行费用以外,还考虑了因电力供给不足所造成的需求侧停电损失成本。在模型中采用蒙特卡罗方法计算系统的概率性发电成本,不仅考虑了风速随机性、机组随机停运、风速序列和负荷序列相关性,而且考虑了风电穿透功率极限的约束。算例表明,文中所提出的模型和算法是可行的,能对风力发电的规划设计提供一定的帮助。     

对我国电力行业应用综合资源规划方法的探讨

剖析传统规划方法存在的问题,对我国电力行业应用综合资源规划方法的必要性进行论述,并对电力行业应用这一规划方法提出了建设性意见。