A Novel Hybrid Approach to Estimate Customer Interruption Costs for Industry Sectors

The power system infrastructure, operations and market have gone through radical changes for the last couple of decades. The society has become more dependent to the continuous electric power supply and hence the concept of electric power reliability has become more significant. At this point, understanding the economic outcomes of power outages is vital and imperative for both utilities and the customers. There are certain methodologies to understand the costs of power interruptions. This paper suggests a novel hybrid method that comprises of customer surveys and direct analytical methods to reach customer specific, objective and reliable results for the industry sector customers. The paper also brings a statistical approach to censor the zero and extreme responses given via the surveys.

Proposed Measures to Mitigate Energy Interruptions in Residential Sector

This study investigates and analyzes the electric energy interruptions impact upon the residential sector in Riyadh city, the capital of the Kingdom of Saudi Arabia (KSA) resulting from severe power outages. The study results show that this sector which constitutes about 54% of the Saudi Electric Company in the Central Operating Area (SEC-COA) will suffer enormous tangible and intangible losses should occur in specific times, seasons and last for longer durations. The results obtained for the costs of these energy interruptions reveal a time-dependent non-linear outage cost variation. In order to reduce these energy interruptions and hence mitigate their adverse effects and consequences, the study proposes proper practical measures and solutions without compromising the consumers’ needs and convenience.

Short-term power generation scheduling rules for cascade hydropower stations based on hybrid algorithm

Power generation dispatching is a large complex system problem with multi-dimensional and nonlinear characteristics. A mathematical model was established based on the principle of reservoir operation. A large quantity of optimal scheduling processes were obtained by calculating the daily runoff process within three typical years, and a large number of simulated daily runoff processes were obtained using the progressive optimality algorithm （POA） in combination with the genetic algorithm （GA）. After analyzing the optimal scheduling processes, the corresponding scheduling rules were determined, and the practical formulas were obtained. These rules can make full use of the rolling runoff forecast and carry out the rolling scheduling. Compared with the optimized results, the maximum relative difference of the annual power generation obtained by the scheduling rules is no more than 1%. The effectiveness and practical applicability of the scheduling rules are demonstrated by a case study. This study provides a new perspective for formulating the rules of power generation dispatching.

Investigation on X-Radiation for 126 kV Vacuum Interrupters

When subjected to high voltages between opened contacts, vacuum interrupters may emit X-rays. In order to ensure that these are of an acceptable level, vacuum interrupters should comply with the limits for X-ray emission and the test procedures to be carried out to verify this based on relevant standards and specifications. In this paper, a comprehensive experimental study has been performed for 126 kV vacuum interrupters used in a transmission system to understand the X-radiation level and its influence by three main parameters, namely applied power-frequency voltage, contact gap and power=frequency voltage conditioning. The radiation instrument is an FJ347 radiometer and the X-radiation dose was measured at the power-frequency test voltage. These tests demonstrated that the X-radiation emission level for a 126 kV vacuum interrupter did not exceed the following： 5 μSv per hour at a rated voltage of 126 kV and 150 μSv per hour at a power-frequency voltage of 230 kV at 1 m distance. The X-radiation dose increased with the applied power-frequency voltage increasing and decreased with the contact gap increasing. The X- radiation dose for 126 kV vacuum interrupters decreased by 57% after the conditioning procedure with a certain power-frequency voltage. During the conditioning procedure, the average value of the X-radiation dose was 4.49 mSv, which means if a professional conditions 180 interrupters per year, it will be safe at the 6.4 m distance.

New Maintenance Strategies for Generating Companies in Power Market

A new approach to maintenance scheduling of generating units(MSU)in competitive electricity markets was presented,which was formulated as a noncooperative game with complete information.The payoff of each generating company(Genco)was defined as the profit from the energy auction market minus maintenance cost and risk loss.The compensation fee of interruptible load was a part of the maintenance cost when the permitted maintenance capacity in the system was insufficient.Hourly energy auction was incorporated in the computation of both revenues from energy market and risk loss of maintenance strategy as a nested game.A new heuristic search algorithm for the calculation of the game equilibrium of MSU was presented,which coordinates the solutions of non-equilibrium,unique equilibrium and multiple equilibria.Numerical results for a two-Genco system and a realistic system were used to demonstrate the basic ideas and the applicability of the proposed method,as well as its computational efficiency.

直流快速开断技术研究进展和展望

由于直流电流无自然过零点且短路电流上升率高,直流电流快速开断与系统故障切除成为制约直流电力系统发展的一大瓶颈。该综述首先介绍了直流快速开断技术要求与难点。其次,详细分析了直流快速开断过程涉及的关键技术,包括电流转移技术、固态式直流开断技术、介质恢复技术和高速机械开关技术等,综述了各种技术的当前发展现状及其应用情况,对比了不同技术方案的特点及适应性。最后,对直流快速开断技术未来发展方向进行了讨论和总结,为小型化、高性能、低成本、高可靠快速直流断路器的研发及推广应用提供了新的技术思路。

基于相对目标接近度的并网型微电网多目标优化调度

为了提高微电网运行的灵活性,将可中断负荷视为一种直接参与微电网运行的可调度资源,并根据峰谷时刻设置联络线传输功率处于不同区间,考虑微电网运行维护折旧成本、环境效益成本和与联络线偏差惩罚成本,构建微电网运行的多目标优化模型,再采用相对目标接近度法将多目标优化转化为单目标优化,由层次分析法和熵权法进行组合赋权。运用Gurobi求解器对微电网内的各种分布式电源24h出力和蓄电池荷电状态进行求解,获得微电网日前调度模型。基于美国地区微电网算例进行分析,验证所提模型可以兼顾微电网经济性、环保性,并能减少主网功率波动;同时表明计及可中断负荷和联络线功率控制的运行方式能有效降低运维折旧成本、环境污染和主网负担。

Electrochemical machining of a convex strips structure on a revolving part by using site directed power interruption

Revolving parts with complex surface structures are widely used in machinery and mechanical equipment. The ECM process provides its adequacy to cut hard materials with different shapes, and its applications are widely increased, due to its outstanding advantages. In this paper, a new method for machining a convex strips structure on a cylinder by using site directed power interruption（SDPI） in the ECM process is presented. A variable correction value of the power-off time was defined and optimized to obtain the ideal interval for better machining accuracy and stability.The electric field distribution and the simulated convex profiles show that the stray current density can be reduced effectively by using the proposed method. The correction value has an important influence on the machining accuracy. A suitable correction value in the range of 0.6–1.2 s can effectively improve the machining accuracy of the convex strips structure. Experiments were also conducted to verify the proposed method. Results have confirmed that the stray corrosion on the convex strips surface is significantly reduced and the machining accuracy of convex strips structure is remarkably improved by using the proposed method with a suitable correction value in the ECM process. Finally, a convex strip with a height of 2 mm on a thin-wall revolving part was also produced successfully using a correction value of 0.9.

航空变频交流真空灭弧室的设计研究

随着航空电气负载的增长,传统恒压恒频电源已难以满足需求,变频电源正成为现代飞机电气系统的发展方向。变频条件下真空灭弧技术面临三方面的挑战:一是开断难度的增加,二是通流能力下降,三是小体积、轻量化的设计限制。通过两个关键技术:小体积下的开断能力提升技术,轻量化结构下的通流能力设计方法,提出适应航空变频条件的变频灭弧室设计方案。分析变频条件下影响电流开断能力的触头因素,设计灭弧室小体积触头结构。提出一体式外置主屏蔽罩结构方案,为增加触头直径提升开断能力提供保障。提出趋肤效应下的导体结构轻量化方法,采用外置屏蔽罩增加散热能力,研制出了航空变频交流真空灭弧室。基于设计的三相接触器样机搭建了符合航空变频条件的实验环境,对灭弧室的开断能力、绝缘性能与温升情况进行了实验研究。结果表明:设计的灭弧室能够在360~800 Hz频率范围内有效开断过载电流1.68 kA,样机成功开断50次三相过载电流1.1 kA。开断前后三相主回路接触压降稳定,最高仅为83.49 mV,所有接触压降均低于设计值100 mV。整机重量仅为975 g,满足设计要求的同时具备更高开断能力。研究为航空变频电源系统的发展提供了实验数据支持,对推进航空电器领域真空开断技术应用具有重要意义。

电压暂降对工业厂房内敏感负荷影响研究

针对电压暂降对工业厂房敏感负荷正常生产可能造成的影响进行研究,首先对电压暂降的概念和相关标准进行阐述,之后通过分析电压暂降形成的原因、工厂中常用设备的敏感特性曲线分析、现场测量的数据等,并结合某工厂实际在运行过程中存在的问题研究,提出针对不同情况电压暂降原因的解决方案,最后通过工厂实际实施项目及现场测量数据,较为完整地说明工厂电压暂降的治理措施。

新型引流线搭接工具的研制与应用

供电过程中配电设备的损坏及检修过程中局部供电中断,使得人们生活中用电间断。为尽快恢复正常供电,更安全便捷地进行检修,设计了一种可伸缩、防电弧、一体化绝缘、适用性强、实时动态电流检测的新型绝缘引流线搭接工具。新型引流线的消弧功能利用张力弹簧实现快速接通和断开,根据绝缘罩利用空气快速灭弧原理,引流线金属夹具的自动绝缘防护能有效提升作业效率和作业安全。通过现场作业进行验证,证明新型装置能够满足作业时的要求和规范,提高了带电搭接引流线作业项目的质量和效率,相比传统引流线作业,效率可提高50%。

桃源水电站23号闸门异常开启不安全事件分析及应对措施

文章对桃源水电站23号泄洪闸门异常开启事件进行了分析。通过现场分析,得知此次异常开启的根本原因是由于PLC(可编程逻辑控制器)受到停、复电冲击,造成PLC死机后输出紊乱,错误发出闸门开启指令,因闸门控制回路没有故障闭锁功能,最终导致23号泄洪闸门异常开启。为防止类似情况再次发生,对泄洪闸控制系统进行改造,经长时间试运行证明措施可行,可为类似情形提供参考。

基于混合式高压直流断路器的故障电流限制与开断机制

高压直流输电技术凭借其远距离传输、低损耗等优点,在电力系统快速发展中占据重要地位,逐渐成为电网建设的重要方向。然而,高压直流系统中故障电流限制和开断处理一直面临着技术方面的挑战。混合式高压直流断路器以其快速响应与高效能量吸收能力,在保证系统安全稳定运行方面展现出独特的优势。文章深入研究混合式高压直流断路器的基本组成、工作原理及其在故障电流限制和开断中的应用,具有重要的理论和实践意义。

二级备用辅助服务市场中可中断负荷管理模型研究

该文研究建立了二级备用(即非旋转备用,或称运行备用)容量辅助服务市场中的可中断负荷(以下简称 IL招标数学模型。电力市场运营管理机构可以采用这个模型对 IL 投标方案进行实时性选择。这个模型基于最优潮流(OPF)算法。该文也对 IL 市场结构进行了研究并提出了建议。模型包括了对 IL 招标方案设计要考虑的主要因素,例如,提前通知,负荷点的位置,负荷的功率因素,等等通过实施可中断负荷管理(简称 ILM),ISO 可以在电网高峰负荷时段拥有充足的运行备用容量。

电力市场可中断负荷合同模型研究

可中断负荷管理是电力市场环境下需求侧管理的重要组成部分,与电力系统安全经济运行密切相关。该文讨论了可中断负荷合同的内容和相关市场组织形式;利用停运表得到考虑负荷波动情况下的系统缺额容量以及采用需求侧报价来反映用户可接受的停电补偿。给出可中断负荷的最优购买模型,模型以购买费用最小作为目标函数,包括停电持续时间和停电总次数等约束。参照机组检修的思路,给出安排可中断负荷的基本原则并采用相应算法求解。实际系统算例表明该模型的有效性。

电力市场下实用可中断负荷补偿机制研究

为有效管理和利用可中断负荷,实现电网经济、安全运行,从经济角度进行成本、效益分析,引入一个停电阈值价格概念,使不同的负荷的利润具有可比性,并提出了根据阈值价格确定可中断负荷补偿费的两种方法,即固定补偿费和动态补偿定价算法,实现了补偿和利润的联动机制,动态反应价格波动对补偿费的影响,符合市场规律。该机制合理地解决了目前可中断负荷研究面临的两大难题:如何激励负荷积极参加可中断负荷服务;如何制定合理的补偿费。文中还提出了供需平衡时购买可中断负荷后区域电价计算的模型。仿真计算利用加拿大不同负荷停电成本为依据,分析说明该方法可行,具有实用价值。

电力用户电压暂降问题分析与仿真

电压暂降事件给用户带来巨大的经济损失。全面分析用户的电压暂降事件,得出导致用户电压质量问题的原因,从而获得解决用户电压暂降问题的方法。分析用户电压暂降事件的类型、地点、发生时间和与天气的关系,并与供电局调度记录对比,以了解用户面临的主要电压问题和产生的原因。通过建立用户的供电模型,对各种故障情况进行仿真分析,获得不同故障地点对用户电压的影响程度,指出供电区域内的输电网故障是引发用户电压质量事件的主要原因,并分析区域内的薄弱环节,有针对性地为解决用户电压暂降问题和提高用户供电质量提供决策依据。

国内外混合式断路器发展与研究现状

混合断路器综合了传统开关的优点,克服了各自的缺点,是未来智能电网的发展趋势与研究热点。为此探讨了国内外混合断路器的发展与研究现状,并根据混合断路器的结构及工作原理对其进行了分类,重点对基于真空与SF_6串联构成的混合断路器及基于电力电子的混合断路器的工作原理、结构型式、应用领域及发展趋势进行了综述,基于真空与SF_6串联的混合断路器的动态绝缘特性、操动机构精度及最佳协同控制策略的研究,将推进其在高压大电流领域的应用。基于电力电子开关的混合断路器的电流转移特性、快速操动结构及短路开断控制策略等关键技术的突破,将为其在低压直流开断领域的应用奠定基础。

电力市场和过渡期电力系统可中断负荷管理(一)——可中断负荷成本效益分析

可中断负荷运行是电力市场环境下负荷侧管理的重要组成部分,与电力系统安全经济运行密切相关,可中断负荷的成本效益分析是可中断负荷研究的基础。对该方面的研究进行了综述,分析了提前通知时间、停电持续时间、停电发生时间、缺电比率等因素对可中断负荷成本的影响,并得到一些可供参考的结论;随后介绍了可中断负荷对提高系统可靠性、削弱价格尖峰、减少运行成本等方面的贡献;最后对相关问题进行总结。

提高电能使用效率的可中断电价与峰谷分时电价的联合优化设计

在发电侧竞价上网的情况下,供电公司通过实行可中断电价可以适当规避购网电价剧烈波动的风险。但我国发电企业并未实施竞价上网,供电公司购网电价由政府制定,相对比较稳定,故实行可中断负荷管理对供电公司缺乏一定的激励机制。本文首先根据估算的用户缺电损失确定可中断电价;随之提出用户可中断电价响应系数的概念,对已确定的可中断电价进行调整;然后根据经济学中供需理论,将可中断电价与峰谷分时电价相结合,在分析供电公司成本和效益基础上,建立联合优化模型,采用分解算法进行求解。算例分析表明,该模型既能使供电公司与用户的利益不受损害,又可解决当前可中断电价缺少激励机制的问题,非常适合我国当前的电价改革模式。