基于层次分析法与改进D-S理论的阀水冷系统状态评估

为了及时评估保障换流阀可靠运行的阀水冷系统运行状态,首先,分析了换流站阀水冷系统整体构成,选取主要历史数据和实时数据构建了评估指标体系,通过三角形函数和半梯形函数以及专家调查法确定各个指标的隶属度;其次,基于层次分析法确定各个评估指标权重,改进D-S理论建立阀水冷系统运行状态评估模型;最后,通过采集实际工程阀水冷系统主要指标数据对模型进行了验证,并以阀水冷系统滤芯清洗前后数据为例对评估结果进行了对比。结果表明,所建模型能够对阀水冷系统运行状态做出准确识别和评估,有利于运维人员及时掌控阀水冷系统运行状态,保障其可靠运行。     

±160 kV直流XLPE海底电缆载流特性仿真及试验

南澳岛±160 k V多端柔性直流输电工程在我国首次采用了高电压、大长度的挤包绝缘直流电缆系统,而目前在国内尚无此电压等级直流电缆工程的运行及维护经验,因此亟需对交联聚乙烯(XLPE)直流电缆的载流特性展开研究,从而为直流电缆线路运行限值的控制以及在线监测系统的定制提供技术支持。通过研究不同敷设环境下直流电缆的散热原理,采用专业有限元软件COMSOL Multiphysics建立了带保护套管埋地敷设方式下±160 k V直流XLPE海底电缆的温度场模型,用以模拟其温度分布和计算其载流量;通过在试验场地开展静态载流试验,对仿真模型的可靠性进行了验证;对试验结果进行讨论,分析得出了直流海缆的载流特性。     

Development of information-and-control systems as a basis for modernizing the automated process control systems of operating power equipment

The main drawbacks inherent in the hardware of outdated control systems of power stations are discussed. It is shown that economically efficient and reliable operation of the process equipment will be impossible if certain part of these control systems is used further. It is pointed out that full retrofitting of outdated control systems on operating equipment in one go with replacing all technical facilities and cable connections by a modern computerized automation system involves certain difficulties if such work is carried out under the conditions of limited financial resources or a limited period of time destined for doing the works. A version of control system modernization is suggested that involves replacement of the most severely worn and outdated equipment (indicating and recording instruments, and local controllers) and retaining the existing cable routes and layout of board facilities. The modernization implies development of informationand-control systems constructed on the basis of a unified computerized automation system. Software and hardware products that have positively proven themselves in thermal power engineering are proposed for developing such an automation system. It is demonstrated that the proposed system has a considerable potential for its functional development and can become a basis for constructing a fully functional automated process control system.     

一种新型大型变压器自适应冷却控制装置

提出了大型变压器自适应冷却控制装置的原理和实现方法。对冷却器组数提出了用温度及温度变化率结合变电站及发电厂实际情况和冷却器组累积运行时间进行自动均衡综合控制,并对运行冷却器组的各种故障进行自适应保护。现场运行表明,该冷却控制装置可靠性高、功能强,满足了大型变压器冷却控制装置智能化无触点控制和自适应保护与免维护的要求。     

退役锂离子动力电池储能系统风冷热管理仿真

为研究退役动力电池储能再利用过程的热管理方法和运行方案,基于退役锂离子动力电池储能系统,设计了风冷热管理的方案和运行策略。建立了舱内退役电池簇的数学物理模型。仿真了不同风量下磷酸铁锂(LFP)电池簇和三元镍钴锰(NCM)电池簇的温度分布,对比分析了有无风冷热管理时电池簇的热行为。结果表明:风冷热管理能满足适宜退役动力电池正常工作时的温度范围;对于磷酸铁锂电池簇和镍钴锰电池簇,增加风冷系统后,簇内电池最大温差可由无风冷时的10 K降低至4 K左右,电池的最大温升由30 K降低至10 K左右。该研究可为退役动力电池储能系统的高效热管理提供借鉴。     

Alternate methods of energy recovery for the mining industry

When mining for certain precious metals such as gold and silver, it is sometimes necessary to excavate to great depths (>3000 m) below the surface, where the environments is hot and humid. Refrigeration plants are needed that require large volumes of cooling water to be brought into and taken out of the mines. By converting the potential energy of the incoming water to electricity rather than to heat results in cooler mine temperatures and less need for off-site power. The objective of the project was to demonstrate the technical and economic viability of energy recovery from the incoming cooling water used in the refrigeration systems. The economic, operational, and logistic constraints imposed by a mining operation where ore production, not power production, is the primary concern were addressed. The final design was an impulse turbine-generator machine rated at 300 kW output at 820 m head and 40 1/s flow rate     

用于削减工业园区用电功率峰值的蓄冷空调系统的动态建模和优化控制

蓄冷可以通过利用峰谷电价差,使空调系统更加经济,还可以作为一种间接蓄电措施,在峰电时段释放冷量,减少空调系统耗电,实现削减用电峰值功率的功能。对工业园区内需要24 h供冷的、包含基载的蓄冷空调系统的控制进行优化建模,在满足供冷及削峰需求条件下,以经济最优化为目标,分别针对非削峰日、2类削峰日提出相应的控制策略。并以工业园区某一水蓄冷空调系统的控制为例进行了算例分析,结果表明蓄冷空调在削峰时具有削峰幅度大、削峰时间长的优势。另外,当该日冷负荷需求越大时,2类削峰日对蓄冷空调系统运行费用的影响越大,此时可能需要增加削峰补贴电价。     

XLPE cable technology for operating voltages of 245 kV and above

The sources of losses, their effects on cables sizing, how they are affected by load growth rates and load shapes, and the economic evaluation of losses are discussed. A slightly different type of loss, the energy costs for operating circulating and cooling equipment for forced-cooled cable systems, is also addressed. Unified consistent methods for the cable engineer and system planner to evaluate the magnitude of losses on a cable system and the costs of those losses are developed. Detailed analyses of the transmission and distribution system addressing the technical and the economic impact of losses is provided     

商业用户电能采暖替代技术选型的边界条件论证

商业用户电能替代主要是电采暖替代传统燃煤锅炉供暖,主流技术选型有二:一是夏季用冷水机组(WCU)制冷、冬季配置蓄热式电锅炉(HSEB)供暖系统;二是采用兼具供暖、制冷功能的地源热泵(GSHP)系统。为掌握两类系统适用的边界条件,在建立成本模型和运行约束条件的基础上,提出一种以两类系统成本偏差最小为目标、直接求解边界条件的优化模型。对天津市综合性办公楼用户群测算边界条件并做摄动分析,结果表明:对特定地区特定用户群,决定两类系统适用性的边界条件参量是夏、冬季最大冷/热负荷比值和利用小时数;拉大峰谷价比或在大昼夜温差地区HSEB+WCU系统更具经济优势,抬高需量电价或对无热水需求的全天供暖/制冷用户则选择GHSP系统有利。     

基于风险评估的高压电缆巡检周期优化模型

高压电缆日常巡检与消缺工作能够及时发现并消除电缆故障隐患,是降低故障率的有效措施.但忽略风险差异的定期巡检方案会导致人力资源被浪费在不必要的检查与测试环节.为了保证电缆可靠运行且兼顾经济性要求,该文提出了基于风险评估的高压电缆巡检周期优化方法.首先针对历史故障数据,提出了一种高压电缆故障数据记录方法,计算电缆故障频率....     

Quasi-Newton method for optimal load-flow solution under emergency mode of operation

Power systems in developing countries periodically experience a shortage of reserve capacity and imbalance between generation, transmission and distribution facilities. This results in the emergency operation of power systems. The solution of load flows under emergency operating conditions is used to decide on appropriate control action so as to prevent the spread of an emergency or to bring the system back to a normal state. This paper presents a method for optimal load-flow solution under the emergency mode of operation. The load flow is viewed as an optimization problem in which ‘inconvenience’ experienced by customers, owing to variation in supply voltage and load curtailment, is minimized subject to the network constraints and operational limits of the system. The problem is decomposed into two sub-problem is decomposed into two sub-problems exploiting the P-Q decoupling technique. An algorithm is given for the minimization of the sub-problems. The solution of the problem is based on recurring factorization of the Hessian matrices. For large systems the time required to compute the Hessian matrices is considerable. It is shown that the time can be reduced by approximating the Hessian matrices using a quasi-Newton method. Two versions of updating the Hessian matrix are given and their comparative advantages are discussed. The method is illustrated using the IEEE 14 bus and 30 bus test systems. Improvements in the method have been suggested and test results are presented.     

计及功率交互约束的含电—氢混合储能的多微电网系统容量优化配置

在混合交直流多微网系统中,其经济性和运行可靠性受到容量优化配置的影响。考虑到基于电储能以及氢储能系统(电解槽/燃料电池/储氢罐)的混合储能系统所具有的优势,建立了电-氢混合储能型多微网系统框架。其次,针对电-氢混合储能型多微网系统,提出了考虑系统的实时能量供需状态和储能状态的多微网运行控制策略。在容量优化配置模型中引入功率交互约束模型,并在配置过程中嵌入所提出的运行控制策略。最后,以算例分析证明功率交互约束的必要性,并采用灰狼-正弦余弦优化算法求解配置模型。所得配置结果优于改进灰狼算法和改进粒子群算法。通过模拟全年运行情况,验证了所提优化配置方法的有效性和电-氢混合储能系统在季节性储能上的优势。     

Optimization Topics Related to Small Power Producing Facilities Operating under Energy Spot Pricing Policies

Small Power Producing Facilities will become more and more common as the various provisions of the Public Utility Regulatory Policies Act (PURPA) are taken advantage of by utility and customers. These facilities incorporate several features which allow the user to increase his operational flexibilty with respect to the local utility. These facilities can be: local generation, local dependent generation, local energy storage facility, and shiftable load schedule. The only true control the utility has over the actual operation of such facilities is through the judicious selection of the energy prices proposed to such users both for the sale and purchase of energy. It is likely that most utilities will react to this novel user-utility relationship by implementing time-varying energy prices to better reflect their own production costs. These time varying energy prices are often referred to as Spot Prices and are rather commonly used in Europe. A key issue is then the simulation of the various SPPF loads under various spot pricing policies and as they would be seen from the utility's point of view. The purpose of the paper is to describe a general and flexible model for a large variety of SPPFs and to demonstrate its use on a number of operations planning and plant design problems.     

大型变压器智能风冷系统分析

针对大型变压器风冷系统中触点多、故障率高、自动化程度低等缺陷,介绍以dsPIC33FJ128GP306为控制核心的智能大型变压器风冷系统的软硬件设计及功能,并通过实例计算验证该系统的应用可以节约电能,提高变压器运行可靠性,降低故障率.     

具有两种制冷方式的CCHP系统优化运行策略及其判别条件

基于冷热电负荷组合和满足制冷负荷的方式,将包含吸收式制冷和电动制冷的冷热电联产系统的运行空间分成4种状态,每种状态下有3种运行策略。基于冷热电联产系统的运行优化模型,采用库恩—塔克(KT)条件获得了4种状态下各个运行策略为最优策略的条件。基于最优运行策略的条件分析,一种新的同时满足冷热电负荷的运行策略被证明具有最优性质。分析表明,最优策略与负荷的特征、购电价格、天然气价格、冷热电联产系统的效率等因素有关,提出的最优策略判别式可基于这些因素得出最优的运行策略。基于冷热电负荷组合和实际系统的计算结果验证了所述最优运行策略条件的正确性。     

电力电缆技术的发展与研究动向

电力电缆广泛应用于城市电网中,经历了从充油电缆(OF电缆)、钢管电缆到交联聚乙烯电缆(XLPE电缆)的发展过程。XLPE电缆与其他电缆相比,有不需要供油、供气设备、防火性能好、安装维护简单等优良性能,被越来越多的国家所采用。电力电缆的安全运行关系到城市电网的安全可靠性,逐渐受到了各国的高度重视。提高高压电缆路径通道的管理水平、安全运行以及输送能力,其关键技术的研究非常重要。笔者叙述了电力电缆及其附件相关技术的研究状况和今后的发展趋势,得出提高城市电网的可靠性和安全性,降低运行成本是今后的发展趋势。     

基于综合能源的区域用能可靠性评估研究

综合能源系统的区域用能可靠性评估是保障其安全可靠运行的重要基础.文章提出了一种基于马尔可夫模型多组件的综合能源可靠性评估方法.针对综合能源系统出现大量组件问题,建立基于马尔可夫模型综合能源供能子系统随机状态模型,对RBTS-Bus2系统模型进行可靠性评估,计算其可靠性指标.根据该评估方法,可以确定光伏、风力、储能、冷热电联供和市电、用户的负载等在综合能源系统中需求比重.案例分析结果表明,综合能源供应体系能有效提升系统的可靠性,但也存在边界效应问题,有待进一步研究解决.     

An Online Dynamic Cable Rating System for an Industrial Power Plant in the Restructured Electric Market

In addition to market information, available energy and capacity to participate in the market are also essential to be an effective market participant. This paper discusses the development of an online dynamic cable rating system (DCRS) that can help a system engineer maximize asset utilization without jeopardizing system facilities or compromising the reliability of the cables. Based on real-time cable loading, cable surface temperature, ambient temperature, and forecasting temperature, the DCRS can estimate both steady-state and dynamic cable rating. To confirm with the actual operation condition, both real-time cable temperature and forecasting ambient temperature are taken into consideration to perform short-term cable ampacity estimation to prevent overestimation and/or underestimation. Based on the information provided by the DCRS, the system engineer can establish or adjust the bidding strategy in time to effectively participate in the restructured electric markets.     

Geographically distributed real-time digital simulations using linear prediction

Real-time (RT) simulator is a powerful tool for analyzing operational and control algorithms in electric power systems engineering. For understanding the dynamic and transient behavior of a power systems, significant RT computation capabilities are essential. A single unit of RT simulator has limited simulation capabilities. The most common way of augmenting simulation capability is using a bank of locally connected RT simulators. However, creating a large-sized bank of RT simulators involves significant financial investments and hence may not be feasible at all research facilities. Power and energy systems research facilities that use RT simulators are at diverse physical locations. In addition to RT simulators, research facilities around the world house an array of facilities with unique power, energy, and control systems for innovative research. To leverage these unique research facilities, geographically distributed RT simulation based on Wide Area Network (WAN) is required. Typical RT simulators perform simulations with time-steps in the order of milliseconds to microseconds, whereas data latency for communication on WAN may be as high as a few hundred milliseconds. Such communication latency between RT simulators may lead to inaccuracies and instabilities in geographically distributed RT simulations. In this paper, the effect of communication latency on geographically distributed RT simulation is discussed and analyzed. In order to reduce the effect of the communication latency, a Real-Time Predictor (RTP), based on linear curve fitting is developed and integrated into the distributed RT simulation environment. Two geographically distributed digital RT simulators are used to perform dynamic simulations of an electric power system with a fixed communication latency and the predictor. Empirical results demonstrate the effects of communication latency on the simulation and the performance of the RTP to improve the accuracy of simulations.     

Light Rail/Rapid Transit: New Approaches for the Evaluation of Energy Savings, Part II?On the Receptivity of a Transit System

New approaches are presented for the determination and evaluation of regeneration in large transit systems. A specific definition of the receptivity of transit systems to available regenerative braking energy is presented, and the analytical base for receptivity evaluations is developed. The construction of a transit system operational model also is described. This operational model is the mechanism by which the values required for the receptivity analysis are generated. The resulting analytical method provides efficient computation by identifying characteristics peculiar to transit system operation and making use of random sample rather than real time techniques. The analysis also uses a simplified network for the transit system (referred to as a single-thread model) that is error-biased to give a worst-case calculation of receptivity so that a lower-than-actual limit always is predicted. The operational model can be used with the synthetic routes described in the companion paper [21] to determine energy consumption values and, thus, life-cycle cost benefits. Through the use of these analytical tools and simulations, a complete evaluation of potential energy savings can be performed at a reasonable computing cost. A complete receptivity analysis, including parameter sensitivity scans for the Toronto Transit Commission's large streetcar fleet, is presented. The analysis predicted that the weighted average receptivity of the streetcar fleet will be in excess of 97 percent with a voltage window of 110 V or more, and that this result is essentially insensitive to the per-car auxiliary power and to moderate variations in the power distribution system resistances.