Rationalization of operation of an industrial network

The paper deals with the rationalization of the electric power supply of an industrial network. The relevant indices characterizing daily load diagrams are defined, and measurement data are statistically processed to select the representative days for the optimization of reactive power compensation. Mathematical models for the optimization of compensation and load shifting are provided and efficiently processed by applying the Hooke and Jeeves’ discrete search approach. Optimal allocation of capacitor banks at available network load points and their sizes have been determined to maximize the annual cost saving related to real and reactive energy consumption charges. The optimal solution recommended is analyzed for harmonics resonance conditions. The optimal phase shifts of daily load diagrams of feeders supplying various groups of loads are determined potentially minimizing the peak of the aggregated load and associated charges.     

Energy-efficient termination control of the servo drives of modules of a solar-power plant

The dependence of the optimal energy-consumption duration of termination control of a dc servo drive on the angular-displacement magnitude and servo-drive parameters was determined. A new formula making it possible to calculate the optimal duration of time of termination control of the servo drive was obtained. The curves of dependences of energy consumption during termination control of the dc servo drive on the duration of the termination control were plotted.     

Calculations of the losses and thermal operation conditions for controlled alternating-current drives

A survey of methods of calculating losses has been proposed for a class of controlled ac drivers that work under extreme conditions with arbitrary control laws of currents and configurations of magnetic systems for electrical machines. It is shown that the existing methods have low calculation accuracy for the considered class of electric drivers (error up to 30%). The results of calculations by the finite-element method and the experimental data of simulations of thermal conditions and losses using 3D models, in which an electromechanical converter is regarded as a system with distributed parameters, have been considered; moreover, the parallel calculating algorithms have been used. For example, the calculations of losses in the 3D models of a field-regulated reluctance machine have shown that the discrepancy with the experimental data is not higher than 2%. Note that the main share of losses in steel is eddy currents. The results of calculations by numerical methods using 3D models allow one to determine the losses in controlled ac drivers for nonsinusoidal control laws of phase current of the stators with complex configurations of the magnet system of the electromechanical converter. For the considered class of electric drivers, the largest share of losses (from 60 to 80%) is eddycurrent losses.     

Application of the vector-pulse method to starting an alternating-current motor

A soft-start method for induction and synchronous motors is considered. The method is based on pulse switching of the motor stator to the supply network at the moments at which the stator- and rotor-flux linkage vectors produce positive electromagnetic torque. A wiring diagram of the experimental soft-start device, its operation algorithm, and experimental outcomes are presented.     

690V电压等级在工业低压配电网中的应用—节约投资成本和改善电网效率

简　介在欧洲低压配电网中工业用电装置最常用的电压等级是 40 0 V。这个电压由于与公用配电系统的电压等级一致而得到广泛应用 ,相应的设备、装置和配件也很容易在市场上采购到。在工厂里 ,中压用户通常采用 40 0 V电压和 60 0 0 V电压等级相关联的方式 ,通常例如电动机。大部分制造商提供的测试设备和标准特性的装置都适用在这两个电压等级中。但是更高等级的“低压”的使用 (即 690 V)往往能使配电方案的选择更为灵活和方便 ,主要的优势就是减少资本投入和改善全网的运行效率。对比这两个电压等级 (690 V和 40 0 V)可以从如下的一些关…     

基于大数据处理的配网运行效率关联性分析

随着配网系统不断发展,系统结构更为复杂,所产生的运行数据量也极为丰富。通过对大数据的有效快速分析,能及时准确提取相关数据,对系统运行效率产生积极影响。基于大数据处理技术,提出一种用于计算配网运行效率相关性的分析方法。首先介绍了大数据处理的相关技术,详细分析了模糊聚类分析在数据提取中的作用。然后对配网运行进行相关讨论,并分析了可能影响配网运行效率的有关因素。随后,利用主成分分析法确定主要影响因素。最后通过算例验证了该方法的有效性,并根据结果为系统运行提供相关参考意见。     

Analysis of the energy performance of an alternating-current drive under transient conditions

The energy properties of an alternating-current drive are analyzed. The suggested method allows us to compare in an analytical form the energy quality indices of various drives under different means of electromagnetic- torque formation in an electrical machine. Using the relation between power and energy characteristics as functions of the energy state, the energy efficiency, and intensity of energy-conversion processes, as well as the usage efficiency of voltage and power applied to motor windings, are estimated. By means of the constructed relations between quality criteria, the developed method allows one to determine at the stage of design the main properties of an electric drive under static and dynamic conditions. Using energy-state functions and arguments based on means of electromagnetic-torque formation, the method allows us to determine the thermal state at selection or testing of an electrical machine on the basis of heating or overload conditions.     

Increasing the cooling efficiency of power semiconductor devices

The task of developing a refined procedure for the determining thermal resistance coefficient of a power semiconductor device (PSD)–cooler contact allowing for roughness of contacting surfaces was set. For this purpose, mathematical modeling methods applying the theory of random functions and full-scale test methods of elements of semiconductor converters were used. Using the developed software and experimental dependences, the compressive forces and roughness of surfaces at which the maximum intensity of the contact heat transfer in power units with the evaporative-air cooling is attained are determined. It is shown that the number of contact spots and actual contact area increase with an increase in pressure thereby lowering the thermal resistance. The lower the surface roughness is, the lower the values of pressure are at which the maximum intensity of the contact heat exchange can be attained. Considerable lowering in the contact thermal resistance for each contact pair occurs for a definite pressure only, after which further increase in the load (larger than 20–30 mPa) does not yield the desirable effect of the contact thermal resistance and losses the sense thereof. The application of KPT-8 heat-conducting paste and K-1 adhesive lowers the contact by more than three times. The application of tin and iridium spacers for the PSD–cooler pair with nickel-plated surfaces has given no positive result. Based on the calculated and experimental data, the requirements for degree of treatment of contact surfaces using nickel coatings, heat-conducting pastes, and spacers that allow increasing in PSD cooling efficiency by 10–14% are refined.     

配网运行提质增效智能化控制技术分析

经济社会的快速发展离不开电力资源的供应。新时代对配网运行的安全性和稳定性提出了新要求。本文分析了配网运行提质增效的技术方法,讨论了相关智能化控制技术,也讨论了有关云导航控制系统的应用。     

基于改进AUGMECON的配网虚拟电厂多目标优化运行

虚拟电厂可聚合配网末端的可调节负荷资源参与电力系统的调用以缓解面临的供需平衡等问题。同时末端资源功率的调节影响着配网的运行质量,负荷侧资源的调用可降低配网区域峰谷差,减少系统网损。为此,以配网运营商为主体构建虚拟电厂,提出一种基于改进AUGMECON的配网虚拟电厂多目标优化模型,以运行效益、配网峰谷差和配网网损为目标函数,调用配网末端负荷资源参与需求响应,在提高运行收益的同时改善配网运行质量。通过改进AUGMECON获取所提多目标优问题的Pareto前沿,并采用考虑公平性的方法获取折中解。最后基于修改后的IEEE 33节点配电网系统进行了仿真分析,验证了所提模型的有效性。     

火蓄联合运行成本效益分析

为解决能耗高的火电机组面临的启停频繁、运行位置差等问题,研究了火电站与抽水蓄能电站联合运行的模型.模型中火电站通过认购抽水蓄能电站的抽水电量提高机组发电量,避免机组的频繁启停.同时,对机组联合运行的成本收益进行了分析.结果表明,火蓄联合运行不仅能够避免机组频繁启停,提高机组的负荷率,降低煤耗,节约成本,同时也有利于其在电网中更好地发挥静动态效益.     

Modern cement plant design with a view to efficiency and theenvironment

Using today's proven technology we can design a cement plant, which not only will meet many of the emission requirements, but also uses the least possible amount of thermal and electrical energy. Today's modern cement plant design will lower initial capital investment, lower operating costs, and also reduce the burden of the cement plant on the environment. These desirable requirements are achieved either directly by reducing process emissions or indirectly by significantly reducing power and fuel consumption per ton of product produced. The author discusses the following areas of design: raw grinding system, pyro-system design, kiln design, kiln burner design, tertiary air-take-off, and clinker cooler design     

Impact of manual versus automatic transfer switching on the reliability levels of an industrial plant

Detailed reliability modeling and analysis of industrial plants provides an estimate of the frequency and duration of load point interruptions. The duration of repair and switching activities necessary to restore a unique power system configuration to a normal operating state from an outage state has a significant impact on the power system reliability levels of industrial power systems. This paper presents and discusses the significant variations in the frequency and duration of load point interruptions at an industrial plant due to manual and automatic switching activities. Three case studies with different percentages of open- and short-circuit failure modes of circuit breakers and fuses will also be presented and discussed for both manual and automatic switching restoration activities.     

Increasing the power efficiency of a 25-kV alternating current traction power supply system

One promising method of increasing the power efficiency of an electrified railway is reducing the power capacity of the transfer process and the consumption of the electric power to the train traction. A 25-kV ac traction power supply a system features the drastically variable one-phase train load, which leads to a change in voltage on substations buses and train current collectors, as well as an increase in loss powers. The rules of the composition of the traction power supply for the fulfillment of the train schedule normalize the voltage on the substation buses and train current collector of no more than 29 kV and no less than 21 kV. Analysis of operation of the traction power supply system is carried out, and steps are taken to increase the engineering and economic performance of 25-kV ac railways. A new notion of normal power supply circuits of traction loads synthesized on the basis of simulation is presented. Analyzing the structure of the imbalance of electric power and voltage in traction network allows one to define steps toward increasing power efficiency. The accuracy of the initial data is determined by comparing the expected and real train schedules, as well as electric load curves. The simulation accuracy is determined on the basis of predictable power and voltage losses with monitoring results.     

A comparison of the energy efficiency of the traction electric drive of alternating-current electric locomotives based on collector and asynchronous motors

An assessment of the overall performance of 3ES5K alternating-current electric locomotives with a collector drive in the regimes of traction and recuperative braking using the concrete example of a staged route between the Khabarovsk-2 and Bikin stations of the Far East Railroad is given in this article. Real traction and brake characteristics of a 3ES5H electric locomotive in the case of a cargo train of large weight and length are shown. Analysis is carried out of all the characteristics of a 3ES5H electric locomotive, and they are compared with the movement of a 2ES5 electric locomotive with an asynchronous drive. It is determined why 3ES5K electric locomotives are more power efficient than 2ES5 ones.     

Developing a database for a reliability, availability, andmaintainability improvement program for an industrial plant orcommercial building

It is argued that database development is a critical part of the design of any industrial reliability, availability, and maintainability (RAM) program. A time-tested process for assembling a sound RAM database is outlined. Its applicability to electrical systems is obvious, but it can also be used successfully in improving the reliability of the various other types of systems in an industrial facility, commercial building, or health care facility     

含储能的主动配电网优化运行研究

围绕含储能系统的主动配电网运行优化这一研究内容,对储能系统、分布式电源的运行特性进行了深入分析,构建了含储能的主动配电网优化运行模型,并通过算例论证了模型的有效性。     

An analysis of the operation of a solar adsorption periodic-duty refrigerating plant

We present estimates of the limiting power performance indicators of solar absorption refrigerating plants that were carried out using the constraints of the first and second laws of thermodynamics, as well as a method for determining the optimal adsorbent regeneration temperature, at which the maximum coefficient for conversion of solar energy into the energy of cold can be obtained. The effect of different parameters on the adsorbent regeneration temperature is analyzed, and the maximum attainable integral coefficient of the conversion of solar energy into the energy of cold is presented.     

Short-term operation scheduling of a hydropower plant in the day-ahead electricity market

This paper presents a novel approach to solve the short-term operation scheduling problem of a hydropower plant that sells energy in a deregulated electricity market with the objective of maximizing its revenue. This paper proposes a nonlinear programming based scheduling model that determines both the optimal unit commitment (start-ups and shut-downs scheduling) and the generation dispatch of the committed units (hourly power output). The power generated by each hydro unit is considered as a nonlinear function of the water discharge and the volume of the associated reservoir. The dependence of the units’ operating limits (maximum and minimum water flows) on the actual gross head has been also taken into account in this model. The results from a case study are also presented to illustrate the application of the proposed approach in a real hydro plant.