Applying high efficiency transformers

Manufacturers can reduce transformer energy losses by utilizing different construction materials and designs for transformer core and windings. While potential reductions in future energy prices may exist due to utility deregulation and retail wheeling of electricity, significant opportunity still remains to impact the corporate bottom line through use of improved efficiency electrical equipment. Electric power transformers may last from 20 to 50 years depending on their loading and application. Thus, the life-cycle or total owning cost must be considered during the initial investment phase to evaluate the total energy savings against the added capital expenditure for an improved efficiency transformer. This involves using an economic evaluation process known as the discounted cash flow method. Many utilities offer economic incentives to companies who implement energy conservation programs. Such programs realize the dual benefits of cost savings and environmental relief from reduced emissions. Another possible benefit is the prevention of economic losses by minimizing the probability of fuel supply curtailment. This article explores existing and future design techniques which enable efficiency improvements in various types of transformers. This work also provides detailed analysis for investment guidance regarding additional dollars chat can be justified for applying improved efficiency transformers     

配电变压器节能设计选型

简述了变压器技术发展的过程。介绍了总拥有费用最低法则来评价和选择变压器的方法。通过案例计算,表明该方法对于配电变压器的节能,提高经济效益是一条非常有效的途径。     

非晶合金配电变压器的应用及其节能分析

分析了我国农网配电变压器运行现状以及阻碍非晶合金配电变压器推广应用的因素,介绍了非晶合金材料的性能特点及国内外非晶合金配电变压器的生产技术水平和应用状况。从年运行费用、投资回收期限、效率与负载系数的关系、总拥有费用等方面对非晶合金配电变压器的节能效果进行了理论计算与分析,利用图表的形式直接反映出非晶合金配电变压器的最佳运行负载率及较好的综合经济性,为用户合理选用非晶合金配电变压器提供了依据。提出用户订购及采用非晶合金配电变压器时应注意的几点问题,针对变压器容量及安装地点的选择给出了相关建议。     

有载调容变压器综合经济性分析及应用研究

笔者基于有载调容变压器结构及运行特点,给出了其适用范围,详细解析了有载调容变压器的调容节能原理。从年运行费用、投资回收年限以及总拥有费用几方面对SZ11-T型有载调容变压器与S11型普通配电变压器进行了综合经济性比较及应用分析,结合10 kV配电变压器的实际使用情况,给出了有载调容变压器的两种应用方案,并提出了解决调容变压器计量精度问题的可行性建议。     

非晶合金变压器节能性分析

非晶合金变压器的空载损耗较低,有助于电网节电降耗,但其销售价格偏高影响了用户的选择。应用总拥有费用法,从经济角度科学地评判非晶合金变压器节能的经济性。同时按总拥有费用最小原则选择非晶合金变压器的容量,有一定的实用价值。     

Optimal design of single-phase shell-type distribution transformers based on a multiple design method validated by measurements

This paper presents a method for the design of shell-type, single-phase distribution transformers to obtain the manufacturing specifications. The method is simple, efficient and accurate. By an exhaustive analysis, it is concluded that the obtained solution is the global optimum. The following constraints are imposed: excitation current, no-load losses, total losses, impedance and efficiency. The methodology of this paper requires only six input data: transformer rating, low voltage, high voltage, connection of low-voltage coil, connection of high-voltage coil, and frequency. These data are included in the transformer nameplate. In this paper, the minimization of the following four objective functions is considered: total owing cost, mass, total losses and material cost. The consideration of these four objective functions is implemented automatically by running the optimization algorithm four times without intervention of a designer. Consequently, transformer manufacturers save design man-hours and increase capacity. A design example on a 25 kVA transformer is presented for illustration. The optimized solutions of transformer design are validated with laboratory and process measurements.     

Cost of Load Losses in Distribution Transformers by the Method of Average Loading

The cost of load losses for distribution transformers may be solved by using the average loading on the transformer. The main calculation is the division of the system-wide average load on distribution transformers by the connected MVA of distribution transformers. This method provides for simple calculations with a minimal amount of data.     

有载调容变压器在农村电网中的应用

变压器损耗在电网损耗中占有较大的比重,因此降低配电变压器损耗成为有效的节能措施之一。介绍了有载调容变压器的结构与节能原理以及采用有载调容变压器后带来的经济效益,预期了有载调容变压器在农村电网中的应用前景。     

从变压器经济运行分析现行电价制度的合理性

目前电价政策存在不合理之处，诱导用户在高负荷状态下运行，增加了变压器和电网的损耗，对配电变压器的经济运行极为不利。结合实例对现行两部制电价的合理性及存在的问题(即按照变压电容量计费)进行了深入的分析，提出了按照最大需量计费的调整建议。使电费与变压器容量不再发生联系，促使用户实行变压器经济运行，从而大幅度降低配电变压器年电能损耗，进而实现整个配电网络降损节能，为国家节约大量电能。     

S11型配电变压器的技术经济分析及应用

阐述我国S11型配电变压器的发展过程，分析比较了卷铁芯和叠铁芯2种结构的优缺点，并对S11和S9型配电变压器的损耗参数进行比较。建立了S11型配电变压器技术经济分析的数学模型，对更换S9型和S7型配电变压器的投资回报以及使用S11型配电变压器对广电集团公司电网线损的贡献分别进行了分析和测算。计算表明S11型配电变压器具有非常可观的经济效益。S11型配电变压器的技术已趋成熟，生产已具规模，具备大批量采购的条件，建议新采购时应以S11型配电变压器为主，对于运行12a及以上的老旧S7型（或更早期的）配电变压器应考虑逐步更换。     

电力变压器附加损耗计算及影响因素分析

为了准确计算并抑制变压器的附加损耗,笔者提出了计算电力变压器附加损耗的涡流场分析方法,对两种型号的油浸式变压器的涡流以及附加损耗分布进行了计算。在涡流场的计算中,通过对铁心材料磁导率和电导率各向异性的处理来等效铁心片之间的叠积效果。文中给出了各主要金属构件中的涡流以及涡流损耗的分布,并对影响附加损耗的几个因素进行了分析。结果表明:结构件采用非导磁材料;适当的调整各结构件之间的尺寸以及采用中部出线的分接类型都可以有效地降低附加损耗。最后,对多种型号的变压器附加损耗进行了试验验证,计算与试验数据吻合很好。     

三相三柱、五柱全斜接缝铁心的片形和选择

电力变压器全斜接缝铁心片的选择关系到变压器的性能和铁心制造的工艺水平。根据国内外变压器制造业的情况,提出了铁心的叠片形式和片形结构的改进建议。     

OPTIMUM DESIGN OF SMALL DISTRIBUTION TRANSFORMER USING ALUMINIUM CONDUCTORS

ABSTRACT

Design Optimization of distribution transformer of small KVA rating using aluminium conductors is considered as a nonlinear multivariable constrained programming problem. For this purpose a set of five independent design variables is identified and suitable constraints are imposed to meet the thermal and other performance requirements of the transformer. The various objective functions are formed in terms of cost of active material, capitalized cost of losses as the operating cost and the overall cost as the sum of these two. This is done to select most effective and appropriate optimized design for these types of transformers. The optimization is achieved through Rosenbrock's method of direct search in conjunction with the sequential unconstrained minimization Technique (SUMT). The optimized design results for a 25 KVA distribution transformer using aluminium conductors are presented along with the design results using copper as the winding material for different objective functions.     

发电机定子冲片底涂层对绝缘涂层的影响

本文对发电机定子冲片底涂层和绝缘涂层进行了扼要的介绍,对三种不同水溶性漆进行了交叉组合试验,研究了漆膜外观、厚度、耐溶剂性、附着力和绝缘电阻等方面的影响,还研究了不同底涂层冲片涂覆绝缘漆后的耐高温、耐腐蚀性能以及冲片断面的覆盖率。结果表明,在上述各方面底涂层对绝缘涂层都有影响,在实际使用过程中需要考虑冲片底涂层与绝缘涂层的兼容性问题。本文为设计和工艺人员选择冲片和涂漆材料提供了参考依据。     

变压器的经济运行方式

分析了电力变压器负荷与损耗的关系 ,通过计算 ,寻求变压器运行中降低变压器的有功功率损耗和提高其运行效率以及提高变压器电源侧功率因数的方法。通过对负荷电流与临界负荷电流进行比较 ,合理选择 35kV终端站和 10kV配电变压器的运行方式 ,达到减少变压器损耗的目的。     

风电定子扇形冲片铁心叠压

在扇形冲片定子铁心叠压时,对叠压模内涨胀胎尺寸公差和导销厚度公差、形位公差以及定子铁心内径尺寸公差和扇形冲片内圆尺寸公差等因素进行了综合分析,阐述了扇形冲片定子铁心叠压质量的影响,提出了保证扇形冲片定子铁心叠压质量稳定性的措施。     

轻负荷时期减少变压器损耗的运行方式

分析了电力变压器负荷与损耗的关系,提出了在轻负荷时期,可通过简易计算,对负荷电汉与临界负荷电流进行比较,合理选择110kV终端站和10kV配电变压器的运行方式,达到减少变压器损耗的目的。     

Economic Considerations of Power Transformer Selection and Operation

The increased emphasis on energy conservation and the rising cost of electric energy have forced users of power transformers to consider the cost of transformer losses. Most of the commonly encountered factors used in transformer selection are reviewed, and a guideline is presented which will assist users in both selecting and operating power transformers more efficiently.     

Transformer Economic Evaluation

Inherently high transformer efficiencies have caused little concern for transformer loss costs in the past, but increasing energy costs in recent years have resulted in greater sensitivity to these losses. Since lower losses are realized through greater investment in engineering effort and material selection, the low-loss transformer is usually obtained at a premium price. Justification of this premium price through energy savings is the reason for the economic evaluation methods presented. Transformer loading, expected increases in utility charges, taxes, and company minimum rate of return are considered in this "present value" evaluation of transformer losses and in rate-of-return comparisons of competing transformers.     

Transformer magnetizing current and iron-core losses in harmonicpower flow

The problem of modifying the harmonic power flow analysis to permit the inclusion of nonlinear anisotropic transformers and computation of their iron-core (and copper) losses are discussed. The nonlinear model used for transformers is capable of simulating saturation of iron-cores, anisotropy of laminations, and the iron-core and copper losses associated with anisotropic transformers, but simple enough to be included in the harmonic power flow algorithm without deteriorating its convergence properties. The dependency of iron-core losses on the maximum value of the total (fundamental and harmonic) flux density and the fact that iron-core losses are a function of the waveform of the induced voltage-that is its harmonic phase shifts with respect to the fundamental phase angle-are included. The induced voltage is transformed from frequency domain to time domain: the instantaneous induced voltage and the computed λ-i characteristics are employed to compute the instantaneous magnetizing and core-loss currents. Thereafter a transformation is made from time domain back to frequency domain to compute the fundamental and harmonic components of the above-mentioned currents. Therefore, transformer harmonic couplings are properly modeled and included in the analysis. The modified harmonic load flow formulation is applied to a balanced three-phase feeder consisting of a grounded-wye, grounded-wye nonlinear anisotropic transformer and linear and nonlinear loads