A general maximum power transfer theorem

The maximum power transfer theorem provides the condition which the load resistance or impedance must satisfy for maximum power absorption from the source network. This paper reviews the conventional maximum power transfer theorem and presents a modification to the theorem by incorporating a measure of the relative importance of power transmission efficiency over power transferred to the load     

On state-space synthesis of reciprocal n-ports

The paper considers the state-space synthesis of reciprocal n-ports with a minimum number of reactive elements. After formulating the synthesis problem new procedures are given for the lossless and for the passive cases which use a directly determinable reciprocal minimal realization as starting point. The methods are presented in terms of admittance matrices and then restated for impedance, hybrid and scattering matrix synthesis.     

On impedance matching and maximum power transfer

This paper investigates the relationship between the impedance matching and the maximum power transfer problems, and presents a predictor–corrector framework for fast estimation of the maximum power transfer limit for the load increase pattern with a common scaling factor. First, a network equivalent technique is presented and a “decoupled” equivalent network is obtained for every load bus. Second, a special form of impedance matching condition is derived for the maximum power transfer problem with an unlimited load variation pattern. Though this is an unrealistic case in power systems, it might have a profound physical mechanism and lead to an interesting explanation and application for the presented equivalent technique. Third, this paper discusses the relationship between the impedance matching and the maximum power transfer problem for the load increase pattern with a common scaling factor. Finally, a predictor–corrector framework is introduced for fast estimation of the maximum power transfer limit for the load increase pattern with a common scaling factor.     

Necessary and sufficient conditions for absolute stability of linear n-ports

A set of necessary and sufficient conditions is stated and proved for the absolute stability (under any passive terminations), in the ‘bibo’ sense, of a linear n-port characterized by its open-circuit impedance matrix. A more explicit set of such conditions is derived for the special case n = 3. In the process of deriving this set of conditions, some results and theorems concerning finding the zero sets of two and three parameter functions, are stated and proved. Also derived is a set of necessary and sufficient conditions for the absolute stability of two-ports characterized by the scattering parameters. Such sets have already been derived previously, but the present set is considerably simpler.     

叠加定理中功率的适用性分析

叠加定理作为线性电路中非常重要的一个定理,它是指当电路中有多个电源共同作用时,或任何1个支路电压(或电流),都可以看成是由各个电源单独作用时,在该支路产生的电压(电流)的代数和.但与电路响应有直接联系的能量问题的求解在该定理中并未直接述及,主要研究在直流电路、同频率正弦交流电路及不同频率正弦交流电路中叠加定理是否适用于功率的计算,并用Multisim软件进行仿真.从仿真结果和理论计算比较得出不同频率正弦交流电路中叠加定理适用于平均功率的计算.     

Existence of hybrid matrices for active n-ports encountered in the analysis of transistor networks

It is shown that hybrid matrices exist for certain types of active n-ports constructed using resistors and controlled sources. Furthermore, it is shown that the existence of these hybrid matrices implies that a certain well-known set of necessary and sufficient conditions, which guarantees the uniqueness of solutions to the nonlinear DC equations of transistor networks, can be simplified. Additional results are presented which show how the amount of computation required to verify these conditions can be reduced.     

Total transfer capability computation for multi-area power systems

This paper presents a method for multi-area power system total transfer capability (TTC) computation. This computation takes into account the limits on the line flows, bus voltage magnitude, generator reactive power, voltage stability, as well as the loss of line contingencies. The multi-area TTC problem is solved by using a network decomposition approach based on REI-type network equivalents. Each area uses REI equivalents of external areas to compute its TTC via the continuation power flow (CPF). The choice and updating procedure for the continuation parameter employed by the CPF is implemented in a distributed but coordinated manner. The proposed method leads to potential gains in the computational efficiency with limited data exchanges between areas. The developed procedure is successfully applied to the three-area IEEE 118-bus test system. Numerical comparisons between the integrated and the proposed multi-area solutions are presented for validation.     

Modeling of transfer Characteristics for the broadband power line communication channel

This paper presents a novel approach to model the transfer function of electrical power lines for broadband power line communication. In this approach, the power line is approximated as a transmission line and the two intrinsic parameters, the characteristic impedance and the propagation constants, are derived based on the lumped-element circuit model. Using these intrinsic parameters, the transfer characteristics for a N-branch power distribution network are derived based on the scattering matrix method. Detail derivation of this line model is given in this paper. The model has been verified with practical measurements conducted on actual power networks. It is demonstrated that the model accurately determine the line characteristics under different network configuration and when different household appliances are connected.     

HEV用动力蓄电池的最大充放电性能

结合动力蓄电池在混合动力汽车(HEV)上的应用特点,分析了最大充放电性能的影响因素和描述方法,并使用车辆在城市和高速道路上的运行情况统计数据设计了新的实验程序,包括长持续期(30 s)和短持续期(10 s)两部分.对Optima D34型12 V 55 Ah VRLA电池进行的实验结果表明,长短持续期的充放电性能相差很大.对于HEV,应将长持续期和短持续期性能区分对待.     

浅谈农村配电网的无功补偿

针对农村配电网的具体状况,说明对农村配电网进行低压无功补偿的必要性及其重要意义,并提出了农村配电网无功补偿的最佳方法.最后,对农村配电网无功补偿实例进行分析,比较补偿前后的功率因数、线路输送的无功功率、线路电压损失、年线损电量.比较结果表明：对农村配电网进行无功补偿的节能降损效果非常好.     

基于广义Tellegen定理的小扰动定理在含光伏源的电力系统潮流算法中的应用研究

广义Tellegen定理与物理系统属性无关,只与物理系统所建立的数学模型有关,因而被广泛地应用于电力系统中。考虑光伏并网影响因素,将光伏系统视为PQ节点,在电流注入潮流模型的基础上,利用小扰动定理建立基于广义Tellegen定理的修正方程。利用新的修正方程,以引入光伏源的IEEE30节点测试系统为例进行潮流计算。算例分析表明,该算法的迭代次数及潮流计算速度均有所改善,同时也表明了广义Tellegen定理在含光伏源系统中同样具有重要的应用价值。     

交联电力电缆故障点的定位

本文详细介绍了用于检测交联电力电缆击穿故障和局部放电定位的方法和使用的仪器 ,以及测试线路的改进     

"皖电东送"输电系统规划

根据华东电网资源分布和区域电力市场状况,提出了"皖电东送"输电规划基本原则,结合"皖电东送"容量和电力流状况,提出了相应的输电系统方案,并对"十一五"期间安徽电网各主要断面输电能力进行了计算校验.     

Modeling emergency interregional electric power transfer

This paper describes a combined model of the U.S. power system that is the first to allow for emergency interregional transmission of electricity. The Interregional Transfer Model (INTRAN) is used with the Baughman-Joskow Regionalized Electricity Model (REM) to simulate the transshipment of emergency interregional electric power exchanges. REM-INTRAN is a tool to assist policy makers concerned with the reliability and adequacy of the U.S. bulk power system. It is the only model available that provides regional detail of the electricity sector and emergency interregional power transfer capabilities. REM-INTRAN considers generation plant mix and monthly load characteristics on a regional basis, and the limiting transfer capacities and costs of emergency interregional power transfers.     

含有风电发电机组可用输电能力新算法的研究

阐述了含有风电发电机组的潮流计算模型,提出将改进蚁群算法、变邻域搜索算法和差分进化算法相结合应用到可用输电能力研究中,该算法克服了陷入局部最优解的缺点,并提高了寻优的效率、全局的寻优能力和结果 的稳定性.以IEEE30节点标准系统作为算例对输电网可用输电能力进行仿真计算,计算结果表明本文提出的算法具有合理性和可靠性.     

Impulse testing of power transformers using the transfer functionmethod

The transfer function of a transformer winding is deconvoluted in the frequency domain from the digitally recorded neutral current and high voltage applied during impulse tests. The integrity of the winding insulation is determined by comparing the transfer function obtained at full and reduced test voltage. Differences between the transfer function plots reveal local breakdowns in the winding that can be dissociated from partial discharges. Thus the method permits unambiguous acceptance or rejection if the transformer and, since the transfer function is theoretically immune to changes in the applied impulse, also allows evaluation of the chopped-impulse test. Some 100 windings of large HV power transformers have been tested using the transfer function method, which on several occasions has revealed transformer faults as well a test setup problems that would have been missed or misinterpreted by conventional techniques     

Monitoring of power transformers using the transfer function method

The transfer function concept is well known as an additional method of evaluating the impulse test of power transformers in the test laboratory, Another application for this method is monitoring of power transformers in service. According to the method of how to measure transient signals for the calculation of transfer functions, two kinds of monitoring can be distinguished: off-line and on-line monitoring. Both kinds of monitoring as well as their influencing factors are discussed with on-site measurements on power transformers in service     

Test facility for investigation of heat transfer of promising coolants for the nuclear power industry

The results are presented of experimental investigations into liquid metal heat transfer performed by the joint research group consisting of specialist in heat transfer and hydrodynamics from NIU MPEI and JIHT RAS. The program of experiments has been prepared considering the concept of development of the nuclear power industry in Russia. This concept calls for, in addition to extensive application of water-cooled, water-moderated (VVER-type) power reactors and BN-type sodium cooled fast reactors, development of the new generation of BREST-type reactors, fusion power reactors, and thermonuclear neutron sources. The basic coolants for these nuclear power installations will be heavy liquid metals, such as lead and lithium-lead alloy. The team of specialists from NRU MPEI and JIHT RAS commissioned a new RK-3 mercury MHD-test facility. The major components of this test facility are a unique electrical magnet constructed at Budker Nuclear Physics Institute and a pressurized liquid metal circuit. The test facility is designed for investigating upward and downward liquid metal flows in channels of various cross-sections in a transverse magnetic field. A probe procedure will be used for experimental investigation into heat transfer and hydrodynamics as well as for measuring temperature, velocity, and flow parameter fluctuations. It is generally adopted that liquid metals are the best coolants for the Tokamak reactors. However, alternative coolants should be sought for. As an alternative to liquid metal coolants, molten salts, such as fluorides of lithium and beryllium (so-called FLiBes) or fluorides of alkali metals (so-called FLiNaK) doped with uranium fluoride, can be used. That is why the team of specialists from NRU MPEI and JIHT RAS, in parallel with development of a mercury MHD test facility, is designing a test facility for simulating molten salt heat transfer and hydrodynamics. Since development of this test facility requires numerical predictions and verification of numerical codes, all examined configurations of the MHD flow are also investigated numerically.