并联支路不平衡变极绕组对称化调整的新方法

本文提出一种解决并联支路不平衡变极绕组的对称化问题的新方法.文中论述了本方法的基本原理及调整规律,并以54槽6/8极双速电机为例,给出了调整后的变极方案.作者按本方案制做了样机,实验结果表明,本方法对于并联支路不平衡的变极绕组有显著的对称化调整作用.     

反向与换相混合变极绕组的并联支路数算法及等效绕组

介绍电机绕组接成网络电路或连接不同线径支路情况下 ,广义等效并联支路数的概念和算法以及反向和换相混合变极绕组的等效电路     

双绕组变极三速电动机电枢绕组选择方案的分析

详细分析双绕组变极三速电动机内部环流形成的原因, 结合维修电动机, 提出变极电动机并联支路内极相组间连接次序、分数槽绕组大小极相组轮换顺序、绕组连接方式及节距选择的正确组合方案     

反向与换相混合变极绕组的并联支路数算法及等效绕组

介绍电机绕组接成网络电路或连接不同线径支路情况下，广义等效并联支路数的概念和算法以及反向和换相混合变极绕组的等效电路。     

双绕组变极三速电动机电枢绕组选择方案的分析

详细分析双绕组变极三速电动机内部环流形式的原因,结合维修电动机内部环流形式的提出变极电动机并联支路内极相组间连接次序,分数槽绕组大小极相组合轮换顺序,绕组接方式及节距选择的正确组合方案。     

关于三相60°-60°相带6/8极双速绕组的研究

研究了采用6Y/3Y(6Y/3△)接法的6/8极变极绕组,指出采用2:1匝比线圈可能消除其相并联支路间的环流,并以定子为72槽的电机为例,说明了变极绕组方案的排列方法,讨论了线圈节距的选择,给出了具体的谐波分析结果。     

绕线型变极感应电动机设计中的绕组接法问题

通过对绕线型变极感应电动机电磁设计中的定子双绕组、转子绕组的接法分析,提出了正确选择绕组并联支路娄和上组联接方式的方法。     

汽轮发电机定子绕组并联结构对电感计算的影响

大型汽轮发电机定子绕组通常为双层短距分布,并联支路数常大于1,基于这一事实,以并联支路数为2的300 MW汽轮发电机为对象,给出了相绕组及其两并联支路绕组的自感计算方法和有限元计算结果.以四方铁心上两个线圈并联为例,研究了相绕组的自感和其两并联支路线圈自感间的关系,并从磁路计算角度和电路角度两个方面对其进行了证明,指出有2条支路并联而成的相绕组的自感等于其中任一条支路的自感,而且有2条支路并联相绕组与其他绕组之间的互感之间也有相同的关系.     

变极凸极同步电机气隙磁导谐波磁场及其在定子并联支路中引起环流的分析

通过对变极凸极同步电机气隙磁导谐波磁场及其定子各支路绕组的分析，从理论上证明了该类类电机气隙磁场中存在很强的分数次谐波分量。这种谐波将会在有并联支路的定子绕组中产生环流。     

绕线型变极调速感应电动机设计中的特殊问题

本文阐述了绕线型变极调速感应电动机定子双绕组、转子绕组的接法以及定子双绕组槽漏抗计算问题分析;提出了正确选择绕组并联支路数和极相组联接方式、槽漏抗的计算公式和方法。     

适用于配电网潮流计算的改进回路电流法

为使回路电流法适于配电网潮流分析,在π型等值电气元件的基础上,以阻抗支路为链支、接地支路为树支,忽略了线路对地导纳和变压器对地支路,建立了配电网回路电流分析模型。采用恒阻抗负荷模型替代恒功率负荷模型,将回路电流方程简化为线性方程组进行求解,给出了对退化节点的处理方法,分析了回路电流法和回路阻抗法的异同。算例结果验证了该方法的有效性。     

电网线损的物理分布机理

电网线损是电力系统运行的基础参数,考虑市场因素,传统意义的网损必须附加来源,因此,网损分摊成为研究的热点,并已出了多种计算方法,但这些方法最终必须面对的问题是两乘数占其积的比例,这是一个没有定义的数学命题,没有解决方案,无法获得到令人满意的解释.该文从网损产生的本质出发,指出电网能量的分布规律;利用能量的一维特性,提出功率线性叠加定理;通过理论分析得到了基于能量线性叠加的电源输出功率、支路传输功率和支路线损解析表达式,给出了电源对线损的能量分布系数和线损与电源关系的解析表达式,从而构建了完整的线损线性分析、计算的理论基础.     

Application of the mixed potential for formulating normal form equations for nonlinear rlc-networks with ideal transformers

For the class of complete nonlinear RLC-networks the normal form equations can be established by a method given in Brayton and Moser¹ using the mixed potential. Before applying this approach it is a crucial point to investigate whether a network is complete. To this end in the present paper an algorithm is given which additionally leads to a partitioning of the network under consideration. Two theorems are given enabling the direct construction of the mixed potential starting from the obtained subnetworks. It is shown that complete nonlinear RLC-networks with ideal two-port transformers (RLCT-networks) can be remodelled into complete RLC-networks using a new approach to model non-hybrid transformers. Noncomplete RLCT-networks often can be remodelled into complete RLCT-networks by inserting additional branches containing controlled sources which do not affect the mixed potential. Further simplifications are possible using the rules given to derive the so-called ‘potential-equivalent’ networks which contain less controlled sources but lead to the same normal form equations. Finally some theorems are given concerning the existence and uniqueness of solutions of a complete network where the conditions can be examined directly at the network before establishing the network equations.     

PROLOG network-graph generation in system surveillance

Based on the PROLOG programming language, the paper develops methods by which the configuration of an interconnected power transmission network may be determined automatically from telemetered status data for circuit breakers and isolators throughout the network in the first stage of state estimation for network surveillance purposes. A structure is first given for the data base from which logic processing begins and which includes the identification of substations at the first level, defined zones within substations at the second level, and individual switching elements within defined zones at the third. For all but the simplest networks, the data base can be a particularly extensive one. Recursive search procedures are then derived for determining closed paths through bus bar complexes of any given configuration. The searches lead to a definition of network nodes, and then to the interconnections between nodes and network branches. A branch incidence matrix in compacted list form gives the complete network graph. Data validation procedures are developed by which the consistency of related data items is checked, and inconsistencies where they arise are resolved, before data are used in graph generation procedures. An application of the methods is given for a section of a network which includes 24 network branches, 42 circuit breakers, and 106 isolators. The automatic network-graph procedures of the paper are validated for numerous combinations of circuit breaker and isolator open/closed positions in this small network section.     

三相变压器模型分析及其对配电潮流的影响

建立详细的三相变压器模型对配电网分析至关重要.在所建立的变压器三相模型基础上,对比分析了相间磁耦合和励磁支路对模型的影响,讨论了零序参数和励磁支路参数的计算方法,并采用4节点配电网测试系统,详细分析了相间磁耦合、励磁支路对配电网三相潮流计算的影响.算例分析表明,在变压器模型中是否考虑相间磁耦合对潮流计算结果的影响较大,而且励磁支路产生的损耗不应忽略.     

On the sensitivity analysis of digital filters

A very quick and simple algorithm for the overall evaluation of the sensitivity performance of a digital filter is introduced. To this end, it is shown that the sensitivity of the system function with respect to a given coefficient comes out equal to the output of a special digital network with unitary input. Having defined, then, an ‘overall sensitivity index’ as the sum of the various network sensitivities, it is shown that such an index can still be considered as the output of a digital network with unitary input. This network is composed of two subnetworks, identical to the original circuit, connected by a special set of branches.     

基于背离路径的输电断面搜索新算法

针对潮流转移引起的连锁过载跳闸问题,分析了过载支路切除后的潮流转移特征,指出受潮流转移影响较大的支路都集中在与切除支路电气距离较近的范围内;给出了一种快速搜索与过载支路相关输电断面的新算法,把实时的电力网络转化成拓扑图,采用基于背离路径的前K条最短路搜索算法,快速搜索出受潮流转移影响较大的输电断面,避免了采用单一路径搜索时因搜索范围过小而使部分支路漏选的情况,保证了输电断面的完整性。当发生过载时,可通过分析过载切除对输电断面内支路的影响来快速估计整个系统安全性的影响,极大地减少了分析计算的负担,有利于防止连锁过载跳闸的发生。最后对中国电力科学研究院(CEPRI)36节点系统进行仿真分析,验证了该算法的有效性。     

The Effects of Load Impedance, Line Length, and Branches in Typical Low-Voltage Channels of the BPLC Systems of Developing Countries: Transmission-Line Analyses

This paper presents the influence of line length, number of branches (distributed and concentrated), and terminal impedances on the performance of a low-voltage broadband power-line communication channel. For analyses, the systems chosen are typical low-voltage power-line networks found in Tanzania. The parameters varied were the network's load impedances, direct line length (from transmitter to receiver), branched line lengths, and number of branches. From the frequency responses of the transfer functions (ratio of the received and transmitted signal), it is seen that the position of notches and peaks in the amplitude responses are affected by the aforementioned network parameters and topology. As a result, the time-domain responses are attenuated and distorted. Time-domain responses of power-line channels under various conditions are also investigated for a given pulse input at the transmitter. The observations presented in this paper could be useful for suitable power-line communication system design.      

配电馈线地理图到电气接线图的转换

为了将配电馈线的地理接线图转换为电气接线图,建立了基于图论的配电网模型。根据空间位置和所含节点数目对分支进行分级,将一条馈线分解成由若干分支构成的集合。在电气接线图上,遵循将偶数级分支水平放置,将奇数级分支垂直放置,并注意确保各个分支的相对走向不变的原则,按照分支级数由小到大的顺序每次添加一条分支,若产生交叉或重叠则采取水平或垂直一维局部拉伸平移法来消除,从而根据馈线的地理接线图逐步生成了电气接线图。结合实例详细说明了所提出方法的基本原理,结果表明该方法可行。     

基于潮流估计和分块负荷削减的配电网可靠性评估算法

基于中压配电网闭环设计、开环运行的特点,以及元件电压降落、功率损耗及树状网络潮流分布的特点,推导出了节点电压、支路传输功率与支路阻抗的关系。在节点负荷矩基础上推导出了计算和修正节点负荷矩的等值阻抗和等值功率计算公式;提出了配电网故障解析中负荷转移后的电压估计模型、送端馈线潮流估计模型和受端馈线潮流估计模型,提高了可靠性评估中元件故障状态下潮流计算的效率。以分块链表简化配电网的结构并给出分块负荷削减的模型,实现了计及潮流约束的配电网可靠性评估。IEEE 33节点系统和工程算例仿真表明,文中提出的负荷削减模型与潮流估算模型相结合可快速、准确地实现中压配电网的可靠性计算,具有较高的工程实用价值。