中文摘要：

电站主接线是电力系统接线的主要部分，其结构不仅决定用户能否获得足够的电能，而且也影响到电站建设和改造的经济性．3／2接线和4／3接线在大型电站中应用广泛．选取3组比较方案，其中第1组为单元接线，其余2组为联合单元接线，每组各包括一种3／2接线和4／3接线方案，并利用电站主接线可靠性综合分析系统，对2种接线的可靠性和经济性进行了综合比较分析．计算结果包括各组方案的充裕性、安全性、经济性指标以及元件可靠性参数的敏感度分析．结果表明3／2接线和4／3接线各有优缺点，但3／2接线的适用性较强；发电机故障率对主接线可靠性的影响最为明显；并且在对主接线方案的设计和抉择过程中，可靠性的定量计算必不可少．

英文摘要：

The main electrical scheme of a station is principal part of power system electrical connection, and its structure not only determines whether customers can acquire enough electric energy, but also influence economical efficiency of construction and reconstruction of a station. 3/2 Connection and 4/3 Connection have been widely used in large scaled station. Three groups of alternative designs are chose in the article, of which the first group is single unit connection, and the other two are combined unit connection, and in each group there are one 3/2 Connection and 4/3 Connection plan. A reliability analysis system of main electrical scheme has been applied, to compare and analyze the reliability and economical efficiency of these two kinds of connection comprehensively. The result involves adequacy, security, economical efficiency indices and sensitivity analysis of component dependability parameter of each design. The result shows both 3/2 Connection and 4/3 Connection has its own relative merits, but 3/2 Connection has well applicability： Failure rate of generation has most obvious influence on reliability of the main electrical scheme. And quantified calculation of reliability is necessary in planning and choice of main electrical scheme of station.