继电保护原理与应用(第三版)3.1-3.5(13)

通过在电路图中建立正确的标识和假定的方向，可以从计算或测试数据中得出相应的相量图。对于图3.2a中的电路图，图3.2b中显示了两种类型的相量图。顶部的图被称为开放式，其中所有的相量都来自一个共同的原点。下图被称为闭合型，其中电压相量从左到右为同一串联电路求和。这两种类型都很有用，但最好使用开放类型，以避免与封闭类型混淆。这将在下一节中详细说明。
3.3 Circuit and Phasor Diagrams for a Balanced Three-Phase Power System平衡三相电力系统的电路和相量图
A typical section of a three-phase power system is shown in Figure 3.3a. Optional grounding impedances ( ZGN ) and (ZHN) are omitted with solid grounding. This topic is covered in Chapter 7. (RSG) and (RSSG) represent the ground-mat resistance in the station or substation. Ground g or G represents the potential of the true earth, remote ground plane, and so on. The system neutrals n‘ , n or N, and n‘’ are not necessarily the same unless a fourth wire is used, as in a four-wire three-phase system. Upper- or lowercase N and n are used interchangeably as convenient for the neutral designation.
三相电力系统的典型截面如图3.3a所示。实心接地省略了可选接地阻抗( ZGN ) and (ZHN)
本主题在第7章中介绍。(RSG) and (RSSG) 表示车站或变电站的接地网电阻。接地g或g代表真实地球、远地平面等的电位。系统中性点n"，n或n，和n""不一定相同，除非使用第四根导线，如在四线三相系统中。大写或小写N和N可互换使用，以方便中性名称。