继电保护原理与应用(第三版)3.1-3.5

3.1 Introduction介绍
Phasors and polarity are two important and useful tools in power system protection. They aid in understanding and analyzing of the connections, operation, and testing of relays and relay systems. In addition, these concepts are essential in understanding power system performance during both normal and abnormal operation. Thus, a sound theoretical and practical knowledge of phasors and polarity is a fundamental and valuable resource.
相量和极性是电力系统保护的两个重要工具。它们有助于理解和分析继电器和继电器系统的连接、操作和测试。此外，这些概念对于理解电力系统在正常和非正常运行期间的性能至关重要。因此，良好的相量和极性的理论和实践知识是一个基础和宝贵的资源。
3.2 Phasors相量
The IEEE Dictionary (IEEE 100) defines a phasor as ‘‘a complex number.’’ Unless otherwise specified, it is used only within the context of steady-state alternating linear systems. It continues: ‘‘the absolute value (modulus) of the complex number corresponds to either the peak amplitude or root-meansquare (rms) value of the quantity, and the phase (argument) to the phase angle at zero time. By extension, the term phasor can also be applied to impedance, and related complex quantities that are not time dependent.’’