IEEE 421.2-2014

This guide includes criteria, definitions, and test objectives for evaluating the dynamic performance of excitation control systems as applied by electric utilities. The term excitation control system (see Figure 1) is used to distinguish the combined performance of the synchronous machine, power system, and excitation system from that of the excitation system alone (see IEEE Std 421.1(TM)). The primary purpose of this guide is to provide a basis for evaluating the closed-loop performance of excitation control systems, including synchronous machines, for both large and small signal disturbances. Confirming the adequacy of mathematical models for excitation control systems for use in analytical studies of power systems, identifying objectives for tests of excitation control systems and their components, and preparing excitation system specifications and additional standards will also be addressed (see IEEE Std 421.3(TM), IEEE Std 421.4(TM), and IEEE Std 421.5(TM),). Portions of this guide will also serve as educational material for people who are becoming familiar with excitation control systems. This guide is applicable to excitation systems used on all sizes and types of synchronous machines including those in nuclear power facilities. Traditionally, large signal performance (see 4.2) has been more closely associated with equipment specification and acceptance testing, while small signal performance (see 4.3) has been more closely associated with stability and model studies. Matching actual disturbance data with model simulations, however, requires that both large and small signal performance criteria be considered during design, specification, and acceptance testing.