IEEE 421-4-2004 pdf download IEEE Guide for the Preparation of Excitation System Specifications
3.4 excitation system stabilizer: A function that serves to modify the voltage regulator forward signal bycither serics or feedback compensation to improve the dynamic performance of the excitation controlsystem.
3.5 exciter: The equipment that provides the field current for the excitation of a synchronous machine.
3.6 line drop compensator: A function that modifies the machine terminal voltage to compensate for theimpedance drop to a fixed point in the external network
3.7 power system stabilizer (PSS): A function that provides an additional input to the voltage regulator tomprove the damping of power system oscillations
NOTE–A number of different quantities may be used as input to the power system stabilizer, such as shaft speed, frequency electric power, and so on, or a combination of these signals.
3.8 reactive droop compensator: A function that causes a reduction of terminal voltage proportional toreactive current. It is generally used to obtain reactive current sharing among synchronous machinesoperating in parallel
3.9 reactive differental compensator: A function used to obtain reactive current sharing amongsynchronous machines operating in parallel without causing reduction of terminal voltage. It requiresinterconnection of yoltage regulators or current transformers of the machines.
3.10 synchronous machine regulator: Ageneral term applied to a regulator that couples the outputvariables of a synchronous machine to control the exciter output through forward and feedback elements forthe purpose of regulating the synchronous machine output variables
3.11 voltage regulation accuracy: The band or zone, expressed in percent of the rated value of theregulated voltage, within which the excitation system will hold the regulated voltage of the synchronousmachine during steady or gradually changing conditions, in the absence of the action of any compensators orlimiters. Unless otherwise specified, the range will be assumed from no-load to rated kilovoltampere andpower factor.
4.Introduction
This guide applies to excitation systemsusing rotating and static exciters. In many cases, equipmentmaintenance, associated with the older excitation systems, and obsolescence of parts may makemaintainability cumbersome and involved. Today, many older excitation systems such as rotating or pilotexciter type are being replaced with new solid state excitation systems to improve or simplify the operationand control of the synchronous machine. Newexcitation systems can enhance the performance of thesynchronous machine by eliminating deadbands and delays inherent in older type excitation systems.
4.1 Basics
is to provide the field current required by a synchronousThe primary function of an excitation systemsystem operating conditions. In addition to fulfilling thismachine to meet a specified range of powerrequirement, there are a number of other factors that should be considered when writing specifications for anexcitation system. Power system stability studies have been found to be useful in identifying dynamicperformance requirements. These performance evaluations help establish the required responsccharacteristics and may identify the need for other control functions, c.g.. a power system stabilizer. Modernexcitation systems may include various auxiliary control clements and protective devices in addition to a basic voltage regulator. The specification should functionally identify all auxiliary excitation control equipment (compensators, limiters, power system stabilizers, etc.) and protective equipment (volts/Hertz protection, overexcitation protection, etc.), which are to be included in the excitation system.
IEEE 421-4-2004 pdf download
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