Voltage versus VAr/power-factor regulation on synchronous generators

Southern California Edison Co., Westminster, MD
IEEE Transactions on Industry Applications (Impact Factor: 1.76). 12/2002; 38(6):1682 - 1687. DOI: 10.1109/TIA.2002.805560
Source: IEEE Xplore

ABSTRACT When paralleled to the utility bus, synchronous generators can be controlled using either terminal voltage or VAr/power factor (PF) control. Selection is dependent upon the size of the generator and the stiffness of the connecting utility bus. For large generators where the kVA is significant, these machines are usually terminal voltage regulated and dictate the system's bus voltage. When smaller terminal voltage regulated generators are synchronized to a stiff utility bus, the system voltage will not change as the smaller generator shares reactive loading. However, if the system voltage changes significantly, the smaller generator, with its continuous acting terminal voltage regulator, will attempt to maintain the voltage set point. As the voltage regulator follows its characteristic curve, it may cause either over or under excitation of the smaller generator. Excessive system voltage may cause a small generator to lose synchronizing torque, while low system voltage may cause excessive heating on the generator or excessive overcurrent operation of the excitation system. Maintaining a constant reactive load on the smaller generating unit can reduce the generator field current variations and, thus, reduce the maintenance of the collector rings and brushes. This paper illustrates the effect of changing system bus voltage on small generators utilizing voltage versus VAr/PF regulation.

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    • "‫ﺑﺎ‬ ‫اﻣﺎ‬ ‫ﻳ‬ ‫اﮔ‬ ‫ﻛﻪ‬ ‫داﺷﺖ‬ ‫ﺗﻮﺟﻪ‬ ‫ﺪ‬ ‫ا‬ ‫از‬ ‫ﺮ‬ ‫ﻳ‬ ‫روش‬ ‫ﻦ‬ ‫ﺑﺮا‬ ‫ﺗﻨﻬﺎ‬ ‫ي‬ ‫ﺟﺒﺮاﻧﺴﺎز‬ ‫ي‬ ‫ﺷـﻮد‬ ‫اﺳﺘﻔﺎده‬ ‫ﻣﻘﺎ‬ ‫در‬ ‫ﻳ‬ ‫ﺟﺒﺮاﻧﺴـﺎز‬ ‫ﺑـﺎ‬ ‫ﺴـﻪ‬ ‫ي‬ ‫ﺧـﺎزﻧ‬ ‫ﻲ‬ ‫ﻧﺎﭘﺎ‬ ‫ﻳـ‬ ‫ﭘ‬ ‫و‬ ‫ﺪارﺗﺮ‬ ‫ﺮﻫﺰ‬ ‫ﻳ‬ ‫ﺑـﻮد‬ ‫ﺧﻮاﻫـﺪ‬ ‫ﺗـﺮ‬ ‫ﻨـﻪ‬ . [12] [13] [14] [15] "
    اولين همايش منطقه اي مهندسي برق, Tehran, Iran; 01/2011
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    • "However, when operated in the voltage control mode, it may cause either over or under excitation of the small generator as it will attempt to maintain the voltage at a set point with its continuously acting terminal voltage regulator [3]. Also, an excessive reactive current may result in overload or loss of generator synchronism [3]. According to [4], small generators' operation at the VAr/power factor control mode is justifiable. "
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    • "The capacity at each site is a decision variable in the problem, as opposed to a fixed parameter. As is common with DG [6], the generators are assumed to be run in constant power factor mode (i.e. with no voltage control), although alternative operational modes are possible. The only customised constraint in this model before security constraints are added is the Kirchhoff current law, where the capacity of any DG expansion site must be added to the net power injection at each bus. "
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