Voltage versus VAr/power-factor regulation on synchronous generators
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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ABSTRACT: The generation capacity connected in distribution networks is increasing, largely because of the necessity of siting renewable generation where resources are available. If distributed generation is connected in inappropriate parts of a network, it can cause a significant decrease in the total potential of the network for new generation. An optimal power flow-based method has previously been proposed for assessing network generation capacities. As, for a realistic assessment, it is necessary to include as many of the relevant physical and technical constraints as possible, limits on the voltage step changes on loss of a generator are added to the model here. Results on the variation of the network capacity with the generator power factors and the allowed voltage step window are presented.IEEE Transactions on Power Systems 25(1). · 2.92 Impact Factor
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ABSTRACT: In this study, a system has been designed for right phase order and phase collapse during the parallel connection of alternators. The system measures the phase angle to determine the right phase order and evaluate the parame- ters in 16F877 microcontroller by using a program written in C programming language. Three phase system is examined by an alarm circuit used at the output of the system developed. If a phase collapse occurs, the visual and auditory data is given to the operator. The main purposes of this study are to use the operations before and after the parallel connection of alternators for engineering education and for industrial products.
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ABSTRACT: HE growing interest in distributed generations (DGs) due to environmental concern and various other reasons have resulted in significant penetration of DGs in many distribution system worldwide. DGs come with many benefits. One of the benefits is improved reliability by supplying load during power outage by operating in island mode. However, there are many challenges to overcome before islanding can become a viable solution in future. This paper point outs some of the major challenges with island operation and suggests some possible solutions.