presented by:
J.Chaithanya Bharathi
A.L.Harika
P.Divya Sree

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ABSTRACT
The performance of any machine can be analyzed with reference to parameters like power factor, total harmonic distortion, voltage regulation, etc. These parameters alter when a machine is subjected to different loads. Depending on the load connected to the system, the voltage and current waveforms are varied. Due to the effect of harmonics, distortion of waveforms from sinusoidal to non sinusoidal is commonly observed. The influence of these harmonics could produce various undesirable effects such as the production of oscillating torque, copper and core losses, losses due to skew-leakage fluxes and end-leakage fluxes, overvoltage and excessive currents in the system, etc; also, the additional power losses incurred by the harmonics also affect the overall temperature rise and local overheating.
This project analyzes these obtained harmonics and develops a suitable filter to minimize them, and by extension, their ill-effects. It also aims to obtain the voltage regulation of different alternators under varying loads using one of the many methods available, and use this data to compare and contrast the machine performance in different cases. The case study included seeks to correct the common misconception that a machine with high voltage regulation indicates low performance and cannot be used in practice. This analysis gives an insight into the practical regulations obtained, and shows a correlation between the voltage regulations obtained and the variation of loads applied. The proposed harmonic analysis is expected to be useful in the design of harmonic filters, power factor correction devices, et al.
Introduction
With the increasing concern of the effects of harmonic distortion and the lack of documentation of harmonic problems associated with synchronous machines. It is imperative that work to understand the effects of harmonics on synchronous machines be accelerated. The growing use of power electronic applications has increased the fraction of non-sinusoidal currents and voltages in utility networks. Nonlinear loads, such as arc furnaces and fluorescent lighting, have always existed but were overwhelmed by the linear load of motors and resistance type devices. Today, electronic versions of motors, office and industrial control equipment, and lighting are becoming more common. As the fraction of nonlinear loads has increased, so has the anxiety over the effect of these loads and whether they should be limited. Several standards organizations have or plan to issue limits for these loads. These limits are based on the effects of these loads. However, because this problem has only recently emerged, literature on the effects of this waveform distortion is still inconsistent and incomplete.
Voltage Regulation
The internal generated voltage of a synchronous generator depends on the flux in the machine, the frequency or speed of rotation, and the machine’s construction. However, this voltage is not the voltage that appears at the terminals of the generator when an armature current is flowing in the machine. The difference between E and V is caused by the armature reaction and the self inductance and resistance of the armature coils.
Case Study
DESCRIPTION OF TEST:
Motor-Generator set is employed as an integral part of Power System Simulator to supply power to various loads during the performance of the test. The speed of the dc motor, the prime mover, can be varied through the use of the field rheostat (0-18 V dc). A three phase alternator is employed as a separately exited synchronous generator.
A calibrated single channel instrument with built-in voltage and current scaling was used to record the voltage and current waveforms of the generator under test. The stored digital samples were transferred via IEEE bus to a computer for harmonic analysis and calculation of other electrical quantities.
Eight independent tests were performed to determine the voltage regulation of single three phase synchronous generator and two three phase generators, connected in parallel, under various load conditions. The generators were tested under linear and nonlinear loads with lagging and leading power factors.
Nonlinear load of a three phase diode rectifier, and a combination of RLC load are used to obtain lagging or leading power factor and produce harmonic distortion.
The following waveforms were obtained.
Voltage waveforms with lagging load: