TECHNICAL AND ENERGY INDICATORS OF MEAN POWER AUTONOMOUS SYNCHRONOUS GENERATOR

Abstract

The energy performance improving of the exciter by switching on the zero diodes and capacitors leads to asignificant change in the harmonic composition of the excitation voltage. The study investigates the harmoniccomposition of the excitation voltage of synchronous generators with asymmetrical bridge exciters using the unitsof forced capacitive switching. To determine the harmonic composition of the excitation voltage, we decompose theexperimental curve into a Fourier series and expressions for calculating the harmonic components. The results ofthe spectral analysis indicate that the excitation voltage at the rated mode of the generator contains a significant thirdharmonic, which is 66 percent of the amplitude of the first harmonic. The significant value of the third harmonic isdue to the large angles of control of the exciter thyristor in the nominal mode of operation of the synchronousgenerator. Due to the significant third harmonic, the secondary winding of the rectifier transformer must beconnected to a triangle. The presence of even harmonics is caused by the voltage asymmetry with respect to theabscissa.A non-symmetrical bridge exciter with a forced capacitance switching unit for a synchronous generator hasbeen developed, which provides improved energy performance during its nominal operation. The scheme of controlof the bridge asymmetrical exciter of the synchronous generator with the node of forced capacitive switching for therated mode of operation, as well as in the mode of the field suppression at short circuits of the stator windings hasbeen described.The comparative estimation of the suppression modes of the field at a short circuit of the windings of thegenerator stator with the possible mode of inverting the exciter and using the node of forced capacitive switchinghas been carried out. Experimental studies have confirmed the calculated dependences of the modes of the magneticfield suppression. The analysis of experimental dependencies shows that the units of forced capacitive switchingprovide a higher speed of the field suppression modes, regardless of the presence and magnitude of the supply ofvoltage the exciter.