Examination of the stability limit on the synchronous machine depending on the excitation current wave shape

Synchronous machines are basic components of systems. Their steady-state performance is a fairly important subject. In general, synchronous generators are connected to network systems through the transmission lines. Therefore, stability analysis is made including the whole system. In this study, a synchronous machine has been examined alone and V-curves have been obtained for motor current amplitude, and wave shape variations have been researched for lagging PF operation. As is known, synchronous machines have to be excited with direct current. In synchronous machines inductive, resistive or capacitive performance as motor mode operation can be obtained by varying amplitude of excitation current. In the generator mode operation, the amplitude of the voltage generated by the synchronous machine can be adjusted with excitation current. In this study, changing of the stability limit of the synchronous motor has been investigated experimentally by changing the amplitude of excitation beside wave shape variations. V-curves and stability limits obtained, studied with five different shapes of the excitation voltage, are listed as excitation with pure direct current supplied from a battery, excitation with vibratory direct current supplied from a generator, excitation current with square and sinusoidal wave rectified half waveform and excitation current with sinusoidal wave rectified full waveform.