A Study on Steady-State Characteristics of a Synchronous Generator under Unbalanced Load Conditions by a Permeance-Based

Static characteristics of 6 kVA scaled-down synchronous generotor under the extreme unbalanced-load conditions are discussed. The waveforms of field and armature currents, and the flux linkage of a search coil are measured and simulated for different single-phase loads and unbalanced three-phase loads. Simulations are carried out by using the permeance-based air-gap flux analysis method which have been developed in our previous paper.The simulated results are well agreed with experimental ones not only for fundamental components but also for higher harmonic components. It shows that our permeance-based method can be used to estimate easily a air-gap flux as well as electrical characteristics of a synchronous generator under various static load conditions. The following features are made clear quantitatively. The higher harmonic components are superposed in field currents as well as armature currents under unbalanced-load conditions. Resonance behaviors occur for not only fundamental component but also higher harmonic components under the capacitive-load conditions. The demagnetization and magnetization in a synchronous generator are estimated easily by using our permeance-based method.