TABLE OF CONTENTS Power quality problems of synchronous machines can be of the following types due to abnormal operation:
unbalanced load,
torques during faults such as short-circuits (e.g., balanced three-phase short-circuit, line-to-line short-circuit), out-of-phase synchronization, unbalanced line voltages, reclosing,
winding forces during abnormal operation and faults,
excessive saturation of iron cores,
excessive voltage and current harmonics,
harmonic torques,
mechanical vibrations and hunting,
static and dynamic rotor eccentricities,
bearing currents and shaft fluxes,
insulation stress due to nonlinear sources (e.g., inverters) and loads (e.g., rectifiers),
dynamic instability when connected to weak systems, and
premature aging of insulation material caused by cyclic operating modes as experienced by machines, for example, in pumped-storage and wind-power plants.
The theory of synchronous machines under load was developed during the first half of the twentieth century by Blondel [1], Doherty and Nickle [2, 3], Park [4, 5], Kilgore [6], Concordia [7], and Lyon [8] just to name a few of the hundreds of engineers and scientists who have published in this area of expertise. In these works mostly balanced steady-state, transient, and subtransient performances of synchronous machines are analyzed. Most power quality problems as listed above are neglected in these early publications because power quality was not an issue during the last century. However, the asymmetric properties of synchronous machines are well known, resulting in an infinite series of even-current harmonics in the rotor and an infinite series of odd-current harmonics in the stator. An...
