POWER QUALITY OF ELECTRIC MACHINES AND POWER SYSTEMS

摘要

Power quality of power systems, which affects all connected electrical and electronic equipment, is a measure of deviations in voltages, currents, frequency, temperatures, winding forces and torques of particular supply systems and their components. In recent years, there has been a considerable increase in nonlinear loads; in particular distributed loads, such as computers, TV monitors and lighting, and distributed sources such as photovoltaic and wind power systems. These draw harmonic currents, which have detrimental effects including communication interference, loss of reliability, increased operating costs, equipment overheating, machine, transformer and capacitor failures, and inaccurate power metering. Power quality is important to engineers involved with power systems, electrical machines, electronic equipment, computers and manufacturing equipment. This paper helps readers to understand the causes and effects of power quality problems such as nonsinusoidal wave shapes, voltage outages, harmonic losses, origins of single-time events such as voltage dips, voltage reductions and outages, excessive winding forces and torques along with techniques to mitigate these problems. Analytical and measuring techniques are applied to power quality problems as they occur in systems based on central power stations and distributed generation relying on renewable energy sources.