Characterization of Electric Power Quality

The term electric power quality broadly refers to maintaining a near sinusoidal power distribution bus voltage at rated magnitude and frequency. In addition, the energy supplied to a customer must be uninterrupted from the reliability point of view. It is to be noted that even though power quality (PQ) is mainly a distribution system problem, power transmission systems may also have an impact on the quality of power. This is because the modern transmission systems have a low resistance to reactance ratio, resulting in low system damping. Usually, a well-designed generating station is not a source of trouble for supplying quality power. The generated system voltages are almost perfectly sinusoidal. Moreover in many cases the utilities operate with a spinning reserve which ensures that the generating capability remains more than the load may demand. In some cases, a temporary shortfall in generation is overcome by reducing the peak of the generated voltage to reduce power consumption.