The Actual Exactness of a Fast RMS Correction during Abrupt Voltage Change

The requirement of RMS (voltage and current) measurements under a fraction of the AC period has become increasingly attractive in power systems. Some of these power applications are responsible for voltage stabilization in distribution lines when the voltage correction should be made in a short time, no more than one or two periods of the AC signal. Previously developed RMS correction applications must be validated in real-world situations characterized by an abrupt change (discontinuity) in voltage magnitude occurring even during a single AC period. Such circumstances can substantially influence the RMS estimation and, therefore, should be considered. This article suggests a mathematically based approach, validated in the laboratory, that improves the accuracy of a voltage RMS estimation for the appropriate measurement devices. It produces better results in cases where the RMS assessment should be done in a fraction of the AC period.