The need for a new generation of var meters

This study extends previous work on the appropriate definition of reactive power in the presence of harmonic voltages and currents to the three-phase, unbalanced case. As in the single phase case, it is advocated that reactive power be defined in terms of the fundamental components (60/50 Hz) of the current and the phase angle separating them. It is demonstrated that common metering techniques for reactive power in the presence of harmonics yield inaccurate results, with errors as great as 200%. Modern digital instrumentation is able to conveniently calculate correct values so the time has arrived to start improvements in the design of a new generation of var meters through comprehensive implementation of these digital techniques.