A wavelet-based approach for reactive power metering in modern three-phase grids considering time-varying power quality disturbances

Three-phase reactive power meters that are currently available in the market can accurately measure reactive power only under time-invariant operating conditions. However when considering time-varying power quality disturbances, the performance of these meters is questionable. In future grids, the emergence of active loads characterized by their dynamic operation could possibly lead to time-varying disturbances that will propagate along the distribution networks. In order to address this issue, a time-frequency approach based on wavelet transform is presented in this study to measure three-phase reactive power while taking into consideration the new time-varying operating environment in three-phase systems. A wavelet-based approach for reactive power measurement has been developed and tested under different time-varying power quality disturbances including balanced and unbalanced systems considering different wavelet basic functions of the Daubechies family. Results are analyzed, and recommendations are presented regarding the operating principles of such reactive meters under the new measuring environment.

► Three-phase reactive power is formulated using wavelet.
► Wavelet preserves both time and frequency information.
► The algorithm is tested in the presence of three-phase time-varying power quality disturbances.
► Suitable mother wavelet is determined for such analysis.
► Recommendations on operating principle of reactive power meters are presented.