Dynamic synchrophasor estimation in the presence of decaying DC offsets

Electrical waveform phasor measurements are receiving a steadily increasing interest due to their relevance in smart grid applications. In particular, the Taylor-Weighted Least Squares (TWLS) algorithm has been recently proposed for the estimation of the waveform phasor in dynamic conditions. Unfortunately, this algorithm provides inaccurate estimates when the analyzed waveform is affected by decaying dc offsets. To overcome this problem, a modified TWLS algorithm is proposed in this paper and its accuracy is analyzed through computer simulations when the acquired waveforms contain one or two decaying dc offsets. Several steady-state and dynamic conditions specified in the IEEE Standard C37.118.1-2011 are considered and the length of the observation intervals spans between two to four cycles at the nominal waveform frequency. Accuracy comparison with the classical TWLS algorithm is also performed.