Weighted least squares synchrophasor estimation in the presence of decaying-DC offset

In this paper a new Taylor series-based weighted least squares (TWLS) algorithm for synchrophasor measurements is proposed in the case of electrical signals affected by decaying dc offset. The proposed procedure is based on an algorithm recently published in the scientific literature, called TWLS-DC(1) algorithm in the paper. The procedure, called TWLS-DC(2) algorithm, requires two iterations. In the first one the parameters of the decaying dc offset are estimated by using the TWLS-DC(1) algorithm. In the second iteration the estimated dc offset is removed from the original signal and the synchrophasor parameters are then estimated by applying the TWLS-DC(1) algorithm to the obtained waveform. The accuracies of both the TWLS-DC(1) and TWLS-DC(2) algorithms are compared each other by means of computer simulations under several steady-state and dynamic conditions specified in the IEEE Standard C37.118.1-2011 for synchrophasor measurements for power systems.