Procedures for measuring the local frequency and voltage phasor magnitude of distorted voltages for power system relaying

In this paper, fast and accurate procedures for measuring the local frequency and voltage phasor magnitude of a distorted bus voltage signal are proposed. The procedures process the instantaneous values of the bus voltage signal and its derivatives for signals corrupted by noise and harmonics. A limited number of samples is required to calculate the voltage phasor magnitude and local frequency (a maximum of seven samples). The effects of critical parameters such as data window size and sampling frequency are studied using synthetic data.