Synchronized Phasor Measurement

Phasor computation is a digital technology of estimating the phasor components from the measured analog waveforms. Devices to perform such digital signal processing are called phasor measurement units (PMUs). This chapter provides a description of methods in computing the phasor quantities, in particular, at off‐nominal frequencies. The basic method used to compute the phasor representation of a sinusoidal signal is the discrete Fourier transform (DFT). Under off‐nominal frequency operation, the phasor expression requires a post‐processing step to correct for the effects caused by the leakage phenomenon, resulting from the truncation of sampled data outside the data window. The chapter then discusses a few applications of PMU data to monitor the impact of disturbances on a power system and extract power system disturbance information. PMU data is also useful for reinforcing some of the power system dynamics concepts.