Impact of Capacitor Voltage Transformers on Phasor Measurement Units Dynamic Performance

Measurements of synchronized phasors, frequency and rate of change of frequency from different locations on a wide area are the outputs of phasor measurement units (PMUs), which enable a frequent and accurate monitoring of power systems. PMUs have been conceived for monitoring ac transmission systems; in this case, they process the measurement signal provided by transducers that may have a strong impact on the overall performance. Capacitor voltage transformer represents one of the most widely employed transducer in high-voltage applications. In this paper, its effects on the response to amplitude and phase step signals of different, well-known PMU algorithms are investigated through numerical simulations. The paper proves that standard PMU characterizations or compliance verifications are not capable to identify the overall dynamic behavior of the device when installed on the field. Therefore, considering the effect of the transducer is a mandatory step towards the definition of measurement specifications for actual applications.