Calibrated Phasor Measurement Unit as a Metrological Tool for Real Time Monitoring of Indian Smart Grid
Around the world, the smart grid concept has gained momentum to tackle the current scenario as it helps control, monitor and analyse the power requirements, which in turn increases overall efficiency and stability. Today's smart grid relies on phasor measurement units (PMUs) to deliver real-time critical data on the voltage, current, frequency, and phase, mainly within the power grid. To ensure reliability and accuracy of the acquired data, PMUs must be calibrated from a traceable PMU calibrator system. The recently installed CSIR-NPL Phasor Measurement Unit Calibration System (PMU-CAL) as shown in Fig.1 can provide perfect solutions for PMU users, manufacturers, electrical power utilities, and organizations associated with electrical power transmission.
Fig.1: CSIR-NPLI Phasor Measurement Unit
Calibration System (PMU-CAL)
Fig.2: (a) Total Vector Error and (b) Magnitude Error of M class Test
The PMU-Cal system can produce multiple complex signals, including harmonics and inter-harmonics. Using this system, one can generate precise voltage and current stimulus up to six digits with accuracy better than 50 ppm. This feature gives us the flexibility to calibrate PMUs by different manufacturers. Fig.2 shows the total vector error (TVE) and magnitude error of measurement class signal magnitude tests run at 50 frame rates per second at 50Hz frequency. Calibrated PMUs will be an essential and reliable tool to provide more intelligent monitoring, control and protection for the smart grid. The PMU-CAL system installed at CSIR-NPL is traceable against the respective national standards. The time taken to calibrate a PMU has been reduced to a few hours, in contrast to the traditional technique that takes more than a week with skilled manpower. The CSIR-NPL PMU calibration system has an uncertainty of ±0.005% to ±0.010%. The automated PMU-CAL system fully complies with the IEC/IEEE 60255-118-1:2018 standard. Calibrated PMUs will provide intelligent monitoring, control and protection for the smart grid. This will increase efficiency, improve reliability and enhance the quality of the power grid.
Dr. Saood Ahmad