On-line monitoring of a transmission line using synchrophasor measurements

Abstract

The research assessed the possibility of using a wide area measurement system that uses synchrophasor data to calculate operational limits of an overhead line. These applications have become achievable to utility companies without the need of expensive phasor measurement units. Phasor measurements can be obtained by applying the IEEE C37-118 standard in general power system measuring equipment. This dissertation presents the use of synchrophasors in the on-line modelling of a transmission line. Using time coherent measurements, the line parameters are continuously derived, which is then also used to monitor line temperature, sag, power transfer and voltage stability. This enables the system operator to base decisions on real field data and less on estimated values as produced by state estimators. The methodology were verified by means of simulation and then validated by field data obtained across a 330 kV, 521 km line. Promising results were obtained and analysis of the results confirmed that comprehensive transmission line performance monitoring is attainable. The electrical characteristic of the line can be made visible by tracking the variation in line parameters, line temperature and also line sag can be estimated. From a stability point of view, further application was shown to be the tracking of power transfer to visualise utilisation of installed line capacity and voltage stability across the line by means of tracking the locus of the operating points on P-V curves.