Measurement of power system phase differences by means of GPS timing

This paper describes the hardware and software to perform phasor measurements at busses of the power network. The advent of the Global Positioning System (GPS) absolute timing reference allows voltage phase angles to be measured, and referred to a common location in order to compute angle differences. The equipment to be described has accuracy dependent upon the microprocessor and represents a simple, low cost, method to synchronize phase measurements at remote points in a power grid. The software is code within simple stand-alone devices or can have an equivalent in Remote Terminal Units (RTU's). Power systems are dense with existing RTU's and with the method of this paper more PMU measurements can be available for State Estimation or coordinating machine swing transients.