Calculation of transmission line parameters from synchronized measurements

Accurate knowledge of transmission system parameters, such as series impeda nce, optimizes distance relay settings and impedance-based fault location. A new method is developed to measure transmission line impedances and admit tances from synchronized phasor measurements. Power system voltage and curr ent phasors were recorded during commissioning tests of a 525 kV transmissi on system containing shunt and series compensation. Steady-state phase angl es (delta) and magnitudes of line-side voltages and currents were measured relative to a satellite-based global time standard at two substations. Fair s of synchronized measurements were used to directly calculate real-time st eady-state ABCD parameters. For comparison, two-port ABCD transmission syst em parameters were derived by classical methods and from an ElectroMagnetic s Transients Program (EMTP) transmission system design model. To verify the accuracy of the measured parameters, a new method comparing f ield measured with calculated power flows was developed. Sending-end power flow was measured from accurate recordings and was compared with pourer flo w calculated using the three estimates of ABCD parameters, sending-end volt ages, and receiving-end voltages. Close agreement was found between field-m easured pourer flows and calculations using the measured ABCD parameters.