Development and validation of a detailed software model for a numerical line protection relay

This thesis reports on the development and validation of a detailed software model for a numerical transmission line protection relay for use in the time domain simulation program PSCADRTM/EMTDC(TM). The transmission line protection relay selected for modelling is the NxtPhase APT LPRO(TM) model 2100 firmware version 2.6b.; A review of transmission line protection systems is provided. The functional characteristics of numerical overcurrent and distance line protection relay elements are explained as well as the generalized functional blocks within a typical numerical protection relay. Phasor based relay models and detailed software models are discussed and their applications explained. Some power system transients of interest driving the development of detailed relay software models are identified. The issues surrounding the development of detailed software models for commercial relays are also explored.; A performance objective is established to have the relay model perform with 100% accuracy for element operating decisions and within +/-1 protection processing interval (+/-2.1 ms) for element pickup and reset timing when compared to the physical relay for the same input signals. The model is developed with a detailed analysis provided for each functional block of the model. A model validation test plan is proposed to validate the response of 5 model protection elements to 25 different transmission line faults simulated in PSCAD/EMTDC. Five of these faults include varying degrees of current transformer saturation. The simulated currents and voltages applied to the model relay are recorded to a file in IEEE COMTRADE format and injected into the physical relay using a relay test set. The response of the model elements and relay elements are compared and the overall accuracy of the relay model assessed. (Abstract shortened by UMI.)...