Date of Award


Document Type

Open Access Thesis


Electrical Engineering


College of Engineering and Computing

First Advisor

Charles Brice


The Electric Power Utilities serves many diverse customers from regular households to major processing plants that develop parts for gasoline vehicles. Those varying customer usages has adverse effects on the Electric Grid in many ways, that requires continuing analysis by the engineers and technical skills specialists who keep the Electric Grid stable. Several papers have been written about harmonics and Non- Sinusoidal waveforms and its effect on the Electric Grid. This thesis will exam a realworld fault event on a transmission line, its effects on the AC Transmission Protection Systems (TPS) that provides electrical energy to a nonlinear load, specifically analyze the microprocessor-based protective relay that controls, detects, and then actuate if need be during the abnormal system condition. The TPS as defined by North American Reliability Corporation (NERC) include:

1. AC current inputs (Current Transformers, cables, aux CTs, etc)
2. AC voltage inputs (Voltage Transformers, cables, aux VTs, etc)
3. Control voltage (Batteries, chargers, cables, etc)
4. Protective relays (numerical, sold state, and electromechanical)
5. Auxiliary relays (numerical, solid state, and electromechanical)
6. Communication equipment associated with protection schemes

The TPS system examined are at 100kV nominal voltage, including the Non-sinusoidal load. An analytical approach was taken for the thesis. The system was modeled using a commercial available software (PSCAD®). A Common Format for Transient Data Exchange (COMTRADE) file was generated from the model. The COMTRADE file was then “replayed” in a microprocessor-based protective relay and compared to the real-world event. This was done to confirm the system model and make any adjustments when necessary. This also allowed verification of relay protection scheme logic, setpoints, etc. A simple logic solution was also presented.