Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Electrical Engineering


Makram, Elham B.

Committee Member

Walker , Ian

Committee Member

Lee , Hyesuk

Committee Member

Corzine , Keith


As one of the renewable resources, wind energy is developing dramatically in last ten years. Offshore wind energy, with more stable speed and less environmental impact than onshore wind, will be the direction of large scale wind industry. Large scale wind farm penetration affects power system operation, planning and control. Studies concerning type III turbine based wind farm integration problems such as wind intermittency, harmonics, low voltage ride through capability have made great progress. However, there are few investigations concerning switching transient impacts of large scale type III turbine based offshore wind farm in transmission systems. This topic will gain more attention as type III wind generator based offshore wind farm capacity is increasing, and most of these large scale offshore wind farms are injected into transmission system. As expected to take one third of the whole wind energy by 2030, the large offshore wind energy need to be thoroughly studied before its integration particularly the switching transient impacts of offshore wind farms.

In this dissertation, steady state impact of large scale offshore wind farms on South Carolina transmission system is studied using PSSE software for the first time. At the same time, the offshore wind farm configuration is designed; SC transmission system thermal and voltage limitation are studied with different amount of wind energy injection. The best recommendation is given for the location of wind power injection buses.

Switching transient also impacts is also studied in using actual South Carolina transmission system. The equivalent wind farm model for switching transient is developed in PSCAD software and different level of wind farm penetration evaluates the transient performance of the system.

A new mathematical method is developed to determine switching transient impact of offshore wind farm into system with less calculation time. This method is based on the frequency domain impedance model. Both machine part and control part are included in this model which makes this representation unique. The new method is compared with a well-established PSCAD method for steady state and transient responses. With this method, the DFIG impact on system transients can be studied without using time-domain simulations, which gives a better understanding of the transient behaviors and parameters involved in them.

Additionally, for large scale offshore wind energy, a critical problem is how to transmit large offshore wind energy from the ocean efficiently and ecumenically. The evaluation of different offshore wind farm transmission system such as HVAC and HVDC is investigated in the last chapter.