Utilizing reactive capability of doubly fed induction generators to enhance system voltage performance and withstand wind variability

Vijayan, Pradip
Major Professor
Venkataramana Ajjarapu
Committee Member
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Electrical and Computer Engineering

The fluctuating global fuel prices, concerns with the depleting fossil fuel reserves and concerns relating to climate change has resulted in an increasing focus on renewable sources to satisfy rising global energy requirements. Wind power is in the fore front of renewable power generation technologies. Within the realm of wind generators, the Doubly Fed Induction Generator (DFIG) is the preferred choice of installation worldwide.

Large scale penetration of wind energy in the system raises significant concerns regarding the reliability implications of the inherent variability of wind. The work presented in this thesis provides a methodology to utilize the capability curve of the DFIG machine to enhance the voltage performance of the system and make the system more resilient to wind variations.

The utilization of wind parks as reactive sources during low wind periods can help maintain balanced system voltages. Any wind park that has direct access to load centers or is on a transmission path carrying large amounts of power will provide a substantial system performance improvement. The offshore wind farms that are very close to the coastal load pockets can act as a reactive source and help increase the capability of the load pocket to import power from remote inland generation.

A novel voltage security assessment technique is also developed which incorporates variable sources of power. With large scale integration of renewable energy, which is variable in nature, the traditional techniques of power system security assessment are not sufficient. This work details a new methodology to determine a Voltage Secure Region of Operation (VSROP), which given the forecasted uncertainty in wind power output, provides a secure region of operation with respect to the system load and the power reserves available.