Fluctuating wind power penetration as limited by frequency standard

Fluctuating wind power is due to wind turbulence and is the part which should be filtered out leaving behind the more predictable mean wind power which can be traded in the hourly energy market. The power fluctuations cause the frequency of electric utility to deviate from the 60Hz standard. This thesis is concerned with estimating the maximum fluctuating wind power before the 1% deviation from the 60 Hz standard (required by some utilities) is exceeded. To keep the thesis manageable, the scope is narrowed to thermal power plants with governor speed control but no Automatic Governor Control (AGC). This thesis shows that each governor speed control system provides energy storage buffer to attenuate the wind power fluctuations and arrives at the estimate that the fluctuating wind power penetration is conservatively around 5% of the generation capacity of the utility grid. The methodologies used to reach this estimate are: (i) Transfer Function analysis of power plants; (ii) digital simulations using HYPERSIM. Through the research, an innovative method of predicting the frequency deviation in an electric grid with multiple power plants has been developed and validated by simulation.; The thesis also shows that fluctuating wind power penetration can be higher when there are filtering also in the wind farms. Wind turbines, with small inertias, driving constant speed squirrel cage induction generators are found to provide poor filtering. On the other hand, the fluctuating wind power penetration limit is increased to 18% in the case of wind turbines, with large inertias, driving variable-speed doubly-fed induction generators (DFIG) with decoupled P-Q control to implement optimal wind power acquisition.