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Enhancement in Frequency Control of Microgrids by Application of Modified Controller in Virtual Synchronous Generator

Pourmohammad, Mehdi | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52107 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ranjbar, Ali Mohammad
  7. Abstract:
  8. global warming and air pollution due to the excessive consumption of fossil fuels have led to the proliferation of renewable energy sources (RESs). RESs are connected to the grid through power electronic converters and therefore, provide insignificant inertia and damping property for the system. As a result, the system overall inertia and damping is decreased and therefore, the system stability is jeopardized. This thesis presents a comprehensive small signal model for a virtual synchronous generator (VSG) integrated into a microgrid. In the developed state space, active and reactive power control loops of the VSG as well as resistances and reactances of the lines are considered. Based on this model, the robust D-stable region in terms of different values of inertia constant (M) and damping coefficient (D) values of the VSG is obtained. To enhance both transient performance as well as guarantee the robust D-stable operation of VSG, an optimization problem is also proposed. Moreover, a new control method is suggested to damp frequency oscillations of the microgrid.The proposed controller is a state feedback which uses the pole placement method and can be used in both of the grid-connected and isolating modes of operation. In this controller, poles can placed in the desired locations in order for the microgrid to achieve the desired transient response. In order to access all state variables, a state observer is used to avoid measurement of state variables. Accordingly, one of the features of the this proposed method is its ability to move poles without requiring additional sensors. The performance of the proposed method is evaluated in MATLAB/SIMULINK, which shows enhanced dynamic behavior of the microgrid
  9. Keywords:
  10. Microgrid ; Virtual Synchronous Generator ; Optimal Control ; Frequency Control ; State Feedback

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