Hybrid AC/DC Microgrid Planning

Shariat, Maryam | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49462 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Fotouhi Firuzabad, Mahmoud; Rajabi Ghahnavie, Abbas
  7. Abstract:
  8. Nowadays, due to the increasing importance and penetration of microgrids, solving the microgrid optimal sizing problem has become more important. The current utility grid and conventional energy sources are mainly ac, however, increasing rate of the replacement of the ac load with dc load lead to a more efficient dc system. So choosing the optimal type of microgrid as a way to increase efficiency of these systems would be a serious issue. This thesis establishes a planning model which finds the optimal size and type of a microgrid to minimize total cost. Total cost includes investment, operation and reliability cost of the microgrid. Sizes of DGs, converters and transformer linking the grid to microgrid are variables to be optimized. Planning problem is solved by a Genetic algorithm approach. Mixed integer linear programming is applied to solve the operation and reliability problem. Operation cost of the system includes the diesel generator operation and maintenance cost and the cost of the electricity purchased from the grid. The profit made by selling electricity back to the grid is deducted from the operation cost. Total investment cost contains the investment cost of the DGs, converters and the distribution system. In the end, to determine the effectiveness of the model, a numerical simulation is applied to a hypothetical microgrid and the impact of different parameters on the results are studied. The hypothetical microgrid is considered to have 13 nodes out of which 6 are linked to load. Peak load is set to 13 KW. Load can be fed by both ac and dc distribution systems but ultimately the model determines the efficient amount of the load to be fed by each. Results indicate that hybrid ac/dc type offers the lowest cost due to elimination of the loss and investment cost of the converters. According to the sensitivity analysis results, the loss and cost of the distribution system and electricity price doesn’t play a significant role in choosing the efficient type of the microgrid. Increasing the electricity price leads to install higher capacity renewable sources. Increasing dc load also leads to install higher capacity renewable sources because it is more efficient to feed the dc load with dc sources than ac sources. Considering emission cost also led to install higher capacity renewable sources
  9. Keywords:
  10. Reliability ; Operation ; Distributed Generation ; Planning ; Hybrid Alternative current-Direct current (AC-DC)Microgrid ; Microgird Planning

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