Optimal Planning of Microgrid applied in Remote Rural Area

With the increase in requirement of low-carbon economy and demand on power supply reliability from customers, more and more attention is being paid on distributed generations (DGs). As an effective means of integration of DGs to the power system, microgrid is being more of a concern. Microgrid integrates DGs, load, storage and control system into a single controllable unit, which can either operate in grid-connected mode or in isolated mode, thus provides a new way for remote rural electrification. There are still some remote rural areas in developing countries nowadays, to where the cost of delivering power from the grid is relatively high. Even if lines are constructed to deliver power from the grid, the power supply quality would be unacceptable due to long distance of power delivery. Microgrid that utilizes renewable energy resources (RES) would be a promising solution for power supply problem of these areas. The main object of this paper is to develop an optimal unit sizing methodology for remote autonomous microgrid with multiple energy sources. In order to truly reflect the value of RES, both economical and environmental objectives are considered in the optimization model in this paper. By deducting environmental benefit of RES DGs from their high initial capital cost, competitiveness of RES DGs can be greatly improved. Differing from conventional power system planning, microgrid planning should consider operation and control problem because control strategy of microgrid has a great impact on the energy contribution of different DGs. An energy dispatching strategy aiming to maximize the utilization of RES and fuel saving is proposed in the paper, and hourly simulation of one year is performed in the planning process. Case study results show that considering the environmental benefit of RES DGs will increase the proportion of wind turbine and PV with a considerable increase of environmental benefit. Although there is a slight increase in the annual total cost compared with the planning result without considering environmental benefit, the true value of RES can be better reflected. The impact of diesel fuel price and average wind speed on unit sizing of microgrid is also investigated. Results show that the increase of diesel fuel price and average wind speed leads to a decrease of proportion of diesel generator in microgrid and increase of contribution of wind and PV generation. For remote areas with a relatively high cost of diesel fuel transportation and abundant renewable energy resource, the value of microgrid utilizing renewable resources can be even raised.