Design and realization of smart microgrid for household in rural area

Abstract: With problems such as the reliability and quality of the power supply for rural areas, this paper proposes a new mode of power supply with a microgrid for the household. This microgrid could extensively absorb distributed energy based on the structure of the local distributed energy. As a result, it could promote the scaled using of distributed energy in rural areas. A detailed scheme for designation of the smart microgrid for the household is presented in this paper, including the structure, control approaches, and so on. Compared with an AC microgrid, a DC microgrid has some advantages below: 1) reducing the investment and improving the energy efficiency because of the sharing of the same inverter for different distributed generation (DG) units; 2) buffering and smoothing the power fluctuation of distributed generation (DG) by DC storage equipment; 3) without regard to the loop current for different distributed generation (DG) units thanks to the sharing of the same inverter, leading to easy control strategies. Taking into consideration the points mentioned above, and the capacity of the microgrid for the household, this paper selects a structure of a DC microgrid. The DC bus' voltage level is 48V, and the AC bus' voltage level is 220 V in single-phase. Some other jobs such as capacity choice, analysis of control strategy, and power balance have been down in this paper. This smart microgrid for the household has flexible operation modes. It can operate in both islanded and grid-connected mode for areas covered by a grid, or just operate in islanded mode for areas without a grid. In the grid-connected mode, the energy from DG is consumed in priority, and the surplus energy is fed back to the grid. While in islanded mode, the energy from DG supplies all loads including DC storage equipment. Besides, considering the demand for the operation and maintenance of the system, a remote SCADA system is designed for the professional staff to monitor the system. The structure of the SCADA system for the microgrid is promoted in the paper. Moreover, six main functional modules will be showed in part two. Two microgrids based on this scheme have been put into operation in turn on a farm and in a village. Due to the different structure of distributed energy and capacity of loads, this paper has designed them respectively. We have recorded a large amount of data since the application of the system. Through the analysis of the recorded data, it was shown that the microgrid could operate in a safe and stable state. In addition, the results fully demonstrated the microgrid for the household could solve the problem of power supply in rural areas and widely absorb distributed energy as well. As a result, it can provide reliable and high-quality power supply for the rural areas.