A Self-Commutated System for Combining Energy Sources to Improve Electric Power Service Reliability

This paper presents a prioritized scheme for combining conventional and non-conventional sources to improve power service reliability. The proposed system interconnects different energy sources (i.e. grid, solar, wind and batteries) in a DC-based core eliminating the necessity of synchronization schemes. If the grid fails, the system acts as an uninterruptible power system proving energy from the other sources without any transfer time. A diode-based OR-gate circuitry is able to self-commutate given the I vs V curve of the solar panel allowing source combination to be transparent to the user. The diode efficiency is estimated and measured reporting close to 94%, which justifies the proposed DC core approach. The system is complemented with converters that, for the case of commercially available devices, produce a measured total efficiency up to 82%. Such performance metric is possible considering a battery system with embedded configuration mechanism that bypasses the batteries when not required. For this work, the battery pack is selected small, so that the system can be kept affordable in terms of price and maintenance. As the backup system is limited, the platform is equipped with a load shedding strategy to provide uninterruptible energy only to predefined essential loads. During normal operation, the proposed system offers economic benefits for users since reduces the power energy required from the grid.