Monitoring of off-grid renewable energy systems and a load oriented model for energy production and consumption

Abstract

Demand for renewable energy sources has increased rapidly due to global warming. Since 1990, the renewable energy consumption ratio has increased among developed countries and the OECD average reached over 10% in 2015. Even in developing countries, an off-grid renewable power system has been implemented in rural areas to provide electricity. However, the power generation characteristics of renewable energy sources are so random that power outages occur frequently. In this research, an off-grid monitoring platform was developed and applied to an off-grid renewable energy system to overcome the instability of a renewable power system in rural areas. Our monitoring platform contains a customized real-time operating system with low-cost hardware for task management. The monitoring platform was capable of bidirectionally transmitting a data set via short message service or the internet. The transmitted data set was uploaded to a cloud system so that the off-grid system could be monitored with any platform. The energy consumption of manufacturing systems and renewable energy systems were modeled, and the operating conditions were simulated. The simulation results provided 1) the design guide for an off-grid system, 2) the failure rate with various scales of off-grid systems, and 3) the calculation method of operation times. Furthermore, the modeling method could be applied to various types of electric load conditions. Finally, an off-grid test bed was installed with our developed monitoring platform and four case studies were conducted: 1) a three dimensional printer, 2) a turning machine, 3) a band saw, and 4) a vaccine carrier, to verify the stability of the off-grid energy system with manufacturing processes. Comparison with previous research was also conducted, and the proposed simulation method provided a smaller scale of off-grid systems with stable operation.