Chapter Ten - Modeling of an isolated microgrid supplying continuous power at stable voltage using a novel pumped hydro storage system with solar energy

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The worldwide growing demand for clean energy at a fast pace needs more and more integration of renewable power systems into the power grids. But high penetration of renewable power, specifically from wind and solar energy systems, creates several types of complications in a grid, because of the volatile and interruptible nature of wind and solar energy. Therefore to avoid such complications as well as to maximize the utilization of clean energy available from renewables, the isolated microgrid provides an easy solution without its penetration into the national grid and also supports the acceleration of the clean energy transition, which is very much required by every country to achieve the target set by the “Paris Agreement 2016” to restrict the global temperature rise to 1.5°C and CO2 emission almost equal to net zero by the end of mid-century. But despite all these good features, quality power having a good voltage profile is very much needed for grid connections as well as for isolated microgrids. Such an isolated microgrid that supplies smooth and quality power continuously day and night at invariable and stable voltage is described in this chapter. The microgrid comprises unique pumped hydro storage (PHS) system, for which solar photovoltaic electricity is exclusively used as the primary energy for driving the operation of PHS, but not to supply to the load at all. Instead, the load is continuously supplied by the hydroelectricity generated using the potential energy of water stored through PHS. Thus the variable and interrupted photovoltaic electricity is exclusively used for PHS operation for storing water throughout the day, and the water stored is used to generate uninterrupted, stable, and smooth hydroelectricity day and night. The hydroelectricity, thus produced, has no impact on the usual fluctuations, interruptions, and even the absence of solar irradiation at all. Therefore such a microgrid has good potential for operating not only as an isolated microgrid but also as a grid-connected. It is a sustainable, simple, and reliable hydropower system utilizing solar photovoltaic electricity for water collection at a high elevation. It has the capability to maintain continuous power generation day and night. Moreover, for water storage, it needs not river water diversion, construction of a dam, or rehabilitation, unlike normal hydropower stations. From an economic point of view, the preferable location for its installation is on a mountain or on a hill beside a lake or a river having sufficient water for the whole year. The unique operational methodology of the system along with design aspects are precisely described in the chapter. Also, to substantiate the viability and feasibility of the novel methodology, a brief discussion on the technological aspects is also provided. The mathematical modeling of the system is carried out. The results of a case study from previous work are also demonstrated to evaluate the performance and effectiveness of the model by way of simulation carried out in MATLAB®. The values of the results indicate a perfect match with that of the design specifications.