Pumped hydro storage for microgrid applications

Energy storage has a significant role in establishing isolated microgrids (MGs) that contain intermittent renewable energy sources. Energy storages based on their technologies can ensure stable and reliable operation of the MGs. Therefore it is indispensable to study MGs operation using appropriate, cost-effective, and sustainable energy storages with necessary control. This chapter elaborates on the necessity of energy storage application in general and more specific to the power system application. The significant role of energy storage has been found for peak shaving, reliable and quality power delivery, spinning reserve support, black start support, deferring of assets upgradation for the power network, load following, and uninterrupted power supply. The energy storage has good potential in resolving the recent issues, such as energy spillage and intermittency effect of renewable energy sources, control and operation, reliability, power quality, and resiliency of MGs. It also describes different energy storage technologies including, their subclassification, application areas, advantage, and disadvantages. Pumped hydro storage (PHS) is a matured and cost-effective large-scale energy storage technology that is deployed worldwide. Battery storage technology has been found with a broad classification, and its application is steadily growing. Hybrid energy storage has been found to be a promising solution to achieve multiobjective functions for MGs. Background of the PHS system, example installations of PHS and their capacities, principal components, and basic operation are illustrated in this chapter. The evolution of the PHS power house settings and their operation are also described. This chapter also sheds light on the recent trend of using PHS for renewable power integration. Renewable energy sources, such as wind and solar, are intermittent with different degrees of intermittency. Wind energy is more intermittent than solar because of the wind velocity’s highly stochastic nature. Moreover, solar energy availability depends on various factors, such as daylight hours, cloud, dust, shadow, solar eclipse, etc. Such fluctuating behavior of renewable energy sources causes random changes in their generated output power. This chapter explains PHS integration with wind power generation to overcome many challenges. It also devises that the PHS application combines with the solar photovoltaic system that resolves the issues mentioned earlier. Furthermore, energy storage has become a promising solution for renewable energy integration in the island grid to curtail fossil fuel-based generation and enhance grid stability. Energy storage is also an integral part of the modern power network, called MG, to increase resiliency, improve reliability and ensure intelligent energy management in the MG domain. A PHS-based MG for a remote location is demonstrated. Moreover, this chapter also illustrates the sizing, operation, and control of a PHS for a case study MG system located in Newfoundland, Canada. Due to the excellent geographical location of the case study MG system, PHS is selected, and the sizing of this storage unit carried out using mathematical models that are based on the system physical dimension. In addition, governor-excitation control based on power-frequency droop is designed for the PHS unit. The controller performance is tested under various changing conditions in the MG, and the results are presented to show the effectiveness of the designed controller. The performance of the MG frequency and the voltage at the MG bus under changing conditions (load disturbances) indicate that the proposed PHS is capable of maintaining the stable operation of the case study MG system. Sizing outcomes and performance analysis of the designed controller have been accomplished using the MATLAB®/Simulink software package. Hybridization of energy storage is evidence for increasing system performance, extending lifetime, improving efficiency and system dynamics, and reducing output power intermittency of renewable-based generations in modern power networks, such as MG. Although academics, researchers, and industries well receive PHS application for various applications, the mix of PHS with other energy storage technologies remains to unfold. This chapter provides a merit order of using PHS with other potential energy storage technologies to develop hybrid energy storage for different applications in the MG domain.