Grid Interconnection protocols for largely dispersed minigrids/microgrids for electrification of rural India

Minigrids are used widely to electrify rural communities in India and all over the world. In India alone, the Ministry of New and Renewable Energy, targets to achieve deployment of at least 10,000 renewable energy systems based mini-grid projects across the country amounting to 500 MW of installed mini-grid capacity within the next 5 years. As the number of the minigrids increase there will be a need to interconnect them one-another to build a larger system and eventually to the main grid. However, there is no well-developed protocol for connecting and disconnecting minigrids without affecting the stability and voltage quality of the grid. Minigrids are heterogeneous in nature since they can include different type of energy sources and generators technologies. Hence, their dynamic operational characteristics varies from one another, for example, a mini-grid with power electronic converter interfaced RES will behave differently compared with a minigrids with directly connected rotating generators for the same transient disturbance or change in operating condition. The integration of two or more heterogeneous minigrids is a challenging task especially if each of the two minigrids is serving appreciable number of local loads. The primary objective of this project is to develop operating guidelines that would ensure a seamless interconnection of minigrids with each other and/or to the main grid and demonstrate their effectiveness both with a numerical and an experimental validation. The project has reviewed existing interconnection protocols and evaluated them for their applicability for synchronization of multiple minigrids with each other and with the main grid pointing out the missing elements in the protocol. The project has further developed synchronization controller and validated it in simulation and with laboratory testing. Although COVID-19 has been major impediment to realize the mobility plans, we were able to realize the physical visit and testing activity by the Indian PI and his PhD student in the National Smart Grids Laboratory in Trondheim through the support of the H2020 ERIGrid 2.0 laboratory access program. In addition, three hybrid workshops have been organized where stakeholders in Norway and India were able to participate and present their related works. The project furthermore has organized a panel session in ISGT 2021 with title: Grid Interconnection of largely dispersed minigrids. There were panellists from four continents sharing experiences. In addition, the project has organized a special session in EEEIC 2022 and participated as presenter in a special session in PowerTech 2023. A master's thesis is published from NTNU with title: A Control Strategy for Seamless Interconnection of Microgrids in a Multigrid Configuration. Another master's thesis is also published at the Indian Institute of Technology Bhubaneswar with title: A Novel Control Scheme for Fault-Ride Through in Power Electronic Interfaced Energy Sources. The project results are also documented and presented in two reports, three conference papers and two journal papers under review.

In the MultiGrid project, synchronization controller has been proposed and validated with simulation and laboratory testing. Interconnection protocols has been reviewed and missing elements has been proposed. Although mobility was inhibited, multiple workshops and dissemination activities has been held. With the EU H2020 ERIGrid 2.0 project a physical laboratory access has been arranged for the Indian PI to test the MultiGrid synchronization controller proposal in the National Smart Grids Laboratory in Trondheim. The project has established strong working relationship among researchers at IIT Bhubaneswar, IIT Delhi, NIT Warangal, SINTEF Energy Research and NTNU. In addition, Industry partners from Norway and India working on the topic, such as BSES Delhi, ETAP India and Fagne As has been introduced to each other’s work. Being an in-kind project with FME CINELDI, joint publications has been made.

Mini-grids are localized power networks, usually without infrastructure to transmit electricity beyond their service area. To address the electricity access problem, the government of India is planning to deploy at least 10,000 RES based mini-grid projects across the country within the next 5 years. The integration of several mini-grids into the conventional power grid can facilitate the electricity supply to unserved population in the rural areas. However, it also increases the complexity of the power system and requires new operational and control strategies as well as clearly defined interconnection, islanding and seamless transitioning requirements. Mini-grids are heterogeneous in nature since they can include different type of energy sources and generators technologies. Hence, their dynamic operational characteristics varies from one another, for example, a mini-grid with power electronic converter interfaced RES will behave differently compared with a mini-grid with rotating generators for the same transient disturbance or change in operating condition. The integration of two heterogeneous mini-grids is a challenging task especially if each of the two mini-grids is serving appreciable number of local loads. Hence, it is critical to define protocols for connecting and disconnecting mini-grids without affecting the stability and voltage quality of the grid. In this project, synchronization strategies will be drafted for multiple mini-grids by carefully driving the relevant synchronization criteria. A reference controller will be selected in the beginning of the project from the range of controller schemes available in the literature. Furthermore, in this project, the developed interconnection protocols and controllers will be validated numerically and experimentally.