Storage to Avoid Congestion and Release Solar Power for Vietnam Power System: The Case Studies of a High Voltage Transmission Network in Ninh-Thuan Province and an Isolated Grid in An-Binh Island

The energy transition is taking place in a diverse manner around the world, and the achievement of clean energy goals could follow very different pathways. However, two recent crises of Covid-19 and Ukraine hit all markets, especially the energy market, thus influencing strongly the energy transition in most countries including Southeast Asian countries. Southeast Asian countries are now playing a prominent role in the supply chain of clean energy sources, with good examples of different renewable energy growths in a very constrained environment of resources. One of these drivers is that the proper Feed-In Tariffs (FIT) mechanism has laid the foundation for the rapid development of renewable energy sources here and as a result, these countries are now standing on their own two feet. Vietnam is a prime example of such growth in solar PV deployment in recent years.Vietnam has become one of the leading countries in solar power in the world in recent years, especially after the Vietnamese government issued the appropriate FIT prices for grid-tied solar photovoltaic (PV) applications in 2019-2020. This has led to an explosion in the installed capacity of solar PV applications during the period of the issuance of these mechanisms in Vietnam. However, these FIT mechanisms seem to be still too simple, leading to the uneven development of these applications across the country. In some places such as Ninh Thuan and Binh Thuan provinces, transmission lines have experienced congestion due to a large number of solar power plants installed here, especially in Ninh Thuan province. In addition, the massive deployment of solar power into the distribution grids has also taken place in many places in Vietnam without being strictly controlled by competent parties.Faced with instability due to the loss of control of solar power in both transmission and distribution networks, the Government of Vietnam has had to find a series of solutions, and one of them is energy storage. Large-scale pumped hydro storage technologies have been considered for high-voltage transmission networks, while small-scale electrochemical storage technologies have been selected for distribution networks. However, the operational risks in static and dynamic security when simultaneously integrating both renewable power and storage systems in the same network need to be thoroughly investigated, especially in large networks. In addition, the use of this hybrid duo in isolated distribution networks in Vietnam is still facing many challenges because it is still very new here and the issues of reliability and vulnerability of these networks are not given the expected attention. For these reasons, this study was conducted to examine the impacts of solar power on transmission and distribution networks in Vietnam and to investigate the potential for integrating energy storage systems into these networks to ensure safety and security during their operation. The findings from this study suggest that choosing the right structure of the power mix could contribute to improving the operational security of isolated distribution networks, while the integration of a large-scale PHS system into the high-voltage transmission network in Ninh Thuan could contribute to solving congestion and supporting grid services in the face of the high penetration of solar power here. Moreover, several solutions to enhance the reliability of these grids are also proposed. The NEPLAN environment was chosen to simulate all scenarios under the Vietnamese grid code.