Abstract: This article highlights the successful deployment of the Huichuan IES100 series two-way energy storage converter at the Qumalai photovoltaic power station located in Yushuzhou, Qinghai Province, at an altitude of 4,200 meters. The project is recognized as the world’s largest and highest-altitude off-grid photovoltaic power station, showcasing advanced microgrid solutions tailored for extreme environments.

I. Introduction:

In December 2013, the world's largest off-grid photovoltaic power station in Yushu Tibetan Autonomous Prefecture, Qinghai Province, was successfully commissioned. With a total investment of 236.25 million yuan, the project marks a significant milestone in renewable energy development in remote areas. At the heart of this system is the Huichuan IES100T500 bidirectional energy storage converter, which serves as the core component for energy storage and power generation.

The system operates independently without any external power supply, featuring a total energy storage capacity of 25.7 MWh. Even during prolonged periods of adverse weather, such as continuous rain, the battery can support the entire load of the power station for 24 hours. Moreover, 50% of the local residents benefit from the energy storage system for up to 72 hours, while critical loads are sustained for an entire week by the battery.

II. Introduction to the Microgrid System:

Off-grid photovoltaic systems are increasingly deployed in remote high-altitude regions, islands, communication base stations, and street lighting applications where grid connectivity is not feasible. These systems provide reliable and sustainable power solutions in isolated areas.

The off-grid photovoltaic power station utilizes a full PV energy storage model, relying solely on solar energy and battery storage for power generation. During daylight hours, the photovoltaic array generates electricity, prioritizing direct load supply and using excess energy to charge the battery pack. When sunlight is unavailable, the energy storage converter transforms the stored DC power into AC power, ensuring continuous supply to connected loads.

A large-scale off-grid photovoltaic plant typically includes key components such as an energy storage converter, energy storage batteries (with a built-in battery management system), a photovoltaic array, a photovoltaic inverter, an energy management system, and supporting power distribution infrastructure. Together, these elements form a self-sufficient and resilient microgrid capable of operating independently under various environmental conditions.

This case study demonstrates how advanced energy storage technologies, like the IES100 series from Huichuan, are enabling sustainable energy solutions in some of the most challenging locations around the globe.