Cuoqin County is a pure animal husbandry county with highest elevation and the harshest environment in Tibet, China, the average elevation of which is about 4700 meters. The harsh condition restrains the connection to the power grid system.

CYG SUNRI provided an integrated power generation and battery energy storage microgrid project. The parallel multiple energy resources, including Solar, wind energy, diesel-generator, hydropower, make the Cuoqin microgrid the most complex and challenging project domestically.

In the dry season, the renewable energy power station operate independently. During the daytime, when PV power is greater than the load, the redundant energy is stored in the battery. When the PV power decreases below the load power, the battery discharge and supply the load together with the PV. After the sunset, the battery supply power to the load independently. When the total photovoltaic power generation is greater than or equal to the total energy consumption of the load, the battery will reach the upper limit of the battery SOC due to the accumulation of electricity energy. If the total photovoltaic power generation is less than the total energy consumption of the load, in order to maintain the stable electricity supply, the diesel will be started to replenish electric energy. If the diesel engines are unable to meet the load or the oil runs up, it is necessary to cut down part of the load to ensure the stable operation of the power supply system.

In the wet season, the hydropower stations and new energy power plant operate together to supply the county load. The two power stations are coordinated maintain the stable operation of the whole system.

System network structure

The total installed capacity of the Cuoqin microgrid project reaches1400 kilowatts. The completion of the 10kV power grid containing three incoming lines and four load outgoing feeders, initially formed a reliable county power grid. The power grid supply scope includes four streets and 4000 surrounding villages and towns. The Cuoqin microgrid has been on operation since 2014, and it totally fulfill the electricity of the local business activities, manufacturing activities, pastoralists and etc.

The total generation amount is about 2900 kilowatts as of 2016 and the operation conditions are fully complied with the expectation.