The micro-grid system is composed of a 2.5MW permanent-magnet direct drive turbine, 500KW of photovoltaic installations, three 200KW power storage units and two 65KW natural-gas engines. The wind turbine is planted on a river bank about 1.7 kilometers from Goldwind's Beijing office in Yizhuang in the southeastern suburbs of Beijing. The micro-grid project became operational in April 2012.
The power storage unit is composed of a 200KW Vanadium redox flow cell, a 200 lithuim cell and a 200KW super capacitor. The first two storage units can last four hours each and the last for 40 seconds.
The two gas engines, introduced earlier this year, help smooth the operation of the micro-grid system and the outer grid. But the two conventional generators will play a key role in an independent micro-grid system, such as one set up in a remote area. The system is being viewed as a plausible one-stop power solution for isolated islands and landlocked border check points, giving the closed, self-sufficient micro-grid system strategic importance. And the gas machines are relied upon for generating the electricity when wind and solar units are not delivering.
As a result of grid issues in the country, it is a solution that is government has been advocating. This was highlighted with Goldwind's deal with the local power grid. Electricity generated by the micro-system supplies the Goldwind office buildings and workshops, which has a designed loading capacity of 200-2,200KW. According to an initial calculation, the system provides 32% of Goldwind Beijing's power use. The rest of the electricity is sold to the local grid for around CNY 400,000 ($64,000) a year.
Goldwind has expressed intention to continue investing in the project. "There is room for further optimisation," said Gu Yanhui, a manager in charge of Goldwind's micro-grid division. It is not known when this system will be ready for commercialised development. The system may have different component units, depending on the actual environment and social conditions of the potential sites. Even the wind turbine may be replaced by other models, Gu said.
The demonstration project currently runs at a deficit, but future commercial projects may prove cost competitive as equipment cost goes down, power prices go up, and the system is streamlined to adapt to varied site conditions, said Gu.
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