I got an information about Japanese VPP system when I read today's newspaper.
According to the article, Japan will introduce a license system of VPP for the purpose of diffusing renewable energy.
In Current system, renewable enegy operating company sell its electric power to electric power campany. Supply and demand of electric power must be equal at anytime, electric power campany must reduce electric power supply by stopping their thermal power plant or hydraulic power plant if supply is more than demand.
If the new VPP system is put into operation, renewable energy operating company is asked to charge their electric power into battery if electric power supply is more than demand. This means we can control the supply of electric power easier than current system and we can fit the supply into the demand quickly.
