Based on the actual variation of the grid frequency deviation

the control purposes on different time scales are discussed according to an analysis of the probability theory. Then

the design idea is defined and a new control performance asssessment criteria frame of China’s interconnected power grid is proposed. There are three standards in this frame: standard of frequency safety

standard of unintended power exchange and standard of frequency quality. They correspond to control performance assessment at minute

hour

month and even above

respectively. The new criteria in the new frame can not only lead the control areas to make fast adjustment

but also lay the foundation for frequency safety on minute and second time scale. On the other hand

the new criteria allow control areas to use good performance to make up for mistakes within a definite time scale

solving frequent adjustment and overadjustment in regional grid companies of China to achieve energy saving. This work is supported by State Grid Corporation of China.