Based on the new frame of the assessment criteria and the design thought of the three standards proposed before

theoretical exploration of the criteria composition is made. The alternative scheme for three standards is given in light of the actual situation of China’s power grid. What is important is translate the frequency qualified percentage indicators of the industrial standard into probability indicators to adapt to China’s power quality assessment mode. As for the actual point of concern with respect to frequency security

frequency security standard indicators in the form of integral type are designed. And the indicator pattern in the case of discrete sampling is given. In the standard for inadvertent power exchange

the length of time is decided by the settlement time scale. By analyzing the coincidence degree of the standard indexes

it can be found that it is necessary setting up the three standards at the same time. This work is supported by State Grid Corporation of China.