In order to effectively realize optimized operation in power plant

so as to fullest possibly satisfy the requirements of energy-saving and efficiency-enhancing in the power plant

it is necessary to evaluate the practical operating state stability in the power plant(for short it is called "plant state stability").For this

the inherent factors affecting fluctuation of the "plant state stability" and their relation with the control effect have been studied

and the periodic characteristics of the fluctuation being analysed by using a statistic regression method

putting forward a practical evaluation index of the stability.Taking the historical data of power signal for a 600 MW unit as example

the stability of thirty operating conditions nearing 400 MW

500 MW

and 600 MW has been evaluated respectively

verifying the effectiveness and practicability of the said evaluation index.