Abstract: Under the background of carbon emission peak and carbon neutrality policy,it is an important development direction to introduce energy storage system combined with generator units to carry out frequency control auxiliary service of power grid.After the energy storage system of power plant is connected to the power grid,the new energy storage monitoring system will inevitably produce a large amount of information exchange with the original production monitoring system of power plant and the power grid dispatching system,causing network security protection problems of the electric power system supervision and control. These problems should be prevented and solved according to the network security protection rules in the design stage.Taking the energy storage auxiliary frequency control system of a thermal power plant as an example,the information interaction between the energy storage monitoring system and the distributed control system,the network control system,the automatic generation control,the phasor measurement unit and other systems of power plant were analyzed,and classified into the corresponding safety zones.The reasonable information exchange mode with the connected system was designed,and the protection measures were checked according to the protection rules.The safety protection points that should be paid attention to when designing the power plant side energy storage supervisory system were systematically summarizes.