Operations of electricity power systems have recently become more intricate due to development of microgrids, execution of open access competition, and use of network-controlled devices, etc. Computer network therefore turns into a key integral of modern power-grid operations. This paper proposes a new utility computer network security management and authentication for actions / commands requests in smart-grid operations. This management covers multiple security domains in a new security architecture designed for smart power grids. This paper presents the strategy and procedure of security checks and authentications of commands requests for operations in the host area electric power system (AEPS) and interconnected multiple neighboring AEPS. Case studies of the new security management and authentication for smart grids operations are presented.