Smart grid is an electricity network to monitor and control all its physical environments of electricity infrastructure in a fully automated way. As the importance of reliable energy utility infrastructure is growing, various security countermeasures to protect power system from security threats have been suggested, whereas there were less consideration on security by design, from the bottom system modeling level. Thus, this paper first highlights the international security standard on network and system management (NSM) requirements suggested from International Electronical Committee (IEC). Then this paper proposes significance of security by design, especially the security object modeling as the most important factor in smart grid environment. In our approach, we propose a common NSM objects for IEC-61850 protocol based substation automation environment. Finally, we present the setup procedures to implement and test NSM objects for IEC 61850-based digital substation in Korean environment.