The introduction of "smart grid" solutions imposes that cyber security and power system communication systems must be dealt with extensively. These parts together are essential for proper electricity transmission, where the information infrastructure is critical. The development of communication capabilities, moving power control systems from "islands of automation" to totally integrated computer environments, have opened up new possibilities and vulnerabilities. Since several power control systems have been procured with "openness" requirements, cyber security threats become evident. For refurbishment of a SCADA/EMS system, a separation of the operational and administrative computer systems must be obtained. The paper treats cyber security issues, and it highlights access points in a substation. Also, information security domain modeling is treated. Cyber security issues are important for "smart grid" solutions. Broadband communications open up for smart meters, and the increasing use of wind power requires a "smart grid system."
