Operational security standards 1 System security criteria The following criteria for system security are to be applied in those respects that are of significance as regards enabling operation of the power system to be upheld with the subsystems interconnected with each other. The criteria for system security shall be based on the n-1 criterion. This is an expression of a level of system security entailing that a power system is assumed to be intact apart from the loss of individual principal components (production units, lines, transformers, bus bars, consumption etc.). For faults having the largest impact on the power system, the term dimensioning faults is used. It is not normally the same type of fault that is dimensioning during frequency disturbances as during disturbances to the transmission system. The loss of the power system’s largest production unit is normally dimensioning as regards determining the frequency controlled disturbance reserve. The definition of serious operational disturbances is operational disturbances having a greater impact than activation of the frequency controlled disturbance reserve. The definition of normal state is an operational state entailing that all consumption is being met, that the frequency, voltage and transmission lie within normal limits and that the reserve requirements have been met. The power system has been prepared in order to deal with dimensioning faults. For the interconnected Nordic power system, the above entails that: a dimensioning fault on a subsystem must not bring about serious operational disturbances in other subsystems. This places demands on the frequency controlled disturbance reserve and the transmission capacity within and between the subsystems if the power system is not in normal state following an operational disturbance, the power system must have been restored, within 15 minutes, to normal state. This places demands on the available fast active disturbance reserve. If there are exceptions from the time requirement, or if there is a departure from the above definition of dimensioning faults, then there must be consultation between the system operators concerned. 2 System protection System protection is used to limit the consequences of faults over and above the disconnection of defective components. System protection can have as its purpose to increase the system security, the transmission capacity, or a
Operational security standards 1 System security criteria The following criteria for system security are to be applied in those respects that are of significance as regards enabling operation of the power system to be upheld with the subsystems interconnected with each other. The criteria for system security shall be based on the n-1 criterion. This is an expression of a level of system security entailing that a power system is assumed to be intact apart from the loss of individual principal components (production units, lines, transformers, bus bars, consumption etc.). For faults having the largest impact on the power system, the term dimensioning faults is used. It is not normally the same type of fault that is dimensioning during frequency disturbances as during disturbances to the transmission system. The loss of the power system’s largest production unit is normally dimensioning as regards determining the frequency controlled disturbance reserve. The definition of serious operational disturbances is operational disturbances having a greater impact than activation of the frequency controlled disturbance reserve. The definition of normal state is an operational state entailing that all consumption is being met, that the frequency, voltage and transmission lie within normal limits and that the reserve requirements have been met. The power system has been prepared in order to deal with dimensioning faults. For the interconnected Nordic power system, the above entails that: a dimensioning fault on a subsystem must not bring about serious operational disturbances in other subsystems. This places demands on the frequency controlled disturbance reserve and the transmission capacity within and between the subsystems if the power system is not in normal state following an operational disturbance, the power system must have been restored, within 15 minutes, to normal state. This places demands on the available fast active disturbance reserve. If there are exceptions from the time requirement, or if there is a departure from the above definition of dimensioning faults, then there must be consultation between the system operators concerned. 2 System protection System protection is used to limit the consequences of faults over and above the disconnection of defective components. System protection can have as its purpose to increase the system security, the transmission capacity, or a
System-Operation-Agreement-appendices-English-2016-update.docx