Operational security limits within the Network Code on System Operation are the acceptable operating boundaries for the electricity system: thermal limits, voltage limits, short-circuit current limits, frequency and dynamic stability limits.
Article 25 of the Network Code on System Operation
Operational security limits
1. Each TSO shall specify the operational security limits for each element of its transmission system, taking into account at least the following physical characteristics:
(a) voltage limits required in accordance with Article 27;
(b) short-circuit current limits according to Article 30; and
(c) current limits in terms of thermal rating including the transitory admissible overloads.
2. When defining the operational security limits, each TSO shall take into account the capabilities of SGUs to prevent that voltage ranges and frequency limits in normal and alert states lead to their disconnection.
3. In case of changes of one of its transmission system elements, each TSO shall validate and where necessary update the operational security limits.
4. For each interconnector each TSO shall agree with the neighbouring TSO on common operational security limits in accordance with paragraph 1.
Article 32(1) of the said Code requires each Transmission System Operators (TSOs) to maintain power flows within the operational security limits defined when the system is in normal state and after the occurrence of a contingency from the contingency list.
According to the Response of 19 July 2017 of EFET, EURELECTRIC, NORDENERGI and MPP to the TSOs’ consultation on Capacity Calculation Methodologies, the capacity calculation methodology should provide explanation and transparency on how the power factor is computed and impacts critical network elements.
The starting case/general rule should be that it is set at a sufficiently high value that could only be reduced in case this would create security problem, with appropriate justification.
It should be backed by a statistical calculation and measurement of actual power factors on relevant network elements.
There should be no double counting. The power factor should also be monitored by National Competent Authorities (NCAs).
Network Code on System Operation, Article 25, 32