N-1 Criterion

Definitions

European Definitions

ENTSO-E

(N-1)-Criterion: The rule according to which elements remaining in operation within TSO’s Responsibility Area after a Contingency from the Contingency List must be capable of accommodating the new operational situation without violating Operational Security Limits.

National Definitions

Australia

‘N-x’ notation, where N refers to the number of

elements in a part of the network and x is the number of elements that can fail at the same time without causing an interruption to power supply.

For example, a network built to a strict N-1 standard will be able to supply peak load with one element not operating, even if it is the largest element in the network.

Belgium

N-1-criterium: het net moet nog kunnen worden uitgebaat na een onvoorziene uitschakeling van een belangrijk element, een productie-eenheid of een verbinding.

Critère N-1: principe suivant lequel le réseau doit rester exploitable même lorsqu'il perd de manière imprévue un élément important, une unité de production ou une liaison.

N-1 criterion: the principle that the grid must remain in operation even during the unscheduled loss of an important component, generation unit or connection.

Netherlands

(n-1)-criterium: Bij volledig in bedrijf zijnd net moeten de door de aangeslotenen gewenste leveringen dan wel afnamen kunnen worden gerealiseerd onder handhaving van de enkelvoudige storingsreserve. Bij een enkelvoudige storing is een onderbreking van maximaal 10 minuten met een maximale belasting van 100 MW toegestaan.

New Zealand

(N-‘k’) criterion denotes that the system is planned such that with all transmission facilities in service the system is in a secure state and for any ‘k’ credible contingency event(s) the system moves to a satisfactory state. If any further contingency events were to occur loads may have to be shed to return to a satisfactory state.

The single contingencies to be considered under an N-1 criterion are:

• loss of a single transmission circuit
• loss of a single generator
• loss of an HVDC pole
• loss of a single bus section
• loss of an interconnecting transformer
• loss of a single shunt connected reactive component, e.g. capacitor bank, SVC

Philippines

N-1 Criterion specifies that the Grid shall continue to operate in the Normal State following the loss of one Generating Unit, transmission line, or transformer.

Switzerland

(n-1)-Kriterium: Bezeichnet ein Prinzip, dessen Einhaltung den sicheren Netzbetrieb auch dann gewährleistet, wenn ein beliebiges einzelnes Element des Systems ausgefallen ist.

See also

• Infrastructure
• Redundancy
• Resilience