During grid congestion, the transmission system operator (TSO) has to direct the providers to adjust their dispatch levels to accommodate the constraint.
Congestion can be permanent, an effect of the system configuration, or temporary, due to a fault in the transmission equipment.
The goal is to ensure that a power flow as defined by the wholesale market result does not violate the constraints during the normal operation of the grid and in the case of failure of any one particular component (so called n-1 criterion).
[citation needed] However, the market result might violate the congestion constraints and thus cannot be implemented at the time of delivery (in "real-time").
If this is the case, the TSO intervenes and uses so called system redispatch by changing the schedules of the generators in a way that the load can be served.
[6] Redispatch payments are usually negotiated in advance and providers are paid as they bid in a "command and control" fashion, without creating a market.
The owner of a transmission right is entitled to transport a predefined amount of electric power from a source location on the network to the destination.