Powerfailures 2008

On Thursday 6 November 2008 an incident involving a terminal box took place at the 380-kV high-voltage substation at Maasvlakte. At approx. 2.30 p.m., a fuse in a terminal box (a connector between a high-voltage line and the substation) blew for reasons as yet unknown. The incident did not result in any injuries, nor did it affect the security of supply in the region.

 

Following the incident, the automatic safety system briefly interrupted the flow of electricity on the line to the E.ON power station. After an initial on-site inspection, all the other connections were able to resume operation at 3.15 p.m. The breakdown of the terminal box resulted in the release of a quantity of oil and gas used in its operation. Immediately after the incident, TenneT began cleaning up the oil in collaboration with a cleaning company.

 

TenneT will analyse the causes of this incident in further detail in the coming period and will conduct an extensive technical investigation. Based on the results of this investigation, we will take follow-up action and repair the terminal box if necessary. The loss of the electricity line that is currently out of operation can be compensated by other connections at the substation. During the investigation, we will also take a close look at the other terminal boxes at Maasvlakte substation.

 

On Thursday 19 June 2008 a power failure occurred in the 150-kV grid of Zeeland province while maintenance work was being performed. As a result, a temporary loss of power occurred at two substations.

 

One circuit failed on the 150-kV connection between the towns of Goes and Woensdrecht (this connection links the electricity grids of Zeeland and Brabant province). The second circuit of the connection was out of operation at the time because maintenance work was being performed on a 150/10 kV transformer. As a result, the electricity link between Zeeland and Brabant province was out of service for a short period of time. A load of 5 to 10 MW and approx. 20 to 30 MW of electricity production was lost. To resolve the interruption in the supply of electricity, operation of the failed circuit was restored, whereupon the substations were switched on one by one. The failure lasted from 2.16 p.m. to 2.26 p.m. inclusive. This publication describes the cause and development of the power failure and indicates the follow-up action that will be taken to prevent recurrence.

 

At the time of the failure, maintenance work was being performed on a 150/10 kV transformer in the 150-kV substation at Rilland. This transformer and the 150-kV connection (black) between Goes and Woensdrecht had been taken out of operation earlier that afternoon. At 2.16 p.m. a switching error during preparations resulted in a short circuit.

 

As a result of the short circuit, the Goes-Woensdrecht 150-kV connection (white) was switched off automatically. In addition, the operational 150/50 kV transformer at Kruiningen 150-kV substation was switched off on both sides by the safety system. This resulted in a complete loss of power at the 150-kV substations at Rilland and Willem-Annapolder; the voltage level at Kruiningen 50-kV substation fell to approx. 47.9 kV.

 

The maintenance activities in question are performed once every two years. Several improvements have been agreed within the organisation to minimise the risk of incorrect switching operations in future.