Wide Area Monitoring

For the first time the power system frequencies of several locations in Europe are being time-synchronised and made publicly accessible with a high degree of precision in one common system. The measuring devices equipped with GPS receivers in each of the substations calculate the frequency and deliver it in real time together with other time-stamped data accurate to the microsecond. These are then collected at Swissgrid in Laufenburg, superimposed on one another and published.

This is the result of many years of close collaboration between Swissgrid and the grid operators from Austria (APG), Denmark (Energinet.dk), Portugal (REN), Slovenia (ELES), Croatia (HEP), Italy (TERNA) and Greece (IPTO).
 

 



Key  
In operation
Scheduled
Voltage angle difference [°]
Frequency [Hz]
Not connected

THIS IS HOW THE ELECTRIC POWER SYSTEMS BREATHES

The differences in frequency that are typical of the system, in the magnitude of the third decimal place, indicate what is known as the «breathing of the European interconnected power system». Both long-term and short-term deviations from the nominal frequency of 50 Hz provide the experts at Swissgrid with indicators of the current grid status. Wide Area Monitoring is therefore an additional tool for guaranteeing the security of supply in Europe.

LOAD FLOWS – IN WHICH DIRECTION IS THE POWER FLOWING

In addition to frequency, each measuring device also provides the current voltage angle in real time. Using the difference between any two measured voltage angles it is possible to represent in approximate terms the load flows between the two measuring points. However, as it is a meshed grid and hence the entire topology is taken into account, these data provide only indicators of the power flows at any moment. A sudden change in the angle difference could, however, point to a transmission line outage, for example.

GRID TIME – THE CLOCKS TICK DIFFERENTLY IN THE ELECTRICITY POWER SYSTEM

The deviations in the grid frequency on the European interconnected power system are so small that the nominal frequency of 50 Hz is actually still used today as a timer in many cases. In spite of the extremely slight deviations, errors of a few seconds a day may still occur. This is also used as a further quality indicator of the power system state.

In order to keep this difference as small as possible and to continuously adjust the grid time to the coordinated universal time (UTC), Swissgrid records the deviations on behalf of the ENTSO-E electricity transmission association and coordinates the necessary corrections.

CONDITIONS OF USE AND DISCLAIMER

Swissgrid makes express reference to the conditions of use and in particular to the disclaimer contained in them.

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