Denmark – grid protection settings for DK1 and DK2

Denmark is divided into two electrical regions:

• DK1:West Denmark, part of the Continental Europe synchronous area.
• DK2: East Denmark, part of the Nordic synchronous area.

System types and applicability:

• Type A systems: Installations up to 125 kW.
• Type B systems: Installations from 125 kW to 3 MW

Type A systems - protection settings

For Type A systems, install a grid monitoring relay, for example ABB CM-UFD.M31 or CM-UFD.M31M, and configure it with the protection settings shown below:

Protection settings for Denmark Type A (DK1 and DK2)

Relay protection setting	Time	Level
Overvoltage - step 1	60 s	1.1 x Un
Overvoltage - step 2	0.2 s	1.15 x Un
Undervoltage - step 1	50 s	0.85 x Un
Undervoltage - step 2	0.2 s	0.8 x Un
Overfrequency	0.2 s	51.5 Hz
Underfrequency	0.2 s	47.5 Hz
ROCOF Short for "Rate of Change of Frequency". In grid monitoring relays, it refers to how quickly the electrical frequency is changing over time. It's used to detect unstable grid conditions - especially during events like load shedding or generator disconnection - and can trigger protective actions if the frequency changes too rapidly.	0.08 ms	+/-2.5 Hz/s

Automatic reconnection settings for type A

DK1: Configure the relay to allow automatic reconnection only when the mains frequency has remained within the range of 49.8 Hz to 50.2 Hz for at least 180 seconds.

In addition, automatic reconnection based on voltage is only permitted when the grid voltage has remained within the range of 0.85 × Un to 1.1 × Un for a continuous period of 180 seconds.

DK2: Configure the relay to allow automatic reconnection only when the mains frequency has remained within the range of 49.5 Hz to 50.5 Hz for at least 180 seconds.

Likewise, automatic reconnection based on voltage is only permitted when the grid voltage remains within 0.85 × Un to 1.1 × Un for a minimum of 180 seconds.

Type B systems - protection settings

For Type B systems, configure the grid monitoring relay according to the following settings:

Protection Parameters for Denmark Type B (DK1 and DK2)

Relay protection setting	Time	Level
Overvoltage - step 1	60 s	1.1 x Un
Overvoltage - step 2	0.2 s	1.15 x Un
Undervoltage - step 1	60 s	0.85 (≤ 1 kV) 0.9 (> 1 kV)
Overfrequency	0.2 s	51.5 Hz
Underfrequency	0.2 s	47.5 Hz
ROCOF	0.08 s	2.5 Hz/s

Automatic reconnection settings for type B

DK1: Set the relay to allow automatic reconnection only when the mains frequency remains within the range of 49.8 Hz to 50.2 Hz continuously for at least 180 seconds.

Automatic reconnection based on voltage must be configured as follows:

• For systems with grid voltage ≤ 1 kV: Reconnection is allowed only after the voltage has been within the range of 0.85 × Un to 1.1 × Un for a continuous period of 180 seconds.
• For systems with grid voltage > 1 kV: Reconnection is allowed only after the voltage has been within the range of 0.90 × Un to 1.1 × Un for at least 180 seconds.

DK2: Apply the same reconnection logic, but adjust the frequency range to 49.5 Hz to 50.5 Hz. The voltage-based reconnection ranges and required timing remain identical to those specified above for DK1.