Frequency

Hz

Expected grid frequency even during islanded mode.

PCC dq-voltage threshold for Grid Connected transition

V

Maximum voltage threshold to close main grid break and leave islanded mode.

PCC dq-current threshold for Isalnded transition

A

Minimum current threshold to open main grid break and enter islanded mode.

Duration of below-threshold V/A for PCC switching

s

This is the duration where the condition must be met to enter or leave the islanded mode. To enter islanded mode, minimum current condition must be achieved for at least this duration. To leave islanded mode maximum voltage condition must be achieved for at least this duration.

Microgrid phase error frequency compensation

Hz/rad

When the islanded microgrid and the grid are out of phase, this will modify the diesel generator frequency so both network can be synchronize before leaving the islanded mode.

P import Grid

pu

Active power P commanded by dispatch.

Q import Grid

pu

Reactive power Q commanded by dispatch.

P ref Grid

pu

Active power P commanded by user.

Q ref Grid

pu

Reactive power Q commanded by user.

P Grid

pu

Active power P measured through the Point of Common Coupling (PCC).

Q Grid

pu

Reactive power Q measured through the Point of Common Coupling (PCC).

wt Grid

radsec

wt of Infeed grid.

Current Grid

A

Current measurement of Infeed grid.

Voltage Grid

V

Voltage measurement of Infeed grid.

Voltage Microgrid

V

Voltage measurement of microgrid.

Islanded enable

-

User island command (should be set to 1 when the microgrid needs to be set in islanded mode).

Angle Error Microgrid

-

Difference between microgrid and external grid angles.

P error Grid

pu

Error between commanded and measured active power P.

Q error Grid

pu

Error between commanded and measured reactive power Q.

PCC current zero enable

-

PCC current is low enough to open PCC.

Current comparison result

-

PCC current status

Current value

pu

PCC current

PCC voltage zero enable

-

Voltage difference across PCC low enough to close.

Voltage comparison result

-

PCC voltage status

Voltage value

pu

PCC voltage

Islanded

-

microgrid is islanded.

w Ref DG

rad

w reference for Diesel generator to compensate microgrid angle error.