Configuring Q on Demand 24/7


With the "Q on Demand 24/7" function, the inverter remains connected to the utility grid overnight and is supplied with power via the utility grid in order that it can provide reactive power. When connected overnight, the inverter only draws an insignificant amount of active power from the utility grid to supply its internal assemblies. The inverter can provide up to 100% of its power as reactive power. The provision of reactive power during feed-in operation leads to a reduction of the feed-in power. This means that at 100% reactive power, the feed-in power is 0%.

The general setting of the grid management services (e.g. cos phi setpoint or Q(V) characteristic curve) can not be fully set independently of the "Q on Demand 24/7" function via the relevant parameters - "Q on Demand 24/7" only permits Q specifications. It is to be noted here that certain settings can have an influence on other grid-support settings and functions.

This means that if the "Q on Demand 24/7" function" is active, no other grid-supporting functions (e.g., cos phi) are possible between day and night operation of the inverter. Should an independent reactive power provision be desired between day- and night operation, the reactive power provision must be communicated to the inverter via a superordinate control unit.

Currently, the provision of reactive power can only be read off via the phase currents and phase voltages in the instantaneous values (Instantaneous values > AC Side > Phase currents / Phase voltage) or requested via Modbus.

Procedure:

  1. Start Sunny Explorer.
  2. Log in as Installer.
  3. Select Options > SMA Grid Guard ....
  4. Enter the SMA Grid Guard code.
  5. Select the relevant device in the System tree.
  6. Select the tab Settings in the device menu.
  7. Select [Edit].
  8. Select the parameter group System and device control system > Inverter > Configuration of the static voltage stability.
  9. Set the parameter Operating mode of the static voltage stability to the desired operating mode. When doing so, note that for "Q on Demand 24/7", none of the operating modes with cos Phi may be selected.
  10. Select the parameter Operating mode of the static voltage stability for Q on demand and set this to the desired operating mode also.
  11. Depending on the selection of the static voltage stability operating mode, set the parameters associated with the selected operating mode (e.g. the reactive power / voltage characteristic curve Q(V) with or without data points or the reactive power setpoint Q).
  12. Click on [Save].