How does Reactive Power Control works ?

Reactive power control works exactly same was as active power control works and is explained here

Instead of only active power, reactive power of the control group meter is also monitored regularly and whenever the reactive power consumption goes above the set limit inverters are given command to generate the excess reactive power by setting up either PF or kVAr directly (dependent on what inverter allows) and hence in the process reactive power consumption from Grid or DG is minimized

Example:

Time	Equipments	Active-kW	PF	Reactive-kVAr	Comment
21st Feb 14:30	Sungrow 50kW Inv-1	5.191	0.198	25.698	Sungrow Inv has set at maximum possible reactive power for the model.
	Sungrow 50kW Inv-3	5.114	0.2	25.053
	DG id-11, Active Power Set-Point 35 kW Reactive Power Set-Point 0.9 kVAr	39.752	0.396	92.096
	Load			142.847

In above example when DG output power crossed its set point 35 , controller starts sending generation command to the inverter and if reactive power is more than setpoint 0.9 kVar, inverters are also sent command to generate reactive power.

In above example as the consumption of reactive power is high , controller has set the PF of the inverter low to product maximum reactive power from the inverter and hence attempting to minimise reactive consumption from DG.

Reactive power calculator

Known Limitations

It works exactly the same way as active power control works but there are limitations depending upon the inverter brands you are using. For example

Sungrow Inverter does not allow more than about 50% of reactive generation.
Most of the inverters does not allow night time reactive power control.