Auxiliary Consumption of Inverters for production of Reactive Power and P-Q curve w.r.t Temperartures while Plant is performing at 0.95 (lead or lag) Power factor

[Thriloknath Palla]

Dear PVsyst Team,

There are quite a few queries w.r.t to the plant's operation point of view 

1. Does PVsyst consider the P-Q curve ability (w.r.t to Temperature) of the Inverters while doing the simulations of plant at Power factor defined at POI?

 To elaborate, in general the Inverters will Perform at Unity Power factor maintained at their terminal end, instead at POI, unless and until commanded by the Power plant controller (PPC) for a specific amount of reactive power generation. Now, the active power generation at the Inverter end should vary or differ between the above two cases as let's say at 50°C (Rajasthan, India) ambient temperatures, the Inverter capability is limited to its rated kW and now if the PPC demands inverter to run at 0.95, then the active power generation at the Inverter end itself should reduce according to the P-Q curve nature of the Inverters. So, the main question is when I simulate a PVsyst at Unity power factor at POI it gives the same generation results without any selection of POI power factor. How do we validate the Inverter's active power reduction due to additional reactive power compensation of Solar plant's internal component's such as Cable, Transformers etc.

1. The second major concern that I have is that Inverter's does consume a certain amount of Active power (may be constant), to state for example - Sungrow latest central Inverters consume an amount of 30-40kW per Inverter for production reactive power and this would be a considerable amount of power during non-generating hours if plant runs at a power factor of 0.95 or even unity at POI. However, I have simulated both the cases and output excel file snaps are attached below, there is no change in the Nighttime Auxiliary consumption. Can it be implemented or modified such that correct amount of Aux. consumption is reflected?

With Unity Power factor at POI.

2. With 0.95 Power factor at POI.

[André Mermoud]

Question 1:  in PVsyst, the required power factor is fixed (yearly or monthly values).  There is no dependency on the temperature. 

The inverter specification indicates wheter the Pnom is specified as Active power [kW] or apparent power [kVA]. In the inverter's definition, page "Output parameters":

During the simulation, PVsyst will apply the PNom limit according to this definition.

Question 2: In principle, the reactive power IS NOT a real power: you cannot produce movement or heat with it. Therefore the production of reactive power doesn't consume any active power.

Now you talk about Reactive power generation during non-producing hours. This is a very special feature of some solar inverters. PVsyst doesn't treat this : the rective power is always generated proportionnally to the available active power.