Practically, Is DG considered as active source of energy or PQ or PV?

It seems the question is referring to load flow analysis, with load busses PQ, Generator busses PV, and slack bus? Is it the question how to model Distributed Generation?
PQ buses - the real power |P| and reactive power |Q| are specified.
PV buses - the real power |P| and the voltage magnitude |V| are specified.

I am try to understand where you are heading to. Please correct me when I am wrong on this following path:
Smaller 'DG' generators like residential PhotoVoltaic (also with acronym PV, but this is confusing in this specific context) feed real power, but do not regulate voltage magnitude, nor are they actively consuming Q (Vars) or involved in frequency stabilisation (auxiliary services) to provide Vars [they could add Vars through their inverter structure, but this is another policy matter not to discuss further now] - Therefore, they should be modeled as a PQ load-bus? In fact it is then a negative load (generation), and Q is actually zero.

I am not the full expert in this topic, yet trying to shed some light on it that others can chime in.
Larger wind and solar farms certainly have to add their share at voltage regulation (and/or auxiliary services). It would be interesing to know when such requirements kick in in terms of respective generation size (might be quite some regional differences here).

Yes, u have understand the question correctly...!!
In my papers, i have modelled DG as PQ load (-P) as well as PV source..

But what is going on in reality, i wanna know.. How the consultants are taking this problem? When they (consultants/planning engrs) modelled DG as PQ or when DG as PV mode?

Eugene will u please explain, what size (MW) of DG is smaller and what size is larger, u talking about (any region standard/example if u know)?

You will have to configure your DG according to what you want to achieve in the real installation.
If fuel cost is high, you may want your DG to just work as a spinning reserve, possibly doing some power factor correction at the same time. If your fuel cost is low, you may want it to supply most of your power demand, etc. The conditions may even change throughout the day, as there could be a time-dependent tariff from the network supplier, and the list goes on.

It is very well to be able to model it all on a computer, but there you will only get answers to the questions you ask, so you need to be able to ask the right questions first, and afterwards you have to bee able to understand why the computer model does not give you the answers you need.