Re: Change 1 PQ to PV -> infeasible problem

Chris, Iterative methods in general (whether they are N-R, FD, G-S, etc.) are prone to failure; you can sometimes mitigate this problem, but you can never eliminate it 100%. It sounds like you may have hit one of those cases where NR iteration fails and it's hard to find "the right seed". Our

Re: Change 1 PQ to PV -> infeasible problem

Dear Jose and Ray, thanks for your replies, I've tested another few things: I deactivated the other two PV-buses, so there is only one reference bus, many PQ-buses and the problematic PQ/PV-bus. With the PQ (result is ok): - Slack inserts: -60 Mvar - Problematic bus: 0.118 Mvar, V=1.0335 pu

Re: Change 1 PQ to PV -> infeasible problem

Sorry for the confusion, Ray: where I said, *"...solvable with the bus running as PV, but unfeasible when the bus is running as PQ"*, I meant to say: "*a valid powerflow solution* with the bus running as PV, but an *unstable* one when the bus is running as PQ" (it is one of the multiple

Re: Change 1 PQ to PV -> infeasible problem

Interesting, I didn't know that enforcing Q-limits also affects generators when their bus-type is set to PQ. Ray, I suggest documenting this behavior in the manual, probably at the end of the last paragraph in Section 4.1. Something to the effect of *"... Note also that this option affects

Re: Change 1 PQ to PV -> infeasible problem

Sorry, one mistake in my example: the BUS_TYPE in the second case should obviously be 2 (PV), not 1. -- Jose L. Marin Grupo AIA On Thu, Apr 28, 2016 at 11:48 PM, Jose Luis Marin wrote: > > Looking at those records I think I may have misunderstood what you're > doing.

Re: Change 1 PQ to PV -> infeasible problem

Hi, @ Jose L. Marin: I used a generator in both cases, hence it should be the correct sign (should result in the same I guess). Anyway P was very small, around 1e-6 MW. I'm not sure if I've modelled something wrong: S_base is 100, my generator is at bus 1 (at the end zeros(1,12)): bus

Re: Change 1 PQ to PV -> infeasible problem

Those are certainly some crazy Mvar injections! Just checking: are you sure you reversed the signs of P properly when switching the type of that bus from PQ (load) to PV (gen with neg real power), also taking care of making the corresponding changes in the bus row and adding a new gen row? If

Re: Change 1 PQ to PV -> infeasible problem

Ray's suggestion is an excellent idea. I'd like to add the following. Suppose you start with "caseA", which solves ok. Now you make only one change to obtain "caseB": you switch one particular PQ bus to PV type, by carefully specifying its Vg as the voltage value you obtained in the solution of

Re: Change 1 PQ to PV -> infeasible problem

It sounds like the voltage at that bus may be very sensitive to the reactive power injection. One thing you might try to get some idea of this is to change that bus back to PQ with the reactive at the lower limit, then try running a few cases with slightly perturbed values of the reactive power

Change 1 PQ to PV -> infeasible problem

Hi, I'm using Matpower (v5.0b1, but the same holds for v5.1) for a 220 kV/110 kV/20 kV-grid quite a while. The grid has 1 reference bus (220 kV), 2 PV-buses (220 kV) and >100 PQ-buses (110 kV & 20 kV). So far calculating the grid using runpf with Newton has never been a problem. Now I've tried