I'll add my 2 cents. I don't know PSAT, but I can attest to the difficulty
in reproducing exactly the same powerflow solution in two different
software tools, in general. First you have to find out how many features
are implemented and enabled/disabled in each tool; but more importantly,
you have to know the internals of how certain devices are modeled.
Here's a number of things to check:
- Implemented in MATPOWER:
- VAR limits in PV. As Shruti points out, different algorithms for
bus-type switching do indeed yield different solutions (few
people realize
that, in general, limits may induce multiple possible solutions; and I'm
not talking about low-voltage solutions here)
- the modeling of transformers and phase-shifters (yes, there could
be differences even here!)
- the modeling of HV DC links
- Not implemented in MATPOWER but typically implemented in other
tools:
- "Jumpers" (i.e. fusing buses connected by branches with very low
impedance)
- Automatic transformer taps (OLTC), regulating either voltage or
MVAR flow. Discretized vs. continuous change.
- Automatic switched shunts. Discretized vs. continuous change.
- Generators, transformers, and shunts regulating remote V-setpoints
- Automatic inter-area exchange constraints
- Simulation of primary regulation ("governor" powerflow)
- ... and many others I'm probably forgetting about
For instance, we have been able to replicate MATPOWER's results with our
in-house powerflow, but we could only get the two solutions to agree to
very high precision after we realized that MATPOWER's basic model for the
transformer is slightly different to the one given in most textbooks. The
differences are not big, but they do affect the behavior of the tap changer
in the admittance matrix (I can provide the details, it has to do with the
location of the tap with respect to the Bshunt parameters). Once we
adopted the same internal models, the solution matched to full precision.
Hope it helps,
--
Jose L. Marin
Gridquant España SL
Grupo AIA
On Fri, Nov 20, 2015 at 7:37 AM, Shruti Rao <sra...@asu.edu> wrote:
> If the system parameters are the same, it could be because the tolerance
> levels that were set for the different software were different i.e. the
> default power balance mismatch tolerances are not always the same in all
> software. Also probably if the VAR limits are active for PV buses,
> different software often have slightly different algorithms for bus-type
> switching and that could affect the solution maybe? Hope this helps.
>
> Shruti
>
> On Thu, Nov 19, 2015 at 9:12 PM, Yogess H Singh <yosh....@gmail.com>
> wrote:
>
>> Dear Fellow Member,
>>
>> I ran load flow analysis on a IEEE-14 bus system using MATPOWER, PSAT and
>> PowerWorld. Voltage magnitudes as well as phases have slightly different
>> values in all three tools. However, the difference is not much but I want
>> to know what causes difference among results obtained with different
>> software tool even if all the parameters are exactly same?
>>
>>
>> Best Regards,
>>
>> *Yogesh Kumar*
>> *Graduate Research Assistant*
>> *NE 2042, EECS Department*
>> *University of Toledo, OH 43507*
>> *+1 (419)530-8295 <%2B1%20%28419%29450-2217>*
>>
>
>
>
> --
> Regards,
> Shruti Dwarkanath Rao
>
> Graduate Research Assistant, Arizona State University
> Vice Chair: IEEE PES ASU Student Chapter
> Tempe, AZ, 85281
> 650 996 0116
>
