Shruti and Jose,
Thank you so much, that helped a lot.
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>*
On Fri, Nov 20, 2015 at 11:37 AM, Jose Luis Marin <mari...@gridquant.com>
wrote:
>
> 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
>>
>
>
