Computer simuloation results

[HamidEle]

I have used ETAP a lot these years almost exclusively. I have come across the situations when the results do not exactly match what came up from other software which were done by others. The mismatches can be around 10%. The input parameters and calculation fundamentals were the same based on the vendor information. Wonder how to convince the clients these are the correct results. Thanks for your inputs.

 

[davidbeach]

Hand calcs would be the best method. Pick a small system that produces different results in different software and then perform a set of validation calculations by hand to show which, if any, of the software packages produce the correct results.

 

[HamidEle]

This is a big system. Hand cal is very time consuming. For instance, dynamic motor staring for hand cal. might be as accurate at computer simulation.

 

[Parchie]

Hamid,
I guess what @davidbeach is trying to say is for you to do a validation calculation by picking a "small system", not necessarily your problem system. Say if you have a 100-bus system, how about a 4-bus system? If the errors are due to rounding of figures, you will see a direct relation looking at the error magnitudes. Just my two cents.

 

[Desrod2]

Current PSA Software have tons of parameters that could explain a 10% difference even if you enter the same installation model. It could something as simple as line/cable default models, transient impedance values for machnes etc.
You might want to ask the ETAP people. I am with another software team and we know our software and are aware of our models and the differences.

 

[ZeroSeq]

I have seen error approaching those levels between SKM and ETAP for the exact same systems doing the exact same calculations. I have done hand calculations that match one software package and not the other for multiple different analyses. In some cases the reason for the discrepancies lie in the fact that the engineers producing the software make some very elementary assumptions that I would not make myself. As always, take results produced by any software package with a grain of salt.

 

[krisys]

Of late I see lot of people are complaining about the accuracy of their software.

I would personally compare it with the modern fast foods. It is simple to buy and eat it. If you have to cook the same food, it would take long time and probably might not taste that good.

ETAP has a very good presentation, simple to understand as it was explained very superficially. If you ask for any deeper question, they will not respond.

I hope slowly other technically sound software supplier would make their presentation better so that people would look at other softwares.

 

[Desrod2]

Like your comment krisys,
We are more on the "slow food" side and our Engineering and Support teams take pride in the quality of our products. Likely the reason why half the large IOU in North America selected us.

HamidEle, when using any tool, it is your responsibility to make sure that the decisions you make are safe for both people and equipment. People used to design systems using slide rules and good practices. Modern tools allow you to optimize your installations by allowing a better risk management of your design.