[Scilab-users] calculate TRMS value in Xcos

[Sachverständigenbüro Niedermaier Holger]

I’m going to try both, the post simulation calculation and the 1st order lag.
Thanks to you Mike and have a nice weekend.
> Am 19.05.2017 um 17:25 schrieb Michael J McCann <mjmccann at ieee.org>:
> 
> RMS Value:  
> In a dynamic system simulation you can readily generate an instantaneous power value that can be recorded  simply by using a volts*current product or any other dimensionally equivalent product.
> If however you want to do some averaging of the power level then you must have a record of that instantaneous  value and do the averaging over the length of the record,  which your request implies you have and therefore implies a post processing operation. You can partition the record into whatever shorter lengths you want and generate true RMS values over those time segments. But beware, if the model is  simulating a fixed frequency  (e.g.50Hz) power system then the periods must be integer multiples of the cycle time.
> 
> If you want a value that appears like a metered  value might appear then you can put the product term through a 1st order lag  (exponentially weighted effect)
>   G(s)=1/(1+sT)       // xdot=(1/T)*(Input- x); 
> and imitate the behaviour of a meter. All you have to do is chose the "time constant",T, of the meter. e.g several cycles.
> 
> The MATLAB (2017a)  Moving RMS includes the exponential weighting option and the true moving window version as well. I expect it could be replicated in XCOS with a SciLab function.
> 
> Mike.
> ==================
> 
> On 19/05/2017 05:51, Sachverständigenbüro Niedermaier Holger wrote:
>> Dear all, 
>> by simulating an electrical power circuit I’d like to plot the voltage and the current over time, which is easy to perform by using the scope block. 
>> In addition to the signal recorded I’d like to calculate the TRMS value of the plotted current and voltage signal. 
>> Unfortunately Xcos does not include a TRMS block like e.g. Simulink do. 
>> Because I’m so far not so familiar with Xcos and Scilab I’d like to ask the community for support. 
>> Does anybody have a good idea or advise how to get the TRMS value of the recorded signal?
>> Thanks and nice weekend
>> Holger
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> 
> -- 
> Dr.M.J.McCann,MJMcCann-Consulting
> 
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