Dear Sabir, 

Can you tell us how did you injected harmonics in the simulated system. Then you can inject harmonics in the practical system as you did in the simulated system. If this could not be made what is the benefit of the simulation?

You inject the harmonics into networks and not in the voltage of network but you super pose the harmonic voltage on the network voltage. So, one has to generate three phase voltage with the required amplitude and frequency which is  synchronized with the network. For example if the network voltage is V coswt, Vcos(wt + 120), V cos ( wt -120),

Then the generated harmonics should be Vn cos nwt, Vh cos( nwt+120 n), Vh cos (wt - 120n)

where Vn is the amplitude of the harmonic n.

Practically you can clip the phase voltages by diode clipping circuits. Clipping the sine wave will automatically produce harmonics.

Best wishes

Dear Sabir,

It depends on what  harmonics want to inject current  o voltage. The voltage may be performed using the voltage sources the current depends on the kind of load and linear part of the circuit. Nonlinear load even in balanced circuit  causes compensation of the 3rd, 9th, 15th etc. harmonics.

Kind regards

Dear Sabir,

If you have a programmable voltage source, you can export he voltage results from your simulation to a comtrade or other format file and playback it back with your voltage source.

With this method, you can add any kind of voltage or even frequency disturbances.

Regards,

Thank you for your answers

Dear Abdelhalim Zekry,

This is my article of the simulation part

I injected the harmonics through a Three-Phase Programmable Voltage Source block of the source programmable on matlab i inject the current harmoninics but  i our lab we don't have "Programmable Voltage Source"

Dear Miroslaw Wcislik 

i want to to inject  voltage harmonics  for distorted the voltage source form  

This is my article of the simulation part 

Dear Mohamed Asmine 

i don't have  programmable voltage source, that's why I'm looking for a trick for a practical realization

This is my article of the simulation part 

Actually quite simple... just inject a calculated current harmonic as a load and you will induce the voltage distortion. depending how stiff you system is, you can calculate the required current harmonic contribution to achieve the required voltage distortion. Add a 6 pulse VFD with a fan motor or even an output resistor. The trick is to size it to achieve your desired result.

This is a real problem. The grid has an existing distortion, before the connection of new loads with harmonics. After the new connection, the distortion on the grid must not exceed defined limits. The new load that have harmonics, are represented by current injections, unless a more accurate model of their power electronics is made. The grid must include the measured harmonic voltages. My first try would be to include them as series voltages, one for each harmonic, in each phase, at the grid connection point. Extensive modeling of the grid is also needed.

if you do not have a harmonic source either two ways:

1) connect a bridge rectifier with considerable load through isolation transformer in the primary to have a visible effect. or

2) if you are using DSP or microcontroller for a model which requires no external hardware, you can generate the rthree phase voltage with harmonics through the digital to analog ports then loop it back to your analog inputs to be used within your original model.

Regards,

thank you Hany hamed