Issue on running PV array/VSC concurrently with Synchronous Machine

Hello,

I am having some trouble in simulating on Simulink this two blocks together:

• PV array / Universal Bridge (VSC average model) - I don't know which is responsible for the errors....
• Synchronous Machine

I am able to run these blocks separately (by commenting one, then running the simulation and later commenting the other and running again) so I know it isn't a problem with parameters and neither a singularity in the synchronous machine, which is one of the errors message that I receive when I try to simulate them together.

Also I know that, probably, it isn't caused by the dynamics of the system because, as you can see in my model, I put a breaker on the PV array, and tried to run with it open, so that it doesn't affect the dynamics of the system/synchronous machine, and even so the simulation goes wrong.

Does anybody knows what may be happening? Did this occur with you too? How can I solve it?

Please, try to run the cases I just said and see for yourself.*

The error happens at t = 0.0566 when both PV and SM are connected and non-commented.

*First, run "init_var.m" for setting the system parameters and variables.

Answer 1

[Joel Van Sickel]

Hello Augusto,

For your inverter controller, try adding a Zero Order hold block and set it to your TS_Control. I have attatched my modifications. To help keep things clean with closed loop controllers, if you use a zero order hold on all inputs, and then put a unit delay on the output, you should steer clear of a lot of algebraic loops and potential solver issues. Your controller had the unit delay on the output which is good, but I think synchronizing at the input side helped clean things up for the solver.

Regards,

Joel

[Augusto Janssen Harger da Silva]

Thank you very much Joel, it worked.

Also, since we are talking about inverters, what is the reason and/or the block inside it that makes it impossible to run a Phasor Simulation?

Is there any way I can replace these blocks for a similar one but that supports Phasor simulation?

I am currently modelling PV farms as programmable alternate current sources, as a simplified model, so I can run the model on Phasor, but I would like to consider the effects of the Power Electronics in my model...

[Joel Van Sickel]

Hello Augusto,

phasor simulation requires that everything be locked to a constant line frequency. Because that block is completely controllable, there is no way to guarentee it is operated only at a constant line frequency. Here is a good example of how to tie in different blocks to work with phasor mode:

https://www.mathworks.com/matlabcentral/fileexchange/51137-one-year-simulation-in-one-minute

Regards,

Joel

[Augusto Janssen Harger da Silva]

Hello Joel,

Last week, I said it worked because the simulation didn't crashed at t = 0.0566 s, but I haven't really simulated more than 1 sec... Now that I had, I noticed that the same error is still happening, but now at t = 3.993 s. I tried to add a Zero Order Hold block and an Unit Delay, as you suggested before, in the speed controller of the SM and in the Excitation System, but it didn't solve my problem. Do you have any other solutions?

I am attaching the file with my modifications.