I am in dire need of some help on this topic. I am trying to simulate the function of three-phase relays in simulink and after implementing the relay logic to control breakers on either side of a transformer. I also need to somehow simulate a three phase fault.
I am currently using the three-phase fault block connected as shown in the attached picture and the current during the fault is extremely low for my (or any correctly configurated) relay to work. I have also tried using a breaker and a small resistance to ground but I am getting the same results (the fault block masks the exact same thing so it is to be expected). I am also attaching a scope displaying the three-phase current (RMS values) of the load. Essentialy I am looking for this current to start rising at very high values so that my relay logic sends a signal to the breaker to open. The same relay logic on the transformer's primary winding works like a charm and the three-phase fault block properly introduces a very large current for it to work. I am convinced that it is a simulink related problem as the block is essentialy a small resistance connected to ground, so theoretically it should bypass my load based on circuit analysis. For reference, I am also including a photo of the model with the fault occuring in the primary winding and the output for the primary current (this is the desired output for the load/secondary current as well). As you can see it starts rising and then goes to zero as my relay logic opens the breaker. I will not delve into detail about the relays and breakers as it is a simple time inverse characteristic. The fault block is configured with very little resistance and a step function turning to 1 at 0,1s. Thank you in advance and I hope it was not a too long explanation.Fault at secondary winding Secondary current during fault Fault at primary winding Primary current during fault-relays work
