Implementing an energy storage system for an electric propulsion system

I'm having trouble designing the energy storage system (ESS) for my dieselelectric propulsion system.

This is an overview of my dieselelectric system.

And this is how I design the energy storage system.

Before I implemented the ESS, the simulation went as expected and followed my load profile. But now with the ESS the motor velocity goes to zero and remains there until the simulation is done.

As you can see we used the Battery model from Specialized Technology and the voltage-current simspace interface. I am wondering about my ESS design linked with the rest of the system. Is there any obvious faults in the design? Is it possible to use the simspace interface block like the picture above shows?

I tried to make a simplified bidirectional converter with the "Average-Valued Inverter/Rectifier", but it didn't work out as I thought. Any ideas to an approach would be much appreciated.

Roy

Answer 1

[Sriram Narayanan]

The usage of the Voltage-Current Simscape interface is fine. One potential issue could be that the Voltage-Current Simscape interface block is causing an algebraic loop because you have provided direct feedthrough for both the Simscape and the SimPowerSystems side. I would have to look at the model to confirm, but, you can try implementing a first-order filter or use a Unit Delay block to break the algebraic loop. This algebraic loop could be preventing the battery from charging which could cause the motor output to zero.

More information about how to fix this algebraic loop is at the following documentation page.

http://www.mathworks.com/help/physmod/sps/powersys/ref/voltagecurrentsimscapeinterface.html

[Roy Azlan Jensen]

Hi, and thank you for your reply.

I've changed the design for the ESS, since it lacked thyristors. I'm still puzzeling with my design, thought. Is it possible to use the "Simpowersystems simscape interface element" for each phase-line to the 3-phase grid?

Like this:

[Sriram Narayanan]

You can use the "SimPowerSystems simscape interface element" to convert each phase to the corresponding phase in Simscape and then combine them together using a 3-phase V-I measurement like you have done above. Can you explain your concern with this workflow?