Allow single function to build different sized systems

[ciaranrob]

I have a function for taking the system size as an argument and read a different .raw file to build the system. Currently it doesn't work because PowerSystemCaseBuilder is always loading the first system that was generated when I call this function.

[claytonpbarrows]

You can do buiild_system() with force_build = true kwarg. That will force it to run the build process rather than just deserialize the system from json.

But, more fundamentally, I think that we'd usually consider these seperate systems. They can share the same build code with arguments applied from the build_system interface to access the different size. So, you'd end up with several options like:

• build_system(MySystems, "my_sys_small")
• build_system(MySystems, "my_sys_big")

but the code that actually builds those systems is shared.

[jd-lara]

@claytonpbarrows I think this will be a valuable way of making systems, particularly for dynamics. We can keep a tag that forces rebuild if the system size doesn't match the kwarg