General rules for using power_statespace function

Hello all,

I am trying to use the power state space function, and I would like to ask about general rules for creating the needed matrices that the function needs to give me the overall system state space matrices.

Qs:

1- If I want to model a voltage source like -VDC, can I announce node 1 (which is the positive node based on the description of the function) as 0 (ground)?

2- In case I want to connect a switch between two elements in a series, the function will only work if this switch has a capacitor in parallel? Is this a rule, or can I do it using another method?

3- Can I connect a switch between two sources, and how can I do that?

Answer 1

[Jaskirat]

Hi @Saif Tawfiq!

It is possible to assign node 1 as the ground (0). In this context, ground is simply a reference point for measuring voltages in the circuit. By doing so, the negative terminal of your voltage source is connected to the reference node, and the positive terminal will be at a potential of "-VDC" relative to the ground.

Furthermore, when connecting a switch in series between two elements, it is often necessary to have some form of energy storage (like a capacitor) in parallel with the switch to ensure that the system's state-space representation is well-defined and to avoid algebraic loops. This is not an absolute rule, but it is a common practice to stabilize the circuit and ensure it is properly defined. Without such an element, the state-space model might not capture the dynamics accurately, as the switch introduces discontinuities.

You can refer to the following documentation to check how to connect a switch between two sources.

https://www.mathworks.com/help/sps/powersys/ref/power_statespace.html#f6-412364

Hope this helps!