A single-line diagram shows connections between objects. However, it does not show what flows between them. This was troubling to me for some time and so I decided to address this issue.

I currently work on software which draws single-line diagrams of high-voltage substations: Angular and diagram rendering in the browser, Java 21 and Quarkus behind it. I decided to create the other side of this to model the electrical implications of these diagrams. I called this project gridtwin. It combines domain knowledge, numerical methods, a 3D front end and a Java back end in one place.

Opening a breaker in either the 3D substation or the single-line diagram will cause an AC power flow to redistribute the load, overload a line and potentially cascade into an outage. These simulations are run on the public IEEE 14-bus and IEEE 30-bus test cases.…