meaning of buses and lines in power system???

I am working on a project "linear solver acceleration by FPGA". Application is power network analysis. I have less knowledge about power generation and distribution. In a paper i am reading i can't understand "power networks of 5000 buses and 10000 lines". what it means? please help.. thanks in advance

"Busses" plural of busbar. This is an arrangement within a power distribution cubicle or frame, where the three phase runs in via its own protection kit, then each phase wire (cable) is connected to a piece of copper or aluminium strip, typicaly 75mm wide and 8mm thick and as long as required. Along these bus bars wires come off to sub- circuit fuses and switches, the other side of the switches then run of to the equipment they power in lighter cable. For instance the incoming supply might be rated at 500A which goes into the busbar and the fuse/switches might all be 50A which then each feed another distribution box where the 50 A circuit is fed out via 10 5 A fuses to feed 10 lighting circuits.
A line is a piece of wire!!!
"power networks of 5000 buses and 10000 lines" is meaning less other then to mean some big arrangement > 1 MW?
Frank

Got it.. Thank you very much