a question about breaker

dear all, I built a multi-machine power system model to simulate the test of cut generator of 25MW) of the generator. However, I found that the steady-state active power output for the original 25MW generator is 0.50125 p.u.), but after the circuit breaker installed in the system, the steady-state active power output becomes 0.225 (p.u.)or so, I want to know why this is? It stands to reason, the installation of circuit breakers should not affect its active power output, how to correct it?

Answer 1

[Walter Roberson]

The circuit break, when closed (circuit active), involves the current passing through one or more wires. In any circuit, the addition of a wire to the circuit affects the total resistance, and potentially affects the impedance, and there is quite possibly resistive heating of the breaker wires unless the total the same amount of current carrying capacity that the rest of the circuit does.

If the material of the circuit breaker is not chosen carefully, then especially with the high voltage and currents you are talking about, then electro-chemical migration of atoms can end up being a significant problem: impurities migrate. But sometimes careful doping with impurities is what is required to handle those kinds of power loads (e.g., to moderate thermal expansion or prevent the material from getting brittle.)

I don't know why your simulated output reacted as it did, but in real-world physics, adding a circuit breaker can make a significant difference to the circuit.