Does Stepping Up Voltage with a Transformer Change Power Output in Generating Stations?

Generator produces power we all know power has got mathematical relation with voltage and current. A transformer is used in generating stations to generally step up the voltage. Doesn't this effect on the power according to mathematical relation?

Power out equals power in, with some losses due to the non ideal characteristics of a transformer. The reason that transmission lines from the generation source are driven with higher voltages is that the power loss in the transmission line (I*I*R) is far higher that the transformer losses over a long length of line. A practical limit is set by voltage breakdown of insulating materials, which in transformers is often oil, and on transmission lines is air,
cheers,
Richard