Smaller turboprops use often generators, (DC power). The advantage is the process is reversible. If directly connected to the battery, those generators are used as starters for the engines, saving weight and costs.
Another advantage of DC power is, you can connect it straight in parallel with other DC sources, whereas with AC power you cannot due to difference in frequency of the phases. That is why the B737 never interconnects is busses when powered by a different power source. The B707 did, but the alternators had to be first synchronized by the flight engineer.
There are a lot pro and contra's using generators versus alternators.
The misunderstanding comes apparently from the USA, where alternators are called AC generators, or simply generators.