Yaogan seems to be a name to cover satellites having an imaging mission with a government or military purpose. Some seem to carry optical payloads and others carry radar. There are also some launches into orbits very like the US NOSS satellites. They probably have an ocean reconnaissance ELINT or SIGINT payload.

For the satellites in sun-synchronous orbit, looking at the orbit heights and inclinations together with the descending node local time gives an indication of related payload sets.