macos – com.apple.powerd.swd every 30 seconds

I see the next line logged every 30 seconds in system.log. Is this normal? If it is not normal, how can I solve this problem? I've looked at the powerd and swd man pages and I knew that they were both related to energy preferences. But I do not know how they should behave normally.

Apr 27 11:25:05 machine name com.apple.xpc.launchd[1] (com.apple.powerd.swd): The service only worked for 0 seconds. Push reappear 30 seconds.