Title: Get power status
Use GetSystemPowerStatus function and SYSTEM_POWER_STATUS structure.
procedure TForm1.Button1Click(Sender: TObject);
var
PowerStatus: TSystemPowerStatus;
begin
GetSystemPowerStatus(PowerStatus);
if PowerStatus.ACLineStatus=1 then
Label1.Caption:='AC power online'
else Label1.Caption:='AC power offline';
end;