To also disable Hibernate mode (standby state S4) run powercfg.
This policy will disable all sleep modes completely. WinWaitActive( 'Local Group Policy Editor') Since I needed to enable / disable sleep mode via Group Policy quite often, I created quick and dirty AutoIt script that opens Local Group Policy Editor and navigates to the correct GP: 50798-how-to-set-up-power-management-by-group-policy-in-windows-7-and-higher looks. To disable sleep mode completely you can use Local Group Policy: