We can schedule task to shutdown at specific time, but you will not be able to shutdown at 30 minutes after logon.
Follow below steps to schedule task:
a.Go to Start >
Control Panel > System and Security > Administrative Tools and click on the Task Scheduler.
b.From the Action
menu in Task Scheduler, click "Create Basic Task..."
c.In the "Create
Basic Task Wizard" windows that pops up, Type in a title and a description. Something basic like "PC Shutdown."
d.Click "Next."
e.On the "Task Trigger"
screen, choose the frequency with which you want the Shutdown PC to run. For nightly shutdown, click on "daily" and click the Next" button.
f.On the "Daily"
screen, enter the date and time you want your PC to shutdown. Click "Next."
g.On the "Action"
screen, choose "Start a program" and click "Next."
h.On the "Start
a Program" screen, type C:\Windows\System32\shutdown.exe in the "Program/script" text field.
i.In the Add arguments
text field type /s.
j.Click "Next."
k.Confirm your
settings on the Summary screen and click "Finish."
Now your Windows 7 computer will automatically shutdown at the same time every day/night.