I tried directly connecting my WD My Passport Ultra 1TB USB hard drive to the Pi but it draws too much power, and it doesn't even run the OS.
Is there any way to connect it without damaging the Pi?
Use an USB hub that has a power supply? You should check how much power your HDD needs and how much the USB hub can deliver.
Maybe this question can help: link
The Pi 2 should be able to run that HDD directly. However, by default the power to USB is limited to 600 mA, which is not enough (I've had the same issue with an external drive).
To make 1.2 A available -- which is fine if your power supply is up to it -- add the following to
And reboot. Your HDD should now light up and be accessible (you will still have to mount any partitions yourself though).