I know there already exits a post on this (Cannot access PPA... please check your internet connection) which doesn't answer my problem.
I was trying to download TLP on Ubuntu-13.04 and I got the following errors while adding a PPA:
royal@royal-Vostro-3550:~$ sudo add-apt-repository ppa:linrunner/tlp
Cannot access PPA (https://launchpad.net/api/1.0/~linrunner/+archive/tlp) to get PPA information, please check your internet connection.