Besides the accidental voting corruption you mention, you might also be seeing the Expert's Ideas Get More Traction effect. People might be posting ideas they just came up with and organized as best as they could, while yours were stewing and benefit from knowing you'd be writing them down some time.

There are many ways to dilute the "first posted, most voted" effect without actually changing how votes get counted. In a way, it's a very similar problem to how voting happens in sites like HN. Mostly you can change how entries are displayed (hidden votes until done?), ordered (new first? random? less voted? trending?) and discovered (tags? keywords?).

In your specific case, next time you can try making sure you add a couple clearly bad ideas (off topic?), maybe one clearly placeholder (or kinda tutorial) idea and maybe some you can remove later could give you a good starting brew to grow user submitted content.

You can also somehow put the same projects to vote again, starting with zero votes. To have two projects done instead of one, maybe that's enough of an excuse.