The problem is not the upvoting yourself. I usually upvote my post when my power is approaching 100%, since there is no point to waste it. There is already a system to discourage that in the curation rewards. The problem is that the curation rewards are way too low. The upvote is usually worth way more than what you get from curation. Yet having a bigger piece of the pie attributed to curators would screw over authors.

I think what the best way would be is to have the weight of the upvotes on your post be correlated with curation rewards. So say if you do not upvote anyone and do not get curation rewards, your author rewards should be reduced. On the other hand, if you get a lot of curation rewards, the upvotes on your posts should have a higher weight.