Easy way to stop self-vote abuse: remove the self vote.
NOT easy, considering the fact that many users are having multiple accounts, considering also the fact of circle voting.
I think useful suggestions to make self-voting, circle-voting and spamming less attractive could be ...implementing diminishing returns when upvoting the same accounts (including own ones) again and again.
reintroducing the restriction to four full paid posts per day (from some hard forks ago) which was very reasonable.
thinking about other ideas like a sigmoid reward curve. Due to it's flat begin it would be far less attractive to upvote posts on which nobody else is voting (self-voting of comments would be less attractive). As it also ends flat, extreme rewards (like with n^2) would be avoided, as well.
considering also other ideas like the one of UserAuthority from @scipio.
Well, using other accounts is technically not self-upvoting, but I understand this argument. That being said, I would still like to ban the self-upvote as well as adopt supplementary changes that address your concerns.
That being said, although the self-upvote does not solve all of our problems, what is the issue with banning it? It removes a portion of self-vote abuse and forces people to upvote other content. While not THE solution, it should be considered as part of one. Then again, people are entitled to their guaranteed rewards. I do like the four posts idea and have no idea why that penalty was removed.
I would prefer implementing diminishing returns as it still allows you to upvote your articles, but the more often you do it the less reward you will get ...
Apart from different preferences most important would be that a real discussion about the problem should take place, where every idea was at least considered with all its pros and cons ...