Don't worry your parents love you more. They will always want your happiness. So if u try in a right way like making em believe that your partner is really nice then they will agree for sure. Also don't worry u will get what u ate destined to.
Try to talk to your parents that life is very long and you wont be able to live with a person just because he/she belongs to the same caste.
Try to make them meet your partner so that they could know what kind of person is he/she.
i have seen around 20 marriages of intercaste in past 10 years where parents were completely happy. but initially everyone needs to struggle to convince parents. First you both need to be sure once both are ready then immediately inform both families.
wish we could all come and convince your parents to stop being so adamant and leave this feelings behind. it will surely happen. there must be some way to it