The Dutch convention is to spell "van der" all in small letters. There are thousands of names like it, for example "van den berg" which means from the mountain, or "van + placename" which is obvious. As there are no names like these in English, the British/American convention is to spell "van" with a capital like in Van Halen

Don't know what Perren actually means, but I'm sure it is some kind of location marker, and his family in the 18th century must have lived close to things called "perren".