Kimagure Orange Road OVA is basically the extension from the TV series. The time frame is probably in the middle of the TV series.

Order to view with the TV series.
White Lovers - among the episodes 35 and 45
Hawai Suspence - among the episodes 17 and 25
I was a cat, I was a fish - among the episodes 17 and 30
Hurricane Akane, the shape-shifting girl - among the episodes 20 and 25
Spring is for Idols - among the episodes 23 and 30
Birth of a Star - Right after "Spring is for Idols"
Unexpected Situation - after the OAV of Akane
Message in Rouge - after the episode 48