Name these young adult sci-fi books

In the late 80s/early 90s, I read a pair of books featuring the same female protagonist, who worked for an interplanetary federation of some sort, and worked to protect less-developed civilizations. In the first book, she’s fresh from the academy, and on a planet with a medievalish level of technology, thwarts a scheme to terrorize the populace with technologies which they take to be magical, including a “dragon.” In the sequel, she’s undercover on a planet locked in a cold war-type confrontation, trying to defuse the situation. As I recall, she fails to do so, but escapes. Any ideas as to what the titles or author of these books might be?

Enchantress from the Stars and The Far Side of Evil by Sylvia Engdahl.

P.S.: here’s here wiki page, which has a list of her titles. I don’t know if the others are part of the same series, or not.

http://en.wikipedia.org/wiki/Sylvia_Engdahl

Thank you! I’ve been trying to come up with those titles for a week, and plugging the recollections I had into Google was getting me nowhere.