Simple past I went to Spain for a year. (Happened sometime in the past, I am no longer there) Present perfect I have been in Spain for a year. (I have been living in Spain for a year and I am still living in Spain) Past perfect I had been in Spain for a year before I got sick. (I was in Spain some time ago for a year before another event in the past - getting sick)

Yes, "had been to" is unnatural in the sentence. You are correct that "I went to Spain to study Spanish for a year and am still studying it today." is better. The past perfect ("had been to") is unnatural without a reference to another event in the past ("I had been to Spain twice before [my last trip].") If you want to talk about a specific time it is good to use the past tense ("I went to Spain last year."), and the amount of time generally doesn't matter ("John went to Spain ten years ago." "John went to the store a few minutes ago."). If the time is indefinite, you can use the present perfect ("I have been to Spain many times over the years.")

Understand. See my comments below my answer below. Cheers!

Hello kenneth, thank you again. No, I wish to indicate that I am not in Spain any longer but am still studying Spanish today.

Just to be clear. Do you mean in the following sentence that you are still in Spain studying? "I had been to Spain to study Spanish for a year and I am still studying it today."