This is somewhat similar to this question: When to use 了 and when to use 过 to express past actions or events. I understand that the 过 particle helps express the idea of having had the experience of something. my question is would you use it with a specific time?
举个例:
我知道我可以说：
我去过中国。
我可不可以这样说：
我去年去过中国。
If the later is possible, what would it mean?
The minor difference between "了" and "过".
Q: Where did you go last year? (去年你去哪了?)
A: 我去年去了中国。
Q: have you been China before? （你去过中国么?)
A: 我（去年）去过中国。
Yes,两个都可以。比如:去了北京与去过北京大体意思是一致的。但是，“去了北京”有已经回来与没有回来两种可能，而去过北京则结果只有一个，那就是现在已经不在北京了！谨记：过的语句后可以加了字，反之不可以！!
Edit (Translation): Yes, both are possible. For example, 去了 Beijing and 去过 have roughly the same meaning. But, 去了 Beijing has two possible meanings; went and already came back, or went and still hasn't returned. However, 去过 Beijing only has one, you have been but you are no longer there! Remember: You can put 过 at the end of a sentence but the reverse is not true!
(Comment by editor) Im not sure if the last sentence is translated correctly or maybe the OP meant something else. Possibly you can put 了 at the end but not 过。
Of course the later is possible, it means "I had been to China last year." the position of adverbs of time is not important, you can express the same meaning like this:
Yes you can. For instance, 我三年前去過這個公園．This of course emphasizes the fact that it was three years ago, and consequently that you have been to "this park" before at a specific point in time.
我去年去过中国is valid, it emphasizes the time (去年) that makes your status become "have been to China". Examples:你昨天刚去过电影院看电影，怎么今天又要去？/他昨天来过这里。/你三个月前参加过体检吗？– Stan Feb 16 '14 at 7:08