Caixin: "The onshore Chinese yuan strengthened past 6.7 per U.S. dollar on Friday to touch its highest level in more than three years, defying expectations of depreciation following the Federal Reserve’s latest interest rate hike. The rally was steered in part by the People’s Bank of China, which set its daily benchmark fixing stronger for eight consecutive trading days to guide market expectations."
With the Trump–Xi summit scheduled for September 24, this probably doesn't come as a surprise.