wine storage in dry climate area

In NingXia, China where I am working on a wine program now, encounter a problem of low humidity, the lowest around 18% to 40%(summer).

So there is two section, one is the master cellar, which I get a humiditifer on the way.

However, for the wine fridge in every outlet, I have no idea on how to increase the humidity. As the wine fridge from supplier around has no option in controlling this.

Does anyone of you know about a specific wine fridge that have humiditifer function? or any other answer that you had?

Thank you in advance.