Hi
I don´t know if as a string variable it will work or not but remind what @fxDreema has explained in the forum about this: if there is no tick coming at that time, it will not be posible to meet the condition time.
@fxDreema suggested to use a period of time to get what you want such as if time > 23:30 --> Close positions using the condition block or a time filter block.
0_1525208656714_807b1bca-22a9-4229-90e7-51908b093e3d-image.png
Should work.