While we might talk about a "stroke of luck" or a "run of good luck", these are more phrases than actual collective nouns.
Here's why it's difficult to create a collective noun for luck:
* Luck is abstract: It's not a tangible thing you can physically gather or count.
* Luck is subjective: What one person considers lucky, another might consider coincidental.
Therefore, while we can use phrases to describe good or bad luck, there's no established word for a group of instances of luck.