The problem is that wind energy can actually cause fluctuations in existing networks, leading to these problems.
In this case, energy demand was on an upswing as 1700 MW of wind power suddenly declined to 300 MW, leading to a load imbalance that required 1100 MW of demand to be denied. The customers who were turned off were so-called interruptible customers, in this case industrial customers who have agreed to be shut down in such cases. The power was off for 90 minutes until the net stabilized and all told the disruption lasted 3 hours.
Wind Energy: it's a bad idea.