Why do my simscape fan modules get errors when connected in parallel？

hallo，This is a parallel fan system I created，When the fan is in a single line, its P-Q curve is correct，But when parallel pipelines appear, the curve will suddenly decrease according to the number of parallel pipelines.

The picture below is the curve of a single pipeline。

The picture below is the curve of the double parallel pipeline，At this time, the curve will have a sudden drop

[zhuo chen]

This problem has troubled me for a long time, can anyone give me some help