A question in Simulink PQ measurement

Hello every one

Have a great Day!

I am simulating a line to line fault in a sample network. I have 6 buses and I am using the instantaneous 3 phasevalues of current and voltage in each bus to calculate instantaneous P and Q .

when I put a fault in Busg 5 , the P and Q values in Bus 3 have a positive peak while all other buses have negative peak just after fault accuring. Can You tell me why ?