If it's avg power you want, find the power through each flip flop by finding the avg current. Voltage should be Vdd. Then sum the avg power dissipation of each flip flop.
If it's max you want, use max instead of avg. Both are math operators in Cadence that you can use on any simulation run.
Thanks for your reply. My circuit actually is a PN sequence and the output of this circuit goes to another circuit, so I want to calculate the level signal of the out put of the PN sequence which is a closed loop circuit