A method for controlling a wind turbine is proposed. Broadcasting of session signaling register messages is supported to reduce the number of registration messages which need to be transmitted between a mobile node and an access node. Periodically, the master policy server and the local policy server synchronize, at which time the master policy server replicates updated policies to the local policy servers and the local policy servers upload client security statistics to the master policy server for consolidation into a global status. The ends of heat sink clip reach to the other side and attach onto the heat sink on. The present invention comprises transmitting a data block on a first physical channel, wherein the data block comprises control information, and transmitting an indicator having a specific value on a second physical channel for indicating the transmission of the control information on the first physical channel. The power cord securing device includes a rotatable plate having a first part for being wound by the power cord, and a resilience element having a first terminal and a second terminal respectively connected to a second part and a third part of the rotatable plate.