Hello Nilesh,
Would like to know whether your WD component is visible or not. By visible I meant is currently active on the screen. If its not active on the screen then you will not be able to get control in your WD components PROCESS_EVENT.
The WD component has to be active on the screen to get control in PROCESS_EVENT, then for each and every FPM event it will trigger your PROCESS_EVENT.
Hope this helps you. 
Regards
Sanket.