How to generate continuous electrical energy from piezo plate? Answered

You can't - it's the nature of the material that it only produces charge during the deformation.

If you want a continuous current from your generator, you will have to "buffer" the pulses from the piezo - use them to charge a capacitor, then drain a constant current from the capacitor.

Its an intrinsically AC device, not DC, you don't extract any power unless you are doing work on it !