CFL wattage

Hello, i am newbie in a lamp tech. I already understand what "SMPS p supply, capacitor p supply, transformer, and so on".
My question : How CFL control the wattage?
Thank you for answering.
This picture just for illustration.

In that circuit, I'd say L1 is the power regulating part; an inductor that provides a certain reactance at the oscillation frequency.
Very similar in principle to a basic inductive ballast on a conventional fluorescent lamp.

eg. from the output of T1, the circuit is virtually identical to a standard 50/60Hz lamp like this:

I agree with mr jenkins, L1 and C6 will provide low impedance at a certain frequency, if the oscillator is off this frequency by a certain amount it will provide an impedance and limit power, an inductor is used in old fashoned fluorecents in the similar manner.
Might also be designed so that on power up the tube gets an extra kick with the frequency being different.

This circuit appears twice. The transformer applies a voltage to R5, 22 ohm and thus Base current to Q1. Lets say 3 volts on the transformer. Substract 0.7V for the B-E. Current flows C-E which causes voltage across R1, 1.8 ohms. The current ramps up to the point where the emitter increases in voltage and the base current decreases. At some point there is not enough Base current to keep the transistor on and it opens up. My point is that the transistor(s) Collector current is measured each cycle and limited to some peak value. The exact current is not well regulated but good enough for the light bulb.