Since your voltages are very low, many resistor values will need to be re-calculated.
Can you help me?
Too much trouble. Use the proper 28VAC or 30VAC transformer and the proper opamps.
I want to limit the input voltage. If the line voltage change. So that the output has always been a 20V.
I don't know why your input voltage changes, mine does not change.
A TIP3055 at 3A has a maximum base-emitter voltage loss of 1.7V.
A BD139 at 110mA has a maximum base-emitter voltage loss of 0.8V.
The 1k series base resistor R15 feeding the BD139 has a maximum voltage loss of 1.5V.
Opamp U2 has a maximum voltage loss of about 3.3V and you are powering it with only +20.4V.
Then the maximum output voltage can be as low as +13.1V when calculated properly.
I decided if I'm have 20V, then i need replace the U4 and D13 (18+2,4=20,4V). I was wrong? The output voltage of 20V was enough for me.
You forgot to see the voltage losses on the datasheets.
The corrected and improved circuit here has an output of +30V at 3A when its unregulated positive supply is +37.6V from a rectified 28VAC transformer.
I decided if I'm have 20V, then i need replace the U4 and D13 (18+2,4=20,4V). I was wrong?
Yes you are wrong.
I think D7 not needed. Am I right?
D7 is a negative 5.6V regulator. It was needed in the original project. Your additional 5V regulator U5 is not needed.