The project has many problems and is corrected at
www.electronics-lab.com in a thread with about 190 pages and in other shorter threads.
1) Its power transformer, rectifier diodes, 2N3055, 2N2219 and some resistors are all overloaded.
2) The TL081 opamps operate at a supply voltage that is higher than their max allowed supply voltage.
3) The 24V transformer's voltage is too low for a regulated 30V/3A output.
4) Its main filter capacitor is much too small.
5) A part number is not specified for D8 its voltage reference zener diode and R4 has it operating at a very low current.
6) The voltage offset adjustment pot has a series resistor with a value that is way too high and it is connected to the wrong voltage.
We use a 28VAC 119VA transformer, two 2N3055 output transistors, a BD139 little power transistor as a driver instead of the tiny 2N2219 and opamps with a higher voltage rating.
The better opamps do not have the problem called "phase inversion" that the TL081 opamps have so Q1 is not needed to short the output of opamp U2 when the power is turned off.
There is another thread about increasing the output current to 5a and it uses 3 2N3055 output transistors.
Here is the latest schematic of the 30V/3A project: