microcontroller based thyristor controlled Automatic voltage regulator

[Nasa28]

Please I want to design an automatic voltage regulator using triac as my switch, microcontroller to fire the triac. in the project i plan to keep the output voltage of the triac constant at 220v. In d simulation i plan to use proteus. I think also that a zerocross circuit should be in the circuit to detect zero voltage. pls can someone suggest or help me with a circuit diagram. Although I have my own but when i connect a voltmeter to the load, it fail to give me desired 220v. Pls I want also to know whethe the project is possible. The input voltage is stepped up to 300v. and i am using phase control and not off and on control method

 

[chuckey]

A triac is a switch, i.e. its on or off. So how can this fact be used to increase an incoming line voltage of 210V to 230 V?
Frank

 

[Nasa28]

pls the input voltage is 1st stepped up using an autotransformer. The control method am using is Phase control and not OFE and ON method