Static VAr Compensation
I have tested my system with smaller reactors, my observations are as follow:


Varying any analog value (mA or V) could not control the amount of the reactive power drived by the SVC driver.
SVC driver could be triggered with different voltage or current values, i.e. 3V, 5V, 10mA etc. There is no difference at all. It totaly ON/OFF the reactors.
Important thing is the Duty Cycle and Triggering Signal Frequency. I have tried triangular, square, and some other waveforms, they all open and close reactors according to reaching the threshold voltage (which means I can control SVC driver like fast switch/contactors).
There is no zero-cross issue. I can drive/ON/OFF the reactors whenever I want and in any order. Hence, I do not need any Capacitor Bank.
I also observed the SVC Trigger outputs of the Reactive Power Relay. It gives pulses (via PNP BJTs) about 100Hz and with ~10% duty-cycle (Please look at the screenshot I upload). I see that the SVC Relay could not operate as desired, who could try to check it yeah!


The only thing remains is the algorithm! It would be challanging, but I will also update this post for the next steps.