Power factor correction (totally lost)
Currents on the lines are equal in all three phases, and they are
  lagging behind the voltages by 30 degree


I read this observation as the line current lagging the line voltage by 30 degrees.

Take a look at a 3 phase phasor diagram: -



And concentrate on one of the line voltages, namely \$V_{RY}\$ - this voltage naturally leads the local phase voltage \$V_{R}\$ by 30 degrees. It's the same for the other line voltages - each line voltage leads its respective phase voltage naturally by 30 degrees.

Given that a resistive balanced load would draw a current in phase with \$V_{R}\$, I have to conclude that your "3 phase electronic motor" is running close to unity power factor.


  We need to make a power factor correction in such a way, that the
  phase difference between the current and voltages becomes less than 10
  degree.


I have serious doubts about that so, get someone in who can be trusted to make proper measurements and make a local recommendation.