An online real time steam or gas turbine engine rotor balancing system is incorporated in a rotor balance plane. A selectively displaceable balancing weight is coupled to the rotor and is selectively displaced by a motor that is coupled to the balancing weight. The motor selectively displaces the balancing weight along a displacement path that is in the balance plane. A turbine engine rotor vibration monitoring system monitors rotor vibration in real-time. A control system is coupled to rotor vibration monitoring system and the motor, for determining in real time a desired balance weight displacement position to counteract the monitored rotor vibration. The controller selectively causes the motor to displace the balancing weight to the desired displacement position. The motor power source is an inductive power source or a permanent magnet generator.