DAMPING OF ELECTROMECHANICAL SWINGING IN DRIVES WITH SYNCHRONOUS MACHINES BY A FIELD CURRENT REGULATION

An electromechanical swinging of a synchronous machine can be damped by a parametric regulation of an exciting current in all cases when a mechanical time constant of a machine is substantially larger than an exciting current constant. The method described is based on the Ljapunov stability theory; it is effective for damping of swinging caused by mains frequency and voltage jitter and by mechanical moment fluctuation. A transfer function choice in an exciting current regulator is demonstrated as well as a real example of a synchronous machine 50 kVA/1500 rpm with a moment of inertia J = 160 kgm2, working as a no-break stand-by energy source. A seven times higher damping of swinging due to mains frequency jitter has been reached which initially had attained up to 50 % of nominal power. The description of the machine can be found in [1] and [2].