Supervisory system for detecting torsional oscillation in the shaft of a rotating electro-mechanical system

An analog supervisory system for simulating the torsional oscillation characteristic of an electro-mechanical power generating system, which latter system has rotatable masses therein which are interconnected by rotatable shaft, said shaft having mechanical resilience, said electro-mechanical system having mechanical damping, said mechanical resilience, said mechanical damping and said masses having the capability of causing torsional oscillation in said shaft when said shaft rotates, said generating system having an output electrical generator with terminals, comprising:

• transducer detecting means interconnected with said electro-mechanical system for measuring the real component of electrical power provided at said terminals of said output electrical generator in said electro-mechanical system for thus detecting shaft torque in a local part of said shaft and thus providing an output signal having a value related to said local shaft torque;
• analog simulating means adjusted to represent said masses, said shaft damping and said resilience of said electro-mechanical system, said transducer detecting means output signal being provided to said analog simulating means to cause said analog simulating means to thereby simulate a torsional oscillation in said shaft relative to any of said masses;
• shut-down means interconnected with said analog simulating means and said electro-mechanical system to shut said electro-mechanical system down if a predetermined torsional oscillation value is achieved;
• and
• fault detecting means for detecting an electrical fault current at said terminals of said output electrical generator, a signal having a value which is relative to said fault being provided by said fault detecting means to said shut-down means to disable the shut-down of said electro-mechanical system until the effect on said generator of said fault has been reduced.