Risk Assessment for Rotors Operational Integrity Loss of Asynchronous Electrical Machines in Heat Power Engineering Systems

The reliability of heat and power engineering systems (HPES) operation is largely determined by the reliability of asynchronous electric machines (AEM), being the part of them. The timely assessment of current operating conditions for AEM rotor and the risk of its operational integrity loss is an actual operational problem, the solution of which will increase the reliability of both AEM and HPES. The scientific component of the problem is implemented in the direction of developing methods for the operational diagnostics of AEM rotors and in the direction of developing appropriate characteristics of the current operating conditions for AEM rotors. The objectives of the investigation is to develop the approximate evaluations for the current operating conditions of AEM rotors and the risk of their current operational integrity loss. These evaluations will enable the operating personal to make quick decisions to continue or stop AEM operation. The set problems were solved by mathematical modeling methods. A mathematical model of a rotor is a system of linear equations including the equations for undamaged and damaged rotor cage loops. The currents and powers for a rotor of an electric motor with a production version 4A355M2C3 with damaged 0,1,2,...,6 rods of a 38-phase cage are calculated and analyzed according to the mathematical model. It is found out that the most significant consequence of AEM rotor damage is the decrease of its power. In this case, 10% rotor power reduction can be associated with AEM limiting state and be the reason to stop operation. The detection of a limiting state allows introducing a deterministic evaluation for a rotor operational integrity loss suitable to scale such risks during AEM operation in HPES and make controlling decisions.