Control of electromagnetic condition of asynchronous machines as a method of limitation of parameters of reverse energy flow

The article explores technical capabilities of the method for limiting the parameters of the reverse energy flow of an induction motor as a means of controlling its electromagnetic parameters based on the application of a short-circuited stator winding. This is due to the need to suppress the reverse EMF of an asynchronous motor of a multi-machine electrotechnical complex of a mine site which is in a freewheel state after a protective supply turning off. It is established that in such electrotechnical complex of mines asynchronous machines of medium and high power are able to create long-term reverse energy flows the presence of which creates a precedent for maintaining the dangerous state of the electrical complex if the cause of the protective switch-off is a short circuit in the power connection or ground leakage. The known and currently developed technical means for detecting the emergency condition of the power grid by autonomous means operate on the basis of monitoring parameters on the side of the motor connections which determines the practical relevance of the presented research in the rational direction of the technical implementation of the device for suppressing reverse energy flows. The main idea of the article is disclosed in the justification of the structure of the model of an asynchronous motor represented as an electrogenerating link with an additional stator winding designed to generate impact on the electromagnetic parameters of the engine. The processes that occur when a short-circuit in this winding is induced, taking into account the existing sizes of power transformers used in the modern electrotechnical complex of mines and the cable network, were investigated. The parameters of the additional stator winding were determined which reduce the currents and voltages to safe values in the circuit of the action of the reverse energy flows of the induction motor and the duration of the reverse EMF existence at a safe level.