ENSURING STABILITY OF SYNCHRONOUS MOTORS WHEN THE VOLTAGE IN THE NETWORK DROPS OR A SIGNIFICANT LOAD IS APPLIED

To increase the stable operation of the LED and increase the reactive power supplied to the network, during short-term voltage drops, in all cases, the network should use either parametric and relay excitation forcing or applying a significant load to the motor shaft. The limitations of the existing thyristor exciters and excitation forcing devices can be significantly expanded. The most effective way to implement the specified task is forcing the excitation with capacitive compensation of the inertia of the excitation circuit by discharging a pre-charged capacitor in this circuit with the simultaneous supply of a forcing voltage from a thyristor converter. Since the electric capacity (capacitor) is included in the excitation circuit, it is therefore appropriate to determine its effect on the transient processes in the rotor circuit, partly on the nature of the current change in the OZ in the excitation forcing mode. For this purpose, the expression of the excitation current is found from the third equation of the system. A comparative analysis of the obtained expressions shows that the presence of electrical capacitance in the excitation circuit allows for a more intensive change in the current in this circuit, since there is a forcing term in the numerator, and the denominator is represented by an oscillating link with an appropriate selection of the capacitance value . In addition, the total voltage in the excitation circuit due to the charged capacity can be 5 to 10 times higher than the forcing voltage of series thyristor exciters. Analysis of calculated dependencies shows that in the first case, the maximum excitation current value of 21.1 A is reached in 0.0091 s, and in the second case, the current value is 19.16 A in 0.45 s. To confirm the theoretical propositions, experimental studies of the model engine were carried out in the forced excitation mode with capacitive compensation of the inertia of the excitation circuit and with serial thyristor exciters.