DYNAMIC STABILITY INCREASE OF THE SYNCHRONOUS GENERATOR OF THE AUTONOMOUS GENERATING SYSTEM

The article considers the use of autonomous generating systems (AGS) on the basis of synchronous generators (SG) for the consumers of the first and second categories. To increase the SG AGS stability and the output voltage regulation on the stator clamps, the relay or parametric forcing of the excitation voltage and the system of automatic regulation of excitation (ARE) are used. However, in cases of natural disasters, when connecting consumers of comparable power, for example, asynchronous motors with short circuit rotor, the SG lose its stability due to the inertia of the excitation circuit, a significant dynamic voltage drop and its duration, which causes the disconnection by the protection of the minimum voltage of the preconnected consumers. Therefore, the speed of forcing modes increase is achieved through the application of a leading phase of the voltage excitation and its multiplicity increase. In addition, an increase in the speed of the forcing mode can be achieved by reducing the inertia of the measuring lines and voltage control. However, the application of known methods and devices for accelerating the voltage excitation does not reduce the inertia of the excitation circuit itself, that is, the current in the exciting winding (EW) always has an aperiodic lag to the accelerating voltage, following the stability determination of the SG. The authors proposed to compensate the electromagnetic inertia of the excitation circuit by activating capacitive energy storage devices (CES) in order to increase the dynamic stability of SG. The mathematical model of SG in Koshy form and the control system of the excitation circuit has been given. The calculations have been made to assess the influence of the CES and the control system of the excitation circuit on the AGS output parameters. The analysis of transient processes shows that the stabilization time of the output voltage SG without CES is t ≈ 0.6 s, and with CES is t ≈ 0.2 s. In addition, the voltage drop is = DU 40% and DU = 10% respectively. In order to confirm the theoretical statements, the experimental research has been carried out using a synchronous generator of MCA-72 type / 4A: Рn = 12 kW; U = 230 V; nn = 1500 rpm in the mode of excitation current speeding up with the proposed device and with serial thyristor exciters with connected consumers of comparable power. It is proved that the time to reach the forced value by the excitation current with the uncompensated circuit is 1 s, and with the capacitive energy storage device – 0,01 s. In this case, the voltage drop is 39%, the compensation of electromagnetic inertia in the same conditions provides a voltage drop of no more than 11%.