Dynamic Stability of Synchronous Turbogenerators with Longitudinally-Transverse Excitation

摘要

The development of high and ultrahigh voltage networks and the increase in their length caused a number of problems associated with the consumption of excess reactive power. Conventional synchronous generators cannot solve these problems, since their operation in the modes of reactive power consumption is limited. The mentioned problems can be solved with the use of turbogenerators with two-axis excitation. The purpose of the article is a comparative analysis of dynamic stability of conventional synchronous turbogenerators and turbogenerators with two-axis excitation in various modes, including the modes of reactive power consumption. The studies of dynamic stability were carried out using a program for calculating the electromechanical transient processes of turbogenerators of various designs. The analysis of the influence of the regulation of turbogenerators with two-axis excitation on stability was carried out analytically. The article presents the results of a comparative analysis of dynamic stability of conventional turbogenerators and turbogenerators with two-axis excitation controlled both synchronously and asynchronously in various modes, including underexcitation modes. It was theoretically proved and confirmed by calculations of electromechanical transient processes, that an important factor in increasing the limits of dynamic stability of turbogenerators with two-axis excitation is not only the law effect of excitation control, directed to the displacement of the phase of the representing vector of the resulting emf of excitation to the direction opposite to the motion of the rotor, but also a shift in the same direction of the phase of emf due to the corresponding change with the increase of the loading angle of free currents in the longitudinal and transverse rotor windings. The results of the investigations make it possible to carry out a deeper analysis of the reasons for improving stability of a machine with longitudinal-transverse excitation. They can be useful in the development of control systems for turbogenerators with two-axis excitation as well as when justifying the use of turbogenerators with two-axis excitation in power systems.