The integration of distributed generation into electric power systems requires advanced methods for control under normal, emergency, and post-emergency operating conditions. Distributed generation can rely on asynchronized synchronous generators (ASGs), which have advantages over synchronous machines. Their application however necessitates sophisticated automatic control systems. This study aims to identify the effects of a self-tuning predictive controller designed to control rotor speed of ASGs of the mini hydropower plant operating within the system for power supply to non-traction consumers of alternating current railway. The paper presents a diagram of the simulation model of the power system under study, which encompasses the mini hydropower plant based on ASGs. To improve the quality of electric power, a DC link is used for connection with the railway power system. The developed models of the ASG excitation system and self-tuning predictive speed controller are described. The method for determining the forecasting time is presented along with the modeling results for normal and emergency conditions of the power system at issue. The modeling results have proven the effectiveness of the proposed automatic speed controller, which exhibits the improved indicators of rotor speed and frequency control in the network. In the short-term remote short-circuit mode, compared to conventional automatic speed controllers, the use of the proposed controller allowed: to reduce the transient process time of the ASG rotor speed and network frequency by 33.3 %; to reduce the ASG rotor speed overshoot by 42.1 % and the frequency overshoot by 28.6 %; to improve the damping degree of the ASG rotor speed oscillations by 56 % and the network frequency by 52 %. After disconnecting a long-term remote short-circuit, the transient process time of the rotor speed decreases by 3.8 times, and for the network frequency - by 2.2 times; also, the maximum deviation of the ASG rotor speed decreases by 29 times. For voltage, a slight decrease in the dip in the long-term short-circuit mode can be noted.
