Runaway failure analysis and optimal design of 200 kW class turbo-generator system

Based on a series hybrid aero propulsion system with power class of 200 kW, voltage of 540 V and speed of 21000r/min, proceeding from the occurrence of the runaway failure during experiment, this study reveals the characteristics and causes of a traditional turbine engine failure in a new application context, focuses on optimizing mechanical issues from the perspective of control strategies and electrical equipment, combined with mechanism analysis and experimental validation. The main conclusions are as follows: the fundamental reason for the high-speed turbogenerator set facing the risk of overspeed runaway is the small rotational inertia of the rotor system, with the direct cause being the power imbalance between the supply side and the demand side of the propulsion system. Experimental verification demonstrated that the active protection scheme based on voltage regulation by battery can keep the speed and voltage of turbine generator set fluctuations below 0.3 % and adjustment time within 0.5 s for load changes within the battery power range, effectively preventing runaway failures caused by minor power fluctuations. Additionally, the passive protection scheme based on power dissipation through resistors reduced the speed of the power turbine from 7000r/min to 2000r/min no more than 2 indicating the effectiveness of this measure in restricting the speed within a safe range.