Integrated penalty control: A highly robust start-up control schedule design method for gas turbine engines

Start-up schedule design is a crucial task in gas turbine engine control system design as it dramatically influences the start-up performance of engines. Traditional N-dot control schedule (NDCS) and corrected fuel control schedule (CFCS) for engines start-up lack robustness. Both face issues under changing engine components characteristics and sensor or actuator errors; NDCS risks engines surge and overtemperature, CFCS declines acceleration performance. Additionally, NDCS is sensitive to starter disturbance early in start-up. An integrated penalty control schedule (IPCS) design method is proposed in this paper to address these issues. This method integrates NDCS and CFCS, using a redundant CFCS early on and switching to a primary NDCS supplemented by the redundant CFCS later. Compared with the traditional methods, its innovations are as follows: 1) a redundancy framework is designed for CFCS based on three pressure parameters, which enhance the robustness against pressure sensor drift; 2) a fuzzy gradual switch process is designed, which avoids fluctuations in fuel flow during the switch from the redundant CFCS to NDCS; 3) a penalty correction mechanism is designed for fuel flow after switching to NDCS, which avoids the issues of overtemperature and surge. The simulation results show that the IPCS has no weaknesses during the start-up process under various extreme weather conditions. In random disturbances tests, the IPCS reduces the average start-up time by 8.9% compared to traditional CFCS and improves the minimum surge margin by 168% over traditional NDCS. Bench tests indicate that the IPCS exhibits less variation in start-up time compared to traditional CFCS. The IPCS effectively enhances robustness against various internal and external disturbances compared to traditional methods.