Research On Dynamic Power Allocation Control And Large-Signal Stability For The Hybrid Power Supply System Of A More Electric Aircraft

With the rapid development of global aviation industry,the environmental pollution issue is becoming increasingly prominent due to the sharp increase of jet fuel consumption,and aircraft exhaust and noise emissions.To alleviate environmental pollution,the global aviation industry is pushing ahead with the more electric aircraft(MEA)technology,which gradually unifies the secondary energy of aircraft into electric energy.In this way,the aircraft energy structure could be simplified,the energy utilization and reliability could be improved,and the weight of aircraft components and jet fuel consumption could be reduced.The stable and reliable green aviation power supply technology has become a focus and urgent content for the development of MEA technology.However,the highly reliable dynamic power allocation of onboard hybrid power supply system(HPSS)is facing great challenges owing to the multi-time scale characteristics of sources and loads as well as the complex and changeable operating conditions.Moreover,with the increasing electrification level of onboard loads,the interaction between sources and loads causes serious stability problems in the onboard HPSS,which has become a major bottleneck restricting the development of MEA technology.Therefore,this paper takes the MEA HPSS as the research subject,and focuses on the key technologies such as dynamic power allocation control,large-signal stability analysis and stabilizing control.The main contents include:(1)The dynamic power allocation mechanism,decentralized control technique and optimal design method of the onboard HPSS under complex operating conditions.Aiming at the problem of highly reliable dynamic power allocation in onboard HPSS,This paper proposes three mixed droop control strategies based on virtual impedance matching(i.e.the mixed droop control strategy based on virtual resistor-capacitor matching,virtual resistor-inductor matching and virtual resistanor-inductor-capacitor matching),which not only achieve the automatic optimal allocation of multi-time scale load power between different power supply units,but also take into account the regulation of state of charge of energy storage elements,regenerative energy recycling,and “hot plug” and redundancy expansion of power supply units.In this way,the reliability,durability,flexibility and energy utilization of onboard HPSS could be improved.In addition,an optimal shaping method of practical dynamic power allocation characteristics based on small-signal analysis and parameter sensitivity analysis is proposed,the relationship between system parameters and dynamic power allocation performance is analyzed,and the dynamic power allocation performance of the system is guaranteed by optimizing the system parameters.(2)The large-signal stability analysis and quantitative evaluation methods of onboard power supply system considering the dynamic characteristics of the control system.The power supply system of MEA is reasonably simplified according to its structure and control strategy,and the power supply system model considering the dynamic characteristics of the control system is established.The large-signal stability problem of the power supply system comes down to the problem of largest estimated domain of attraction(LEDA)based on Lyapunov stability theory.This problem can be further translated into a sum-of-squares(SOS)optimization problem combined with the SOS programming theory.In this paper,the SOS programming algorithm is proposed to obtain the LEDA of the power supply system,the influence of typical parameters on the LEDA of the power supply system is analyzed,and the dominant parameters affecting the large-signal stability of the power supply system is clarified,which provides a practical guiding basis for the parameter optimization design of the power supply system to ensure the safe and stable operation of the system under large disturbance conditions such as startup,fault emergency and large load switching.(3)The stabilizing control technique of onboard HPSS under the influence of multiple factors such as parameter uncertainty,external disturbance and modeling error,the correlation mechanism between system parameters and dynamic performance index under nonlinear control,and the parameter tuning method considering the dynamic performance of the system.The state-space model of onboard HPSS is improved by comprehensively considering the influencing factors such as parameter uncertainty,external disturbance and modeling error.Based on passivity-based control and disturbance observer,a stabilizing control strategy that does not rely on load models is proposed,which can not only ensure the global stability of onboard HPSS under the influence of multiple factors,but also improve the robustness of onboard HPSS.Based on the classical control theory,the relationship between system parameters and dynamic performance indexes is analyzed,a parameter tuning method of composite controllers considering the system dynamic performances is proposed,which lays a theoretical foundation for the optimal design of system parameters.In this paper,the key technologies of the MEA HPSS are deeply studied under the background of actively promoting the large aircraft strategy in China.The research results could make up for the theoretical shortcomings in this field,enrich and develop the theoretical system of MEA technology,help to promote the rapid development of MEA technology,and seize the commanding height of green power supply technology for the next generation MEA.