Research On Comprehensive Assessment Method Of HVDC Power Quality For More-Electric Aircraft

With the development of more / all-electric aircraft(MEA/AEA),the types and quantity of airborne electrified loads are increasing rapidly,and the power capacity is greatly improved.In order to meet the power demand of MEA,270 V high voltage DC(HVDC)power supply is introduced into the airborne power grid to supply for airborne high-power loads.HVDC power grid can improve power supply capacity and reduce the volume and weight of airborne equipment effectively,but the power quality problems also increase significantly.Power quality is a comprehensive index to reflect the overall operation of the electrical system.How to assessment the aircraft HVDC power quality reasonably and accurately is not only helpful to mine and solve the problems of power distribution of the airborne electrical system,but also can provide evidence for prognostics and airworthiness certification technology of the whole power grid,which can be effectively used to ensure the safety and reliability of the electrical system,and improve the safe operation level of aircraft.Firstly,based on the analysis of the technical standards of aircraft power supply system at home and abroad and sorting out the differences between standards,the technical indexes of HVDC power quality of MEA are determined.Then,according to the definition and formulate of technical indexes,the characteristics of each technical index and the relevance between the indexes are defined,furthermore the scientific index system of power quality for assessment is established.According to the limit scope of technical standards,the grade of power quality is divided reasonably.Secondly,based on the research of existing literature and analysis of various classical weighting methods applied to assessment,a power quality weighting method based on the fusion of intuitionistic fuzzy and analytic network process is proposed,and establishes a combination weight calculation model of the best consistent attribute.Considering that the aircraft power quality is a small sample database,it will cause uncertainty and fuzziness in the assessment process.The application of grey relational analysis and grey clustering assessment technology are introduced to enhance the applicability and accuracy of power quality assessment of MEA.Finally,according to the structure of B787 HVDC electrical system,the equivalent simulation model of HVDC load is established.simulating the working conditions of HVDC system in different flight phases from the perspective of power equivalence,and the HVDC electrical data is obtained.The grey theory method based on the combination of intuitionistic fuzzy analytic network process is applied to carry out the weight and result of comprehensive assessment.Through the analysis of the assessment results,the feasibility and rationality of the proposed method are verified.Based on the experimental data obtained by the 270 V HVDC power supply experimental platform,the power quality assessment system is designed by using the module embed in MATLAB platform,and the proposed methods are applied to assessment the experimental data.Through the analysis of the assessment results and the application of the assessment system,the practicability and rationality of the proposed method are further verified.