面向未来多电飞机的低气压下局部放电

Partial discharge characteristics of future more electric aircraft under low air pressure

多电飞机(MEA)采用电气装置取代部分传统的机械部件,可以有效提升飞行效率,降低温室气体排放。为了提高多电飞机供电系统容量,未来的供电电压将会提高至千伏级,这将导致严峻的局部放电风险。为此,以多电飞机实际状况与运行场景为依据,在实验室搭建平台,模拟了航空电机绕组放电与航空电缆对地放电两种典型绝缘故障,在400 Hz正弦电压、1~101 kPa气压范围内进行了大量重复实验,探究了气压对两种故障起始放电电压(PDIV)、放电幅值、放电重复率以及相位分辨局部放电(PRPD)谱图等统计特征的影响。实验结果表明:不同模型下的PDIV随气压直线降低;随着气压的降低,放电幅值先增加后降低,放电重复率随着气压降低逐渐增加,根据累积放电幅值的分析,最高点均出现在30 kPa处;随着气压的降低,两种绝缘故障的PRPD相位宽度逐渐增加并向左偏移,电机绕组放电和电缆对地放电分别以“兔耳朵”和“极性效应”为主要特征。本实验对不同故障及气压下放电特征的探究及分析,将有助于多电飞机电气系统绝缘测试的开展和评估,为未来多电飞机向大功率高电压方向的发展提供借鉴和参考。

More Electric Aircraft(MEA) adopts electricity to replace some traditional mechanical parts, which can effectively improve flight efficiency and reduce emission of greenhouse gases. To enhance the capacity of the MEA power supply system, potential supply voltage will reach up to several kV, which will lead to severe risk of partial discharge. Two typical insulation failures of turn-to-turn discharge in the aviation machine and cable-to-ground discharge of the MEA are modeled in the laboratory. A number of experiments are carried out to explore the influence of air pressure on Partial Discharge Inception Voltage(PDIV), discharge amplitude, discharge repetition rate and Phase-Resolved Partial Discharge(PRPD) at 400 Hz sinusoidal voltage and 1-101 kPa air pressure. Experimental results show that PDIV decreases linearly with air pressure under different models. As the air pressure decreases, discharge amplitude increases first and then decreases, and the discharge repetition rate gradually increases. According to analysis of the cumulative discharge amplitude, the highest point always appears at 30 kPa. As the air pressure decreases, PRPD with two insulation failures offsets left together, and phase width gradually increases. The PRPD in turn-to-turn discharge and in cable-to-ground discharge are characterized by “rabbit ears” and “polarity effect”, respectively. Our study can contribute to insulation testing and evaluation of the MEA electric system, and the results are expected to provide reference for the development of high power and high voltage electric system in MEA.