大型客机油箱结构雷电点火源防护验证

为确定大型客机油箱结构雷电点火源防护设计有效性,表明燃油箱防爆条款适航符合性,通过仿真分析与试验相结合进行点火源防护验证研究。仿真分析结果表明:对于大型客机传统铝合金油箱结构,在雷电直接影响下,油箱内部结构与系统管路电流电压分量很低,电流值仅为407 A,电压值仅为11 V,远小于能够引起油箱内部点燃的门槛值。通过试验考察,进一步证实了在雷电3区试验波形作用下,油箱内部不会产生高于200μJ能量的点火源。电流和电压试验实测值为175 A和100 V,量级与仿真分析相当。据此可表明,对于传统铝合金大型客机整体油箱,油箱内部雷电点火源防护是偏安全的。

Weibull Statistics in Dielectric Strength of Oil-impregnated Pressboard under Ramped AC and DC Voltages

AC and DC breakdown tests were performed on large populations of oil-impregnated pressboard samples. The effect of voltage ramp rate on dielectric strength has been investigated. A statistical analysis of breakdown data was carried out using the Weibull distribution. The 90% confidence intervals of Weibull graphs were calculated. The study shows that dielectric strength and shape parameter change versus ramp rate. The variations are attributed to the size and number of defects. Discharges occur from the oil to the oil-pressboard interface and lead to breakdown. DC dielectric strength is larger than that corresponding to AC voltage. This is ascribed to the dissipated energy difference under the two types of field and the fatigue produced by the alternating voltage. This phenomenon is related to space charge. Under DC stress, dielectric strength is higher under negative polarity. It is assigned to the different quantities of space charge accumulated under the two polarities.

基于HWLL的同期线损模型研究

同期线损是电力系统运行中一个重要的指标,其反映了电网输电线路的效率和负载状况。目前,半波长线路(Half-wavelength lines, HWLL)传输已被研究为应用于超长距离电力传输的替代方案。因此,基于HWLL输电线路,提出了一种同期线损的评估模型。首先,通过相量图计算分析了沿线的电压和电流幅值分布。其次,提出了HWLL输电线路的同期线损的代数表达式,用于HWLL的经济评估。最后,仿真实验表明所提出的模型计算值与实际线路损耗存在较高的一致性与拟合度,因此,应用所提出的模型可以清楚地了解其在不同负载情况下的运行状态。同时,研究为电力系统的运营和规划提供了重要的参考依据,有助于提高系统的效率和可持续性。