低频输电高压电力电缆多物理耦合场数值分析及载流量计算

Multi-physics Coupling Field Numerical Analysis and Ampacity Calculation of High-Voltage Power Cable Under Low-Frequency Transmission Mode

近年来,随着可关断电力电子器件的逐渐成熟和广泛应用,柔性低频交流输电技术受到广泛关注。由于频率越低,交流电磁场的集肤和邻近效应越弱,因此低频运行工况下电力电缆的载流量与工频50 Hz运行工况下电力电缆的载流量将不尽相同。为此,基于多物理耦合场及有限元法,提出了三芯海底电缆埋设方式下磁热流耦合场计算模型和计算方法,分析了不同截面电缆在低频输电工况下载流量数值变化规律及损耗特性。计算结果表明,降低输电频率可有效提升电缆载流量;电缆截面积越大,载流量提升效果越显著;当截面积为500 mm 2、1000 mm 2和2000 mm 2时,相比于工频输电方式,电缆载流量分别提升11.33%、23.26%和34.40%;降低频率可减少电缆总损耗,由环流引起的护套及铠装层损耗平均分别降低了14.85%、6.34%。计算结果为低频输电方式下电缆选型及输电容量提升提供数据决策依据。

In recent years,with the gradual maturity and wide application of switchable power electronics devices,the flexible low-frequency AC transmission technology has been widely investigated.The lower the frequency is,the weaker the skin and neighboring effects of AC electromagnetic fields are.The ampacity of cable under low frequency operation will inevitably be different from that of cable under 50 Hz frequency operation.Therefore,based on the multi-physics coupling field and finite element method,the calculation model and calculation method of magnetothermal flow coupling field under the buried mode of three-core submarine cable are proposed,and the change law and loss characteristics of download flow values of different cross-section cables under low-frequency transmission conditions are calculated.The numerical results show that reducing the transmission frequency can effectively increase the cable ampacity.The larger the cross-section area of the cable,the more significant improvement effect of the ampacity.When the cross-section area are 500 mm 2,1000 mm 2 and 2000 mm 2,respectively,the cable ampacity is increased by 11.33%,23.26%and 34.40%compared with the power frequency transmission mode.Reducing the frequency can reduce the total loss of the cable,and the loss of sheath and armor layer caused by circulating current is reduced by 14.85%and 6.34%respectively.The calculation results provide a data decision-making basis for cable selection and transmission capacity improvement under low-frequency transmission mode.