With the extensive integration of renewable energy sources in power system, the fluctuation characteristics of transmission and distribution network load have been further strengthened. However, for the power cable widely used in power system, its dynamic thermal behavior under continuously fluctuant load cannot be well modeled by the IEC method. It has not been sufficiently addressed in the literatures either. In this paper, the variation of the time-dependent Van Wormer coefficient and the error cumulative phenomenon of adopting the constant Van Wormer coefficient in conventional methods (including the IEC 60853-2 and the classical thermo-electric equivalent method) under continuously fluctuant cable load are discussed. Moreover, several different modification ways on the lumped thermal model of cable insulation to mitigate the possible error cumulative phenomenon are presented. The superiority of the modified methods compared with the conventional methods is verified by the real cable experiments. The results show that the modified methods can better reflect the cable's real thermal behavior under continuously fluctuant load. The modified methods are instructive for maximizing cable utilization while still ensuring cable reliability, which can be easy to be integrated into the existing real-time cable thermal rating system.

随着可再生能源在电力系统中的广泛应用，输配电网负荷的波动特性得到进一步加强。然而，对于电力系统中广泛使用的电力电缆，其在连续波动负载下的动态热行为不能用IEC方法很好地建模。文献中也没有充分论述。本文研究了在连续波动的电缆负载下，常规方法（包括IEC 60853-2和经典热电等效法）中Van Wormer系数的瞬态变化和采用恒定Van Wormer系数的误差累积现象进行了讨论。而且，提出了几种不同的电缆绝缘集总热模型修改方法，以减轻可能出现的误差累积现象。实际电缆实验验证了改进方法与传统方法相比的优越性。结果表明，改进后的方法可以更好地反映电缆在连续波动载荷下的真实热行为。修改后的方法对于最大限度地提高电缆利用率具有指导意义，同时仍然确保电缆可靠性，可以很容易地集成到现有的实时电缆热评级系统中。s 在连续波动负载下的真实热行为。修改后的方法对于最大限度地提高电缆利用率具有指导意义，同时仍然确保电缆可靠性，可以很容易地集成到现有的实时电缆热评级系统中。s 在连续波动负载下的真实热行为。修改后的方法对于最大限度地提高电缆利用率具有指导意义，同时仍然确保电缆可靠性，可以很容易地集成到现有的实时电缆热评级系统中。