Abstract：Under the large-scale renewable energy integrated with uncertain output characteristics，balancing

the supply and demand within a local area becomes a new challenge. The long-distance transmission and

consumption scheme is utilized for the sending-end grid to meet the requirements of renewable energy consumption.Within the constraints of thermal stability，dynamically improving the transmission lines' rating capacity has become a critical method for the sending-end power grid. However，due to the insufficient thermal stability calculation model，the existing improvement methods have the problems of significant evaluation deviation and narrow applicability in the practical application of the sending-end power system the improvement scheme usually needs to be customized and modified for specific line. In order to solve above issues，firstly，the influence of dustcorona heating on the thermal stability transfer capacity at the sending end was analyzed，and an improved model of line thermal rating based on the dust effect was proposed. Furthermore，considering the uncertainty of the dust effect，a calculation method of dust effect control parameters based on fuzzy analysis was proposed，and the thermal rate capability calculation model was improved. Finally，combined with the meteorological forecast，a scheme for improving the thermal rating capacity of the renewable energy transmission power grid was constructed，which can be analyzed for multiple lines simultaneously. Via the practical engineering case of the Ningxia power grid and the power meteorological forecast data of China Electric Power Research Institute，the effectiveness and applicability of the improvement model of dust effect and the improvement scheme of multi-line thermal stability transmission capacity were verified.

      Key words：renewable energy sending-end power system；thermal stability transfer capacity；dust effect；

thermal balance equation；improvement method