特高压管廊GIL热特性的数值模拟

Numerical simulation of thermal characteristics of gas-insulated transmission lines in UHV pipe gallery

摘要:

为研究管廊绝缘气体输电线路(gas-insulated transmission lines, GIL)的热特性影响因素，考虑外壳的电感效应和阻抗的温度效应，提出了含外部空气域GIL热特性的三维气热耦合有限元数值计算方法.针对苏通GIL综合管廊工程的特点，利用该方法研究空气流速、负载电流、环境温度、绝缘气体压强、表面辐射率5个因素对该GIL热特性的影响.计算结果表明：空气流速低于10 m/s时，增大空气流速可有效降低GIL温度，但随着空气流速的继续增大，降温效果下降；负载电流增加会导致GIL温度的急剧升高，且导体温升＞外壳，两者之间温差将增大；GIL温度与环境温度呈线性比例关系，而导体与外壳温差随环境温度的升高略有减小；绝缘气体压强在0.5 MPa时，增大气体压强有利于导体散热，但外壳温度变化＜0.5 ℃；增大外壳内表面或导体外表面的辐射率都将使导体温度降低，但外壳温度不变，同时导体温度对导体外表面的辐射率变化更为敏感.

Abstract:

To study the influencing factors on the thermal characteristics of Gas-insulated Transmission Lines (GIL) in pipe gallery, considering the inductance effect of the enclosure and the temperature effect of the impedance, including external air domain, a three-dimensional finite element method of coupling fluid field and thermal field was established. With this model, aiming at the characteristics of Sutong GIL integrated corridor project, the effects of five factors, such as air flow rate, current, ambient temperature, the pressure of insulation gas and emissivity, on the thermal characteristics of the GIL were studied. The simulation results show that increasing the air speed at an air flow rate below 10 m/s can effectively reduce the temperature of GIL, but with the air flow rate continues to increase the cooling performance is poor. With the increasing of current, the temperature of GIL will rise sharply, the temperature rise of the conductor is much higher than that of the enclosure, and the temperature difference between the conductor and the enclosure will increase. The temperature of GIL is linearly proportional to ambient temperature, and the temperature difference between enclosure and conductor becomes smaller. When the pressure of insulating gas is within the range of 0.5 MPa, increasing the gas pressure facilitates the heat dissipation of conductor, and the temperature changing of enclosure is less than 0.5 ℃. With the increasing of emissivity of the inner surface of enclosure or the outer surface of conductor, the temperature of conductor will reduce while the temperature of enclosure is constant, and the temperature of conductor is more sensitive to the changes of the emissivity of conductor surface.