采用MATLAB仿真的变电站高压进线温度场和载流量数值计算

Numerical Calculation of Temperature Field and Ampacity of High-voltage Lines Using MATLAB

随着电力电缆在输配电线路中的广泛应用,准确确定电力电缆及其周围环境温度场的分布和电缆的载流量对于提高电力电缆的使用率、动态调整负荷具有重要的意义。为此,以地下排管敷设的交联聚乙烯电力电缆为研究对象,其实际模型为1个容量为250MVA、额定电压为230kV的变电站的高压进线。根据传热学和有限元法(finite element method,FEM)基本原理,建立了1种基于有限元法的水泥排管敷设电缆温度场计算模型,并对电缆及其周围环境的求解区域进行复合有限三角形单元剖分,即对电缆区域进行较密集的网格划分,而对电缆周围的土壤区域则进行较为稀疏的网格划分,以提高程序的运算精度和运行速度。结果表明:用MATLAB软件仿真,从而得到电缆及其周围环境的温度场分布,迭代计算了排管敷设交联聚乙烯电缆的载流量。证明使用有限元的方法分析地下电缆温度场,为电力工程中电缆载流量确定提供了一个比较可靠的计算方法。

As more and more power cables are being used in power circuits,identifying the thermal field distribution of power cables and cable ampacity is very important to improve the capacity utilization of power cables so that adequate adjustment of cable loading can be achieved.Consequently,we evaluated the ampacity of XLPE cables laid in duct with pipes,which was 230 kV high voltage power cable in 250 MVA transformer substation.Using the principle of heat transfer theory and finite element method（FEM）,we developed a model for power cable thermal field,in which complex triangle finite element was divided as meshes in region,namely,dense meshes in cables and sparse ones in other areas were divided so as to improve the running speed of the program and operation precision.The thermal field of cables and surrounding cables was computed using FEM.The results show that through simulation with MATLAB,the temperature field distribution of the cable and its surroundings are obtained,the ampacity of single XLPE power cable systems are calculated by iteration method,proving that FEM can be used to analyze temperature field of underground cable system.