中文说明：该代码是电力系统分析中应用牛顿拉夫逊法的潮流计算程序。代码开始部分求出了节点导纳矩阵，接着是节点电压的代码，最后部分给出功率的程序编写。
English Description：
The code is the power flow calculation program of Newton Raphson method in power system analysis. At the beginning of the code, the node admittance matrix is obtained, then the node voltage code, and finally the power programming is given.