电力系统最优潮流新模型及其内点法实现

New Optimal Power Flow Model and Its Solution by Using Nonlinear Interior Point Method

为了加快内点法求解电力系统最优潮流OPF(optimal power flow)问题的计算速度,通过在有载调压变压器LTC(load tap changing transformer)支路模型中增加虚拟节点,其支路功率方程由该节点的电压来表达,使其不含有变压器变比这个变量,由此在直角坐标系中建立了电力系统最优潮流问题的二阶新模型。该模型的海森矩阵在优化过程中是恒常矩阵,只需要计算1次,缩短了内点法的计算总时间。利用列近似最小度法COLAMD(column approximate minimum degree)对内点法牛顿方程的系数矩阵进行节点优化排序,以减少三角分解注入元的产生,从而进一步减少优化时间。通过对IEEE14到IEEE300的5个测试系统进行了仿真计算,结果验证了所建模型与方法的正确性与有效性。

To accelerate optimization speed for optimal power flow （OPF） by using interior point method,a new optimal power flow model in rectangular form is proposed in this paper.In this model,the load tap changing transformer （LTC） branch is represented by introducing a dummy node located between series impedance and its ideal transformer.The dummy node can replace the tap ratio of LTC to express the LTC branch power equations,so that the OPF model becomes quadratic.These results in the proposed model have the constant Hessian matrices,which speed up the calculation greatly.Column approximate minimum degree （COLAMD）algorithm is used to order the coefficient matrix,which greatly reduces fill-in elements.The new and conventional methods are developed in Matlab to compare the performances.The results obtained from the implemented five test systems ranging from IEEE 14 to IEEE300 buses indicate that the proposed method achieves a superior performance than the conventional rectangular coordinate-based OPF.