基于非线性内点理论的交直流系统无功优化新模型

摘要

在交流侧有载调压变压器(Load tap changing transformer, LTC)支路中引进虚拟节点，并通过虚拟节点的电压来表示有载可调变压器支路功率方程；对于直流系统，在换流变压器的理想变压器和换流阻抗之间引进一个虚拟节点，虚拟节点电压幅值等一些变量被用来表示换流器支路方程；耦合方程把不同坐标系下的方程耦合到一起，由此建立了交直流混合系统无功优化问题的二阶新模型。预测-校正原对偶内点法被用来实现这个无功优化问题，该模型的海森矩阵在优化过程中是恒常矩阵，只需要计算一次，这样缩短了内点法的计算总时间。通过测试系统对新模型与传统模型进行仿真计算比较，结果验证了所建模型有较好的收敛特性。%For the AC system, the artificial node voltage is used to express the LTC branch power equations. For the DC system, an artificial node is introduced to locate between the ideal transformer and commuting impedance. Some variables such as artificial node voltage amplitude corresponding to the converter branch are included to express the converter equation. The coupling equations integrate the quadratic AC and DC equations from the different coordinates into a united quadratic AC-DC ORPF model. The predictor-corrector primal-dual interior point method (PCPDIPM) is used to implement the optimization. The Hessian matrices in this model are constant and require to be computed only once in the optimal process, which speed up the calculation greatly. The simulation results show that the proposed method achieves a good convergence property than the conventional one.