节点电压为状态变量的交直流电网潮流算法

A Hybrid AC/DC Grid Power Flow Algorithm With Node Voltages as State Variables

当今,交直流电网快速发展,交流与直流的关联与耦合程度越来越强,交直流电网潮流问题必须得到有机、统一的处理。从同步电网角度出发,交直流电网潮流的本质依然显现交流电网的特性。由此,以包含电压源型换流器(voltage source converter,VSC)的直流网络为例,以交流网络和直流网络的节点电压为最小状态集,推导换流站仅关联状态变量的功率方程,并通过对直流节点分类,在不同的控制方式下演绎相关节点潮流方程的修正,用牛顿-拉夫逊方法对其求解。修正方程式中的雅克比矩阵体现了交直流的耦合关系且维持良好的稀疏规律,可以实现在算法中沿用稀疏技术,有利于进一步分析和研究交直流电网性能。以修改的IEEE 57节点交直流电网为例,验证了所提算法的有效性和求解效率。

Recently, hybrid AC/DC grid enters rapid development stage, and correlation and coupling between AC and DC becomes increasingly stronger. In this case, problem of hybrid AC/DC grid power flow must be uniformly processed. Based on synchronous power grid, essence of hybrid AC/DC grid power flow reflects characteristics of AC grid. Embarking from this mentality, based on DC grid with voltage source converters（VSCs）, with node voltages of AC and DC grids as state variables, this paper deduces power equations of converter station only related to these state variables and power flow equations. Using Newton-Raphson method, hybrid AC/DC grid power flow algorithm is realized. In this algorithm, Jacobian matrix of modified equations is the same as that in AC grid, contributing to application of sparse technology and showing sensitivity between AC and DC grids. This algorithm is suited for profound analysis and study of hybrid AC/DC grid properties. The algorithm is proved effective with simulation of a modified IEEE 57-bus AC/DC grid.