中文摘要：

针对多区域电力系统的无功优化问题，提出了基于Ward等值的分解协调算法。将所有子区域分为主区域和从区域，并确定边界节点在不同区域中的节点类型和区域间相角传递方法。在基态条件下，根据潮流计算结果确定边界节点等值注入功率初值。采用矩阵求逆辅助定理，提高优化过程中外部网络变压器变比变化引起的等值导纳矩阵计算效率问题，且大幅度提高了外部网络等值精度。引入适合无功优化算法的外部协调策略，以较少的协调通信量获得较好的协调效果。以IEEE39节点和538节点实际系统为例，通过与集中优化方法进行比较，验证了该方法的有效性。

英文摘要：

This paper presents a new decomposition and coordination algorithm based on Ward equivalent to solve the reactive power optimization problem in the multi-area power system. First, the multi-area interconnected power system is partitioned into master and slave areas. The boundary buses are defined as different bus types respectively corresponding to different areas, and the transfer method of phase angles from master area to slave areas is determined. Second, the initial value of equivalent injection power is obtained according to power-flow calculation in the basic operating state. Then the computational inefficiency of the equivalent admittance matrix of the external network due to the variation of transformer ratios is solved by adopting the inverse matrix modification lemma. The equivalent accuracy of the external network is greatly improved. An external coordination strategy suitable for reactive power optimization calculation is introduced to obtain better coordination effects with less coordinating communications. In comparison with the centralized optimization method, the algorithm proposed has yielded test results concerning IEEE 39-bus and 538-bus practical systems that are both correct and effective.