换流器限流状态下的配电网潮流计算方法

Power flow calculation for distribution network under the current limiting status of grid-connected inverter

在利用潮流计算方法分析配电网的电压稳定性时,由于换流器本身的限流作用,当配电网电压下降到一定程度后,换流器并网型分布式电源可能进入限流状态。因此,引入一种新的Iθ节点模型对运行于限流状态下的换流器型分布式电源进行等效,同时提出一种含Iθ节点配电网的潮流计算方法。该方法根据Iθ节点功率平衡方程的变化,利用牛顿迭代法,构造新的雅克比矩阵和修正方程组对配电网潮流进行计算。最后在IEEE33节点标准算例中对所提潮流计算方法进行了验证。算例结果验证了所提方法的有效性。

If the voltage stability of distribution network is analyzed according to power flow calculation method, inverter based distributed generation could get into the current limiting status after distribution network voltage drops to a certain degree due to its inverter’s current limiting function. So a novel Iθ bus model is introduced to describe the inverter based distributed generation under current limiting status. Meanwhile a power flow calculation method based on the Iθ bus type is proposed. According to the variation of bus power equation of Iθ bus and the Newton iteration method, a new Jacobian matrix and correction equations are established to calculate the power flow. Finally, some tests are done in a typical IEEE33 distribution network to verify the proposed method. The results show the method is correct and accurate.