含低电压穿越型分布式电源配电网的短路电流计算方法

换流器型分布式电源(DG)在配电网中的应用使传统配电网的短路电流计算方法不再适用。根据DG在配电网故障点前后位置的不同,将DG处理为不同类型的故障等效模型,故障点上游DG采用低电压穿越故障等效模型,故障点下游DG采用恒定电流源故障等效模型。提出了一种基于叠加定理的短路电流迭代计算方法,在每一次迭代过程中,根据当前节点电压和DG的故障等效模型分别修正故障点上游DG和下游DG的输出短路电流,并利用节点电压方程求解配电网的短路电流和节点电压分布,直到满足收敛条件。通过对算例系统的分析计算,验证了所提方法的正确性。该方法可应用于含DG的大规模配电网的短路电流求解。

Short-circuit Current Calculation of Distribution Network with Distributed Generators Controlled by Low Voltage Ride Through

The application of inverter-based distributed generators (DGs) in the distribution network has made the conventional short-circuit current calculation method of the distribution network no longer applicable. According to DG locations in the distribution network, the DGs are treated as different types of fault equivalent model. The DGs connected upstream are modeled as the low voltage ride through (LVRT) fault equivalent model while those connected downstream the constant-current-source fault equivalent model. Then an iterative short-circuit current calculating method based on the superposition theorem is proposed. In each iterative procedure, the short-circuit current outputs from the DGs are modified according to the current bus voltage and the corresponding fault equivalent model of DGs. And the bus voltage equation is used to calculate the short-circuit current and bus voltage distribution until the convergent conditions are met. Finally, the calculation results concerning the test systems show that the proposed method is effective and accurate. The method can be applied to short-circuit current calculation in large-scale distribution network with DGs. This work is supported by National Natural Science Foundation of China (No. 51507139), Shaanxi Provincial Specialized Fund for Key Discipline Developmemt (No. 5X1301), and Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP) of China (No. 20126118110009)