An Improved Power Flow Algorithm for Distribution Networks Based on Zbus Algorithm and Forward/Backward Sweep Method

This paper presents a new method: Zbus algorithm combined with the forward and backward algorithm to deal with power flow calculation of the distribution network with ringnet. The topological structure of the network can be analyzed by decomposing the branch network into radial parts and ringnet parts through the forward path which is the concept of the signal flow graph, using forward and backward algorithm on radial parts, calculation speed can be greatly improved by adopting parallel calculation, Zbus algorithm is used on ringnet parts, then the voltage and power of the boundary nodes will be corrected with the two parts calculation result to keep the whole network calculation in consistency. Finally, a practical example analysis shows that the method can not only processes the ring network problems very well, but also improves the calculation speed.

I. INTRODUCTION

Distribution power flow calculation is the basis of power system analysis. It plays an important role in the power system security, economic analysis, network reconfiguration and fault treatment. The structure of the distribution network is significantly different from transmission grid: it is generally closed-loop design, but open-loop operation; the resistance and reactance ratio is larger. These characteristics make the flow calculation of transmission grid distribution network a big difference.