Influence Rules and Mechanism Analysis of Distribution Network Flexibility Degree on Distributed Generator Accommodation

Two hot topics in distribution network research are power electronics flexibility and distributed generator (DG) accommodation. This paper revealed the influence rules and their mechanisms of distribution network flexibility degree on DG accommodation. Firstly, the concept of distribution network flexibility degree was introduced, and its definition was improved. Then, by taking typical wiring modes and the expanded IEEE RBTS-Bus4 test system as the research objects, the change in the DG accommodation ratio was observed as the flexibility degree started from 0, and the rules and mechanisms were analyzed. The results show that not all distribution network flexibility can improve DG accommodation, and there is an effective condition. In other words, there is a surplus of DG relative load in the feeder on one side of the soft open point (SOP) and a DG shortage on the other side. However, the regularity between the DG accommodation ratio and flexibility degree doesn’t appear after the effective condition is met. This paper thus proposes two approaches, namely analyzing the restriction conditions of DG accommodation increase and observing SOP installation order, and finds the hidden rules: The flexibility degree and DG accommodation ratio have a positive correlation when there is available space for DG accommodation increase, without the SOP capacity restriction, or when they are in the same SOP installation order. The rules and mechanisms found in this paper provide a new theoretical basis for guiding the flexible development and DG accommodation of distribution networks.