Research on Aggregation Flexibility Method of AC/DC Distribution Network Considering Flexibility Balance and Its Application

The large number of connected renewable energy sources has greatly increased the flexibility demand in the system. At the same time, the ac/dc active distribution network (ADN) will also become the main form of the future distribution network. Therefore, it is very meaningful to study how the ac/dc ADN aggregates flexibility and participates in the dispatching of the transmission network as a flexibility resource. To this end, this article aggregates the ac/dc ADN into a virtual generator with ramp and power parameters. In particular, the flexibility in the ac/dc ADN is subdivided into ramp and power flexibility and incorporated into the aggregation model. Then, an energy-based flexibility cost function is constructed for the aggregated distribution network. Therefore, without relying on the electricity market, the distribution network can be used as a flexible resource to participate in the flexible dispatching of the transmission network. Finally, the effectiveness of the proposed method and model is verified by several case studies.