Network partitioning and hierarchical voltage regulation for distribution networks using holomorphic embedding method‐based sensitivity

The fluctuation of photovoltaics (PVs) output may cause the voltage out‐of‐limit, while the PV inverters and hybrid distribution transformers (HDTs) bring flexible controllability to distribution networks (DNs). However, there are differences in response speeds between power electronic equipment and traditional discrete regulating equipment. Therefore, a network partitioning and hierarchical voltage regulation method using holomorphic embedding method (HEM) ‐based sensitivity is proposed. Firstly, the HEM‐based voltage sensitivity is derived, and the network partitioning method is proposed using the HEM‐based sensitivity matrix. Then, the hierarchical voltage regulation framework is constructed. The objects of the upper layer are the minimum network loss and voltage deviation, which centrally optimizes the operation status of discrete regulation equipment. The lower layer exploits the fast control ability of PV inverters and HDTs, so as to autonomously regulate the voltage of each partition. Finally, a practical 10 kV DN in China is used for case studies. The results demonstrate that the HEM‐based voltage sensitivity calculation method has advantages in computational efficiency and accuracy compared with the conventional method. Moreover, the proposed voltage regulation method can suppress the voltage fluctuation. 1. The voltage sensitivity based on HEM is derived, and the network partition method is further proposed using HEM‐based sensitivity matrix. 2. The hierarchical voltage regulation framework is constructed. The objects of upper‐layer are the minimum network loss and voltage deviation, which centrally optimizes the operation status of discrete regulation equipment. 3. The lower‐layer excavates the fast control ability of PV inverters and HDTs, so as to autonomously regulate voltage of each partition.