Distributed control of active distribution networks to support voltage control in subtransmission networks

Abstract

Utilizing highly distributed energy resources (DERs) dispersed in distribution networks is attracting recent attention as an effective solution to support voltage control in subtransmission networks. However, a subtransmission network usually has a large number of DERs within a small number of distribution networks. It is impractical to control these DERs directly by the subtransmission voltage controller (STVC). To solve this challenge, each distribution network with DERs is treated as a distributed energy resource cluster (DERC) and serves as the intermediary between DERs and the STVC. The primary objective of each DERC is to rapidly follow the active power change command given by the STVC. However, due to the high R/X ratio of lines in distribution networks, the active power changes of DERs can also lead to serious power quality issues. To overcome these issues, this paper develops a novel distributed control framework for DERCs. The proposed control framework consists of two modules: a command following module and a power quality management module. The former one aims to rapidly track the active power change command from the STVC by coordinating the active power of DERs in an optimal distributed manner. The latter one aims to improve the power quality by coordinating both the active and reactive power of DERs also in an optimal distributed manner. The effectiveness of the proposed control framework is tested through a modified IEEE 30-bus test system as the basic network to gather with IEEE test feeder networks.