Combined decentralized and local voltage control strategy of soft open points in active distribution networks

With the integration of high shares of distributed generators (DGs), it is increasingly difficult to cope with the voltage violations and puts forward a higher requirement for the operational flexibility in active distribution networks (ADNs). Soft open point (SOP) can realize accurate power flow control and continuous voltage regulation, which is usually operated by the centralized control strategy. However, the heavy burden of communication and complex global optimization process hinder its application on fast voltage control. This paper proposes a combined decentralized and local voltage control strategy of SOPs to rapidly cope with the frequent voltage fluctuations. Based on the dynamic network partition results, the decentralized optimization is applied to regulate active power transmission of SOPs among the connected areas. The Q-V control curve is optimally tuned to locally regulate the reactive power outputs of SOPs by using the intra-area information. Compared to the widely-used centralized strategy, the proposed combined control strategy of SOPs can effectively reduce the communication and computational burden with acceptable voltage control performance. Finally, the effectiveness of the proposed control strategy of SOPs is validated on the modified PG&E 69-node distribution system and modified IEEE 123-node distribution system.