Centralized-Distributed Coordinated Voltage Control of Active Distribution Networks With Renewables

With the growing integration of diverse distributed energy resources in large-scale active distribution networks (ADNs), adopting only centralized or distributed methods is challenging to ensure the voltage control performance in terms of optimality and instantaneity simultaneously. This paper proposes a centralized-distributed coordinated voltage control (CDVC) strategy, which facilitates the optimal scheduling and the real-time control of various distributed resources in multi-level ADNs to guarantee voltage security against uncertainties. The multi-level ADN is physically divided into the medium-voltage primary ADN and low-voltage secondary ADNs, controlled in a centralized and distributed manner, respectively. An integrated distributed optimization method is developed to optimally coordinate primary and secondary ADNs over multi-time steps. In this method, the alternating direction method of multipliers and the back-and-forth communication (BFC) are employed to coordinate multi-voltage-level ADNs and achieve distributed optimization of secondary ADNs, respectively. Additionally, to promote fast real-time control, global sensibilities obtained by the distributed BFC are used to stimulate devices in the secondary ADN to alleviate all possible voltage violations caused by uncertainties. The event-triggered simplified centralized voltage optimization is further constructed in the primary ADN with rapid resource response to ameliorate voltages of the entire ADN while avoiding privacy infringement of secondary ADNs. Numerous case studies based on a modified 33-bus/123-bus primary ADN and 11-bus secondary ADNs demonstrate the effectiveness and efficiency of the proposed CDVC strategy.