Stabilizing plug-and-play regulators and secondary coordinated control for AC islanded microgrids with bus-connected topology. (15th January 2018)

• Record Type: Journal Article
• Authors: Riverso, Stefano; Tucci, Michele; Vasquez, Juan C.; Guerrero, Josep M.; Ferrari-Trecate, Giancarlo
• Is Part Of: Applied energy. Volume 210(2018)
• Page Start: 914
• Page End: 924
• Publication Date: 2018-01-15
• Subjects: Distributed control -- Secondary control -- Plug-and-play design -- AC islanded microgrid -- Reactive power sharing -- Voltage and frequency control; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2017.08.110
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: Distributed control scheme for guatanteeing stability in Islanded microGrids (ImGs). Modular procedure for designing Plug-and-Play controllers in bus-connected ImGs. Automatized update of the primary layer when units plug in/out. Stability ensured. Definition of a secondary layer for bus voltage tracking and reactive power sharing. Feasibility of the proposed control design framework validated through experiments. Abstract: This paper presents a distributed hierarchical control architecture for voltage and frequency stabilization and reactive power sharing in AC islanded microgrids. In the primary control layer, each generation unit is equipped with a local regulator for voltage and frequency stability acting on the corresponding voltage-source converter. Following the plug-and-play design approach previously proposed by some of the authors, whenever the addition/removal of a distributed generation unit is required, feasibility of the operation is automatically checked by designing local controllers through convex optimization. The update of the voltage-control layer, when units plug-in/-out, is therefore automatized and stability of the microgrid is always preserved. Moreover, local control design is based only on the knowledge of parameters of power lines and it does not require to store a global microgrid model. In this work, we focus on islanded microgrids with bus-connected topology and enhance the primary plug-and-play layer with local virtual impedance loops and secondary coordinated controllers ensuring bus voltage tracking and reactive power sharing. In particular, the secondary control architecture is distributed, hence mirroring the modularity of the primary control layer. We validate primary and secondary controllers by performing experiments with both linear and nonlinear loads, on a setup composed of three bus-connected distributed generation units. Most importantly, the stability of the microgrid after the addition/removal of distributed generation units is assessed. Overall, the experimental results show the feasibility of the proposed modular control design framework, where generation units can be added/removed on the fly, thus enabling the deployment of virtual power plants that can be resized over time.