Distributed ADRC-Based Secondary Voltage Control of Droop-Controlled AC Microgrid

Abstract

The voltage of MG in islanded mode is vulnerable to various disturbances due to its low inertia characteristic. This chapter proposes a robust distributed secondary control method for voltage restoration of an islanded MG with inverter-based distributed generators (DGs). In the proposed method, each DG only requires the knowledge of its own and immediate neighboring information. And it dispenses with the need of complex communication network. Unlike most of the existing methods relied on detailed and accurate mathematic models, the proposed method adopts an active disturbance rejection control (ADRC) technique which only needs minimal model information but significantly mitigates the impact of model uncertainties and unknown disturbances. By means of dynamically linearizing compensation, the proposed robust distributed secondary voltage controller can be built on a quasi-linear model with proportional feedback control design. The control law design and parameter selection of the proposed ADRC-based distributed secondary voltage controller are discussed considering the closed-loop stability constraint for the composite system. The robust performance of the proposed control approach is verified based on a 4 DGs-based islanded MG test system. Results show that the proposed control method is entitled with high robustness against both constant perturbation and time-varying disturbance.