Secondary frequency regulation scheme based on improved virtual synchronous generator in an islanded microgrid

To aim at the defects of the traditional VSG (virtual synchronous generator) control schemes to only complete the primary frequency regulation equivalent to droop control, and not to realize the secondary frequency regulation, this paper proposes a new control scheme to realize the secondary frequency regulation of the VSG, such that system frequency can return to the rated value. In this method, the torque change process of the rotor of synchronous generator is firstly analyzed when the system active power fluctuates. And then, a novel secondary frequency regulation control strategy of the VSG is proposed, where the small-signal model of power transmission of the VSG is established and transfer function is analyzed, and parameters design and stability analysis of the control system are conducted. Finally, simulation experiments show the correctness and effectiveness of the proposed method

Hybrid AC/DC Microgrid Mode-Adaptive Controls

The lack of inertial response at microgrids is usually compensated by configuring primary controllers of converter‐interfaced devices to contribute in the transient response under power disturbances. The main purpose of this chapter is to study the modes of operation of primary level techniques of generation, storage, loads, and other devices attached to hybrid ac/dc microgrids. Although the chapter includes an analysis of the modes of operation of lower‐level regulators, the focus is on upper‐level or primary controllers. In this context, we analyze mode‐adaptive controls based on voltage and frequency levels and we evaluate their behavior by simulation in the Matlab/Simulink® environment. The results demonstrate that mode‐adaptive techniques are adequate for maximizing the energy extracted by distributed generation (DG) systems and limit demand side management actuations while ensuring an adequate regulation of the microgrid