An Adaptive Parameter-Based Control Technique of Virtual Synchronous Generator for Smooth Transient Between Islanded and Grid-Connected Mode of Operation

Abstract

This paper deals with the development of a control technique for the control of voltage source converters (VSCs) as an interface between renewable energy sources (RESs) and power grids. The lack of inertia in converter-based generators and their unconventional dynamic behavior increase the negative impacts on the power grid, unlike the operation of the conventional synchronous generators (SGs). In this sense, the proposed control technique emulates the behavior of SGs in the control loop of the interfaced converter acting as a grid-forming power generator. Thus, supportive functionalities for enhancing electric grid stability (e.g., frequency oscillation damping) will be provided by interfaced converter as a virtual synchronous generator (VSG). The main targets of the proposed control technique include virtual inertia emulation, frequency oscillation damping, primary and secondary frequency regulation, and voltage regulation. The main contribution of this work over the existing methods is that the optimal values for swing equation parameters are employed to ensure well-designed damping feature of the VSG-based converter which adapts grid-connected and islanded operating modes, enabling a smooth resynchronizing to the grid as its plug-and-play capability requirement. The control structure is evaluated through simulation in MATLAB/Simulink.

A Power Decoupling Method for Virtual Synchronous Machine in Low Voltage Micro-grid

“…Linking the inverter and grid synchronous frames yields vector transformation from inverter's, xc , to grid's xs by ∆x s = ∆x c + j x0 ∆δ, where x0 is the steady-state vector and ∆δ is the control imposed angle perturbation. Connecting the controller (21), filter (22,23), and grid (24) by angle dynamics yields the closed-loop VSG system through the input ĩs g and output ṽs c being T g ∆ṽ s c = C i C v (∆ṽ r − ∆ṽ s c ) + jG θ,v ∆θ + (sL s + β k C i + jX ∆ ) Ỹg ∆ṽ s n ,…”

“…Static P Q decoupling involves using a rotational power frame to match grid impedance angle [20]- [22]. To adapt to grid topology variations, event-based adaptive tuning strategies are proposed by [23], [24]. Full-state feedback P Q decoupling is also proposed in [25].…”

Power stability control of wind-PV-battery AC microgrid based on two-parameters fuzzy VSG

“…The adaptive regulation of the virtual inertia was achieved in Fathi et al (2018) and Hou et al (2020), but the effect of the damping coefficient on the system was not considered, and the adaptive adjustment of the damping coefficient helped to avoid frequency instability and collapse of the system (Skinder et al, 2022). In Pouresmaeil et al (2021), the optimal value of the damping coefficient in the VSG oscillation equation is investigated for facilitating a smooth transition between grid-connected and islanded modes. The effect of the damping coefficient on the inertial capacity enhancement was considered, but the adaptive nature of the virtual inertia was neglected.…”