Enhanced modeling and control of VSIs in microgrids operating in grid-connected mode

Abstract

This paper focus on the influence of filter dynamics on the performance and stability of current control loops of threephase, pulse-width modulation (PWM) voltage source inverters (VSIs) in grid-connected operating mode. The analysis considers the application of those devices in microgrids. Based on a detailed state-space model of VSIs and their companion filters, enhanced controller design techniques are applied in order to prevent the drawbacks of conventional microgrid control strategies. The effectiveness of the proposed control strategy is verified via computer simulations.

Small-Signal Stability and Resonance Perspectives in Microgrid: A Review

“…The resulting small-signal model is time-variant due to the presence of periodic switching actions. Hence, transformation into a rotating reference frame must be conducted to obtain a time-invariant small-signal model, as depicted in [12,15,25]. A detailed representation of time-averaged switching components of the PWM control scheme has been studied and reported in [12].…”

Comprehensive modeling and practical verification of grid connected VSI with LCL filter

“…The DC-link voltage can be placed as a constant in the B matrix of a state-space system, while the switch positions is a part of the input vector u(t). This approach has been used in [4][5][6]. The alternative is to consider nonconstant DC-link voltage, but dependent on the capacitor charge.…”

“…All values are averaged over one switching period, simplifying the model by replacing inverter switches with voltage sources [2]. This is a commonly used simplification and is used in similar papers such as [3][4][5]. While this approach can be used to analyze traditional control algorithms, a more detailed model is needed to simulate variables within one switching period.…”

Grid connected VSI with LCL filter — Models and comparison

“…All values are averaged over one switching period, simplifying the model while the inverter switches are replaced with voltage sources [1]. This is a commonly used simplification used in similar papers such as [2][3][4]. Another commonly used simplification, is assuming constant DC-link voltage where the capacitor is replaced by a constant voltage source.…”

“…Another commonly used simplification, is assuming constant DC-link voltage where the capacitor is replaced by a constant voltage source. This approach has been used in [3][4][5]. In [6], none of the two simplifications above are used.…”