Analysis of the Interaction Among Power Converters Through Their Synchronization Mechanism

Fundamentals of power systems modelling in the presence of converter-interfaced generation

“…The synchronization [53,54], and external control layers [55] may bring negative damping in the low frequency range, while the inner control layers impact on the stability in the high frequency range. The accurate analysis of resonance instabilities requires special attention to the modelling of power electronic converters and adapting it depending on the observed phenomenon [56].…”

“…On the contrary, state-ofthe-art grid connected converters adopting PLLs or similar synchronization techniques, do introduce an unavoidable delay, due to the necessity for an accurate estimation of amplitude and phase of the instantaneous grid voltage for the proper injection of the required amount of current. Therefore, driven by the need for enhancing the performances of grid-connected converters in reducing their reaction time following a grid event, studies have shown that there are physical limitations to the highest PLL bandwidth of grid-following (GFL) converters [53,59]. To this extent, a trade-off for the design of PLL bandwidth has to be made between power quality and stability of the grid.…”

“…To this extent, a trade-off for the design of PLL bandwidth has to be made between power quality and stability of the grid. The concept of grid-forming (GFM) converters, initially introduced for micro-and islanded grid applications, has been recently proposed for applications in wide interconnected systems, and it will be discussed in section V. Studies have shown that, in contrast to GFL converters using PLLs [53,59], power-synchronization based algorithms are particularly suitable for weak grid applications [60][61][62].…”

System Frequency Dynamic Response of a Novel, Self-Synchronizing Inverter in a High Renewable Penetration Grid

“…One reason for this drawback is that modern power converters require fast detection and accurate knowledge of the grid angle [6]. For faster angle detection, increasing the bandwidth of a PLL has been considered, [8], but is limited by the presence of other converters operating nearby [9], weaker grid conditions tied to short circuit ratios [9], [7], and large penetration levels of DG units which can correspond to low-frequency power oscillations and system instabilities [7]. Many of the attempts to design a better PLL to handle such conditions have not considered the coupling effects and interactions between the PLL and system impedance network, which impacts PLL tuning [8].…”

Grid-Synchronization Stability Analysis for Multi DFIGs Connected in Parallel to Weak AC Grids

“…Instability is attributed to the interaction of the qq channel impedance of the two VSCs and the impedance characters can be shaped by PLL tuning. Literature [12] introduces a stability margin index in the multi-input multi-output framework to study the coupling between two VSCs in parallel, and indicates that the interactions between VSCs become stronger with the decrease of grid SCR. Similar results are also reported for parallel-operated PMSG-based wind turbines in [13].…”