Abstract
Continuously expanding deployments of distributed power generation systems are transforming conventional centralized power grids into mixed distributed electrical networks. The higher penetration and longer distance from the renewable energy source to the main power grid result in lower grid strength, which stimulates the power limitation problem. Aimed at this problem, case studies of inductive and resistive grid impedance with different grid strengths have been carried out to evaluate the maximum power transfer capability of grid-connected inverters. It is revealed that power grids with a higher short circuit ratio (SCR) or lower resistance-inductance ratio (R/X) provide higher power transfer capability. Moreover, under the resistive grid conditions, a higher voltage at the point of common coupling (PCC) is beneficial to increase the power transfer capability. Based on mathematical analysis, the maximum power curves in the inductive and resistive grids can be found. Moreover, a performance index is proposed in this paper to quantify the performance of the system with different parameter values. Finally, the effectiveness of the analysis is verified by simulation.
Highlights
Due to a foreseen exhaustion of conventional fossil-based energies and their climate impact, traditional centralized power generation using fossil fuels has been increasingly considered unsustainable in the long term
A high voltage direct current (HVDC) system can replace the alternating current (AC) system for long-distance power transmission [4,5], the grid-side converter of the HVDC system still faces the challenge of connecting to a weak grid in some cases [6,7]
Based on our early work, this paper reveals that the point of common coupling (PCC) voltage amplitude is a key factor affecting the maximum power transfer capability of the system, especially in the resistive grid case
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The natural maximum power transfer capability of grid-connected inverters mainly depends on the physical parameters of the system, which is constant for an existing system [17,18] It is a key property for engineering design and analysis. It was reported in [19] that the SCR and the resistance-inductance ratio (R/X) of grid impedance affects the maximum power transfer capability of gridconnected inverters. Based on our early work, this paper reveals that the PCC voltage amplitude is a key factor affecting the maximum power transfer capability of the system, especially in the resistive grid case. It was found that a higher PCC voltage than the rated value in a resistive grid is beneficial to increase the power transfer capability of grid-connected inverters.
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