Harmonic Power-Flow Study of Hybrid AC/DC Grids with Converter-Interfaced Distributed Energy Resources

TL;DR

This paper extends a harmonic power-flow method to accurately model hybrid AC/DC grids with converter-interfaced distributed energy resources, capturing harmonic interactions and validating results with detailed simulations.

Contribution

The paper updates the Harmonic Power-Flow method to include the modeling of Network-Interfacing Converters and their coupling effects in hybrid AC/DC grids.

Findings

The updated HPF method accurately predicts harmonic interactions.

Validation confirms the model's effectiveness against time-domain simulations.

The approach reduces costs and losses in hybrid power systems.

Abstract

As the share of Converter-Interfaced Distributed Energy Resources (CIDERs) in power distribution systems increases, hybrid AC/DC distribution systems are drawing more interest. Indeed, CIDERs usually rely on DC power and hybrid AC/DC grids with few Network-Interfacing Converters (NICs) are a promising solution to decrease installation costs and conversion losses compared to a pure AC grid. However, interactions between the AC and DC subsystem of a hybrid AC/DC grid can lead to undesirable amplification and propagation of harmonics. The authors of this paper have recently proposed a Harmonic Power-Flow (HPF) method that accurately represents the AC power flows including the coupling between different harmonics. The HPF framework is formulated through the mismatch equations of the nodal equations between the grid and the resource models and solved by a Newton Raphson algorithm. This paper updates the HPF method to model hybrid AC/DC grids interconnected through NICs. To this end, the model of the NICs and the resulting coupling between the AC and DC subsystems is included in the mismatch equations and the Jacobian matrix of the algorithm. The updated HPF method is applied to a typical hybrid AC/DC grid, and its accuracy is validated through detailed time-domain simulations with Simulink.