Augmentation of Generalized Multivariable Grid-Forming Control for Power Converters with Cascaded Controllers

TL;DR

This paper introduces a multivariable MIMO-GFM control strategy for power converters that couples AC and DC loops, enabling simultaneous and optimal tuning without relying on traditional decoupling assumptions, resulting in improved robustness.

Contribution

It proposes a novel multivariable feedback control design for power converters that integrates AC and DC loops using H-infinity synthesis, enhancing robustness and performance.

Findings

Experimental results confirm improved robustness.

Simultaneous tuning of all loops is achieved.

Control performance surpasses traditional decoupled methods.

Abstract

The classic design of grid-forming control strategies for power converters rely on the stringent assumption of the timescale separation between DC and AC states and their corresponding control loops, e.g., AC and DC loops, power and cascaded voltage and current loops, etc. This paper proposes a multi-input multi-output based grid-forming (MIMO-GFM) control for the power converters using a multivariable feedback structure. First, the MIMO-GFM control couples the AC and DC loops by a general multivariable control transfer matrix. Then, the parameters design is transformed into a standard fixed-structure H-infinity synthesis. By this way, all the loops can be tuned simultaneously and optimally without relying on the assumptions of loop decoupling. Therefore, a superior and robust performance can be achieved. Experimental results verify the proposed method.