Power Decoupling Control of MMC and Small-Signal Stability Analysis of AC/DC Distribution Network With Renewable Energy

The ever-increasing integration of power converter-coupled renewable energy sources reduces carbon footprints yet weakens power system inertia due to the retirement of synchronous generators. Inertia shortage makes modern power systems sensitive to frequency variations, thereby leading to undesirable load shedding, cascading failures, or even large-scale blackouts. To address the inertia concern, distributed virtual inertia from grid-tied power converters is emerging as an attractive solution. On top of that, there are upcoming standards of grid-tied power converters, such as PV inverters, that require grid formulation. As such, this paper proposes flexible distributed virtual inertia delivered by grid-forming converters without additional energy storage units. It is revealed that virtual inertia control may possibly cause stability problems. Through the derived state-space model and sensitivity analysis, the mechanism of instability is disclosed. Although droop control may stabilize converters, it inevitably necessitates extra energy storage, and is hence not cost-effective. Instead, a lead compensator, together with its design procedure, is proposed. Finally, simulation and experimental results validate the correctness and effectiveness of the proposed model and compensator. Moreover, the results demonstrate that the proposed grid-forming converters allow significant improvements in inertia and frequency regulation.

show abstract

A Unified Modeling Scheme of Modular Multilevel Converter for Hybrid AC/DC Power Grids

Xie

et al. 2022

Front. Energy Res.

View full text Add to dashboard Cite

Modular multilevel converters (MMCs), as one of the core components of hybrid AC/DC power grids, become the preferred converter topology and show good developments. Urgently, a general MMC modeling scheme with good model accuracy needs to be developed to realize small-signal analyses and designs for the large-scale AC/DC power grids easily. This paper proposes a unified modeling scheme (UMS) for MMC systems in a synchronous rotating (dq) reference frame. Based on the dynamic phasor theory and with the proposed modular decouple modeling (MDM), the nonlinear state-space model of the overall MMC system can be obtained by configuring and connecting the input and output of the state-space model of each subsystem. Besides, the unified controller, modeling different control modes, normalizes the MMC systems modeling. Simultaneously, with the proposal of UMS, linearization and splicing could be uesd to develop a small-signal model of the overall MMC system directly. Therefore, the proposed model is suitable for simulating the large-scale hybrid AC/DC power grids and analyzing the stability of small-signal. Finally, the simulation results verify the accuracy and effectiveness of the proposed modeling method.

show abstract

Power Decoupling Control of MMC and Small-Signal Stability Analysis of AC/DC Distribution Network With Renewable Energy

Cited by 3 publications

References 36 publications

Planning and Thinking on Multi-Energy System Intelligent Control and Simulation Laboratory

Planning and Thinking on Multi-Energy System Intelligent Control and Simulation Laboratory

State-Space Modeling, Stability Analysis, and Controller Design of Grid-Forming Converters With Distributed Virtual Inertia

A Unified Modeling Scheme of Modular Multilevel Converter for Hybrid AC/DC Power Grids

Contact Info

Product

Resources

About