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Microgrid Building Blocks for Dynamic Decoupling and Black Start Applications

Samrat Acharya, Priya Mana, Hisham Mahmood, Francis Tuffner, Alok Kumar Bharati

TL;DR

This work tackles the challenge of securely integrating modular microgrids with the bulk grid by employing Back-to-Back (BTB) converters as a Microgrid Building Block (MBB). It develops a phasor-domain BTB model implemented in GridLAB‑D, enabling efficient, system-level simulations of networked microgrids with realistic DC-link dynamics ($V_{dc}$) and grid-forming/ following control modes. Through case studies on two identical IEEE 13-node-based microgrids, the paper demonstrates flexible power exchange, dynamic decoupling of microgrid dynamics, and black-start capabilities, all while maintaining stable DC-link operation and local droop control. The approach supports scalable, fast simulations (e.g., a 26-node network in under a minute), underscoring the practicality of BTB-based MBBs for large-scale, resilient microgrid networks at the grid edge.

Abstract

Microgrids offer increased self-reliance and resilience at the grid's edge. They promote a significant transition to decentralized and renewable energy production by optimizing the utilization of local renewable sources. However, to maintain stable operations under all conditions and harness microgrids' full economic and technological potential, it is essential to integrate with the bulk grid and neighboring microgrids seamlessly. In this paper, we explore the capabilities of Back-to-Back (BTB) converters as a pivotal technology for interfacing microgrids, hybrid AC/DC grids, and bulk grids, by leveraging a comprehensive phasor-domain model integrated into GridLAB-D. The phasor-domain model is computationally efficient for simulating BTB with bulk grids and networked microgrids. We showcase the versatility of BTB converters (an integrated Microgrid Building Block) by configuring a two-microgrid network from a modified IEEE 13-node distribution system. These microgrids are equipped with diesel generators, photovoltaic units, and Battery Energy Storage Systems (BESS). The simulation studies are focused on use cases demonstrating dynamic decoupling and controlled support that a microgrid can provide via a BTB converter.

Microgrid Building Blocks for Dynamic Decoupling and Black Start Applications

TL;DR

This work tackles the challenge of securely integrating modular microgrids with the bulk grid by employing Back-to-Back (BTB) converters as a Microgrid Building Block (MBB). It develops a phasor-domain BTB model implemented in GridLAB‑D, enabling efficient, system-level simulations of networked microgrids with realistic DC-link dynamics () and grid-forming/ following control modes. Through case studies on two identical IEEE 13-node-based microgrids, the paper demonstrates flexible power exchange, dynamic decoupling of microgrid dynamics, and black-start capabilities, all while maintaining stable DC-link operation and local droop control. The approach supports scalable, fast simulations (e.g., a 26-node network in under a minute), underscoring the practicality of BTB-based MBBs for large-scale, resilient microgrid networks at the grid edge.

Abstract

Microgrids offer increased self-reliance and resilience at the grid's edge. They promote a significant transition to decentralized and renewable energy production by optimizing the utilization of local renewable sources. However, to maintain stable operations under all conditions and harness microgrids' full economic and technological potential, it is essential to integrate with the bulk grid and neighboring microgrids seamlessly. In this paper, we explore the capabilities of Back-to-Back (BTB) converters as a pivotal technology for interfacing microgrids, hybrid AC/DC grids, and bulk grids, by leveraging a comprehensive phasor-domain model integrated into GridLAB-D. The phasor-domain model is computationally efficient for simulating BTB with bulk grids and networked microgrids. We showcase the versatility of BTB converters (an integrated Microgrid Building Block) by configuring a two-microgrid network from a modified IEEE 13-node distribution system. These microgrids are equipped with diesel generators, photovoltaic units, and Battery Energy Storage Systems (BESS). The simulation studies are focused on use cases demonstrating dynamic decoupling and controlled support that a microgrid can provide via a BTB converter.
Paper Structure (9 sections, 10 figures, 1 table)

This paper contains 9 sections, 10 figures, 1 table.

Table of Contents

  1. Introduction
  2. BTB Converter as A key MBB Component - Modeling and Use Cases
  3. Typical Use Cases of MBB
  4. Implemntation of Phasor Domain Model of BTB Converter
  5. Case Study
  6. Flexible Power Exchange Between Microgrids
  7. Dynamic Decoupling of Microgrids
  8. Black Start of Microgrids
  9. Conclusion

Figures (10)

  • Figure 1: High-level architecture of BTB converter configuration and control.
  • Figure 2: DC-link voltage building dynamics of the Back-to-Back converter.
  • Figure 3: Two microgrids connected via a Back-to-Back converter.
  • Figure 4: MG1 - the networked microgrid: (a) Loads in MG1 are picked up with support from MG0 via BTB converter, (b) MG1 BESS operation to avoid overloading, and (c) PV at MG1 is brought up once the microgrid is stabilized.
  • Figure 5: MG0 - the parent microgrid: Changes in (a) BESS, (b) DG and (c) PV output in MG0 to support MG1 for flexible power exchange capability.
  • ...and 5 more figures