Dual-Port Grid-Forming Interconnecting Power Converters for Reliable Integration of Hybrid AC/DC Grids

Core Concepts

Dual-port grid-forming control of interconnecting power converters can simultaneously form a stable voltage on both the AC and DC sides, enabling reliable integration of hybrid AC/DC power grids.

Abstract

This paper analyzes the dual-port approach, a control law that achieves grid-forming capability on both the AC and DC sides of interconnecting power converters (IPCs). The key insights are:

Small-Signal Stability Analysis:

The dual-port approach is more robust against variations in power flow compared to state-of-the-art control laws.
The dual-port control minimizes the sensitivity of the system's eigenvalues to changes in power flow.
Passivity analysis shows the dual-port approach is more passive, especially in the hybrid AC/DC coupling, making it less prone to stability issues.

Dynamic Performance Comparison:

The dual-port approach can withstand the loss of generation units in both AC grids, while many state-of-the-art control combinations fail to do so.
The dual-port's ability to use its internal energy to damp perturbations contributes to its superior dynamic performance.

Transient and Islanded Mode Validation:

In a down-scaled laboratory platform, the dual-port approach can operate in weak grid conditions and AC/DC islanding scenarios, unlike many state-of-the-art control combinations.
The dual-port's grid-forming capability on both AC and DC sides enables it to maintain stability even when the DC link is lost, a key advantage for multi-terminal HVDC systems.

Overall, the dual-port grid-forming control of IPCs is shown to be a robust and versatile solution for reliable integration of hybrid AC/DC power grids.

Stats

The system has a short-circuit ratio (SCR) of 5.5 on AC grid 1 and 4.5 on AC grid 2.
The dual-port approach minimizes the sensitivity of the system's eigenvalues to changes in power flow.
The dual-port approach can withstand the loss of generation units in both AC grids, while many state-of-the-art control combinations fail to do so.

Quotes

"The dual-port approach is more robust against variations in power flow compared to state-of-the-art control laws."
"The dual-port control minimizes the sensitivity of the system's eigenvalues to changes in power flow."
"The dual-port's ability to use its internal energy to damp perturbations contributes to its superior dynamic performance."

Key Insights Distilled From

Dual-Port Grid-Forming Interconnecting Power Converters in Hybrid AC/DC Grids

by Jose... at arxiv.org 05-01-2024

https://arxiv.org/pdf/2404.19625.pdf

Deeper Inquiries

How can the dual-port control scheme be extended to handle more complex hybrid AC/DC grid topologies, such as multi-terminal HVDC systems with multiple AC grids

To extend the dual-port control scheme to handle more complex hybrid AC/DC grid topologies, such as multi-terminal HVDC systems with multiple AC grids, several considerations need to be taken into account.

Topology Configuration: The control scheme would need to be adapted to accommodate the additional terminals and AC grids in the system. This would involve developing control algorithms that can coordinate the operation of multiple converters in a coordinated manner.

Communication and Coordination: With multiple AC grids and terminals, communication and coordination between the converters become crucial. The dual-port control scheme would need to incorporate communication protocols to ensure synchronization and stability across the entire grid.

Dynamic Behavior: The control scheme should be designed to handle the dynamic behavior of the system, considering interactions between different AC grids and the DC link. This would involve advanced modeling and simulation to predict system responses accurately.

Fault Tolerance: In a multi-terminal HVDC system, fault tolerance becomes critical. The dual-port control scheme should be designed to detect and mitigate faults to ensure the reliability and stability of the grid.

What are the potential challenges and limitations of the dual-port approach in terms of scalability, computational complexity, and practical implementation

While the dual-port control approach offers several advantages, there are potential challenges and limitations that need to be addressed:

Scalability: As the complexity of the grid increases with more terminals and AC grids, the scalability of the control scheme may become a challenge. Ensuring that the control algorithms can effectively scale up to larger systems without compromising performance is essential.

Computational Complexity: Handling multiple terminals and grids can increase the computational complexity of the control scheme. Efficient algorithms and real-time processing capabilities are required to manage the increased computational load.

Practical Implementation: Implementing the dual-port control scheme in a real-world system may pose challenges in terms of hardware compatibility, integration with existing infrastructure, and regulatory compliance. Practical considerations such as cost, hardware limitations, and system interoperability need to be addressed.

Robustness: The dual-port approach must be robust against uncertainties, variations in operating conditions, and external disturbances. Robust control strategies and fault-tolerant mechanisms need to be integrated to ensure the stability and reliability of the system.

Given the advantages of the dual-port control, how might it impact the design and operation of future power systems with high penetration of renewable energy sources and power electronic interfaces

The adoption of the dual-port control scheme in future power systems with high penetration of renewable energy sources and power electronic interfaces can have significant impacts on design and operation:

Enhanced Grid Stability: The dual-port control scheme can improve grid stability by providing grid-forming capabilities on both the AC and DC sides. This can help maintain voltage and frequency stability, especially in systems with high renewable energy integration.

Increased Flexibility: The dual-port approach allows for seamless integration of multiple AC grids and HVDC systems, enabling greater flexibility in power flow management and system operation. This flexibility is crucial for accommodating variable renewable generation.

Optimized Energy Exchange: By forming stable voltage on both AC and DC sides simultaneously, the dual-port control scheme can optimize energy exchange between different grids and terminals. This can lead to more efficient utilization of renewable energy resources.

Grid Resilience: The dual-port control scheme's ability to handle complex grid topologies and fault scenarios enhances grid resilience. It can support islanded operation, fault ride-through capabilities, and rapid system restoration, improving overall grid reliability.

Integration of Energy Storage: The dual-port control scheme can facilitate the integration of energy storage systems into the grid, enabling better management of intermittent renewable generation and enhancing grid stability during fluctuations.

In conclusion, the dual-port control scheme offers a promising solution for future power systems, addressing the challenges of renewable energy integration, grid stability, and system flexibility. Its adoption can pave the way for a more sustainable and resilient energy infrastructure.