The increasing penetration of inverter-based resources and HVDC interconnections have created unfavourable dynamic interactions, oscillations and low inertia related stability issues. With the planned continuous growth of inverter-based resources into the system, it is essential to develop real-time modelling and simulation studies for fundamental understanding and mitigation strategies of various types of oscillations.
This project aims to develop a real-time simulation of a region of GB power system in both phasor and EMT modes for transient stability assessments. It investigates when and where to use the phasor mode and EMT mode simulations for a given system condition and provide real-time simulation of the grid in that region for system stability and security and identification of stability risks.
Benefits
The GB power system is transforming into a lower inertia system and facing the decline in short circuit level. The ESO needs to ensure that the sophisticated methodologies and simulation models under consideration are accurate and robust before incorporating them into the decision-making when maintaining system stability. Inaccurate simulation model or inappropriate use of a model in the wrong time and region carries tremendous technical risk, as well as significant business risk if making incorrect judgments based on it. This project investigates the real-time simulation phasor-EMT models to utilise the advantages of both simulation modes to increase the stability and reducing the uncertainties involved in the modelling and stability studies.
Learnings
Outcomes
Frequency Stability in Low-Inertia Systems: Maintaining frequency stability in low-inertia grids is a critical challenge. The project demonstrated that droop-based frequency support from wind farms and VSC-HVDC links can significantly improve frequency recovery rates and reduce the severity of frequency nadirs. However, the effectiveness of these ancillary services depends on the tuning of control parameters and the speed of response from inverters and HVDC converters
Commutation Failures in LCC-HVDC Systems: The vulnerability of LCC-HVDC systems to commutation failures during AC-side faults was highlighted. Coordinated control strategies between LCC and VSC converters can improve fault recovery and prevent cascading failures. Enhanced fault-ride-through capabilities in LCC-HVDC systems are essential for grid stability during disturbances
Platform Performance and Scalability: HYPERSIM showed faster execution speed compared to PSCAD, but PSCAD retained an edge in precision for detailed component-level analysis. Scalability remains a challenge for both platforms, particularly when simulating large-scale systems with microsecond-level time steps. Parallel processing techniques and modular hardware configurations were identified as potential solutions to this challenge
Intellectual Property Details
1. Conversion Methodology
Description:
The project developed a unique methodology for converting models from PowerFactory to PSCAD and subsequently to HYPERSIM. This process involved ensuring the removal of commercially sensitive data while maintaining high fidelity in simulations.
Key Features:
Efficient removal of sensitive data during conversion.
Maintenance of model integrity and fidelity throughout the conversion process.
Enhanced interoperability between different simulation platforms.
Potential Applications:
Can be applied in other projects requiring model conversion between different simulation tools.
Useful for NESO looking to protect sensitive data while conducting detailed simulations.
2. Insights into Inverter-Based Resources and HVDC System Impacts
Description:
The project provided significant insights into the transient behaviour of inverter-based resources (IBRs) and the impact of HVDC links on system stability. These insights contribute to a deeper understanding of dynamic interactions and stability issues.
Key Findings:
Identification of critical transient behaviours in IBRs.
Analysis of the impact of HVDC system commutation failures on frequency stability.
Detailed understanding of interconnector tripping effects.
Potential Applications:
Informing future research and development in power system stability.
Enhancing operational decision-making processes.
Consideration for using these insights to develop new analysis techniques or tools.
Conclusion
The project has successfully generated valuable intellectual property that can contribute to advancements in power system modelling and analysis. We can evaluate potential collaborations or partnerships to further develop the IP
Lessons Learnt
Platform Validation and Benchmarking: The project identified discrepancies between offline PSCAD and real-time simulations, particularly for complex components like wind farms and HVDC links. This underscores the importance of platform validation and the need for standardized benchmarking practices to ensure consistent and reliable simulation results across different platforms.
Hybrid Simulation Framework: Developing a hybrid simulation framework that combines RMS and EMT models can provide a comprehensive approach to grid stability analysis. This framework would enable a more detailed understanding of both system-wide and local dynamic behaviours under normal and faulted conditions
Platform Validation and Benchmarking: The project identified discrepancies between offline PSCAD and real-time simulations, particularly for complex components like wind farms and HVDC links. This underscores the importance of platform validation and the need for standardized benchmarking practices to ensure consistent and reliable simulation results across different platforms.
Hybrid Simulation Framework: Developing a hybrid simulation framework that combines RMS and EMT models can provide a comprehensive approach to grid stability analysis. This framework would enable a more detailed understanding of both system-wide and local dynamic behaviours under normal and faulted conditions
Advanced Control Strategies for IBRs: Future research should focus on advancing control strategies for inverter-based resources (IBRs), such as synthetic inertia and grid-forming inverter technology. These approaches could help stabilize frequency in low-inertia conditions and provide enhanced system resilience
