# Dynamic Ancillary Services: From Grid Codes to Transfer Function-Based Converter Control

**Authors:** Verena Häberle, Linbin Huang, Xiuqiang He, Eduardo Prieto-Araujo, Florian Dörfler  
**arXiv:** [2310.01552](https://arxiv.org/abs/2310.01552)  
**Date:** 2023-10-02  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/2310.01552v3/

## Key points

- Authors address the challenge of implementing conventional grid-code specifications for dynamic ancillary services provision in converter-based generation systems
- No customary methods have been developed yet for practical implementation of these specifications
- Authors propose a systematic approach for practical implementation of piecewise linear time-domain curves to provide dynamic ancillary services
- Approach ensures both grid code requirements and device level requirements are reliably satisfied
- Key idea is to translate piecewise linear time domain curves into a desired rational parametric transfer function in the frequency domain
- Obtained transfer function can be easily implemented using a PI based matching control in power loop of standard converter control architectures
- Numerical grid code compliance tests conducted, comparing proposed approach with classical droop and virtual inertia schemes
- Proposed method outperforms traditional schemes in terms of grid code compliance
- Paper presents a systematic approach for implementing piecewise linear time domain curves in converter-based generation systems to provide dynamic ancillary services while ensuring compliance with grid codes and device level requirements

## Summary

In this paper, the authors address the challenge of implementing conventional grid-code specifications for dynamic ancillary services provision in converter-based generation systems. These specifications typically involve defining piecewise linear step-response capability curves in the time domain for fast frequency and voltage regulation. While the specification of these curves is straightforward, their practical implementation in converter-based systems is not immediate and no customary methods have been developed yet. To overcome this challenge, the authors propose a systematic approach for the practical implementation of piecewise linear time-domain curves to provide dynamic ancillary services. Their approach ensures that both grid code requirements and device level requirements are reliably satisfied. The key idea behind their approach is to translate the piecewise linear time domain curves for active and reactive power provision into a desired rational parametric transfer function in the frequency domain. This transfer function defines the dynamic response behavior that needs to be realized by the converter. The obtained transfer function can be easily implemented using a PI based matching control in the power loop of standard converter control architectures. To demonstrate the effectiveness of their method, the authors conduct numerical grid code compliance tests. They compare their approach with classical droop and virtual inertia schemes which may not satisfy grid codes due to their structural limitations. The results show that their proposed method outperforms these traditional schemes in terms of grid code compliance. Overall, this paper presents a systematic approach for implementing piecewise linear time domain curves in converter based generation systems to provide dynamic ancillary services while ensuring compliance with grid codes and device level requirements. The proposed method offers a practical solution to an important problem in power system operation and control.