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Operating envelopes for the grid-constrained use of distributed flexibility in balancing markets

Abhimanyu Kaushal, Wicak Ananduta, Luciana Marques, Tom Cuypers, Anibal Sanjab

TL;DR

This paper addresses the challenge of safely leveraging distributed flexibility from distribution networks in centralized balancing markets without sharing full network models. It proposes operating envelopes (OEs) that constrain bids to maintain grid safety and compares two OE calculation approaches: a two-step method and a one-step method. Using a linearized PTDF-based market model and Monte Carlo simulations on coupled transmission and distribution networks, the study shows that the two-step OE approach delivers grid-safe outcomes with near-optimal procurement cost, while the one-step approach can still allow constraint violations. Weighting schemes (price-based or quantity-based) influence market efficiency, with the two-step, price-weighted approach emerging as a practical, scalable option, and the authors note ongoing work to provide theoretical grid-safety guarantees and extend to nonlinear power-flow models.

Abstract

The increasing share of distributed energy sources enhances the participation potential of distributed flexibility in the provision of system services. However, this participation can endanger the grid-safety of the distribution networks (DNs) from which this flexibility originates. In this paper, the use of operating envelopes (OE) to enable the grid-safe procurement of distributed flexibility in centralized balancing markets is proposed. Two classes of approaches for calculating OEs (one-step and two-step methods) are compared in terms of the level of distribution grid safety they can provide, the impact they can have on the market efficiency, and the volume of discarded flexibility they can yield. A case study considering different system scenarios, based on Monte Carlo simulations, highlights a trade-off between the market efficiency, DN flexibility resource utilization, and the grid safety delivered by the different OE methods. The results showcase that the use of the two-step OE approach results in a more grid-secure albeit less-efficient use of distributed flexibility.

Operating envelopes for the grid-constrained use of distributed flexibility in balancing markets

TL;DR

This paper addresses the challenge of safely leveraging distributed flexibility from distribution networks in centralized balancing markets without sharing full network models. It proposes operating envelopes (OEs) that constrain bids to maintain grid safety and compares two OE calculation approaches: a two-step method and a one-step method. Using a linearized PTDF-based market model and Monte Carlo simulations on coupled transmission and distribution networks, the study shows that the two-step OE approach delivers grid-safe outcomes with near-optimal procurement cost, while the one-step approach can still allow constraint violations. Weighting schemes (price-based or quantity-based) influence market efficiency, with the two-step, price-weighted approach emerging as a practical, scalable option, and the authors note ongoing work to provide theoretical grid-safety guarantees and extend to nonlinear power-flow models.

Abstract

The increasing share of distributed energy sources enhances the participation potential of distributed flexibility in the provision of system services. However, this participation can endanger the grid-safety of the distribution networks (DNs) from which this flexibility originates. In this paper, the use of operating envelopes (OE) to enable the grid-safe procurement of distributed flexibility in centralized balancing markets is proposed. Two classes of approaches for calculating OEs (one-step and two-step methods) are compared in terms of the level of distribution grid safety they can provide, the impact they can have on the market efficiency, and the volume of discarded flexibility they can yield. A case study considering different system scenarios, based on Monte Carlo simulations, highlights a trade-off between the market efficiency, DN flexibility resource utilization, and the grid safety delivered by the different OE methods. The results showcase that the use of the two-step OE approach results in a more grid-secure albeit less-efficient use of distributed flexibility.
Paper Structure (7 sections, 7 equations, 3 figures, 2 algorithms)

This paper contains 7 sections, 7 equations, 3 figures, 2 algorithms.

Table of Contents

  1. Introduction
  2. Central flexibility market model
  3. Operating envelope integration
  4. Integration
  5. Calculation methods
  6. Case study
  7. Conclusion

Figures (3)

  • Figure 1: (Top) Comparison of total numbers of violations for case set 1. (Bottom) Comparison of market inefficiencies for case set 1. Note that $\eta=0$ indicates the procurement cost is equal to that of the full-DN.
  • Figure 2: Comparison of unqualified flexibility for case set 1.
  • Figure 3: Comparison of unqualified flexibility for case set 2.