Fair Cost Allocation Mechanism for Ramping Ancillary Services Based on Responsibility Coefficients

In the future market operation of new power systems, establishing a fair and reasonable cost allocation mechanism for ramping ancillary services is crucial. Such a mechanism would incentivize both the generation and load sides to reduce ramping demands. It will also promote the active participation of flexible resources across ramping services. However, the ramping ancillary service market currently piloted in Shandong, China, exhibits significant shortcomings. Net load volatility and uncertainty have increased the ramping service demand. Yet load-side Users, as beneficiaries, do not share the costs. Meanwhile, flexible units that wish to provide service still bear costs even if they fail to win bids. This violates the “who triggers, who pays” principle. To address this, this paper proposes a fair cost allocation mechanism based on ramping responsibility coefficients of market entities. First, a source-load ramping demand assessment model is developed. It quantifies both deterministic demand from net load variations and uncertain demand from net load forecast errors. Second, a two-layer cost allocation model is constructed using source-load ramping responsibility coefficients. In the first layer, system attribution is performed: initial allocation of ramping service costs is based on the responsibility share of each component—net load variations, load forecast deviations, and renewable energy forecast deviations—in total ramping demand. The second layer—responsibility-retrospective allocation—further assigns these costs by source: costs from net load change are allocated to power Users and renewable energy units; costs from load forecast errors and renewable forecast errors are assigned to the power Users and renewable energy units, respectively. For costs from renewable forecast errors, a differentiated allocation method is designed based on the deviation between declared and actual forecast errors. Case study results show that the proposed mechanism improves fairness and traceability in ramping cost allocation. It offers a market-based reference and supports the development of ramping ancillary service markets.