Research on the ramping ancillary service mechanism considering the fair-sharing of ramping costs based on the contribution degree to ramping demand

China’s pilot Ramping Ancillary Service (RAS) market offers a viable approach to cope with the growing demand for flexible ramping capacity under the high penetration of variable renewable generation (VRG). However, the current RAS mechanism exhibits deficiencies in both ramping demand calculation and cost allocation, failing to adequately address issues such as real-time dynamic uncertainty in ramping demand and the fairness and traceability of cost distribution. Therefore, a ramping demand prediction method considering the probability distribution of historical errors and a fair cost sharing mechanism for ramping costs based on the contribution degree of market entities to ramping demand are proposed in this paper. Firstly, in the calculation of ramping demand, based on daily categories, meteorological data, and VRG-load prediction values, using constrained K-means clustering to categorize similar daily samples, obtaining the errors probability distribution, and constructing a physics-informed LSTM quantile regression (PIQ-LSTM) model to obtain the uncertain ramping demand. In terms of ramping cost allocation, based on the contribution degree of net load variations, load forecast deviations, and VRG forecast deviations to the ramping demand, the ramping costs are distributed proportionally to the corresponding consumers. Furthermore, a cost-sharing mechanism is designed for VRG forecast deviations, accounting for the discrepancy between the market declaration errors interval and the actual forecast errors. Case studies demonstrate that the proposed probabilistic forecasting method more accurately captures the system’s uncertain ramping demand compared to the baseline methods. Moreover, the designed cost allocation mechanism proves to be fairer and more traceable, providing a valuable reference for market-based ramping cost distribution and supporting the development of RAS market.