Calculating Individual Resources Variability and Uncertainty Factors Based on Their Contributions to the Overall System Balancing Needs

The variability and uncertainty of wind power production require increased flexibility in the power systems, or more operational reserves to maintain a satisfactory level of reliability. The incremental increase in reserve requirement caused by wind power is often studied separately from the effects of loads. Accordingly, the cost in procuring reserves is allocated based on this simplification rather than a fair and transparent calculation of the different resources´ contribution to the reserve requirement. This work proposes a new allocation mechanism for variability and uncertainty of resources regardless of their type. It is based on a new formula called the grid-balancing metric (GBM). The proposed GBM has several distinct features: 1) it is directly linked to the control performance standard scores and interconnection frequency performance, 2) it provides scientifically defined allocation factors for individual resources, 3) the sum of allocation factors within any group of resources is equal to the groups´ collective allocation factor (linearity), and 4) it distinguishes helpers and harmers. The paper illustrates and provides results of the new approach based on actual transmission system operator data.