Quantifying Spatial-Related Inertia Value for High Share of Wind Power Integration

Large-scale integration of variable renewable resources (such as wind power) not only leads to the reduction of inertia, but also changes the spatial distribution of inertia in the power system, which raises spatial-related dynamic frequency instability risk. Therefore, it poses a novel problem how to reasonably schedule the inertia on the premise of the spatial distribution characteristics of dynamic frequency in the power system operation. In addition, with increasing importance of inertia and the difference in inertia provision at different nodes by a variety of regulation resources, it is important to analyze nodal inertia economic value and compensate units accordingly. In this paper, we propose an approach on pricing the nodal inertia. First, we infer the node-related rate of change of frequency (RoCoF) considering the network constraint according to disturbance power; then establish inertia demand constraints of RoCoF for each node and the frequency nadir for the whole system, which are then introduced into establishing the optimal inertia scheduling model. Accompanied by generation scheduling scheme, the nodal inertia price is also given based on the concept of marginal price according to the duality theory. Case studies on the modified IEEE-39 system and Northwest power grid of China demonstrate the proposed inertia scheduling model can enhance the ability of the system to maintain frequency stability, in the same time with good economy. The proposed node-related inertia pricing approach can be used to guide properly planning the inertia resources.