Core Concepts
The largest initial RoCoF following a disturbance will occur at one of the generator buses in an interconnected power system, rather than at load buses. This finding enables the development of a convex and concise optimal nodal inertia dispatch method and a nodal inertia market mechanism.
Abstract
The content establishes a nodal RoCoF model and proves that the largest initial RoCoF after a disturbance will occur at one of the generator buses, rather than at load buses. This is because the power variations at load buses are constant during the contingency, while the power variations at generator buses depend on the system topology and parameters.
The key highlights are:
A post-contingency nodal RoCoF model is developed, which accounts for the disparities in frequency dynamics across different regions of the power system.
It is proven that the maximum initial RoCoF will occur at one of the generator buses equipped with inertia, rather than at inertia-less load buses.
This finding enables the formulation of a convex optimal nodal inertia dispatch problem, where RoCoF security constraints only need to be applied to generator buses.
A nodal inertia market mechanism is also proposed, where the shadow prices of virtual inertia at different generator buses can be determined based on the nodal RoCoF model.
Simulation results of the South East Australian power system verify the effectiveness of the proposed methods under various scenarios.
Stats
The largest initial RoCoF is -1.206 Hz/s at Bus 404 in Scenario 1, and -1.279 Hz/s at Bus 302 in Scenario 3.
In Scenario 2, the largest initial RoCoF is -1.834 Hz/s at Bus 404.