Headroom as A Grid Service in Software-Defined Power Grids: A Peak-to-Peak Control Design Approach
Zhongda Chu, Fei Teng
TL;DR
The paper tackles frequency stability in low-inertia grids with high inverter-based resources by introducing a peak-to-peak control design to bound frequency trajectories via invariant ellipsoids. It then leverages these bounds to define IBR headroom as a linear grid service and integrates it into a frequency-constrained system scheduling framework, replacing nonlinear nadir constraints with linear headroom constraints. A semidefinite-programming (SDP) based offline procedure computes the required headroom and iteratively refines the control gains, while enabling real-time reveal of exact parameters close to dispatch. Case studies on a modified IEEE-39 bus demonstrate lower system operation costs, reduced IBR headroom requirements, similar computational times, and improved uncertainty management, validating the approach for software-defined power grids and alignment with UC/ED workflows.
Abstract
To address system frequency challenges driven by the integration of renewable generation, advanced control strategies are designed at the device level to provide effective frequency support following disturbances. However, typically relying on energy-based performance metrics, these methods cannot guarantee the system frequency constraints such as frequency nadir and maximum Rate-of-Change-of-Frequency (RoCoF). Moreover, locally-designed frequency support cannot minimize the overall system cost to maintain frequency stability. On the other hand, the concept of frequency-constrained system scheduling is introduced, which incorporates frequency dynamic constraints into the system economic optimization, so that frequency requirements can be maintained with minimum cost. However, these works rely on analytical approximations of the frequency dynamic metrics, which are mathematically complicated and tend to be over-conservative for the approximation of IBR headroom requirements.