Data-driven continuous-time framework for frequency-constrained unit commitment

M. Rajabdorri, E. Lobato, L. Sigrist, j Aghaei

International Journal of Electrical Power & Energy Systems Vol. 162, pp. 110327-1 - 110327-11

Summary:

The conventional approach to solving the unit commitment problem involves discrete intervals at an hourly scale, particularly when integrating frequency dynamics to formulate a frequency-constrained unit commitment. To overcome this limitation, a novel continuous-time frequency-constrained unit commitment framework is proposed in this paper. In this approach, Bernstein polynomials represent continuous variables in the unit commitment problem and enable the calculation of frequency response-related metrics such as the rate of change of frequency, quasi-steady-state frequency, and frequency nadir, and the corresponding continuous-time constraints are introduced. Notably, startup and shut-down trajectories are meticulously considered, transforming the formulation into a fully continuous-time model and simplifying constraints related to variable continuity. To address the complexities associated with integrating the obtained non-linear frequency nadir constraint into a mixed-integer linear problem, an alternative data-driven frequency nadir constraint is proposed, which accurately constrains frequency nadir deviations throughout the time interval. To validate the proposed model, it is applied to the real-life network of the Spanish Island of La Palma. The data-driven method for estimating frequency nadir has demonstrated a minimum accuracy of 99.61% and has consistently maintained the frequency above the defined threshold.

Spanish layman's summary:

Se propone un modelo continuo para el compromiso de unidades con restricciones de frecuencia, usando polinomios de Bernstein para calcular métricas de frecuencia. Aplicado a La Palma, logra 99.61% de precisión, manteniendo la frecuencia sobre los límites definidos.

English layman's summary:

A new continuous-time frequency-constrained unit commitment model uses Bernstein polynomials to represent continuous variables, enabling accurate frequency metrics in unit commitment, including frequency nadir constraints. Applied to La Palma, it achieves 99.61% accuracy, keeping frequency above thresholds.

Keywords: Frequency-constrained unit commitment; Continuous-time formulation; Data-driven frequency nadir; Start-up and shut-down trajectories; Bernstein polynomials

JCR Impact Factor and WoS quartile: 5,000 - Q1 (2023)

DOI reference: https://doi.org/10.1016/j.ijepes.2024.110327

Published on paper: November 2024.

Published on-line: October 2024.

Citation:
M. Rajabdorri, E. Lobato, L. Sigrist, j Aghaei, Data-driven continuous-time framework for frequency-constrained unit commitment. International Journal of Electrical Power & Energy Systems. Vol. 162, pp. 110327-1 - 110327-11, November 2024. [Online: October 2024]