Thrust one. Differentiable Reliability for Long-Term Planning
Stochastic Gradient Estimation, Differentiable Optimization, Integrated Planning
Accreditation is a derivative, not a re-run.
Capacity accreditation sets how much each resource counts toward reliability, and so what gets procured and built. As the mix shifts toward renewables, storage and flexible demand, that value turns on weather, location, portfolio and dispatch rather than nameplate. U.S. markets are moving to probabilistic, marginal accreditation, but the methods are computationally heavy.
adequacy simulator pathwise aggregation
baseline run +perturbed run finite difference
the pair shares common random numbers
One IPA run returns every non-storage resource’s gradient; a perturbation-based method needs a baseline and a perturbed run for each resource.
Challenge
How to make the capacity accreditation process computationally efficient? And how to build a scalable resource planning framework ensuring the system reliability and investment incentive?
Solution
- Accreditation as the directional derivative of a reliability metric: under expected unserved energy, ELCC and MRI reduce to the same local object.
- An infinitesimal perturbation analysis (IPA) estimator recovers every non-storage gradient from a single Monte Carlo simulation, over 1000× faster than perturbation-based methods.
- Optimization-based accreditation for intertemporal resources, read from the duals of a storage dispatch problem with ISO New England, extends to multi-zone production-cost models in one or two solves.
Impact
Begun during a research internship at ISO New England. Invited to an EPRI ISO/RTO working group, reaching engineers across all U.S. regions, and carried toward industry standards with consulting firms and software vendors. A related industry report has shaped the wider accreditation-reform discussion.
Papers in thrust I 2
| No. | Title | Authors | Status |
|---|---|---|---|
| 01 | A Gradient-Based Capacity Accreditation Framework in Resource Adequacy: Formulation, Computation, and Practical Implications | Q. Zhang, F. Zhao, G. Stephen, et al. | To appear |
| 02 | Reformulating Energy Storage Capacity Accreditation Problem with Marginal Reliability Impact | Q. Zhang, F. Zhao, T. Zheng, L. Xie | Early access |