Unified Formulations for Combined-Cycle Units

TL;DR

This paper develops comprehensive edge-based and node-based mathematical models for combined-cycle units, capturing various physical and operational restrictions of turbines, balancing accuracy and computational complexity for system operators.

Contribution

It introduces one of the first models that simultaneously captures configuration details and all physical restrictions of turbines in combined-cycle units.

Findings

Models vary in decision variable complexity and accuracy

Tradeoff between model accuracy and computational effort

Applicable to both ISOs and VIUs

Abstract

In this letter, we describe and develop edge-based and node-based formulations for combined-cycle units (CCUs) with different levels of accuracy in respecting physical restrictions of each turbine, from no restriction requirement of each turbine, to include min-up/-down time restrictions of each turbine, to finally include most restrictions such as min-up/-down time, capacity, and ramping restrictions of each turbine. We develop corresponding models for Independent System Operators (ISOs) and Vertically Integrated Utilities (VIUs), respectively. These models demonstrate the complexity in terms of the size of decision variables and show the tradeoff between accuracy and computational complexity. In general, to the best of our knowledge, this letter provides one of the first models that can capture both configuration-based model needs and all physical restrictions for each turbine within CCUs.