Unit commitment problem for transmission system, models and approaches: A review

Abstract

The realistic power systems include several types of controllers in transmission lines, different types of energy storage systems (ESSs), and integration of various renewable energy sources (RESs) with thermal generation units. The unit commitment (UC) problem of practical systems has been the subject of a great deal of research for the past few years. An extensive investigation of the system modeling, solution methodologies and future scope in the area of UC problem is presented in this paper. It outlines the problem formulation and solution approaches for stochastic UC, cost-based unit commitment (CBUC), and profit-based unit commitment (PBUC) problem. With the aid of a tree diagram representation, the UC models for the power system in three stages including thermal UC in first stage, security constrained unit commitment (SCUC) and stochastic/robust UC in second stage, and SCUC with contingency and SCUC with uncertainties in third stage are presented. Additional diagram is shown to represent the various modules that can be integrated with UC models to enhance system performance such as hydro units, flexible alternate current transmission system (FACTS) devices, high voltage direct current (HVDC) lines, ESSs, etc. The solution techniques, including relaxation based approaches, mathematical optimization solvers, meta-heuristic approaches, learning based approaches, and other established methods, are recapitulated in tabular form.