Assessing the Cost of Network Simplifications in Long-Term Hydrothermal Dispatch Planning Models

A. W. Rosemberg, A. Street, J. D. Garcia, D. M. Valladão, T. Silva and O. Dowson, "Assessing the Cost of Network Simplifications in Long-Term Hydrothermal Dispatch Planning Models," in IEEE Transactions on Sustainable Energy, vol. 13, no. 1, pp. 196-206, Jan. 2022, doi: 10.1109/TSTE.2021.3106810. [Download PDF]

 

Abstract—The sustainable utilization of hydro energy relies on

accurate estimates of the opportunity cost of the water. This value

is calculated through long-term hydrothermal dispatch problems

(LTHDP), and the recent literature has raised awareness about

the consequences of modeling simplifications in these problems.

The inaccurate representation of Kirchhoff’s voltage law under

the premise of a DC power flow is an example. Under a nonlinear

AC model, however, the LTHDP becomes intractable, and

the literature lacks an accurate evaluation method of different

modeling alternatives. In this paper, we extend the state-of-theart

cost-assessment framework of network approximations for

LTHDP and bring relevant and practical new insights. First, we

increase the quality of the assessment by using an AC power flow

to simulate and compare the performance of five policies based

on different network approximations. Second, we find that the

tightest network relaxation (based on semidefinite programming)

is not the one exhibiting the best performance. Results show that

the DC power flow with quadratic losses approximation exhibits

the lowest expected cost and inconsistency gaps. Finally, its computational

burden is lower than that exhibited by the semidefinite

relaxation, whereas market distortions are significantly reduced

in comparison to previously published benchmarks based on DC

power flow.

Index Terms—Long-term hydrothermal dispatch, Multistage

Stochastic Programming, Network model relaxations, Optimal

Power Flow, Time consistency.