SOCRATES: A system for scheduling hydroelectric generation under uncertainty

Jonathan Jacobs*, Gary Freeman, Jan Grygier, David Morton, Gary Schultz, Konstantin Staschus, Jery Stedinger

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

99 Scopus citations


The Pacific Gas and Electric Company, the largest investor-owned energy utility in the United States, obtains a significant fraction of its electric energy and capacity from hydrogeneration. Although hydro provides valuable flexibility, it is subject to usage limits and must be carefully scheduled. In addition, the amount of energy available from hydro varies widely from year to year, depending on precipitation and streamflows. Optimal scheduling of hydrogeneration, in coordination with other energy sources, is a stochastic problem of practical significance to PG&E. SOCRATES is a system for the optimal scheduling of PG&E's various energy sources over a one- to two-year horizon. This paper concentrates on the component of SOCRATES that schedules hydro. The core is a stochastic optimization model, solved using Benders decomposition. Additional components are streamflow forecasting models and a database containing hydrological information. The stochastic hydro scheduling module of SOCRATES is undergoing testing in the user's environment, and we expect PG&E hydrologists and hydro schedulers to place progressively more reliance upon it.

Original languageEnglish (US)
Pages (from-to)99-133
Number of pages35
JournalAnnals of Operations Research
Issue number1
StatePublished - Dec 1 1995

ASJC Scopus subject areas

  • Decision Sciences(all)
  • Management Science and Operations Research


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