A dynamic model of the electricity generation market

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (leaves 105-107).This thesis proposes that the bidding process that occurs daily in the competitive short-run power market can be modeled as a dynamic system, or a dynamic game played by electricity generators. Such a game is a finitely repeated one of complete but imperfect information. In this thesis, a dynamic model representing a small shortrun power market is formulated as a repeated game. Daily price competition provides sufficient information for the generators to estimate their bids. The next bids of each generator are proposed as functions of the previous and current bids. Results from the dynamic model show that the generators' bidding strategy affects the dynamics of the modeled power market. Different strategies yield different market clearing price patterns. Moreover, a step-supply function bid, in which an offer price relates to an offer quantity by a marginal-cost function, and the maximum available capacity of each generator, can cause inefficient prices in some scheduling periods and/or might result in inefficient dispatches in each scheduling day. In addition, depending on the bidding strategy that is uniformly applied to the model, although there is certainty of inelastic anticipated demand in the model, the repeated bidding processes tends to allow the generators to "learn" from the market so that they can tacitly collude to create demand deficiency. It is further suggested here that when demand deficiency unexpectedly occurs in peak-load periods, a real-time market (i.e., an hour-ahead market) might be needed so that supply always meets demand.by Poonsaeng Visudhiphan.S.M

An agent-based approach to modeling electricity spot markets

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 323-327).(cont.) The model could also be used to analyze market factors (such as new market rules) and their effects on market price dynamics and market participants' behaviors, as well as to identify the "best" response action of one participant against the opponents' actions.Current approaches used for modeling electricity spot markets are static oligopoly models that provide top-down analyses without considering dynamic interactions among market participants. This thesis presents an alternative model, an agent-based model, and uses it to analyze the markets under various conditions. These markets, in which the participants engage in sealed-bid auctions to sell and/or buy electricity regularly, are viewed as multiagent systems, or as repeated games, played by participants with incomplete information. To represent these market characteristics, the agent-based model is selected, consisting of several power-producing agents with non-uniform portfolios of generating units. These agents employ learning algorithms, including Auer et al. 's, softmax action selection, or Visudhiphan and IliC's model-based algorithms, in determining bid-supply functions from available information. The simulated outcomes from the agent-based model depend on the choice of non-uniform portfolios and on the learning algorithms that the agents employ. Model verifications against the actual markets are suggested; however, due to a lack of certain confidential information, numerical examples cannot be presented. Nevertheless, the model is used to analyze the effects of market structures and the effect of load-serving entities on the power-producer bidding behavior and market outcomes. This model could provide one of the main tools for regulators, system planners, and market participants to use scenario simulations to investigate market conditions that could lead to high electricity prices.by Poonsaeng Visudhiphan.Ph.D

Clinical features, acute complications, and outcome of Salmonella meningitis in children under one year of age in Taiwan

<p>Abstract</p> <p>Background</p> <p><it>Salmonella </it>meningitis remains a threat to children below two years of age in both developing and developed countries. However, information on such infections has not been well characterized. We analyzed data related to twelve years of experience in order to clarify the comprehensive features of <it>Salmonella </it>meningitis in our patients, including admission characteristics, acute complications, and long-term outcome.</p> <p>Methods</p> <p>The records of patients with spontaneous <it>Salmonella </it>meningitis from 1982 to 1994 were retrospectively reviewed. The long-term outcome was prospectively determined for survivors at school age by the developmental milestones reported by their parents and detailed neurological evaluation along with intelligence, hearing, visual, speech and language assessments.</p> <p>Results</p> <p>Of the twenty-four patients, seizures were noted in fifteen (63%) before admission and thirteen (54%) during hospitalization. Acute complications mainly included hydrocephalus (50%), subdural collection (42%), cerebral infarction (33%), ventriculitis (25%), empyema (13%), intracranial abscess (8%), and cranial nerve palsy (8%). Three patients (13%) died during the acute phase of <it>Salmonella </it>meningitis. The twenty-one survivors, on whom we followed up at school age, have sequelae consisting of language disorder (52%), motor disability (48%), intelligence quotient < 80 (43%), epilepsy (33%), sensorineural hearing loss (17%), visual deficits (10%), abducens nerve palsy (5%), microcephaly (5%), and hydrocephalus (5%). Overall, good outcome was noted in six (28.6%) of twenty-one survivors, mild sequelae in three (14.2%), moderate in six (28.6%), and severe in six (28.6%).</p> <p>Conclusion</p> <p><it>Salmonella </it>meningitis in neonates and infants had a wide spectrum of morbidity and acute complications, leading to a complicated hospital course and subsequently a high prevalence of permanent adverse outcome. Thus, early recognition of acute complications of <it>Salmonella </it>meningitis and a follow-up plan for early developmental assessment of survivors are vital.</p