Rodrigo Henríquez

Participation of Demand Response Aggregators in Electricity Markets: Optimal Portfolio Management

Demand response (DR) is a versatile way of providing flexibility in power systems. In order to manage the flexibility of a large number of scattered DR resources, in the context of electricity markets, they must be aggregated by a new participant called the DR aggregator. This paper presents an optimization model to determine the optimal operation of a DR aggregator that manages a portfolio of DR programs in wholesale electricity markets. The aggregator is considered to be a strategic participant in the real-time market. The portfolio is composed of various contracts of load curtailment and flexible loads that can be executed for hourly load change. Uncertainty of market prices and balancing requirements are represented through a set of scenarios based on historical data. The proposed model is a stochastic bi-level mathematical program that is reformulated as a mixed-integer linear program. Several case studies with numerical results are presented.

Fluctuating minds: spontaneous psychophysical variability during mind-wandering

Mind-wandering is the occasional distraction we experience while performing a cognitive task. It arises without any external precedent, varies over time, and interferes with the processing of sensory information. Here, we asked whether the transition from the on-task state to mind-wandering is a gradual process or an abrupt event. We developed a new experimental approach, based on the continuous, online assessment of individual psychophysical performance. Probe questions were asked whenever response times (RTs) exceeded 2 standard deviations from the participant’s average RT. Results showed that mind-wandering reports were generally preceded by slower RTs, as compared to trials preceding on-task reports. Mind-wandering episodes could be reliably predicted from the response time difference between the last and the second-to-last trials. Thus, mind-wandering reports follow an abrupt increase in behavioral variability, lasting between 2.5 and 10 seconds.

Escribir historia desde las evidencias. Géneros históricos y sentido histórico en estudiantes de 8vo de Educación Básica

The purpose of this paper is to identify and characterize the structure of the historical genre and discursive mechanisms utilized by Chilean 8th graders as evidenced in a written task. This task consists of students responding to a historical question using on historical evidence. Our analytical framework and methodological design are based on the notion of historical genre and Appraisal Framework used in Systemic Functional Linguistics (Coffin 2006; Martin & Rose, 2008; Martin, 2009). Considering the characterization of historical genres developed by Coffin (2006) and Martin and Rose (2008), the concept of ‘historical account’ genre is reformulated and defined as a ‘historical account writing task.’ Our analysis helped identify and characterize four stages to develop the historical account: a) Start, b) Contextualization, c) Reformulation and c) Closing. We unpack each stage into smaller phases. The results show that there exists a set of criteria afforded by the proximity of the response to the historical evidence, which are expressed in the stages and phases characterized in this study. This set of criteria shapes the quality of the response as evidence of students’ historical understanding.

Portfolio Design of a Demand Response Aggregator with Satisficing Consumers

This paper studies the impact of consumer behavior on the portfolio design of a demand response (DR) aggregator. Consumer behavior is modeled using elements of satisficing theory. We develop an optimization model to decide the optimal portfolio of DR contracts for an aggregator participating in the electricity market. In our model, the aggregator must pay a premium to enable the participation of consumers who have a certain aspiration threshold, below which they will not participate. Thus, the proposed model determines the premiums to be offered to consumers in order to obtain a DR portfolio that maximizes the aggregator’s operating surplus while satisfying the aspirations of participating consumers. Several simulations are performed to obtain insights on the value of the DR resource, and the importance of parameters used to model the consumer behavior.