Impact of Demand-Response on the Efficiency and Prices in Real-Time Electricity Markets

International audienceWe study the effect of Demand-Response (DR) in dynamic real-time electricity markets. We use a two-stage market model that takes into account the dynamical aspects of gen-eration, demand, and DR. We study the real-time market prices in two scenarios: in the former, consumers anticipate or delay their flexible loads in reaction to market prices; in the latter, the flexible loads are controlled by an independent aggregator. For both scenarios, we show that, when users are price-takers, any competitive equilibrium is efficient: the players' selfish responses to prices coincide with a socially optimal policy. Moreover, the price process is the same in all scenarios. For the numerical evaluation of the properties of the equilibrium, we develop a solution technique based on the Alternating Direction Method of Multipliers (ADMM) and trajectorial forecasts. The forecasts are computed us-ing wind generation data from the UK. We challenge the assumption that all players have full information. If the as-sumption is verified, then, as expected, the social welfare increases with the amount of DR available, since DR relaxes the ramping constraints of generation. However, if the day-ahead market cannot observe how elastic loads are affected by DR, a large quantity of DR can be detrimental and leads to a decrease in the welfare. Furthermore, the DR operator has an incentive to under-dimension the quantity of avail-able DR. Finally, we compare DR with an actual energy storage system. We find that storage has a faster response-time and thus performs better when only a limited amount is installed. However, storage suffers from charge-discharge in-efficiency: with DR, prices do concentrate on marginal cost (for storage, they do not) and provide a better welfare

On the presence of humpback whales in the Persian Gulf: rare or rarely documented? Report of the IWC Scientific Committee Meeting SC/67A/CMP/14, Bled, Slovenia, May 2017

We critically review the evidence for humpback whale presence in the Persian Gulf. Five specimen records, assumed to belong to the endangered Arabian Sea population, are confirmed in the period 1883- 2017: Bassore Bay, Iraq; Doha, Qatar; Kuwait Inner harbour, Kuwait; Qeshm Island, Iran; and Akhtar, Bushehr Province, Iran. The two Iranian cases, both juveniles, are newly recorded. With accumulating reports, an alternate hypothesis to 'rare stragglers' deserves consideration, one in which Arabian Sea humpback whales may enter the Persian Gulf with some regularity, perhaps as normal visitors, if not permanent residents. Deficiency of records may reflect a general sparsity of whale research effort in the Persian Gulf. The historical description of Megaptera indica Gervais, 1883 is translated from French

Relevant Norms of Holy Places and Times in Three Sacred Books

Basically speaking, saintliness is considered as a commented and valued issue allotting to religion realm which without the presence of such a meaning, no religion is worthy of its name.This article aims to consider the normative prepositions related to holy places and times in three sacred books : Quran, Pentateuch, and Gospel with their similarities and differences. A specific software program is used with quantitative and qualitative research method to process and analyze the data by means of a profound content analysis method.As a result of searching in these three sacred books, 10396 normative propositions were found which are categorized in 123 sections. One of these sections includes 295 prepositions with the content of holy places and the other one has 301 prepositions with the content of holy times.Therefore, 5.7 percent of the dos and don'ts of these three books presented in tables of this article is based on the norms of holy places and times. According to these tables, Pentateuch considers do's and don'ts in our relation and holy places as well as us and holy times more than the two other books. In a section of holy places, the share of normative prepositions related to us and sacred objects is more in Pentateuch rather than Quran and Gospel. However Gospel compared to the other books has more relevant norms related to places of worship like churches and synagogues. Additionally, the least normative propositions related to us and holy times could be found in Gospel. The normative prepositions related to religiously prohibited months are just seen in Quran.This article lists 596 normative propositions with their identity numbers by representing the exact address of the source of verses.Eventually, a symmetry model of fivefold contents of places and times norms in three sacred books is computed and designed. Factors to be taken in to accounts in this model are reaching to coefficient correlation of 0.7 between the contents of Eids and holy times with holy objects and places

Decentralised District Multi-vector Energy Management: A Multi-agent Approach

International audienceDespite its many advantages, the non-controllable and intermittent nature of renewable energy sources is adding further stress to the energy networks and hence, grid operators are often forced to curtail RES generation or to limit its further penetration in the most congested areas. Smart tri-generation districts (electricity, gas, heat) can be key to mitigate these issues and increase the renewable hosting capacity of the grid, provided their feature an optimal use of their energy conversion and storage capabilities. This paper presents a district energy management approach based on Multi-Agent System (MAS) that takes into consideration the tri-energy vectors (electricity, gas, thermal). The optimization problem is solved in a distributed way based on the Alternating Direction Method of Multipliers with the objective of minimizing district costs and preliminary results show the efficiency of our approach to achieve this objective

Residential Demand Response under Uncertainty

This paper considers a residential market with real-time electricity pricing and flexible electricity consumption profiles for customers. Such a market raises an optimisation problem for home automation systems where they need to schedule consumption activities to reduce costs, whilst maintaining a base level of comfort and convenience. This optimisation problem faces uncertainty in real-time prices, weather conditions, and occupant behaviour. The paper presents an online stochastic combinatorial optimisation algorithm that produces fast, high-quality solutions to this problem. This algorithm is compared with reactive control strategies and an approach using an expected scenario. Our results demonstrate the value of stochastic information and online stochastic optimisation in residential demand response.

Distributed Multi-Period Optimal Power Flow for Demand Response in Microgrids

The scalability and privacy preserving nature of distributed optimisation techniques makes them ideal for coordinating many independently acting agents in a microgrid setting. However, their practical applicability remains an open question in this context, since AC power flows are inherently non-convex and households make discrete decisions about how to schedule their loads. In this paper, we show that one such method, the alternating direction method of multipliers (ADMM), can be adapted to remain practical in this challenging microgrid setting. We formulate and solve a multi-period optimal power flow (OPF) problem featuring independent households with shiftable loads, and study the results obtained with a range of power flow models and approaches to managing discrete decisions. Our experiments on a suburb-sized microgrid show that the AC power flows and a simple two-stage approach to handling discrete decisions do not appear to cause convergence issues, and provide near optimal results in a time that is practical for receding horizon control. This work brings distributed control for microgrids several steps closer to realit