There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

世界経済・社会統計 = World development indicators

2 1 The innovative transport systems and the CityMobil project 10 1.1 The research questions 10 2 The state of art in the field of automatic transport systems 12 2.1 Case studies and demand studies for innovative transport systems 12 3 The design and implementation of surveys 14 3.1 Definition of experimental design 14 3.2 Questionnaire design and delivery 16 3.3 First analyses on the collected sample 18 4 Calibration of Logit Multionomial demand models 21 4.1 Methodology 21 4.2 Calibration of the “full” model. 22 4.3 Calibration of the “final” model 24 4.4 The demand analysis through the final Multinomial Logit model 25 5 The analysis of interaction between the demand and socioeconomic attributes 31 5.1 Methodology 31 5.2 Application of Mixed Logit models to the demand 31 5.3 Analysis of the interactions between demand and socioeconomic attributes through Mixed Logit models 32 5.4 Mixed Logit model and interaction between age and the demand for the CTS 38 5.5 Demand analysis with Mixed Logit model 39 6 Final analyses and conclusions 45 6.1 Comparison between the results of the analyses 45 6.2 Conclusions 48 6.3 Answers to the research questions and future developments 52

The European commission

Climate change 2014 - Synthesis Report

Rural electrification is critical for the social and economic development of developing countries. Off-grid energy systems are attractive solutions for rural electrification which may offer technical and economic benefits compared with network expansion. However, given the conditions in remote areas, off-grid energy systems are often exposed to high impact and low probability (HILP) events such as natural hazards. This is an issue as off-grid planning practices traditionally focus on average performance reliability indicators, and neglect studying resilience to HILP events. This paper proposes a practical off-grid assessment framework which brings together average and risk performance indices to optimally size off-grid energy systems and quantify their reliability and resilience performance. The proposed methodology, based on Sequential Monte Carlo simulations, is demonstrated with two off-grid energy systems: PV and CHP based systems. In addition, through case studies with applications on windstorms, the impacts of natural hazards are systematically quantified and explicitly considered in the sizing of the off-grid plant. Power system planners and operators can use this framework to quantify the reliability and resilience of off-grid energy systems and inform the decision-making on optimal portfolios for rural electrification.

Comparative Studies on Cost, Reliability and Resilience of Off-Grid Energy Systems

—The ongoing integration of controllable distributed energy resources (DER) makes distribution networks capable of aggregating ﬂexible power and providing ﬂexibility services at both transmission and distribution levels. The aggregated ﬂexibility of an active distribution network (ADN) can be represented as its feasible operating area in the P-Q space. The limits of this area are pivotal for arranging ﬂexibility markets and coordinating transmission and distribution system operators (TSOs and DSOs). However, motivated by the current technical limitations of distribution networks (e.g., protection schemes), existing literature on ADN ﬂexibility and TSO-DSO coordination mostly focuses on radial networks, overlooking the potential beneﬁts of network reconﬁguration. This paper, using a realistic meshed distribution system from the UK and the exact ACOPF model for ﬂexibility estimation, demonstrates that network reconﬁguration can increase the limits of ADN aggregated ﬂexibility and improve the economic efﬁciency of ﬂexibility markets.

Impacts of Distribution Network Reconfiguration on Aggregated DER Flexibility

This paper presents modelling approaches and results relevant to smart distribution system development with DG in European grids as from the work performed by Imperial College in the EC FP6 “More Microgrids” project. The studies are based on real data and DG/consumption scenarios of distribution networks as provided by project partners from different European countries. Comparison among the different networks enables to get strategic information on common trends and differences. In addition, being based on real network data, the results provide an invaluable opportunity to gain insights on impact, benefits and main drivers of DG and Smart Grids on real large-scale networks, differently from most studies based on small test or ideal networks.

/pdf/distributed-generation-and-smart-grid-development-case-4jol13dkax.pdf

Distributed generation and smart grid development: case studies in different european countries

Synergic operation of electricity, heating and cooling networks can bring savings and low carbon footprint through energy efficiency. In such context, the present work proposes a novel Smart Thermal Loop (STL) solution: a fully electrified thermal generation and distribution system where a low-temperature underground loop and reversible heat pumps are used to supply users’ heating and cooling demand. Additionally, STL includes short and long-term thermal energy storage (TES) by means of sensible storage tanks and geothermal boreholes. The proposed solution is described and investigated in the case of the new campus of the University of Melbourne (with aggregated peak load of about 2 and 3 MWth, respectively, for heating and cooling). A numerical model is proposed to simulate the yearly operation of STL with 1-hour resolution. Key features include (i) network model for the underground loop to track temperature evolution over space and time, (ii) variable heat pump performance, which depends on network temperatures, (iii) physical model for the heat transfer between system and soil, in the geothermal storage, (iv) modelling of the interaction between neighbouring boreholes. Results explore the dynamics of the integrated STL system, with a focus on the role that energy storage over different timescales plays in enabling efficient and flexible operation of system components. TES contribution to system operation goes beyond the use of low-price electricity and allows energy savings through efficient scheduling of heat pumps operation and reduction of pumping work. Benefits from the flexible operation of STL are quantified as a 10% reduction in energy expenditure and 28% in system running costs. The presented model can also instruct on the impact of different design choices on STL operation. 

/pdf/daily-and-seasonal-thermal-energy-storage-for-enhanced-3fizksu1.pdf

Daily and seasonal thermal energy storage for enhanced flexible operation of low-temperature heating and cooling network

Floods can cause widespread and prolonged power outages by inundating substations. However, assessing the inundation failure of substations to improve power system resilience is challenging, as there may not be sufficient historical data to capture the impact of flooding on substations at a given location, due to their evident temporal and spatial variability. To tackle this gap in knowledge, this paper proposes a geo-referenced statistical model that is not constrained by historical flooding data. The geo-referenced model embeds a hydrological model that uses established digital rainfall and topography data to simulate flood depths at the location of selected substations, and calculate associated inundation risks. The stochastic inundation profiles are used within a Monte Carlo simulation to model substation failures and explore options to improve power system resilience (e.g., asset elevation). The proposed model is demonstrated using a case study from Bintulu, Malaysia, where real empirical data was used to identify the breaking points of the power system and estimate probability density functions of energy not supplied caused by inundated substations. The simulation results show that substation failures can abruptly lead to significant energy not being supplied, whereas elevating the substation to withstand an additional 20 cm flood depth will significantly delay flood impacts, and effectively improve system resilience. The proposed methodology and key findings will enable system planners and operators to understand when and where the power system will experience energy losses under unpredictable extreme floods and help them to decide on the most effective resilience enhancement strategies.

Pierluigi Mancarella

Papers

Comparative Studies on Cost, Reliability and Resilience of Off-Grid Energy Systems

Impacts of Distribution Network Reconfiguration on Aggregated DER Flexibility

Distributed generation and smart grid development: case studies in different european countries

Daily and seasonal thermal energy storage for enhanced flexible operation of low-temperature heating and cooling network

Assessing Power System Resilience to Floods: A Geo-Referenced Statistical Model for Substation Inundation Failures