Wednesday, December 4, 2013

Wind power or photovoltaics?

Wind power is an interesting option for producing renewable energy. In contrast to Photovoltaics, wind generated energy costs less but it requires transmission infracstructure between wind parks and the consumers.Germany has more than 32 GW of installed wind power capacity and is now building transmission lines to transport the energy to the south.

How predictable is wind in comparison to PV output? The yield of both depend on some meterological factors which are hard to predict. However there is one big difference: you can easily calculate the maximum amount of solar intensity that your PV system has to cope with. With wind speed, it is hard to define a maximum possible wind speed, since on rare occasions wind speed can be significantly higher than the expected value.

Which could be dangerous: If the generator spins faster and faster, large forces produced could cause a wind turbine to self destruct:

Luckily, todays wind turbines have an overspeed control (a braking or featherin mechanism) and a cut-out mode. Still, I don't want them in my garden :-)

Sunday, December 1, 2013

Open position for an Associate Professor at the Faculty of Electrical Engineering and Information Technology at Vienna University of Technology

The Faculty of Electrical Engineering and Information Technology of Vienna University of Technology invites applications at the Institute of Energy Systems and Electrical Drives for a Tenure track position with qualification agreement for associate professor in the area of Electrical Energy Distribution Systems in form of a initially fixed-term (6 years) tenure track position starting from 01.04.2014. Research areas to be independently covered are automated distribution system operation including information and communication technologies (Smart Grids), integration of renewable and distributed energy resources into the energy system, electro-mobility, Microgrids as well as protection technology. The successful candidate is expected to initiate independent, creative research programs and to establish an own research group.
A strong emphasis is placed on the broad fields of planning, modeling, simulating and analyzing electrical energy distribution systems as well as the integration of decentralized renewable energy resources, hybrid energy storage systems and application of information and communication technologies for automated distribution system operation.
The following requirements for applications to this position exist. The successful candidate is expected to be an internationally recognized scientist with a PhD relevant to the field and perennial experience in one or several of the following research areas:
- Impact of distributed energy resources on distribution system operation and protection
Integration of decentralized renewable energy resources and distributed storage into the energy system
Integration of electro-mobility into the energy system
Application of information and communication technology in energy distribution systems
Reliability, resilience and island capability of energy distribution systems
Real time simulation of energy distribution systems and Microgrids
and experience and commitment to excellence in teaching and supervision of undergraduate, graduate and PhD students.

The successful candidate is expected to participate in teaching according to the curricula of the faculty of electrical engineering and information technology and to establish an own research group.
Salaries and benefits of the tenure track position are according to collective labor agreement for employees at universities, salary group B1, based on 40 hours per week, and a monthly minimum salary of currently € 3.411,70 (14 times per year). After signature of the qualification agreement salaries and benefits are raised to salary group A2 and thus monthly € 4.034,70 (14 times per year).
Applications should include curriculum vitae, list of publications, copies of 5 most relevant publications, list of successful grant applications, and list of teaching experience. Applications should be directed to the Dean of the Faculty of Electrical Engineering and Information Technology of Vienna University of Technology, Erzherzog Johann Platz 1, 1040 Wien, Austria. Applications should include a CD-ROM with an electronic version of the complete application documents. Candidate evaluation will begin on 04.01.2014.
Candidates are not eligible for a refund of expenses for travelling and lodging related to the application process.

Monday, November 18, 2013

Impressions from BuildSys 2013

The 5th ACM Workshop On Embedded Systems For Energy-Efficient Buildings (BuildSys) 2013 were hold from the 13th to 14th of November in Rome, where the two researcher Dominik Egarter and Andrea Monacchi participated in. According to the general BuildSys chair the Workshops' aims can be summarized as follows:

The entrance of La Sapienza University, Rome, where SenSys and BuildSys were held
"BuildSys is a venue for discussing new directions in the monitoring, control, and management of energy consumption in buildings, and the generation of awareness and sustainability for an efficient energy market. BuildSys brings together researchers from a multitude of disciplines with a common goal to develop energy saving strategies that can have a major impact worldwide. BuildSys 2013 follows four successful predecessors held in Berkeley, Zurich, Seattle, and Toronto."

This year the workshop had 7 different season such as:
  • Energy Efficiency in Homes,
  • Data Analysis,
  • Occupancy Detection, Monitoring & Use,
  • Sensing for Energy,
  • Energy and Water,
  • HVAC, Modeling and Control and
  • Thermal Comfort Management,
Andrea and Dominik at their posters 
where in total 22 papers were presented. In addition to the general paper presentation, the workshop offers a poster and demo session, where 10 posters and 8 demos were presented. The Smart Grid Group not only visited workshop, Dominik and Andrea were presenting two posters. Dominik showed his current result of Non-Intrusive Load Monitoring (NILM) techniques with the title Appliance State Estimation Based on Particle Filtering. In this paper he showed how it is possible to apply Particle Filtering to the problem of aggregated power loads and how beneficial this approach can be. Moreover, Andreas poster has the title Insert Coin: turning the household into a prepaid billing system and propose an approach for raising energy awareness by combining appliance-level consumption information with prepaid billing so as to turn appliances in pay-as-you-go devices.

D. Egarter, Venkata Pathuri Bhuvana, W. Elmenreich. Appliance State Estimation Based on Particle Filtering5th ACM Workshop on Embedded Systems For Energy-Efficient Buildings, Rome, Italy, 2013.

A. Monacchi, W. Elmenreich. Insert Coin: turning the household into a prepaid billing system,5th ACM Workshop on Embedded Systems For Energy-Efficient Buildings (BuildSys'13), Rome, Italy, 2013

Thursday, November 7, 2013

Appliance State Estimation based on Particle Filtering

The load disaggregation problem
Dominik Egarter will present his work on Appliance State Estimation based on Particle Filtering at  the 5th ACM Workshop on Embedded Systems for Energy-Efficient Buildings (BuildSys'13) which will take place in Rome, Italy at 13th and 14th October 2013.

Non-Intrusive Load Monitoring is a single-point metering approach to identify and to monitor household appliances according their appliance power characteristics. In this paper, we propose an unsupervised classification approach for appliance state estimation of on/off-appliances modeled by a Hidden Markov Model (HMM). To estimate the states of appliances, we use the sequential Monte Carlo or Particle Filtering (PF) method. The proposed algorithm is tested with MATLAB simulations and is evaluated according to correctly or incorrectly detected on/off events.
On other approaches for solving the NILM problem, see:

Particle filter method
Read more about the approach in:

D. Egarter, Venkata Pathuri Bhuvana, W. Elmenreich. Appliance State Estimation Based on Particle Filtering, 5th ACM Workshop on Embedded Systems For Energy-Efficient Buildings, Rome, Italy, 2013.

On other approaches for solving the NILM problem, see:

D. Egarter and W. Elmenreich. EvoNILM - Evolutionary appliance detection for miscellaneous household appliances. In Proceedings of the Green and Efficient Energy Applications of Genetic and Evolutionary Computation at the 2013 Genetic and Evolutionary Computation Conference (GECCO 2013 GreenGEC). ACM, July 2013.

D. Egarter, A. Sobe, and W. Elmenreich. Evolving non-intrusive load monitoring. In Proceedings of the 15th European Conference on the Applications of Evolutionary and bio-inspired Computation, pages 182–191, Vienna, Austria, April 2013.

Friday, October 18, 2013

Strategies for domestic energy conservation in Carinthia and Friuli-Venezia Giulia

A recent study carried out by Ernst & Young on the behalf of the German Federal Ministry of Economics analyzed benefits and costs of smart metering in the country and concluded that the savings for the residential customers do not justify the costs. Therefore, a less precipitous replacement of existing meters should be arranged, which would place German utilities in conflict with the EU's target of 80% of consumers equipped with smart meters by 2020.

In the MONERGY project, we aim at providing ICT solutions to promote energy awareness and conservation, in order to lower wastages and costs, and thus CO2 emissions. In particular, we are committed to propose specific strategies considering the peculiarities of two regions under experiment: Carinthia (Austria) and Friuli-Venezia Giulia (Italy). Our initial decision was therefore to conduct an analysis of typical scenarios in the regions, in terms of electrical devices used, availability of smart metering and adaptive tariff plans, exploitation of renewable energy generation. Results of this study are presented in the paper "Strategies for domestic energy conservation in Carinthia and Friuli-Venezia Giulia", which is to be presented next November 12th at the EnergieInformatik conference, in Vienna. Beside spotting similarities and differences in the regions, we also provide a short survey on existing conservation strategies that could be implemented to our purposes.

A simple conservation strategy improving energy awareness is prepaid billing. The user can buy a certain amount of energy in advance, and get his credit decreased upon consumption, and until it reaches zero, which causes a disconnection from the grid. This simple mechanism was shown leading to up to 11% of savings for the customers in UK.
From the survey it turned out that the highest savings can be achieved by employing persuasive interfaces, i.e. interactive computing systems displaying enhanced consumption information in order to promote behavioural change. In particular, appliance-level consumption information, both indirect and real-time can boost user's energy awareness, while self-learning mechanisms can be triggered by analytics and recommendations. We therefore decided to implement a prepaid billing system charging individual electrical appliances upon occurrence of consumption events. The system is currently based on the open hardware metering platform called OpenEnergyMonitor. Basically, consumption information is collected down to individual monitored devices by means of current transformers, enhanced with situational information such as time and duration, and sent to a cloud-based web service which manages the user's credit. An Android app was implemented to manage the credit and to provide the user with a smart notification system, which alerts him upon specific events (e.g. credit is over).

We believe that this system can increase the resolution of the consumption feedback and boost energy awareness of users in Carinthia and Friuli, being already applicable in spite of the differences previously spotted. We are currently planning to assess the acceptance of the system and the deriving savings within a case study in actual households in the regions. The strategy will be discussed in the poster session of the next ACM Workshop on Embedded Systems for Energy-Efficient Buildings (BuildSys'13), specifically in "Insert coin: turning the household into a prepaid billing system". We are very much looking forward to getting your comments on our ongoing research. 
In case you are interested in getting further information, an extensive overview of the project is provided by our first deliverable and the project website.
on Embedded Systems for Energy-Efficient Buildings (BuildSys’13) - See more at:
on Embedded Systems for Energy-Efficient Buildings (BuildSys’13) - See more at:
on Embedded Systems for Energy-Efficient Buildings (BuildSys’13) - See more at:
on Embedded Systems for Energy-Efficient Buildings (BuildSys’13) - See more at:

Monday, September 9, 2013

Open Professorship on Sustainable Energy Management

Alpen-Adria-Universität Klagenfurt invites applications for a Full Professorship on
Sustainable Energy Management
prospectively to be filled by January 1, 2014.

The professorship is limited according to §99 UG to a duration of 5 years. After that duration, it is planned to establish a tenured professorship on Sustainable Energy Management.
The successful candidate has an international reputation in research on business economics and energy management, experience in the management of projects and interest in setting up multidisciplinary projects together with industry and research institutions. Furthermore, candidates should be committed to excellence in undergraduate/graduate teaching and in supervising PhD students. Candidates are expected to have good language skills in English and German.

With more than 10000 students, the Alpen-Adria-Universität Klagenfurt is a vibrant and innovative university in the southern part of Austria, a region with top quality living conditions at the confluence of Alpine and Mediterranean culture. The position is located at the Faculty of Management and Economics

In order to increase the number of women in leading academic positions, we specifically encourage women to apply.

Applications should be sent by September 18, 2013 to Sabine Tomicich ( and should be accompanied by a descriptive summary of at most 5 pages. The complete call for applications (in German) can be found at
For more details contact Univ.-Prof. DI. Dr. Erich Schwarz (Tel.: +43 463/2700-4050 or

Thursday, August 29, 2013

PhD position at ETH Zurich on Public Acceptance of Energy Infrastructures

The newly formed Human-Environment Systems (HES) group at ETH Zürich seeks to hire a PhD student, commencing as soon as possible, for a period of up to three years. Our group is part of the Institute for Environmental Decisions, within the Department for Environmental Systems Science. The student would pursue research within the thematic area of energy, development and security (HES:EDS) in an externally funded research project.

ETH Zürich (Foto: Roland zh, CC)
The HES:EDS thematic area concerns social and governance challenges and risks of a transition to a very large electricity system with high shares of renewables, spanning all of Europe, and possibly North Africa and the Middle East. Issues we are investigating include:

• the social acceptance of devoting large land areas to renewable power generation, centralized and decentralized, and transmission in one’s own back yard and in far off places;
• the methods and tools to involve stakeholders in the processes concerning electricity infrastructures and generation facilities, and the governance options to resolve competing interests for scarce resources, primarily land and water;
• the social and political implications of a system transformation, in particular energy security and human development impacts of cooperation between industrialised and developing regions, and ways of arriving at improved outcomes;
• the financing, construction and maintenance of an integrated power system across disparate and changing political and regulatory systems.

The successful applicant will have the opportunity to contribute to research within all research lines of the HES-EDS group, but in particular within the area of social acceptance of electricity transmission lines. Funding for this work comes from a new, European Commission-funded research project: INSPIRE-Grid (“Improved and eNhanced Stakeholders Participation In Reinforcement of Electricity Grid”), and the successful application will work with other project members in completing the research tasks already specified. The overall aim of this project is to provide the evidence base to support improvements to the permission processes for new electricity transmission lines in Europe, and in so doing improve the feasibility of renewable power options. The research tasks to be undertaken at ETH Zürich include analysing existing practices in different national contexts including different stakeholders’ needs and concern. The focus will be on why people oppose or support electricity grid projects, and what possible changes in the permission processes for such projects could accomplish.

Qualifications and skills: We seek a person with some degree of background knowledge on energy systems, gained through study or work experience, who is interested in focusing on social science research questions involving quantitative and qualitative methods, leading to a continuing career in research. Suitable candidates will hold a master’s degree in a relevant social science (e.g. political science, sociology, economics) or interdisciplinary field (e.g. environmental studies, geography, public policy). Excellent command of oral and written English, and willingness to actively engage with new concepts and methods in an interdisciplinary and international team are essential requirements. Proficiency in German, French, or Arabic would be an advantage, but is not a requirement. Prior work or research experience in risk communication processes would also be an advantage.

Position: We intend the position to be the context within which the successful candidate will complete a PhD degree. This will entail a limited amount of coursework, the preparation of a self-motivated research plan consistent with the INSPIRE-Grid project obligations, and ultimately the writing of a number of separate research papers for publication in the peer-reviewed scientific literature. Depending on the candidate’s past course transcripts, the ETH Zürich doctoral program office may also require the successful applicant to pass one or more entrance examinations within the first year. PhD students at ETH Zürich also typically engage in some undergraduate teaching, participate in workshops and seminars, and take on limited administrative duties.

The position will start as soon as possible, and is intended to be for a period of three years, within which time the successful candidate will fulfil project commitments and complete a PhD. The initial contract will be for a period of one year, with a transparent review process to determine annual renewal.

The working location will be Zürich, Switzerland, with some work-related travel within and potentially outside of Europe. All members of the HES group contribute to and benefit from a dynamic, friendly, and supportive work environment, where they have the opportunity to pursue independent and self-motivated scholarship at the same time as they benefit from close collaboration with more senior colleagues, as well as a wide international network. We have a policy of supporting all HES group members in their professional development, including attending academic conferences and workshops, and assistance in preparing for their next professional step. ETH Zürich consistently ranks among the top universities in the world, while the city of Zürich is one of the most liveable. Salaries and benefits are extremely competitive, and compensate for the high cost of living in Switzerland.

Application process: To apply, please submit a written application as an email attachment to Anthony Patt, whose contact information may be found on the HES website:<> . Please include the words “PhD Student Application” in the email header. The application, in English, will consist of: (a) a cover letter, in which you describe your background, interest in the position, and interest in pursuing a PhD degree at ETH Zürich; (b) a resume or curriculum vitae, including past education, qualifications, work experience, and any publications; (c) scanned copies of university grades or transcripts at the bachelor and masters levels, with any additional information needed to interpret that information; (d) the names, affiliation, and contact information (telephone and email address) of two references who would be willing to discuss your qualifications. If you wish to submit a sample of written work, please feel free to do so.

You will receive a confirmation of receipt within several days. On 12 September 2013 the team members involved in the INSPIRE-Grid project (Anna Scolobig, Anthony Patt, and Johan Lilliestam) will review all applications received by then, and will continue to review new applications until the position is filled. Following the initial review, we will schedule telephone interviews with a short list of candidates, and may invite one or more candidates for an interview in Zürich. We will notify all unsuccessful candidates as soon as we have reached an agreement with the successful candidate. It is our intention to make a decision as quickly as possible after having received an excellent application from a suitable candidate. We welcome international applications, and applications from women, disabled people, and historically disadvantaged minority groups.

NOTE: DO NOT submit applications to the email address<>. Instead, use the address for Prof. Anthony Patt found on

Friday, August 16, 2013

Final two Interns@SmartGrid_Group

For the last two months we had further two interns working at our institute. We report a short interview about their work and experiences at our research group.

What's your name?
What are you studying?
I am studying electrical engineering and industrial electronics at the HTL Mössingerstraße in Klagenfurt and this year I've finished the 4th class.
What are your expectations for the future?
I want to conclude the HTL with good marks, then I would like to study something that combines electrical engineering and economics.
What are you working on?
LabView GUI
I have worked on a LabVIEW measurement program for a photovoltaic system and have also created a consumer box for the lab, where we want to simulate a household. I have installed input modules, which are used for measuring voltage and current, and an output module, which is used for turning the devices on and off. These modules are implemented into my LabView program and further I have created an interface, where the user is able to input data to the program and view power and current consumption. There is also the possibility to read the measured data and control the devices through a web service in the network. I have also installed the hardware elements in the cabinet, created the wiring plan and ordered appliances. The aim of the program is to be used as a control of consumer devices like a refrigerator, water heater and radiator, which are turned on at the time, when the current price is on the lowest peak. Thus this could be an innovative application for saving costs and has to be researched.
Laboratory Installations
What did you like of the project
I liked about my work that I had the chance to contribute my own ideas and expand my programming skills in LabVIEW. It was a very varied project and I liked the mix of manual work and logical thinking.

What's your name?
What are you studying?
I'm studying electronics and technical informatics at the HTL Mössingerstraße in Klagenfurt. I have finished my second year.
What are you expectations for the future?
After finishing the HTL, I want to study computer science.
What are you working on?
I was working on Java classes for a Smart Grid Simulator which make it possible to use algorithms from the GridLAB-D simulator. To submit this, I converted all data stored by objects from the Smart Grid Simulator into a file which is then used by GridLAB-D. The output files made by GridLAB-D are read and the values are assigned to the proper object.
GridLAB-D to Smart Grid Simulator 
I was also working on an open source energy monitor made by Openenerymonitor. My task was to enable it to change the refresh rate on the transmitter (emonTX) by using buttons on the receiver (emonGLCD). The difficult thing was to send and receive data at a time using the same transceiver.
Power Profile Generation in Java
My final project was the implementation of a Java program, which generates random power profiles of different appliances out of a given database, place this random profiles randomly in time and finally, tries to detect which appliance was used or not. The technique of appliance detection is called Non-Intrusive Load monitoring and enjoys currently an great interest in research.
What did you like of the project?
I like programming a lot. So I had the opportunity to improve my skills.

Tuesday, August 6, 2013

Smart Grid @ GECCO 2013

On July 6th - 10th we attended the Genetic and Evolutionary Conference GECCO 2013 in Amsterdam. GECCO is the largest conference in field of genetic and evolutionary computation. The conference was organized by 18 different tracks like Genetic Programming, Genetic Algorithms or Real World Applications, had 35 different tutorials and hosted 13 workshops.

From the Smart Grid group, Dominik Egarter took part at the Green and Efficient Energy Applications of Genetic and Evolutionary Computation Workshop 2013, where he presented his paper EvoNILM - Evolutionary Appliance Detection for Miscellaneous Household Appliances.
In this workshop 5 different papers were presented, which topics were widely spread from power flow optimization, wind power forecasting to wind power siting.

Tuesday, July 30, 2013


Today we report of a short interview we had with two of our interns, who have been working for one month on developing a web-based home energy management system, consisting in an Android application and a web service.

What's your name? 

What are you studying?
I have been studying electronics and technical informatics a the HTL Mössingerstraße in Klagenfurt. This year I finished the 2nd class. 

What are your expectations for the future?
After the HTL I want to study software/game development and found a software company.

What your working on?
I worked on two different versions of the same Android app, as well as a REST webservice implemented in PHP.
Basically, I have designed and implemented a MySQL database, and used the php webservice to handle the data and expose the functionalities to the android app I then developed. The apps differ for the JSON protocol used. In fact, only one of these apps is using the php webservice I implemented, the other one is a solution we prepared to mantain retro-compatibility with the old version of the app that was already working for an older project and running on the Google App Engine platform.

Beside calling the REST interface, the apps also implement a smart notification system which exploits the Google Cloud messaging infrastructure to implement push messages from the cloud to the terminals. We use this smart notification system to inform users upon occurrence of certain events of interest.

What did you like of the project?
I like the idea to show the users how much they consume. I think it would be cool if in future energy providers such as Kelag worked with an automatic metering system, so that nobody is required to read the electricity meter for being charged and it is easier to get an understanding of how energy is actually used.

What's your name?

What are you studying?
Electronics and technical informatics at the HTL Mössingerstraße in Klagenfurt.
This year I finished the 4° class, therefore next year I will conclude the HTL.

What are your expectations for the future?
After working for our military I would like to start studying in a similar kind of education or this combined with economics.

What your working on?
During my internship I worked on interactive data visualization. At the beginning I analyzed existing libraries and made a summary of their characteristics before selecting the ones we were looking for. Then, I prepared a graphical interface exploiting the Google Chart and the Chap links chart libraries. The website can do the same things of the Android application.
Basically, the system collects events, such as running a washing machine, which are enhanced by a cost and a duration and shown on a timeline. We can also see the trends for the costs, as users can add money to devices and get an understanding of the cost of carrying out daily life activities.
Currently the data is retrieved from the database using PHP, and all events and payments are shown on the timeline. This raises several issues on performance that I am currently trying to solve using asynchronous calls to the DB, using XMLHttpRequest (i.e., the famous AJAX used in many of the websites we used everyday). I am also investigating ways of keeping the interface up to date, especially concerning the itemization of the energy consumed for the day, using periodically running procedures and/or using triggers on the database.

What did you like of the project?
I had the possibility to work on something I haven’t worked with before. I didn’t have much knowledge on javascript and php but after this month I can say I have programmed a whole website, using advanced tools such as sessions and cookies. I think this was more useful for me than working with programming languages I already know better.

Monday, June 24, 2013

Tales from PowerTech 2013 in Grenoble

The PowerTech Conference is the main conference of the IEEE Power Engineering Society in Europe. At least this is what we were told in the opening speech on Monday the 17th of June in the World Trade Center of Grenoble. And honestly they really made a lot of effort to leverage the conference impact. Even though the French Minister for research and higher education did not made it personally to the sight still her video message was part of the conference opening session. Executive officers from local transmission and distribution grid operators and electric industries had a slot in that session as well. You might have guessed, by help of the picture, that one of them was from Schneider Electrics which is a quite important player in that region. But there is even more famous things coming from Grenoble: It was the town where Fourier was working and teaching. His house is accessible for public as a museum. Unfortunately I could not find time to visit it as many interesting talks waited to be listened to. 

The representers of industries gave an idea about how their companies deal with the topic Smart Grid. The speakers associated with political institutions gave their perspective about the problems to be solved. It was mentioned several times in this session that there is a big leak of business models for the smart grid. This is associated with missing motivation to invest in technology and its general roll out. Further I was quite surprised to see very familiar content in the slides of the invited speaker M. Masera from the JRC-European Commission. He presented slides related to Ettore Bombard's presentation from last year's Lakeside Labs Research Days about modeling a social layer for smart grid, including user behavior. My own presentation titled “Simulating the Smart Grid” was scheduled to the second day right after the invited speakers in the session about dynamic modeling:

  • M. Poechacker, A. Sobe, and W. Elmenreich. Simulating the smart grid. In Proceedings of IEEE PowerTech, Grenoble, France, 2013.

About seven to eight different tracks were running simultaneously over the 11 sessions, additionally two poster sessions, several invited speakers and special sessions held by companies. Around 500 attendees from all over the world, mainly Europe, have been there. 
The main conference program was enriched by technical visits to power system related facilities and the touristic visits in the region. I participated at a tour to the INES (Institute Nacional de Energia Solar), an impressive research center with around 400 employees. The visit has good chance to become content of a further post in this blog. I would say the organizers did a good job. A resume that is strong influenced by the daily served lunch (including the obligatory French chees and wine) and the nice Gala dinner (with life music and artistic presentations) in the ice stadium of Grenoble. 

If I caught your interest in this conference now, the next PowerTech conference will be 2015 in Eindhoven, Netherlands.

Monday, June 17, 2013

Evolutionary Appliance Detection for Miscellaneous Household Appliances

The paper "EvoNILM - Evolutionary Appliance Detection for Miscellaneous Household Appliances" was accepted to the Workshop "Green and Efficient Energy Applications of Genetic and Evolutionary Computation" at Gecco 2013.

To improve the energy awareness of consumers, it is necessary to provide them with information about their energy demand, not just on the household level. Non-intrusive load monitoring (NILM) gives the consumer the opportunity to disaggregate their consumed power on the appliance level. The consumer is provided with information about the energy demand of each individual appliances. In this paper we present an evolutionary optimization algorithm, applicable to NILM purposes. It can be used to detect appliances with a probabilistic power demand model. We show that the detection performance of the evolutionary algorithm can be improved if the single population approach of the evolutionary algorithm is replaced by a parallel population approach with individual exchange and by the introduction of application-oriented pre-processing and mutation methods. The proposed algorithm is tested with Matlab simulations and is evaluated according to the fitness reached and detection probability of the algorithm.

This paper is an improvement and follow up paper of the previous work "Evolving Non-Intrusive Load Monitoring".

Thursday, May 30, 2013

Impressions from e-Energy 2013

On May 22th, 23rd and 24th we attended the fourth International Conference on Future Energy Systems (ACM e-Energy) in Berkeley, California.

The conference was open by the beautiful keynote talk held by Dr. Jeffrey Taft from Cisco. It gave to the audience a complete understanding of current trends in the smart grid.
In their vision, the smart grid is a network combining 4 layers, the energy production and distribution, the market, the information layer and the social network (yes social networks). In the last years the progressive installation of renewable energy generators made the grid more and more unstable, as consequence of the sources exploited. To realize the vision of smart grid, it is necessary to provide the means for applications rather than looking for a killer application that justifies the need of such a change. Indeed innovation in the greed should foster developers, which would create a positive feedback to promote more and more innovation on the system. Basically, the stakeholders are looking for a system that can let them implement closed-loop controllers and attach them to the grid in a plug&play manner. This raises various concerns. The presenter mentioned data interoperability issues in the grid and showed the need of a multilayer network architecture able to tackle the complexity of the system.
In fact there is ongoing research in this direction (e.g. CoAP) but current solutions lack in scalability and still require high degree of mantainability. A multilayer network architecture should be deployed to give stakeholders the possibility to work at different abstraction levels and implement controllers as optimization problems broke down from the overall goal of ensuring a certain degree of reliability and stability.
In this model, the lower levels consist of components exploiting real-time delivery of information to manage safety-critical aspects. In the upper levels, the information is processed (e.g. to produce analytics) and delayed so that decision makers (both human and automatic) can exploit it to optimize specific goal functions.

The other two keynote talks seemed to converge to the need of a distribution network closer to the internet. However, the existing infrastructure will unlikely be replaced with a new smart grid. We will most likely assist to the progressive replacement of crucial components with new ones. This will certainly bring high risk of failure into the system.
On the other hand, developing countries will be able to directly install innovative components into their energy systems, which will let them experiment new technologies and enable them to catch developed countries up. In the third keynote held by Arun Majumdar, the similarities with the internet network are even more evident. He clearly mention the need for something like power routers that would transform a strictly hierarchical network to a more flexible one. Current challenges and trends are very well presented by the speaker, altough for obvious reasons, ongoing solutions studied at Google are not even introduced to the audience.

  1. Storage integration
    The first two papers dealt with the problem of mananging storage so as to reduce peak periods and optimize running costs of devices. The following two were as much interesting, as they proposed the use of batteries to reduce outages and improve power qualities in areas were energy provisioning is particularly unreliable. The third paper was in particular interesting, as it proposed to use a ups on a device-level, so that the ac-dc conversion losses can be minimized for consumer eletronics devices, and the problem of managing storage capabilities can be distributed.
  2. Measurements and their use
    The second session concerned the exploitation of consumption data to infer further information. The first paper presented an approach to demand forecasting, although they only used a feature for their predictor, which definetely makes the solution completely context-less. The second paper proposed a set of requirements and a cloud-based architecture very similar to the one proposed in our paper "Integrating households into the smart grid". However, they used a tailored protocol and data representation and did not consider scalability issues that might arise from this approach. The third paper presented a very interesting approach to infer household and inhabitants characteristics out of metering data. Finally the last paper proposed the use of ethnografy and other kind of studies used in humanities to enrich the data collected through sensor networks, so as to produce much more descriptive representations of inhabitants activities that can be better analyzed during studies promoting energy conservation.
  3. Distributed control
    The third session mostly included papers dealing with distributed vehicle charging.
  4. Data center energy management
    The papers of this session were related to energy-efficient data centres. In particular, the third paper dealt with the efficiency of ethernet interfaces.
  5. Energy efficient networking and network inference
    The first paper presented an approach to infer the topology of the distribution network out of time series collected on meters. The second paper introduced the concept of hierarchical state estimation in the energy grid and reported possible ways of detecting malicious attacks to this system. The following two papers dealt respectively with the performance of network interfaces and the TCP protocol.
  6. Smart homes and buildingsThis session was definetely the last but not the least interesting. In the first paper an implementation of supervised random forest classifier was used to detect the device type connected to a sensing unit, as well as its operational state. In the third paper, a kinect interface was used to determine the amount of clothing weared by people. A voting mechanism was used as comfort feedback for the heating controller of the room. The final goal will be suggesting to the user to wear a coat when he start feeling cold and giving lower rates to the system. The last paper of the session concerned activity recognition in office spaces. In the study they used finite state machines to describe the state logic of the environment. However, this raised an interesting discussion on the need of domain expertise to specify the transitions. Therefore they decided to also use a LHMMs (Layered Hidden Markov Models) and learn the transition probabilities from a dataset. This model is then used to manage the light dimming and status. They showed remarkable savings of energy using this method.
  • Poster and Demo session
    • The poster and demo session was no less interesting than the papers. Among those the work of University of Southampton should be mentioned. Basically, they use a HMM to build a model of inhabitants out of the events created in the household. Beside the HMMs they compared various algorithms, and showed HMM outperforming all of them. In fact it was very interesting to discuss the concept drift issue with classical data stream mining algorithms, as well as to the necessity of binding detected events to the inhabitant who actually performed it in order to improve the model.

  • Panel discussionThe panel discussion was brought up a general discussion and interesting questions summarizing current trends and challenges in:
    • Fossil fuels are not sustainable and we will have to cope with this problem already now, as climate change is evident.
    • Renewable energy are destabilizing the energy grid, due to the volatile sources exploited for the production.
    • Institution will play a crucial role: incentives will have drive customers to more efficient products and technologies, essential role is played by research and development activities.
    • We will move to a situation where users are empowered with energy awareness and their decision making will be enriched by pervasive components, tracking their daily life activities and assisting them in reducing the footprint.
    • Energy will have to flow in a bidirectional way and information regarding energy price will have to be available to users to get them into the loop.

Wednesday, May 22, 2013

Integrating Households into the Smart Grid

On May 20th 2013 we attended the first IEEE Workshop on Modeling and Simulation of Cyber-Physical Energy Systems. The workshop was collocated with the fourth International Conference on Future Energy Systems (ACM e-Energy), to be held in Berkeley on May 22th, 23th and 24rd.

The topics presented were very variegated. In the first session the papers were mostly concerning simulations of building or system-scale aspects in the grid (distribution, market, power flow modeling). The opening presentation was given by Kyle Anderson from Stanford University, presenting the GridSpice simulator, a cloud-based simulation tool which relies on multiple agents to run different existing simulation tools (MATPOWER and GridLab-D) and mantain the overall simulation consistence with a central coordinator. It also provides a RESTful interface to access the simulation, so that it can be integrated in third-part applications.

In the second session more applied and variegated aspects were presented.
We opened this session with the paper "Integrating Households into the Smart Grid". It deals with the problem of device and data interoperability created by the highly heterogeneous ecosystem of digital devices present in homes. In the paper we discuss requirements that should be addressed when copying with such a complex network. We show that an architecture based on REST webservices and linked data streams would be able to tackle this complexity. Applications can access the data through a uniform interface consisting in specific APIs and standardized query languages, as well as agreed ontologies for the specific use case.

The following presentation surveyed existing ontologies for smart home and smart energy systems and was held by Marco Grassi from Università Politecnica delle Marche. This completed the device and data interoperability issues and gave the audience a complete overview of this side of the smart grid.
The following presentations dealt with security aspects of the grid, such as detecting spoofing attacks on power grid GPS sensors. Also, multi-agent algorithms and control schemes were proposed for various aspects involving cyber-physical energy systems (i.e., resource bargaining, model-predictive control, coordination of power flow controllers).