Paper accepted for presentation at 2003 IEEE Bologna Power Tech Conference, June 23th-26th, Bologna, Italy
Architectural Framework for the Integration of Distributed Resources J. Jimeno, I. Laresgoiti, J. Oyarzabal, B. Stene and R. Bacher
Abstract-- Deregulation of the electricity sector, environmental concern, advances in Information and Communication Technologies (ICT) and the appearance of new cost effective energy generation technologies, are driving the traditionally safe and reliable electrical network onto a situation in which the quality level of electricity supply will not only have to be maintained, but even increased, although difficulties for doing it will be greater than before due to uncertainties arising from competitive market driven transactions. The integration of market management together with the physical management of the electrical network creates several problems that the use of ICTs is going to help to solve. In this context, Internet and the Semantic Web technologies appear as the most cost effective and promising way to achieve the interoperation of both interrelated worlds. Scada is the basic system for every process control. The data provided by the Scada system is mainly focused onto the control of the process without taking into account that the information can be used for other means and by other services within a utility. The research performed in this paper reports on the ways to achieve the utilization of the SCADA information in different kind of applications by wrapping the data values coming from the process with the semantic meaning of what they mean, and its use for different energy related applications.
Index Terms-- Binary information, distributed generation, Internet, metering, multi-dimensional data, Power balance group, semantic web, Scada.
I. NOMENCLATURE Semantic web is a term coined by its inventor Tim Berners Lee [1], director of W3C to describe the next intelligent generation of the World Wide Web. II. INTRODUCTION
T
his paper presents an application driven approach towards the realization of systems that support the integration of
The work is being supported by the IST program of the 5th framework of the European Commission under contract nº IST-2001-.30067 J. Jimeno is with Fundación LABEIN, Parque Tecnológico, edificio 101, 48170 Zamudio, Spain (e-mail:
[email protected]). I. Laresgoiti is with Fundación LABEIN, Parque Tecnológico, edificio 101, 48170 Zamudio, Spain (e-mail:
[email protected]). J. Oyarzabal is with Fundación LABEIN, Parque Tecnológico, edificio 101, 48170 Zamudio, Spain (e-mail:
[email protected]) B. Stene is with the SINTEF Energy Research, Sem Saelandsbei 11, Trondheim, 7465 Nokrway (e-mail:
[email protected]). R. Bacher is with BACHER Cosulting, Hochstrasse 3, CH 5405 Baden Switzerland (e-mail:
[email protected])
0-7803-7967-5/03/$17.00 ©2003 IEEE
Distributed Generation in the network (wind parks in this case), the management of metering information and the management of information related to balance groups. The paper is divided into three main sections: Handling of multi-dimensional binary information stored by SCADA systems, implementation of an extendable server architecture capable of handling binary data along with their associated semantics and demonstrators for distributed generation (wind parks) integration, metering management and balance groups management.
III. HANDLING MULTI-DIMENSIONAL BINARY DATA AND ITS ASSOCIATED SEMANTICS Currently there are different alternatives for handling massive amounts of multi-dimensional data and there exist formats associated to them. COMTRADE[2] is a protocol used at the electrical substations level, to store the wave form resulting from a disturbance detected by a protective relay and the evolution of it until the fault is cleared. This multi-dimensional information is acquired in real time by the protective relays, stored in binary format in the relays storage and finally sent for analysis to the Integrated Substation Control System as non priority information. The information can be stored either in binary or in text format and there are software packages that are able to display the wave forms graphically. HDF5 [3] is a protocol used at the space agencies to store the information, in binary format, of myriad of sensors that a spacecraft has in its different processes, and to transmit it for processing to the control rooms. There exist a set of free software tools that facilitate the treatment of the information, providing functionalities, such as: Creation of a data binary file, storage of new values into an existent file, retrieval of instant values, retrieval of subsets of values within a set and/or belonging to different types of sensors. Whichever way is used to store and transmit the information, the associated semantics belong to the logic of the processing system receiving the information and do not form part of the envelope of the message transmitted. In this project, Semantic Web technologies and Internet standards are used to construct the envelope that wraps the multi-dimensional binary data. The objectives of the approach are two fold: On the first place to make available across Internet the data
acquired by the SCADA systems so that it can be accessed independently of its location by using cheap, reliable and standard access mechanisms and tools. On the other hand to make available semantic information associated to the data values acquired for SCADA in the way to allow the construction of intelligent support tools that are able to reason about the information received, such as: diagnosis systems, service restoration, etc. IV. IMPLEMENTATION OF A SERVER ARCHITECTURE At the present moment there exist certain uncertainty about how the energy market will evolve in the future and as a consequence what the applications required in the future will be like. Then having in mind that the applications to be built in the future may diverge from the ones currently built, an extensible framework architecture has been designed to support semantic transactions of multi-dimensional binary data. The architecture has been divided into layers to guarantee its flexibility and extensibility, such as, communication layer, services layer, storage management layer and storage layer. This allows a diversity of applications and tools in the different layers without affecting the main objective, which is the exchange of multi-dimensional semantically rich information. Internet and the tools and techniques associated to it, the use of standard software and the possibility to use low cost components in most parts of the architecture have been considered as the main issue for implementation, to take advantage of a reliable and cheap communications channel. Storage Layer
HDF5
DBMS
Storage Management Layer
Persistency management XML - Objects tranformation Query service
Update service
Transform Events service service
Security service
Services Layer
Other ……. Corba
DCOM Socket
HTTP
RMI
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Communication Layer XML Interface
Fig. 1. Framework architecture.
Storage layer: As one can see from Fig. 1, this layer includes the storage mechanisms that consist of a database management system for storing the static and dynamic information (semantics) and a binary data management system based on HDF5 for storing the data values acquired by the SCADA system from the process. Commercial and open software tools can be used at this layer, and for our purposes MySQL, PostgreSQL and HDF5 are being used. Storage management layer: This layer includes the software used to manage the persistency of the information (database and HDF5 based), as well as, the processing needed to manage
the relation between both backends. Finally this layer provides an XML based interface to the external world, which in this case is the services layer. Services layer: This layer provides the external access to information that in a normal SCADA system is represented by services that can be used by client applications, such as: Data storage service, monitoring service, events subscription service, events notification service, security services for authentication, accounting (log) and authorization. Other application specific services can be built at this layer. Communication layer: This layer consists of the different communication mechanisms that can be offered to the external application depending on their needs. For example, a monitoring application would need a communication capable of notifying events as they are produced, a browsing mechanism may be based on static Internet forms, other services may be defined as web services, an application may need its own proprietary communication with the sensor, etc. External layers site or applications specific can be added to the server. In our case the external components that we are currently using are: APACHE Web server, TOMCAT application server and Java as development language V. APPLICATIONS Support systems that make extensive use of knowledge have been implemented in the past. Many attempts to built knowledge based systems for aiding the dispatcher of electrical network control rooms have been done. Intelligent alarm processors, disturbance diagnosis systems, service restoration systems, etc. The main characteristic of those systems lied on the fact that the knowledge used for reasoning was scattered along different databases and experts and was being discovered after lengthy knowledge acquisition sessions. The results of this project that allow the wrapping of data values with their associated semantics is a way to alleviate this problem and to facilitate the development of knowledge intensive support tools. Uncertainty is going to be the main factor for the management of electricity networks in the future and the best way to deal with it is to rely on big logs of data, altogether with process knowledge and reasoning capabilities. Three applications of critical importance for the new world of deregulated electricity markets are being designed within the project and they all share the same base technology and framework architecture, but implement different types of services. The main objective of the demonstrators, at this stage, is not to convert them into commercial products but to facilitate the validation of the approach used and the feasibility of the technological solutions adopted. A. SMALL GENERATOR METERING AND CONTROL DEMONSTRATOR The objective of this application is to show that the technological solution developed within the project provides
an adequate solution to the problem of data acquisition and control for a future with high penetration of distributed generation. In a future, such as the one envisioned, the concept of “virtual utility” may start to play an important role in relation to what we now know as a Utility. A “virtual utility” can be thought as a utility that has establishes temporal/opportunity based contracts with energy suppliers and consumers to manage a certain part of the grid. This grid will be composed of the local grid owned by the utility, some equipment to guarantee certain quality of service owned by the utilities themselves, and some generators and loads not directly controlled by the utility but that can give away part of their independence based on profitable contracts negotiation. The control center of such a “virtual utility” needs the flexibility that may allow it to easily modify its configuration by incorporating or removing controlled participants. One important characteristic of such a control center is the openness of its data acquisition and control systems that will facilitate the configuration operations, being able to represent information from different types of consumers and producers in such a way that the software packages used are able to work properly without requiring any updating of their data and knowledge handling capabilities. The SCADA system has been used for years to perform this type of functionality and will continue doing it in the future, but the current SCADAs lack flexibility being closed worlds in which all the applications are integrated and it is extremely difficult to integrate new things in an easy way. Apart from the basic capabilities provided by SCADA that we want to demonstrate in this task, such as, On-line data monitoring, Commands execution, Historical data analysis, Events notification, User profile management, this demonstrator intends to build a small diagnosis system to show that the same technology is also able to provide higher levels of reasoning capability using rule based inference engines. The following are the main concepts needed to represent the semantics associated within a Wind Power Park monitoring application: • Product: The complete lifetime of a physical object. • ProductLifeSegment: A product for a period of time. • PhysicalObjectSet: A set that has physical objects as members. • PhysicalProperty: A property that is defined for a physical object; that evaluates to give a physical quantity; and that can be determined directly or indirectly by measurement. • Distribution: The complete set of evaluations of a Distribution indicate how a PhysicalProperty varies within the PhysicalObjectSet. In the example described in Fig. 2, first it is shown how a ProductLifeSegment relates to a specific Product (WGrd Wind Grid Information – IEC 61400-25). Next, the relation of the ProductLifeSegment with the set of ProductAtInstants is described and finally how the set of ProductAtInstants are related with the property being measured (measuredActivePower), the set of values acquired (Table) and the measurement unit used (kW).
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Fig. 2. Data values within a time stamp.
B. CONSUMER METERING DATA DEMONSTRATOR The metering process for small industrial and household consumers is complicated, because the ability to change suppliers within the de-regulated energy market requires information exchange between different market players and internal applications. The information flows between each of the work processes has to be examined, in order to create an overall model for this information. The scope of the information may among others include consumer energy usage; fault and interruption data; voltage and delivery quality, interruption alerts; and tariffs. A Nordic standard proposal is fundamental for this work. Some of the information is sensitive, therefore security will be part of the application. Consumers, suppliers and other market actors will have a much active role in managing the network in the future, than the one they currently have. It is not difficult to envision an increase in demand side management and demand side bidding approaches for managing the quality of supply of the network and the introduction of distributed generation based voltage control between others. A communication possibility between the different actors’ is shown in the Fig. 3 below, where ScadaOnWeb – technology enables one-to-many, as well as many-to-many communication/information exchange.
Customer
Customer SOW
Service Provider
SOW
software environment which allows the flexible definition of Time series as a specialized version of the techniques used in the project. A main feature will be the aggregation of time series values into new time series. Time series will be “packaged” in such a way that a user can forward (e.g. by Email) such an aggregated time series to another user who will – assuming that ScadaOnWeb base software is installed automatically understand from the underlying semantics what type of information has been received. The demonstrator software serves as a prototype software solution from which commercial power balance group software solution can later be derived. Also, the demonstrator software can support power balance participants (regulatory bodies, electric utilities, potential power balance groups, network operators) as a help and mind-supporting environment to understand problems and potential new solution for handling the complex power balance group information exchange requirements. VI. CONCLUSIONS
SOW
SOW
Network Operator
Supplier
This paper shows that the inclusion of semantic information to the binary data acquired by SCADA systems is a valid solution for the integration of distributed generation information and other kind of applications such as consumer metering and power balance group management. It also demonstrates that the use of web technologies is an approach that may allow in the future the link of the business and the process fields, as well as, the implementation of sophisticated support applications VII. REFERENCES Periodicals:
Fig. 3. Communication between actors. [1]
This demonstrator will aim at a limited integration of market actors and in particular will demonstrate the use of the ScadaOnWeb technology for a (Third Parties) Service Provider that wants to offer a new customer handling of all electricity issues, including price as well as quality aspects. To be able to identify potentials for cost-reductions, quality improvements etc, he will need information: consumption data and statistics, power quality data and statistics. When his “products” are defined and agreed on he will during the contract period need to communicate the following information to his customers: consumption data and statistics, price data and statistics, power quality statistics, and if his “product” involves some elements of control: load management, power quality services. C. POWER BALANCE GROUP A balance group is responsible for the determination of the planned power consumption and planned power generation of all of its "balance group contractors". Balance group contractors are power users which can be either power consumers or power providers. Within a balance group, the total consumed power must be equal to the total generated power, usually measured in 1/4 hour intervals. The demonstrator “Power Balance Group” will realize a prototype
Tim Berners-Lee, James Handler and Ora Lassila: The Semantic Web, Scientific American (www.sciam.com), May 2001.
Standards: [2] [3]
COMTRADE (Common Format for Transient Data) IEEE Standard (C37.111), 1999, http://www.beckwithelectric.com/powerlines/articles/i38/comtrade.htm. HDF5, Hierarchical Data Format, http://ncsa.hdf.hdf5lib
VIII. BIOGRAPHIES Joseba Jimeno was born in Bilbao, Spain, on November 26, 1975. B. Sc. in Electrical Engineering (2001) from the School of Engineering of the University of the Basque Country in Bilbao. Master in Networks, Telematic Services and Internet (2001) from the School of Engineering of the University of the Basque Country in Bilbao. His employment experience included Euskaltel (2001), Basque telecommunications operator. Since November 2001 to date, he has been working at Labein at the Energy Department, in the Internet Technologies area. Within Labein he has worked in energy market modeling and the application of ontologies to energy.
Iñaki Laresgoiti was born in Mexco D.F., Mexico in 1951. He received his Bachelors degree from the School of Engineering of the University of the Basque Country in 1973. He received a Msc. Degree in Mechanical Engineering from the University of California at Berkley in 1976 and an Msc in Applied Mechanics from the University of Michigan at Ann Arbor in 1986. In 1976 he started working in ASCARG S.A:, a company located in Bilbao, as a designer of access mechanisms and hatch covers for the ship building industry. In 1987 joined the Electronics department of LABEIN and was responsible for the application of Artificial Intelligence techniques in Power Systems. In 1992 he became responsible the research activities related with distributes system, Internet and its applications. In 2000 became responsible of the research activities related with the use of Information Technologies for Power systems. During all these years he has participated in several Esprit and Vth framework projects within the IST and EESD programs, being currently responsible for the ScadaOnWeb project. He is the Spanish national representative at the WG14 of the TC 57 within the IEC
José Oyarzabal was born in Bilbao, Spain, on 1967. He received the M.Sc. degree in Industrial Electrical Engineering, from the University of the Basque Country, Bilbao, in 1992. Since 1994 he has been working in Labein, involved in several applications related to power transmission and distribution control systems as well as protective relays. His special field of interest includes the application of information and communication technology standards to energy management systems. He is a member of the association of industrial engineers of Bilbao. Birger Stene was born in 1946 in Norway. In 1970 obtained a Scientific degree: MSc in Electrical and Computer Engineering from the Norwegian University of Science and Technology. He spent several years in research and development related to power systems analysis, network analysis and load forecasting; IT manager at SEfAS, and leader for software development, installation and maintenance in a UserService-Centre with 40 persons; exploitation workpackage leader in the ESPRIT project REMAFEX. In the EU IST ScadaOnWeb project he will be responsible for the Norwegian activity, and will deal with administrative tasks within the project. He also has some technical involvement. Its Present position: Research scientist in the Energy Systems division at SINTEF Energy Research.
Rainer Bacher was born in Västeras, Sweden on December 12, 1958. After receiving his doctorate (Dr. sc. techn. ETH) in 1986, he was employed at Control Data Corporation (CDC) in Minneapolis, MN (U.S.A.), (89) Colenco Power Consulting AG in Baden, Switzerland, (93) Assistant Professor of 'Energy Management Systems' at ETH Zürich. In 2000, he started his own consulting company, Bacher Consulting (Switzerland) which focuses on consulting of electric utilities and regulatory bodies in the area of power system liberalization and regulation. Since July 2002, Dr. Bacher also cooperates with the Bundesamt für Energie (BFE), in Bern, Switzerland. In this activity, he is responsible for the design of the Swiss electricity market. Dr. Bacher is member of IEEE, SEV/ETG, CIGRE TF 38, IEEE PES and of the technical committees of PSCC 93/96/99, PICA 93/95/97/99 (Technical Vice Chairman). He was also technical chairman of EPSOM 98 (ETH Zürich).
