The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.

An Architecture for Wireless Sensors in Distributed Management of Electrical Distribution Systems

Mikael Nordman

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S4 at Helsinki University of Technology (Espoo, Finland) on the 19th of November, 2004, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7298-9)   [682 KB]
Dissertation is also available in print (ISBN 951-22-7297-0)


This thesis presents a distributed architecture for the use of wireless sensors in the management of electrical distribution systems. Although the general concept of using wireless sensors for measuring quantities of power lines has previously been introduced, the proposed solutions have not been well integrated within the power system equipment and the automation system. This has severely compromised the applicability of the sensors in the field. However, wireless sensors have several features that make them an attractive instrumentation solution in the harsh environment of electrical distribution networks. Wireless sensors do not need signal or power cables and they are therefore easy to install and use in system refurbishment. They thus provide an interesting and cost effective alternative that is worth studying.

In this thesis, the concept developed for enhancing the applicability and integration of wireless sensors within the power distribution system is based on an architecture that uses the properties of the system itself to preserve functionality and to minimise the power consumption and thus the size and weight of the wireless sensors. In this architecture the following essential components and aspects are identified.

First, a time synchronisation method for wireless sensors is developed. The main goal with this method is to provide energy optimised means to determine the phase angle in wireless sensor cells where several sensors measure phase current and one sensor measures voltage. Secondly, a fault detection and location method with wireless sensors is proposed. This method enables implementation of fault management using wireless sensors that operate autonomously and asynchronously and measure only phase current. With this approach the hardware and software implementation of a sensor can be simplified compared to previous solutions. The combination of these developed methods enables the construction of lighter, smaller and more flexible wireless sensors. Consequently, the ability to integrate the sensors within components and equipment as well as their robustness and functionality are enhanced.

Third, an architecture for the distributed management of electrical distribution networks is developed. The primary intention with this architecture is to provide a distributed computing platform that integrates the wireless sensors within the automation system and manages the related functionality in a controlled and simple way. The developed architecture also creates a generic concept for distributed and local control in the management of electrical distribution systems. This concept will be valuable in the future when the vast amount of data produced by sensors must be locally processed to avoid saturating the communication and computational resources of the control centre.

This thesis consists of an overview and of the following 6 publications:

  1. Nordman M., Kozlowski W., and Vähämäki O., 2001. A method for synchronizing low cost energy aware sensors used in industrial process monitoring. Proceedings of the 27th Annual Conference of the IEEE Industrial Electronics Society (IECON 2001). Denver, Colorado, USA, 29 November - 2 December, 2001, pages 100-106.
  2. Nordman M., Lehtonen M., and Vähämäki O., 2003. Managing concurrent duties and time of wireless sensors in electrical power systems. Proceedings of the 9th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA 2003). Lisbon, Portugal, 16-19 September 2003, pages 521-528.
  3. Nordman M., and Lehtonen M., 2004. A wireless sensor concept for managing electrical distribution networks. Proceedings of the IEEE PES Power Systems Conference and Exposition (PSCE 2004). New York, USA, 10-13 October 2004, accepted for publication.
  4. Nordman M., Nieminen T., and Lehtonen M., 2004. Characteristics of wireless sensors for electrical distribution networks. IEEE Conference on Mechatronics & Robotics. Aachen, Germany, 13-15 September 2004, 7 pages.
  5. Nordman M., and Lehtonen M., An agent concept for managing electrical distribution networks. IEEE Transactions on Power Delivery, accepted for publication.
  6. Nordman M., and Lehtonen M., Distributed agent based state estimation for electrical distribution networks. IEEE Transactions on Power Systems, accepted for publication.

Keywords: wireless sensors, time synchronisation, agent technology, distribution automation communication, distributed fault management, distributed state estimation

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© 2004 Helsinki University of Technology

Last update 2011-05-26