Measurement 34 (2003) 75–83 www.elsevier.com / locate / measurement Development of a data acquisition system for remote monitoring of renewable energy systems * Kostas Kalaitzakis , Eftichios Koutroulis, Vassilios Vlachos Department of Electronics and Computer Engineering, Technical University of Crete, GR-73100, Chania, Greece Received 27 January 2002; received in revised form 14 February 2003; accepted 20 February 2003 Abstract The widespread application of Renewable Energy Sources (RES) requires the use of data acquisition units both for monitoring system operation and control of its operation. In this paper, the development of a data acquisition system for remote monitoring and control of RES plants is presented. It is based on the Client / Server architecture and it does not require the physical connection of the monitored systems to the data collection server. This feature is essential in RES plants since they are usually installed in inaccessible areas. The measured parameters are available on-line over the Internet to any user.  2003 Elsevier Ltd. All rights reserved. Keywords: Distributed measurement system; Renewable energy sources; Monitoring; Internet; Java; Data acquisition 1. Introduction for remote access to data and control [3], as illus- trated in Fig. 2a. The data distribution system is The recent growth of networks and especially the based on the Client / Server architecture, while the spread of the Internet have boosted the development data transmission is carried out through the Internet. of distributed measurement systems for a variety of A similar application is proposed in Ref. [4], where a applications. Most distributed measurement systems master monitoring station is used to collect power follow the Client / Server architecture [1,2], as out- and current related data from slave stations. Each lined in Fig. 1. According to this architecture, one or slave station monitors the operation of a power more instruments are connected to a measuring system and transmits the collected data to a server station, which operates as a server, while the ac- station, through a serial port interface, as depicted in quired data are available through a network to the Fig. 2b. The clients retrieve the data through an clients. Intranet network. Regarding power networks monitored by SCADA Another interesting application area of distributed systems, distributed measurement systems are used measurement systems is the remote control of instru- ments [5], as illustrated in Fig. 3. According to this topology, a number of instruments are connected to a server station using standard interfaces such as the *Corresponding author. Tel.: 1 30-28210-37213; fax: 1 30- VXI-11, the IEEE-488 and the RS-232 protocols. 28210-37530. E-mail address: koskal@electronics.tuc.gr (K. Kalaitzakis). The clients communicate with the server using the 0263-2241 / 03 / $ – see front matter  2003 Elsevier Ltd. All rights reserved. doi:10.1016 / S0263-2241(03)00025-3