70/LM-0064 - MEASUREMENTS FOR ELECTRIC ENERGY
Academic Year 2021/2022
Free text for the University
SARA SULIS (Tit.)
- Teaching style
- Lingua Insegnamento
|[70/82] ELECTRICAL ENGINEERING||[82/00 - Ord. 2020] PERCORSO COMUNE||9||90|
This course examines from a practical point of view the devices and methods used for measurements in industrial electrical systems, with reference to voltage and current transducers, measurement systems based on microprocessors and digital signal processing. Particular focus is dedicated to aspects related to measurements for power quality and for Smart Grids.
More in detail, the educational goals of the course can be expressed through the following five descriptors:
- Knowledge and understanding
In-depth knowledge and understanding of the theoretical fundamentals and practical aspects of industrial measurements, with particular focus on those performed on electric power systems.
- Applying knowledge and understanding
Capability to set the design and management of measurement systems, even complex, with the choice of the most suitable components from a technical and economic point of view.
- Making Judgements
Capability to correctly interpret the results provided by a measuring system, on the basis of the characteristics of its components.
- Communication skills
Capability to communicate technical information both orally and in writing. Ability to discuss problems and solutions with specialists and non-specialists.
- Learning skills
Capability of continuous learning, through the proper interpretation of scientific and technical literature, manuals of manufacturers and technical standards.
The prerequisites are those indicated in the regulations of the "Laurea Magistrale in Ingegneria Elettrica" for admission to the first year.
1) Measurements for Power Quality (16 hours - lessons)
The concept of power quality. Disturbance classification and measurement needs. Characterization of non-sinusoidal signals. Powers under non-sinusoidal conditions. Electromagnetic compatibility. International standards on power quality.
2) Voltage and current transducers (16 hours - lessons)
Metrological characterization of instrument transformers. Magnetic core instrument transformers: behavior under non-sinusoidal conditions. Shunts and voltage dividers. Isolation amplifiers. Hall-effect transducers. Air core transducers: Rogowski coils. Optical current and voltage transducers.
3) Microprocessor based measurement systems (10 hours - lessons)
Data acquisition boards. Modular measurement systems (cRIO, PXI, VXI, LXI ect.). Discrete measurement systems. Distributed measurement systems. Measurement systems based on Low-Cost devices (Raspberry PI, Beaglebone, etc.)Remote management of measurement instruments. Serial and parallel communication. IEEE 488 interface. USB and firewire. LAN. Virtual instrumentation.
4) Digital processing of measurement signals (10 hours - lessons)
Time domain analysis. Continuous-time and discrete-time systems. FIR and IIR filters. Frequency domain analysis. Discrete Fourier Transform (DFT) and its metrological aspects. Smoothing windows. Fast Fourier Transform (FFT). Time-frequency analysis.
5) Phasor Measurement Units (PMUs) (5 hours - lessons)
Definition of synchrophasor (IEEE Standards). Total Vector Error. PMUs hardware. Synchronization systems. Phasor Data Concentrators and Wide Area Monitoring Systems.
6) Measurements for Smart Grids (5 hours - lessons)
Concept of Smart Grid and measurement needs. Smart metering. Measurement infrastructures for monitoring, control and protection.
7) Experimental activity (30 hours)
The course includes intensive laboratory and student's group work for the realization of virtual measuring instruments aimed at measuring the power in non-sinusoidal conditions and parameters of power quality according to the requirements of IEC 61000-4-30 .
The course, lasting a total of 90 hours, is developed through 60 hours of lessons, during which the teachers expose the topics of the program, and 30 hours of laboratory, during which students, working in small groups under the supervision of teacher, design, implement with the techniques of virtual instrumentation, and verify experimentally a measurement instrument for power measurement and assessment of power quality. For working students who cannot attend classes, the work in groups is replaced with an individual activity aimed at deepening the study of a subject agreed upon with the teacher.
Verification of learning
The acquisition of the learning outcomes is verified through a single oral exam, during which students are asked to discuss some of the topics covered in the course, possibly with the help of simple numerical examples.
The score of the examination is provided by a grade out of thirty.
To pass the exam, thus reporting a mark of not less than 18/30, the student must demonstrate a basic knowledge of all the topics discussed.
To achieve a score of 30/30 with honors, the student must demonstrate an excellent knowledge of the topics discussed.
The assessment takes into account the capacity of both present with rigor and effectiveness the theoretical subjects and highlight their practical aspects.
Teacher notes (made available to students)
C. Muscas, A. Monti, F. Ponci: “Phasor Measurement Units and Wide Area Monitoring Systems”, Academic Press, 2016.
M. H. J. Bollen, I. Y. H. Gu: Signal Processing of Power Quality Disturbances. Wiley-IEEE Press, 2006.
D. Mirri: Strumentazione elettronica di misura. CEDAM, 2003.
Keithley Instruments: Data acquisition and control handbook, 2001.
The teachers make available to students, in electronic format, the notes on which the lectures are based and the slides that are used for their presentation. Technical documents by instrumentation manufacturers and international standards are also presented and discussed.