Tutorials

ICHQP 2018 Tutorials will be given on Sunday, May 13, 2018. To register, please visit the Registration portal. Information on the tutorials and instructors is shown below.


Harmonic Stability in Power Electronic Based Power Systems

Speakers:
Xiongfei Wang, Aalborg University, Denmark;
Frede Blaabjerg, Aalborg University, Denmark

Power electronics is changing from a technology that drives renewable energy generation and energy-efficiency improvement to the foundational technology for grid modernization. With the proliferation of power electronics apparatus, the power electronic based power system is being envisioned in the near future. In contrast to rotating electrical machines, electronic power converters are operating with much faster and nonlinear control dynamics, which consequently bring in a series of new challenges on the stability and power quality of the power grid. The high-frequency (2-150 kHz) switching harmonics are being aggravated by power converters, which may trigger the resonance frequencies of the power system. A multiple-timescale control system is generally equipped with power converters for regulating the current and power exchanged with the grid. The dynamic interactions among converters, passive power filters, and other power system components tend to cause the harmonic instability phenomena, which are in the form of resonances or abnormal harmonics over a wide frequency range. Differing from the traditional, steady-state harmonic distortions and resonances, the harmonic instability is highly dependent on the control dynamics of power converters.

This 3-hour tutorial aims to provide a systematic discussion on the concept, modeling and analysis of harmonic stability in modern power electronic based power systems. It will begin with a review of the control fundamentals of grid-connected power converters, from which the concept of the harmonic stability will be elaborated. The instability phenomena will be demonstrated by a series of field measurement results under the different grid conditions. Then, a critical review of the linearized modeling techniques for extracting the frequency-coupling dynamics of converters will be presented, ranging the synchronous reference (dq-) frame small-signal models to the harmonic state-space models based on the linear time-periodic theory. Next, the system-level stability analysis tools will be discussed and illustrated based on renewable power plants and microgrids. Lastly, perspectives on the challenges and future trends on the stability and control of power electronic based power systems will be given.

This is the first time for the instructors organizing the tutorial in a PES conference, though some of the topics have been discussed by instructors in other tutorials of the previous PELS conferences (PEDG 2015, APEC 2015, ECCE 2015). The intended audiences are graduate students, practicing engineers, and researchers in the areas of harmonics and power quality, grid integration of renewables, and power electronics applications in power systems.


Voltage Fluctuations and Light Flicker in Modern Electrical Power Systems: New Findings and Challenges

Speakers:
Prof. Roberto Langella, IEEE Senior Member, Università degli Studi della Campania “Luigi Vanvitelli”;
Prof. Alfredo Testa, IEEE Fellow, Università degli Studi della Campania “Luigi Vanvitelli”;
Prof. Jiri Drapela, IEEE Senior Member, Brno University of Technology, Czech Republic

The aim of the tutorial is to give basic concepts to understand causes (covering all nowadays known origins in modern electrical power systems) and effects of voltage fluctuations (VF) with particular attention to their main effect that is Light Flicker (LF).
VF can be described as repetitive or random variations of the voltage envelope due to sudden changes in the real and reactive power drawn by a load; their characteristics depend on the load type and size and the power system capacity. LF is produced by the fluctuations on the luminous flux emitted by the lamps when fed by a fluctuating voltage. For historical reasons, the instrument aimed to measure LF, known as Flickermeter, was designed in the early seventies starting from epidemiological studies conducted using incandescent lamps. Today, the scenario is totally different, in fact in some countries incandescent lamps are only a small fraction among the different other technologies (CFLs, LED, …) and are destined to be banned in the future and other VF related to LF performance of new lamp technologies have to be considered.
The tutorial is organized as follows. Firstly, basic definitions on VF will be given and a quick overview on their causes and effects will be done. Afterwards, effects different from LF (e.g. transformers and AC motors reduction of useful life, excitation of turbo-generators shaft mechanical resonances, PLL inaccuracies, …) will be briefly recalled and analyzed. Then, after an initial recall on the LF phenomenon produced by incandescent lamps, the effects of VF on lamps different from incandescent will be described analytically and experimentally; successively, a generalized lamp model proposed by the speakers will be described. Finally, a brief overview on the historical development of IEC flickermeter will be done explaining its implementation and its limitations in terms of assessment of LF for lamps different from incandescents concluding with the description of new proposals of flickermeters discussed in the scientific community.

The Tutorial is structurated in three blocks each of 30 minutes length.

Block 1: “Voltage fluctuations: definitions, causes and effects”
In this block basic definitions on voltage fluctuations will be given and a quick overview on their causes and effects will be done. Finally, effects different from light flicker (e.g. transformers and AC motor reduction of useful life, turbo generators shaft mechanical resonance, PLL and PQ instruments inaccuracies, …) will be briefly recalled and analyzed.

Block 2: “Light Flicker effects produced by voltage fluctuations on different Lamp technologies”
In this block after an initial recall on the Light Flicker phenomenon produced by incandescent lamps, the effects of voltage fluctuations on lamps different from incandescent will be described analytically and experimentally; successively, a generalized lamp model proposed by the authors will be described.

Block 3: “Toward New Flickermeters able to take into account lamps different from incandescent”
In this block a brief overview on the historical development of IEC flickermeter will be done explaining its implementation and its limitations in terms of assessment of LF for lamps different from incandescent. Finally, new proposals of flickermeters (Light FM and Simulation based FMs) discussed in the scientific community will be described.