Two tutorials will be offered to attendants to Electrimacs 2014, organised by Prof. Valkealahti and Prof. Leva.

Tutorial: Modelling and simulation of the operation of PV power generators

Prof. Seppo Valkealahti was born in Alavus, Finland, 1955. He received the M.Sc. and Ph.D. degrees in physics from the University of Jyväskylä, Jyväskylä, Finland, in 1983 and 1987, respectively. From 1982 to 1997, he was a Teacher and Researcher of physics at the University of Jyväskylä, in the Riso National Laboratory in Denmark and in the Brookhaven National Laboratory in Upton (NY) in the USA.

From 1997 to 2004, he worked in ABB Corporate Research heading research and product development activities. In the beginning of 2004, he joined the Tampere University of Technology, Tampere, Finland, where he is currently a Professor in the Department of Electrical Energy Engineering. His research interests include electric power production and consumption-related technologies, solar energy, and multiscientific problems related to power engineering.

Tutorial contents:

The focus of the tutorial will be in theoretical modelling and simulation of the operation of PV power generators under varying environmental conditions. Also experimental verifications of the used models and obtained simulation results will be presented.

Theoretical models to describe the electrical behavior of PV cells and modules under varying radiation, temperature etc. environmental conditions will be introduced based on the physical properties of PV semiconductors and other PV generator components. The applicability of the widely used one diode model to model the electrical properties of PV cells and modules will be discussed. The limitations of the model will also be demonstrated by comparing simulation results to experiments. For example, the shortages of the model under low irradiance conditions will be demonstrated and the shortages and behavior of input parameters, such as ideality factor and shunt resistance, will be discussed.

Then basic principles to simulate the operation of different electrical and spatial PV generator topologies will be discussed. Several environmental quantities influence simultaneously on the operation of PV generators and they have spatial and temporal variation within the area of the generator. How to approach and simulated the electrical operation of PV generators under these kind of conditions will be discussed. Some examples of recent scientific finding related to the behavior of maximum power points and mismatch losses will be presented.

Then as a continuation and complement a state of the art dynamic thermal-electrical simulation model of the operation of PV generator under varying environmental condition will be presented. It can be used to simulate even the fastest environmental phenomena affecting to the electrical operation of PV generators. Its functionality will be demonstrated in example cases which are related to the experimental results of the TUT Solar PV power research plant. It includes a comprehensive climatic measurements system, where all environmental quantities affecting to the operation of the PV generator are measured with100 ms sampling frequency.


Tutorial: PV and Wind Power output forecasting at 6-12-24 hours ahead

Prof. Sonia Leva was born in 1970 in Tradate (Italy). She received the M.Sc. degree in 1997, and the Ph.D. degree in 2001, both in Electrical Engineering, from the Faculty of Engineering, Politecnico di Milano, Italy. In 1998 she registered as Italian professional Engineer.

From 1999 to 2010 she was Research Associate of Electrical Engineering at the Dept. of Electrical Engineering, Politecnico di Milano, Italy. In 2010 and 2012 she has been Visiting Professor at Tongji University, Shanghai.

Since July 2010 Sonia Leva is qualified as Associate Professor, starting her professor activity on December 16, 2010. She is a senior member of the IEEE and a member of the IEEE Working Group “Distributed Resources: Modelling & Analysis” (General Systems Subcommittee, Transmission and Distribution Committee, IEEE Power and Energy Society)  and of the Task Force “Modeling and Analysis of Electronically-Coupled Distributed Resource (DR) Systems” (General Systems Subcommittee, Transmission and Distribution Committee, IEEE Power and Energy Society).

Prof Leva is member of the Italian Standard Authority (CEI) Technical Committee CT 82 “Sistemi di conversione fotovoltaica dell’energia solare (Photovoltaic Systems)” since 2008. She collaborated to write the second edition of the technical guide.

Her research interests include: electromagnetic compatibility, power quality, renewable energy and modelling and analysis of photovoltaic systems, RES (PV and Wind in particular) Power output forecasting at 6-12-24 hours ahead.

She is project manager of research groups with Politecnico di Milano and Private or Public Companies  and head of the Solar Tech Lab at the Dept. of Energy, Politecnico di Milano (www.solartech.polimi.it).

Tutorial contents:

The electricity produced by renewable energy sources (RES) is constantly world-wide increasing thanks to government policies and technological advancements. Europe have experienced one of the largest growths: in the last five years the electricity generation by RES, and in particularly by photovoltaic (PV) and wind plants, is doubled. However the RESs energy production are characterized by fluctuating output: the output power is influenced by meteorological conditions.

Challenges of controlling and maintaining energy from inherently intermittent sources in grid-connected systems involves many features: efficiency, reliability, safety, stability of the grid and ability to forecast energy production. In particular, forecasting of PV and wind, as an estimation from expected power production, is very important to help the grid operators to better manage the electric balance between power demand and supply and to improve the penetration of distributed renewable energy sources and, in stand-alone hybrid systems, for the optimum size of all its components and to improve the reliability of the isolated systems. Additionally, in countries with a day-ahead electricity market, large power plants based on RES can act, as any other electricity producer, providing power generation sale offers (bids) to the market. In electricity markets, when a power producer does not follow the scheduled bid it will be penalized with retributions lower than those established in the market for those hours with deviation between the electric energy actually produced and that presented in the bid.

These technical and economic reasons have driven the development of short-term power forecasting models for wind farms or for relatively large grid-connected PV plants.

In recent years several short-term power forecasting models related to wind and PV plants have been published. The existing solutions can be classified into the categories of physical, statistical and hybrid methods. Some of these models for PV plants were at first oriented to obtain solar radiation predictions. Some works present models specifically dedicated to the hourly power generation forecasting in PV and wind plants. The most applied technique in these forecasting models is a specific soft-computing technique known as Artificial Neural Networks (ANNs) but some papers use simple physical methods.

The aim of the tutorial is:

– present a review of forecasting methods for short-term power of PV and WIND plants;

– introduce error definitions based on statistical theory and also on Authority or Regulation Agency;

– show some examples with reference to real plants considering very-short-term and short-term forecasting.