Renewable energy systems (Wind energy systems)

After passing the exam, the students will acquire the following knowledge: - the main technologies to convert wind energy into electricity by AC rotating generators, power electronic converters, transformers and distribution lines for the grid connection; Then, the students will acquire the following skills and abilities: - the calculation of the wind-speed frequency and the energy productivity, according to the manufacturer power curve and the variations of wind speed (magnitude and direction); - the calculation of the power losses, efficiencies and voltage regulation of AC rotating generators with their power electronic converters, transformers and distribution lines; - the calculation of the optimal power ratings of photovoltaic and wind power systems to maximize self-sufficiency and self-consumption of active users, subjected to environmental, electrical and economic constraints in the regions of the installations.

Solar photovoltaic systems

After passing the exam, the students will acquire the following knowledge: - the main technologies to directly convert solar energy into electricity by photovoltaic generators (from the solar cells to the PV arrays with the proper protections); - the main technologies to convert DC power into AC power with optimal efficiency (including general aspects of power electronics) to obtain grid-connected PV systems. Then, the students will acquire the following skills and abilities: - the calculation of the evolution of the electrical parameters and the energy production, according to the variations of solar irradiance and cell temperature; - the assessment of the reverse voltages and reverse currents in the case of current-voltage mismatch in a PV array; - the correct choice of the main components (PV generator and inverter) for the system design; - the setup of the experimental test for verifying the actual performance of PV generators and inverters.

Renewable energy systems (Wind energy systems)

Basic knowledge about electric circuit theory (electrical circuit analysis) and applied mechanics.

Solar photovoltaic systems

Basic knowledge about electric circuit theory (electrical circuit analysis).

Renewable energy systems (Wind energy systems)

Lectures (about 12 h) Energy conversion from wind kinetic energy to mechanical energy of blades (horizontal axis and vertical axis). Aerodynamics of blades: lift and drag forces, thrust and torque components. Coefficient of power vs. tip-speed ratio in a horizontal axis wind turbine: variable-speed operation for maximum power tracking. AC rotating generators and power electronic converters in the variable-speed wind turbines: equivalent circuits of DFIG generators with induction machines and PMSG with synchronous generators. Power transformers and distribution lines for connection to Medium Voltage (MV) and High Voltage (HV) grids with proper protection devices: equivalent circuits, voltage regulation and power losses. Factors affecting the energy production of a wind park: wake losses, reliability and availability of wind power systems, deviations from the power curve of the turbine manufacturer, curtailment of wind power. Optimal choice of power ratings of photovoltaic and wind power systems to maximize self-sufficiency and self-consumption of active users, subjected to environmental (slope of the terrain, altitude of the sites, distances from buildings, extreme climatic conditions, ...), electrical (power profiles of consumption, location of point of common coupling, hosting capacity, ...) and economic (levelized cost of electricity, net present value of investment, internal rate of return, ...) constraints in the regions of installation.

Solar photovoltaic systems

Lectures (about 39 h) Summary of electric circuit theory. State of the art in Photovoltaic (PV) technologies: general advantages and drawbacks; manufacturing process of crystalline silicon solar cells; thin film technologies and high-efficiency technologies; configurations and tasks of power conditioning units (inverters). Structure of the semiconductors: energy bands; doping with electron/hole; p-n junction, diffusion and electric field; losses in the energy conversion; spectral response and efficiency of the main technologies. The current-voltage characteristic curve (I-V curve) and the equivalent circuit of the solar cell; dependence on irradiance and temperature; profiles of meteorological and electrical quantities under clear sky conditions. Focus on an application problem: series/parallel connection of real cells; mismatch of their I-V curves due to production tolerance, defects and shading effect; hot spots and breakdown; bypass and blocking diodes. Structure of a PV module; datasheets of the commercial PV modules; qualification tests to simulate accelerated ageing; detection of faults by thermography and electroluminescence imaging. Unconventional aspects of PV generators with respect to the voltage sources; use of fuses in large PV plants; use of blocking diode in case of reverse current in a shaded string; the designer issue in case of partial shading of strings (concentrated and equally distributed shadings). The usage of transistors in DC-AC converters; PWM modulation and H-bridge voltage source inverter; paths of current with positive, negative and zero output voltage; active/reactive power control for grid connection; Maximum Power Point Tracking (MPPT). Conventional calculation of energy production: evaluation of solar radiation, loss sources in the productivity. An innovative procedure to assess the energy production: automatic data acquisition systems, experimental tests and results on operating PV plants; economic analysis by the Net Present Value (NPV) method. Cost of energy production. Summary about the stand-alone and grid-connected PV plants equipped with electrochemical batteries.

Renewable energy systems (Wind energy systems)

Solar photovoltaic systems

Renewable energy systems (Wind energy systems)

The course is organized with 12 h of lectures (above described) and 8 h of project work in team groups. The team groups consist of 2 to 4 students who are responsible for the writing of design documents regarding: - schematics of photovoltaic generators and wind turbines with power electronic converters for grid connection by transformers and distribution lines; - power losses in the energy conversion from mechanical power to electric power for AC generators in variable speed turbines; - power and energy productivity according to the power ratings of generators and the sun/wind resources; - voltage regulation and power losses within the transformers and the distribution lines at MV and HV levels; - maximization of self-sufficiency and self-consumption for active users with grid/environment constraints, knowing their hourly power profiles of consumption.

Solar photovoltaic systems

The course is partitioned into about 39 h of lectures (above described) and 21 h of classroom exercises and laboratories. Classroom exercises for a total of about 12 h, starting from a summary of electric circuits. 1) Usage of PVGIS software for solar radiation and PV energy estimation. 2) Calculation of the electrical parameters of the PV modules in conditions different from the rated STC by datasheet of the manufacturers. 3) Calculation of reverse voltage across the terminals of a shaded cell in a string subject to mismatch and calculation of reverse current in a shaded string supplied by irradiated strings. 4) Optimal coupling between PV array and inverter: constraints of power/voltage/current from MPPT. 5) Calculation of the energy production in a PV system from SO-DA database. 6) Simulation of integration of electrochemical storage to increase the self-sufficiency of active users. Laboratories for a total of about 9 h: 1) Measurement of the I-V curve of a diode by digital multimeters. 2) Familiarization with oscilloscope and function generator. 3) Measurement of the I-V curve of a PV module by digital storage oscilloscope. 4) Measurement of the output characteristics by digital multimeters for a transistor operating as a switch . 5) Measurement of efficiency and power quality for single-phase inverter by automatic data acquisition system. 6) Guided tour to one of the PV plants operating inside the Politecnico di Torino headquarter.

Renewable energy systems (Wind energy systems)

Teaching documents (handouts on wind power systems and slides on the lectures) on the POLITO portal of the teacher. For deepening, it is suggested to read the book "M. Patel, Wind and Solar Power Systems, 2006, CRC Press, USA”.

Solar photovoltaic systems

Teaching documents (handouts on photovoltaic power systems and slides on the lectures) on the POLITO portal of the teacher. For deepening, it is suggested to read the books "T. Markvart, Solar Electricity, 2nd Edition, 2000, J. Wiley & Sons, USA" and “M. Patel, Wind and Solar Power Systems, 2006, CRC Press, USA”.

Renewable energy systems (Wind energy systems)

Lecture slides; Lecture notes; Lab exercises; Student collaboration tools;

Solar photovoltaic systems

Lecture slides; Lecture notes; Exercises; Lab exercises; Video lectures (previous years); Self-assessment tools;

Renewable energy systems (Wind energy systems)

Exam: Written test; Group project;

Solar photovoltaic systems

Exam: Written test;

Renewable energy systems (Wind energy systems)

The written test lasts 1 h and consists of two theoretical questions regarding the knowledge of multiple topics (each one with 10 points) and one exercise regarding the skills and abilities of the "Expected Learning Outcomes" (7 points), like the sample written tests on the portal. The theoretical questions for a total of 20 points require short discussions, drawings and formulas, while the numerical exercise regards the skills and abilities acquired during the classroom exercises for a total of 7 points. Up to additional 3 points may be given by the exam commission as a result of the project-work assessment. The exam is passed if the students reach 18 points as a summation of the scores in the two theoretical questions and in the exercise, without any constraint regarding a minimum score in each of the three parts (theoretical questions and exercise), including the project-work assessment. The "30/30 cum laude" grade can be obtained only if the exam commission, with mark of 30/30, decides to ask a specific oral question about the content of the written test and the student responds in an effective way to that oral question. It is possible to use a pocket electronic calculator, but it is not permitted to use handouts or notes regarding the program of the course. NO oral test is possible to improve the grade, The space at disposal for the answers, on the single sheet of the written exam (front and back sides), is limited to test the ability of the student to summarize the concepts.

Solar photovoltaic systems

The written test lasts 1 h and consists of two theoretical questions regarding the knowledge of multiple topics (each one with 10 points) and one exercise regarding the skills and abilities of the "Expected Learning Outcomes" (10 points), like the sample written tests on the portal. The theoretical questions for a total of 20 points require short discussions, drawings and formulas, while the numerical exercise regards the skills and abilities acquired during the classroom exercises for a total of 10 points. The exam is passed if the students reach 18 points as a summation of the scores in the two theoretical questions and in the exercise, without any constraint regarding a minimum score in each of the three parts accounting for 10 points. The "30/30 cum laude" grade can be obtained only if the exam commission, with mark of 30/30, decides to ask a specific oral question about the content of the written test and the student responds in an effective way to that oral question. It is possible to use a pocket electronic calculator, but it is not permitted to use handouts or notes regarding the program of the course. NO oral test is possible to improve the grade. The space at disposal for the answers, on the single sheet of the written exam (front and back sides), is limited to test the ability of the student to summarize the concepts.