Ewald F. Fuchs - Introduction to Energy, Renewable Energy and Electrical Engineering

Figure P.5 Electric power (generation and consumption) requirements in Germany during 16–27 January 2017. The lightly‐shaded area, which exceeds the full line indicating consumption, represents generation, while the full line indicates consumption: generation = (consumption +losses), that is, generation > consumption.

During the period as indicated in Figure P.5, about 90% of the electric energy had to be provided by natural gas, coal, and nuclear power plants, the latter two of which are scheduled to be discontinued or decommissioned during the coming decade. Such a shutdown appears to be not prudent because short‐term (e.g. battery) and long‐term (e.g. pumped hydro) storage plants [8, 9] are unable to have an output power of 70 GW even only during a few days. Note that 70 GW is the power provided, for example, by either 35 nuclear and 70 coal or natural gas‐fired plants each having a rated output of 1 GW and 500 MW, respectively, or 300 hydro storage plants with each 233 MW output power rating. Clearly such a switch from conventional (e.g. coal, natural gas, nuclear) plants to storage plants appears to be not feasible. The transition from combustion engines (e.g. gasoline, diesel) to electric drives in automobiles, trucks, and trains will lead to significantly increased additional power consumption that cannot be provided by renewable energy during the times as indicated in Figure P.5. As a result, the strategy is to keep natural gas power plants each having an output of 200 MW operating together with some of the nuclear power plants that serve as a frequency leader. The supply of electric energy of Guangdong in southern China via high‐voltage DC (HVDC) lines led to a breakup [10] of the alternating current (AC) grid due to the lack of a frequency‐leading AC power plant and through the lack of sufficient reactive power to control voltage and frequency ( Figure P.6). It is well known that inverters converting direct current (DC) to AC at the point of common coupling (PCC) can supply reactive power only if the DC voltage at the DC input voltage of the inverters is significantly increased, as discussed in Chapters 10and 12. The renewable energy approach, where 100% of the energy is generated and transmitted via DC transmission lines, appears to be clearly too optimistic: there is indeed a climate dilemma.

Figure P.6 The breakup of China's southern power grid due to the concentration of high‐voltage DC transmission lines in Guangdong, making the AC grid unstable.

As a prerequisite to this effort, students must understand the following core competencies based on Applied Mathematics (APPM) 2350 Calculus III:

1 Single‐variable calculus (e.g. differentiation, integration),

2 Functions of several variables,

3 Vectors and vector operations,

4 Curves in space,

5 Multivariable functions,

6 Partial differentiation, multiple integrals,

7 Line integrals, e.g. Stokes' theorem and Gauss' theorem,

8 Complex numbers, complex calculus in Gaussian complex plane.

In summary, the intent of this text is to educate undergraduate students in non‐electrical engineering disciplines, physics, and chemistry as well as professionals in related fields who want to acquaint themselves in electrical engineering as applied to conventional and renewable energy.

1 NOAA (2014). Global climate report – January 2014. NOAA National Centers for Environmental Information, State of the Climate (published online February 2014). https://www.ncdc.noaa.gov/sotc/global/201401(accessed 31 May 2020).

2 Proxy (Indirect) Measurements. Data source: Reconstruction from ice cores. Credit: NOAA. https://climate.nasa.gov/vital‐signs/carbon‐dioxide(accessed 31 May 2020).

3 Hansen, J., Sato, M., Kharecha, P. et al. (2008). Target atmospheric CO2: where should humanity aim? Open Atmospheric Science Journal 2: 217–231. https://doi.org/10.2174/1874282300802010217.

4 Tans, P. and Keeling, R. http://www.c2es.org/content/main‐greenhouse‐gases(accessed 31 May 2020).

5 Koningstein, R. and Fork, D. (2014). Energy's creative destruction. IEEE Spectrum (December 2014): 26–31.

6 ntv.de, kst (2017). Kohlekraft muss einspringen Dunkelflaute zeigt Makel des Ökostroms. Foto: picture alliance/dpa. https://www.n‐tv.de/wirtschaft/Dunkelflaute‐zeigt‐Makel‐des‐Okostroms‐article19691796.html(accessed 31 May 2020).

7 Wetzel, D. (2017). Die “Dunkelflaute“ bringt Deutschlands Stromversorgung ans Limit. https://www.welt.de/wirtschaft/article161831272/Die‐Dunkelflaute‐bringt‐Deutschlands‐Stromversorgung‐ans‐Limit.html(accessed 31 May 2020).

8 Fuchs, E.F. and Masoum, M.A.S. (2011). Power Conversion of Renewable Energy Systems, 2nd Printing. New York: Springer 692 pp.

9 Masoum, M.A.S. and Fuchs, E.F. (2008). Power Quality in Power Systems and Electrical Machines, 2e. Amsterdam: Academic Press/Elsevier 1123 pp.

10 Fairley, P. (2016). Why Southern China broke up its power grid. IEEE Spectrum (December 2016): 13. 14.

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