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PVGS - Exercises

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The objective of this experiment is to study the steady-state operation of the PVGS. Real-time simulation results are shown in the “Main Interface” and “Help Contents” tabs of the laboratory panel.

MPPT Operation Mode

What active power is achieved under standard test conditions (STC) with E = 1000 W/m2 and temperature ϑ = 25 °C?

What active power is achieved under normal operating test conditions (NOTC) with E = 800 W/m2, an environmental temperature of 20 °C and a wind velocity of 1 m/s.
The cell temperature is approximately ϑ = 45 °C.

Calculate the efficiency, shown in the equation below, for the cases of STC and NOTC.

Compare and explain the results, while assuming an area of A = 30 m2.
It should be noted that the value of active power PMPP can be obtained directly from the “Help Contents” tab.
Alternatively, the student could choose to measure the active power (p.u.) in Scope31, and then multiply by the obtained value by the base power chosen as 750 kVA.

Assuming a summer day in August in Hamburg (HH) and in Munich (M), both with 28 °C, how much does the active power PMPP differ?
Compare it with the values that can be achieved in winter (January; 5 °C). Use:

  • Esum,HH,Aug = 128 kWh/m2
  • Esum,M,Aug = 150 kWh/m2
  • Esum,HH,Jan = 20 kWh/m2
  • Esum,M,Jan = 33 kWh/m2

Note that the given global radiation the monthly sum (31 days) and not the current value that is needed for the simulation.
For converting, you can assume that the irradiation is constant over the whole month.
Hint: (E = Esum/(number of hours in a month))

Examine the temperature dependency (figure 9 below shows the I-U-characteristic depending on the temperature of a PV cell, figure 10 below shows the P-U-characteristic), first under the assumption that the ambient temperature is equal to one of the solar cells and is 20 °C.
Investigate the effect of the temperature, considering that the solar module’s temperature ϑ is higher than the ambient temperature Ta:

Compare solar modules with free elevation (c = 22 °C) with those on roof surfaces with poor rear ventilation (c = 32 °C).
(Roof-integrated systems without rear ventilation have a significantly higher constant c = 43 °C and those that are facade-integrated generally have higher constant than roof-integrated ones.)
Assume an irradiance of E = 600 W/m2.

Explain the importance of reactive power that can be provided by the PVGS.

Set the reactive power reference value to Qref = 1 p.u. and irradiance to E = 600 W/m2.
Explain what happens.

Figure 9: Temperature Dependency of I-U-characteristics of a PV Cell [3]

Figure 10: Temperature Dependency of P-U-characteristics of a PV Cell [3]

Curtailment Operation Mode

Explain the importance of the curtailment mode.

Start with ϑ = 20 °C, E = 600 W/m2 and Pref = 0.5 p.u.
Determine the minimum irradiance that is required so that the active power can follow Pref.

Comprehension Task

Think about the simulations performed, how does the PVGS challenge the grid?
Are there other problems that were not considered in the simulations?

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