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Figure 4. Equivalent circuit for a round rotor (cylindrical) synchronous generator [29]. The generator actuated by a hydraulic turbine can be represented by a large mass rotating under two opposite direction moment loads. When the mechanical moment T,, increases the rotation speed, the electrical moment T,. has a counter-effect to reduce the speed. When both moments are equal in magnitude, the rotation speed of the turbine becomes constant (w = wo). If the electrical load is increased, i.e. Te is greater than Tm, the whole system starts to decelerate. Since an excessive deceleration may harm the system, it is required to increase the mechanical moment. This process is made possible by setting a balance between the moments so that the turbine rotates with a required and acceptable speed. The generator equations to carry out this process numerically were obtained by considering the equivalent circuit given in Figure 4.

Figure 4 Equivalent circuit for a round rotor (cylindrical) synchronous generator [29]. The generator actuated by a hydraulic turbine can be represented by a large mass rotating under two opposite direction moment loads. When the mechanical moment T,, increases the rotation speed, the electrical moment T,. has a counter-effect to reduce the speed. When both moments are equal in magnitude, the rotation speed of the turbine becomes constant (w = wo). If the electrical load is increased, i.e. Te is greater than Tm, the whole system starts to decelerate. Since an excessive deceleration may harm the system, it is required to increase the mechanical moment. This process is made possible by setting a balance between the moments so that the turbine rotates with a required and acceptable speed. The generator equations to carry out this process numerically were obtained by considering the equivalent circuit given in Figure 4.

Related Figures (13)

Figure 1. Speed control loop.
Figure 1. Speed control loop.
Figure 2. Schematic view of a conventional MHPP. A conventional MHPP model is shown in Figure 2. There is no water collection process in the MHPPs mostly built as river-type power plants. Instead, there exists a structure (forebay) at the penstock and river connection point that regulates the water height. Therefore, MHPPs do not cause the negative environmental impacts (such as inundation of residential and historical areas, deterioration of ecological structures, etc.) that are often caused by the large-scale HPPs [14]. Although there are different classifications of HPPs, the most accepted one is the classification of UNIDO. According to this classification, MHPPs have installed power ranging between 5 and 100 kW [15].
Figure 2. Schematic view of a conventional MHPP. A conventional MHPP model is shown in Figure 2. There is no water collection process in the MHPPs mostly built as river-type power plants. Instead, there exists a structure (forebay) at the penstock and river connection point that regulates the water height. Therefore, MHPPs do not cause the negative environmental impacts (such as inundation of residential and historical areas, deterioration of ecological structures, etc.) that are often caused by the large-scale HPPs [14]. Although there are different classifications of HPPs, the most accepted one is the classification of UNIDO. According to this classification, MHPPs have installed power ranging between 5 and 100 kW [15].
Figure 3. Schematic view of prototype MHPP. The prototype MHPP used in this study is developed such that it can work in the laboratory environment. The general figure of the prototype is given in Figure 3. All possible situations that can occur in a conventional MHPP were modeled with the help of this prototype. Testing of different turbines or of experiments on the same turbine under different operating conditions can be carried out with this prototype.
Figure 3. Schematic view of prototype MHPP. The prototype MHPP used in this study is developed such that it can work in the laboratory environment. The general figure of the prototype is given in Figure 3. All possible situations that can occur in a conventional MHPP were modeled with the help of this prototype. Testing of different turbines or of experiments on the same turbine under different operating conditions can be carried out with this prototype.
Figure 5. MATLAB/Simulink model of round rotor synchronous generator.
Figure 5. MATLAB/Simulink model of round rotor synchronous generator.
Figure 6. Pelton turbine and the turbine blade with its injector.
Figure 6. Pelton turbine and the turbine blade with its injector.
Figure 7. Inlet and outlet velocity triangle of the Pelton turbine. The net fall is obtained as
Figure 7. Inlet and outlet velocity triangle of the Pelton turbine. The net fall is obtained as
Figure 8. The injector and its parameters. If the area where the water jet flows out is represented by S, the real flow rate (debit) can be written as follows. If the area S shown in Figure 8 is written as a function of Xq, Eq. (15) is obtained
Figure 8. The injector and its parameters. If the area where the water jet flows out is represented by S, the real flow rate (debit) can be written as follows. If the area S shown in Figure 8 is written as a function of Xq, Eq. (15) is obtained
Figure 9. The efficiency curve of the Pelton turbine of the prototype MHPP.
Figure 9. The efficiency curve of the Pelton turbine of the prototype MHPP.
Figure 10. MATLAB/Simulink model of the Pelton turbine of the prototype MHPP.
Figure 10. MATLAB/Simulink model of the Pelton turbine of the prototype MHPP.
Figure 11. Load rejection experiment under 10 bar pressure (open-loop).
Figure 11. Load rejection experiment under 10 bar pressure (open-loop).
Figure 12. Load rejection simulation under 10 bar pressure (open-loop).
Figure 12. Load rejection simulation under 10 bar pressure (open-loop).
Figure 13. Load rejection experiment under 5 bar pressure (open-loop).
Figure 13. Load rejection experiment under 5 bar pressure (open-loop).
Figure 14. Load rejection simulation under 5 bar pressure (open-loop). Figure 13 shows the experimental results of the transition of the open-loop prototype working under 5 bar pressure from 20% load condition to 10% load condition. Figure 14, on the other hand, shows the simulation results under the same conditions. The horizontal axis of the experimental results denotes the real time, whereas the vertical axis denotes the frequency (Hz). The results of the experiments are screenshots captured from a PLC 87 300 interface. Therefore, the experimental studies and the simulation studies could not be shown in the same platform. It is seen that the results obtained from the model and the real system, excluding the vibrations, are very close to each other, which proves the validity of the approach. The effects of very small variations in the pressure values on the speed were not observed in the simulations. Figure 13 shows the experimental results of the transition of the open-loop prototype working under 5
Figure 14. Load rejection simulation under 5 bar pressure (open-loop). Figure 13 shows the experimental results of the transition of the open-loop prototype working under 5 bar pressure from 20% load condition to 10% load condition. Figure 14, on the other hand, shows the simulation results under the same conditions. The horizontal axis of the experimental results denotes the real time, whereas the vertical axis denotes the frequency (Hz). The results of the experiments are screenshots captured from a PLC 87 300 interface. Therefore, the experimental studies and the simulation studies could not be shown in the same platform. It is seen that the results obtained from the model and the real system, excluding the vibrations, are very close to each other, which proves the validity of the approach. The effects of very small variations in the pressure values on the speed were not observed in the simulations. Figure 13 shows the experimental results of the transition of the open-loop prototype working under 5
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