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Three-phase controlled/uncontrolled converters have been used in renewable energy applications such as photovoltaic and wind energy as a rectifier and inverter. The main drawback of these converters is the high THD in their line currents. Many techniques have been used to remedy this problem. Third harmonic current injection is one of the best opti...
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... power when the power exceeds the rating of the attached generator. So, it is always better to track the maximum power when the mechanical power is lower than the generator capacity and track the constant power (rated power of the generator) when the power available from WT is greater than the generator capac- ity which is shown in path ABCD of Fig. 10, which is explained in detail in Ref. 25. The mechanical power generated from WT at the shaft of the generator as a function of x m is shown in Fig. 10. It is clear that the mechanical output power is maximized at a particular rota- tional speed (x opt ) for each wind speed. 1 So, the MPPT continually tracks the optimum rota- tional ...
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... than the generator capacity and track the constant power (rated power of the generator) when the power available from WT is greater than the generator capac- ity which is shown in path ABCD of Fig. 10, which is explained in detail in Ref. 25. The mechanical power generated from WT at the shaft of the generator as a function of x m is shown in Fig. 10. It is clear that the mechanical output power is maximized at a particular rota- tional speed (x opt ) for each wind speed. 1 So, the MPPT continually tracks the optimum rota- tional speed (x opt ) for each wind speed by controlling the pitch angle, b, of the WT. A detailed description of this MPPT controller has been introduced in ...
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... relationship between the output power and the terminal voltage for different radiations and temperatures is shown in Fig. 11, where each curve represents certein radiation and tempera- ture. It is clear from this figure that the MPPs are located at different terminal voltages. For this reason, a wide variety of MPPTs have been developed and discussed in many literatures such as Refs. 3 and 4. The partial shading can cause many local peaks and one global ...
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... global peak. As discussed in Ref. 4, the PSO technique for MPPT is the technique that can catch the global peak without being stuck in any local peaks. For this reason, the PSO technique is used as MPPT for the PV system in this paper. The proposed MPPT used in this study uses the boost converter to change the terminal of the PV array as shown in Fig. 13. The optimal duty ratio for the boost converter connected to the PV system can be obtained from the PSO ...
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... connection of the zigzag transformer is shown in Fig. 12. An approximate formula for obtaining the Volt-Ampere rating of the zigzag transformer in the case of the unity turns-ratio can be obtained as shown in (23), ...
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... MPPT of the WT and PV array has been discussed earlier. The MPPT details are given in Refs. 1, 2, and 25. The MPPT of the PV array is achieved by controlling the duty ratio of the boost converter as shown in Fig. 13. The relationship between the input voltage to the PV boost converter, V PV , and its output, V dc , voltages is shown in (24). In the case of the dc- link, voltage is kept constant, whereas in the case of this controller, the terminal of the PV array, V PV , will be controlled by controlling the duty ratio of the boost converter, D PV ...
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... voltage is kept constant, whereas in the case of this controller, the terminal of the PV array, V PV , will be controlled by controlling the duty ratio of the boost converter, D PV . So, the values of V PV and I PV are used in the PSO module to get the optimal value of the duty ratio of the boost converter of the PV array, D PV , as shown in Fig. 13. Also, the internal control loop can be used to enhance the stability of the dc-link voltage by adding an incremental value to the optimal duty ratio, D PV , as shown in Fig. 13. As can be implied from (24), if the terminal voltage of the PV array, V PV , is constant, the duty ratio of the boost converter can be used to control the ...
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... D PV . So, the values of V PV and I PV are used in the PSO module to get the optimal value of the duty ratio of the boost converter of the PV array, D PV , as shown in Fig. 13. Also, the internal control loop can be used to enhance the stability of the dc-link voltage by adding an incremental value to the optimal duty ratio, D PV , as shown in Fig. 13. As can be implied from (24), if the terminal voltage of the PV array, V PV , is constant, the duty ratio of the boost converter can be used to control the dc-link voltage, V dc . The dc-link voltage, V dc , is directly proportional to the duty ratio, D PV . So, as shown in the PV MPPT module of Fig. 13, the reference value of dc link ...
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... the optimal duty ratio, D PV , as shown in Fig. 13. As can be implied from (24), if the terminal voltage of the PV array, V PV , is constant, the duty ratio of the boost converter can be used to control the dc-link voltage, V dc . The dc-link voltage, V dc , is directly proportional to the duty ratio, D PV . So, as shown in the PV MPPT module of Fig. 13, the reference value of dc link voltage, V Ã dc , is compared with the actual value, V dc . If V Ã dc is greater than V dc , it means that the dc link voltage should be increased by adding an incremental value to the duty ratio obtained from PSO as shown in the PV MPPT module in Fig. 13 and vice versa. So, the function of the PV MPPT ...
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... the duty ratio, D PV . So, as shown in the PV MPPT module of Fig. 13, the reference value of dc link voltage, V Ã dc , is compared with the actual value, V dc . If V Ã dc is greater than V dc , it means that the dc link voltage should be increased by adding an incremental value to the duty ratio obtained from PSO as shown in the PV MPPT module in Fig. 13 and vice versa. So, the function of the PV MPPT module is to track the maximum power from PV and to help to increase the stability of dc-link voltage against any ...
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... WT MPPT module shown in Fig. 13 tracks the maximum power from the WT and also participates in enhancing the stability of dc-link voltage, V dc . The input to the WT MPPT module is the mechanical rotational speed and the pitch angle, b. Depending on these values, the reference maximum power from WT and its corresponding value of the firing angle of the three-phase ...
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... maximum power from WT and its corresponding value of the firing angle of the three-phase rectifier, a R , can be obtained as shown in (25). Also, an internal control loop can be used to enhance the stability of the dc-link voltage by adding an incremental value to the value of the firing angle of the three-phase rectifier, a R , as shown in Fig. 13, whereas, as shown in the WT MPPT module in Fig. 13, the reference value of dc link voltage V Ã dc is comparable with the actual value, V dc . If V Ã dc is greater than V dc , it means the dc link voltage should be increased by reducing the firing angle of the rectifier, a R , as shown in (25) and vice versa. So, the func- tion of the ...
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... of the firing angle of the three-phase rectifier, a R , can be obtained as shown in (25). Also, an internal control loop can be used to enhance the stability of the dc-link voltage by adding an incremental value to the value of the firing angle of the three-phase rectifier, a R , as shown in Fig. 13, whereas, as shown in the WT MPPT module in Fig. 13, the reference value of dc link voltage V Ã dc is comparable with the actual value, V dc . If V Ã dc is greater than V dc , it means the dc link voltage should be increased by reducing the firing angle of the rectifier, a R , as shown in (25) and vice versa. So, the func- tion of the WT MPPT module is to track the maximum power from WT ...
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... values also represent the angle between V a and I F for minimum THD in line currents in the third harmonic frequency domain. As shown in the rectifier harmonic injection module in Fig. 13, the value of the firing angle of the single phase controlled converter with respect to phase a voltage, a SR , can be obtained by applying (29). In the same way, for the inverter, the value of a SI can be obtained by apply- ing (30) to the inverter harmonic injection module shown in Fig. 13. This part will ensure the optimal angle of ...
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... As shown in the rectifier harmonic injection module in Fig. 13, the value of the firing angle of the single phase controlled converter with respect to phase a voltage, a SR , can be obtained by applying (29). In the same way, for the inverter, the value of a SI can be obtained by apply- ing (30) to the inverter harmonic injection module shown in Fig. 13. This part will ensure the optimal angle of the HIC in the rectifier and the ...
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... I FI , respectively, should be controlled to become 1.391 times the dc-link current, I o , for minimum THD as explained above. This can be achieved by comparing 1.391 times the value of I o with the peak value of HIC, and the error signal will be used to control the duty ratio of the boost converter at the rectifier and the inverter as shown in Fig. 13. This part will control the HIC amplitude for minimum ...
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... II shows the results obtained from mathematical, simulation, and experimental work. Figure 14 shows the simulation results of this circuit at a ¼ 40 (as an example). The optimum value of the turns-ratio of the single-phase transformer (1:11.36) ...
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... obtained from mathematical, simulation, and experimental work. Figure 14 shows the simulation results of this circuit at a ¼ 40 (as an example). The optimum value of the turns-ratio of the single-phase transformer (1:11.36) has been used. Also, the value of D opt ¼ 0.07 is used to get the optimum value of q (q opt ¼ 1.391). The upper trace in Fig. 14 shows the supply current at optimum conditions along with the voltage of phase a and the optimum HIC. It is clear from this trace that the supply current becomes very near to the sine wave with THD ¼ 3.64%. The middle trace in Fig. 14 shows the input and output current of the boost converter. Figure 15 shows in the upper trace the wind ...
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... used. Also, the value of D opt ¼ 0.07 is used to get the optimum value of q (q opt ¼ 1.391). The upper trace in Fig. 14 shows the supply current at optimum conditions along with the voltage of phase a and the optimum HIC. It is clear from this trace that the supply current becomes very near to the sine wave with THD ¼ 3.64%. The middle trace in Fig. 14 shows the input and output current of the boost converter. Figure 15 shows in the upper trace the wind turbine, PV, and electric utility currents. Also, the power from PV, that from wind, and the power transferred to electric utility are shown in the lower trace in Fig. 15, where I aw , I PV , and I au are the currents from wind, PV, ...
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... middle trace in Fig. 14 shows the input and output current of the boost converter. Figure 15 shows in the upper trace the wind turbine, PV, and electric utility currents. Also, the power from PV, that from wind, and the power transferred to electric utility are shown in the lower trace in Fig. 15, where I aw , I PV , and I au are the currents from wind, PV, and electric utility, respectively. ...
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... becomes very near to the sine wave with THD ¼ 3.64%. The middle trace in Fig. 14 shows the input and output current of the boost converter. Figure 15 shows in the upper trace the wind turbine, PV, and electric utility currents. Also, the power from PV, that from wind, and the power transferred to electric utility are shown in the lower trace in Fig. 15, where I aw , I PV , and I au are the currents from wind, PV, and electric utility, respectively. Also, P w , P PV , and P u are the power from wind, PV, and electric utility, respectively. It is clear from this figure that the utility grid current is almost equal to the total currents of the PV and wind ...
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... this system, the required firing angle input to the kit and the required pulses for each switch of the system are present. Figure 16(a) shows the utility grid current of the three-phase controlled inverter along with utility grid voltage of phase a without harmonic injection at a ¼ 40 , and its FFT components are shown in Fig. 16(b). Figure 17 shows the utility grid current of phase a and HIC along with phase a voltage and utility grid current FFT components. ...
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... systems an easy task. In this system, the required firing angle input to the kit and the required pulses for each switch of the system are present. Figure 16(a) shows the utility grid current of the three-phase controlled inverter along with utility grid voltage of phase a without harmonic injection at a ¼ 40 , and its FFT components are shown in Fig. 16(b). Figure 17 shows the utility grid current of phase a and HIC along with phase a voltage and utility grid current FFT components. It is clear from this figure that the ZZ-HID is an effec- tive technique to reduce the THD of supply current to 3.64% when injecting HIC with an amplitude ratio of q ¼ q opt ¼ ...
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... 16(a) shows the utility grid current of the three-phase controlled inverter along with utility grid voltage of phase a without harmonic injection at a ¼ 40 , and its FFT components are shown in Fig. 16(b). Figure 17 shows the utility grid current of phase a and HIC along with phase a voltage and utility grid current FFT components. It is clear from this figure that the ZZ-HID is an effec- tive technique to reduce the THD of supply current to 3.64% when injecting HIC with an amplitude ratio of q ¼ q opt ¼ 1.391. ...
Citations
... Eltamaly [18] introduced a new current injection system for harmonically reducing renewable energy utility interface three-phase controlled converters. In renewable energy applications such as photovoltaics and wind energy, three-phase controlled or uncontrolled converters have been applied as rectifiers and inverters. ...
... THBT single-phase equivalent circuitFigure 4. THBT equivalent magnetic circuit The inductance of each phase of the THBT is defined by(18), ...
Zero sequence blocking transformers (ZSBTs) are used to suppress third harmonic currents in 3-phase systems. Three-phase systems where single-phase loading is present, there is every chance that the load is not balanced. If there is zero-sequence current due to unequal load current, then the ZSBT will impose high impedance and the supply voltage at the load end will be varied which is not desired. This paper presents Third harmonic blocking transformer (THBT) which suppresses only higher harmonic zero sequences. The constructional features using all windings in single-core and construction using three single-phase transformers explained. The paper discusses the constructional features, full details of circuit usage, design considerations, and simulation results for different supply and load conditions. A comparison of THBT with ZSBT is made with simulation results by considering four different cases.
