Simulation of a large electric distribution system having intensive harmonics in the industrial zone of Konya

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1. 13 58 18 02 16 73 20 94 24 57 24 78 24 89 values Changed 89 20 93 55 92 30 95 26 78 04 78 46 78 37 values Percentage –27 –61 –47 –36 –11 –53 –36 –61 60 –49 60 –40 60 83 comparison Conclusion In this study, an electrical model of a large distribution system was made according to the measurement values taken from the KOIA in order to comprehend the behaviors of the harmonics in large electrical distribution systems. The measurement values and simulation values were compared to confirm the accuracy of the simulation. If the comparison of the reference simulation values in Table 8 and the measurement values in Tables 2 and 3 are compared, it can be seen that the current distortion values are close to each other. However, the voltage distortions are high in the simulation because all of the nonlinear factories are working in the simulation, and the distorted currents induce distorted voltages in the lines. In addition, the transformer connection types’ and impedances’ simulations were presented to understand and solve the harmonic problems in electrical distribution systems. According to Table 9, changing the transformer connection types changes the voltage and current total harmonic distortion of the shunting stations, causing the transformer connection types Dyn11 and Dyn1 to make almost no changes in the voltage and current total harmonic distortion. However, at the Yyn and Ynyn transformer connection types, it has been seen that the voltage and current distortion dropped by about 10% according to reference simulation. According to Table 11, increasing the transformer impedances decreases the voltage and current distortion of MM1, MM2, MM3, and MM6. The voltage distortions of the CF2 and CF4 at the low-voltage side of the transformers whose impedances are changed increased to 13.78% from 11.24%. The current distortions, on the other hand, decreased. As being fed from a feeder that has a lower-voltage harmonic distortion is much more important for distribution system users at the low-voltage side, the voltage THD increase in the low-voltage side is much more important than the voltage THD decline in the high-voltage side. In other words, it is an undesirable situation for distribution systems because the increases of the transformer impedances increase the voltage THD of the factories. Hence, the short circuit ratio of the factories’ transformers is better at high levels. The higher transformer short circuit ratio means lower transformer impedances. On the ot