Abstract
The verifications of the calculated harmonic impedances are necessary for harmonic impedance estimation. Among the existing methods of the verifications, the method, by matching the calculated background harmonic voltage with the measured voltage when the customer is out of operation, is widely used. The background harmonics can be calculated based on IEC61000-3-6 (named as the IEC method) or the superposition index. However, some researchers ignore the fact that these two methods cannot be chosen arbitrarily, otherwise, the misjudgments may occur. In our study, the nonlinear customers are classified into two categories according to the ways how they are out of operation: 1) only the harmonic source is cut off, and 2) the harmonic source and the impedance of the customer side are both cut off. Then, the differences in using the IEC method and the superposition index to match the calculated and measured background harmonic voltage are investigated. Finally, based on the properties of the two methods and the categories of the customers, a framework is proposed to accurately validate the calculated harmonic impedance. The effectiveness and reliability of the proposed framework are verified through simulation and field case studies.
Highlights
With the development of power electronic devices and the increase of nonlinear loads, harmonic pollution in power system becomes more and more serious [1]–[4]
For the category 2, the measured background harmonic voltage should only be matched with the calculated values based on the superposition index instead of the IEC method
In the Norton circuit corresponding to the IEC method (Figure 3), Zu, Zc and Iu, Ic are the harmonic impedances and currents of the utility and the customer sides respectively, while Vpcc and Ipcc are the harmonic voltage and current measured at the PCC
Summary
With the development of power electronic devices and the increase of nonlinear loads, harmonic pollution in power system becomes more and more serious [1]–[4]. For the category 2 (defined as model B in Figure 2), the measured background harmonic voltage should only be matched with the calculated values based on the superposition index instead of the IEC method. In reference [11], [12], where the nonlinear customer is just arc furnace, the IEC method is used to validate the calculated harmonic impedance. According to the category of the customer, the method of calculating the background harmonic voltage is selected to validate the harmonic impedance.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
