**8. References**

206 Power Quality Harmonics Analysis and Real Measurements Data

Eddy current loss of transformer core depends on the squares of both current and frequency (Bird). Therefore, the core loss for different experiments is compared to each other using equation 16. *fh1* and *fh2* correspond to the frequency components of the different cases in

A similar approach is used for the hysteresis effect. However, hysteresis effect comparison is

A new approach is presented for the analysis of switch mode devices and their effect on distribution network. In this approach, model of electronic devices are derived from detailed circuit simulation and the results are transformed to a circuit model which is a combination of passive current circuits. The model contains the odd harmonics of the power system frequency. Based on this model, we developed a probabilistic model for the electronic device and used numerical calculation to estimate the probability distribution of the power system current as a whole. This model shows that adding electronic devices to the power system must be carefully planned so that the power system KPI do not exceed the recommended levels. This stochastic simulation is a strong tool to evaluate the situation of the power system and its capacity for growth. In case of mass use of electronic devices, additional capacity must be provided both for transformers and distribution lines, in order

We also presented a list of the power system KPI and the devices that can be affected by the additional current harmonics. We classified the equipments into the feeding and consuming sides and studied the effects on each side separately. Mass usage of switch mode devices in different power systems must be planned carefully in order to avoid any unexpected negative effects on the other equipments in the system. The most vulnerable equipments of the power system are the ones which contain solenoids, such as transformers and measurement equipments, especially on the feeding side. Therefore, extra care and calculations are required in different power systems for a safe use of electronic devices. Electronic devices are affected by the harmonic distortion and may need to be either equipped with protective filters or be replaced by more advanced ones. Based on the power system KPI and the specification of the distribution and consumption devices we can use the stochastic analysis approach for dimensioning an optimal power system with respect to

The authors of this paper wish to acknowledge the support of Mefragh Company, Tehran Iran, especially Mr. Hashem Khoee, president of the company. We also wish to thank Iran

Relative core loss

Relative hysteresis

(16)

(17)

*f I*

*f I* 

*f I*

*f I* 

*N h h <sup>h</sup> N h h <sup>h</sup>*

 

*N h h <sup>h</sup> N h h <sup>h</sup>*

 

comparison.

**6. Conclusion** 

obtained using equation 17 (Bird).

to avoid harms in the network via harmonic mitigation.

equipment costs and safety margins.

**7. Acknowledgment** 

Key, T. S.; Jih-Sheng, L., (1996). Costs and benefits of harmonic current reduction for switch mode power supplies in a commercial office building, IEEE Tran. on Industry Applications, vol. 32, Issue 5, Sep/Oct 1996, pp. 1017–1025.

Schneider Electric. Electrical Installation Guide, 2009.


**Part 4** 

**Industrial Environments** 

Chapman, D. Rating of Transformer supplying harmonic loads. Leonardo Energy. Mathworks. www.mathworks.com Bird, J. O. Electrical circuit theory and technology. Newnes, May.
