Power quality analysis of energy efficient harmonic loads

It is now very common that depending on the voltage-current relationship, loads are divided into two groups: linear and nonlinear harmonic loads. Literature review and previous studies found in published articles discuss the basic voltage-current characteristics and harmonics presented in the the energy efficient harmonic loads but they did not discuss much on the performance of the devices, in terms of power quality, during the operating condition. Along with this, the information on PQ study for the most common and high power consuming motor drive appliances like washing machine and vacuum cleaner are hardly available. In this paper, the power quality (PQ) of different energy efficient residential harmonic loads has been analysed. More than 200 measurements have been taken randomly in a residential building located in Dublin, Ireland where the variation of voltage THD is found from 1.2 to 1.7%. Magnitude of the current harmonic order above 21 is found less than 5% of the fundamentals. Therefore, harmonic order upto 21 is considered for all the analysis. During the power quality analysis of the energy efficient appliances of a building, it is found that some of the harmonic loads change their active and reactive power consumption or harmonic current injection characteristics depending on their operating mode. This study shows the power quality analysis of the appliances during their different operation mode. Therefore, depending on the operating condition/performance the residential and energy efficient harmonic loads have been divided into two groups: (i) static and (ii) dynamic. In the static group, harmonic loads do not change their performance during operation. Smart TV, CFL bulb, microwave oven and refrigerator fall into this category. Whereas laptop, washing machine and vacuum cleaner change their performance characteristics during operation and they fall into the dynamic group. The impact of source voltage disturbance on the current THD for each of the load- has also been discussed.