A study of harmonic impacts on high voltage, medium voltage and low voltage networks in PT. PLN distribution system

This paper presents the characteristics and levels of harmonics on PT. PLN´s (Indonesia state owned electric utility company) 150 kV/70 kV high voltage, 20 kV/380 medium and low voltage networks in West Java and Banten Area. Within this paper a study and measurements for various types of loads in some types of industries connected to high voltage, medium voltage and low voltage network are conducted and verified. This paper also discuss the phenomenon of harmonics, the effects on the high voltage, medium voltage and low voltage networks, harmonic-producing sources, standards and recommended practice limits according to the IEEE 519 and IEC 61000 standard. Harmonic measurements method on high voltage network was done by continuous logging for one week on two samples of 150 kV big customers and one sample of 70 kV big customer to know the harmonics levels and their probability occurrence The harmonic current measurements results indicated that Total Demand Distortion-TDD conditions for two big customers were above 4% of standard limits as suggested in IEEE 519-1992. One customer using arc furnace load has contributed the highest current harmonic pollution to the network. Harmonic measurements methods on medium and low voltage networks were done on two types. The first method was done by continuous logging for a week duration on 8 samples of medium voltage customer to know the harmonics levels and their probability occurrence. The second method was done by instantaneous measurements for 5 minutes during peak load on 20 samples of low voltage distribution loads. From the measurement results show that harmonic current conditions-THDi on the measured distribution substations are all above 5%, and 70% of customers measured have THDi more than 10%.