Improved design of LED lamp circuit to enhance distribution transformer capability based on a comparative study of various standards

Abstract

Nowadays, light-emitting diode (LED) lamps replaced the conventional types because of its higher brightness and lower energy consumption. The lamps represent about 20% of the total load all over the world. The sever distortion produced by LED lamps to network voltage and current waveforms became high challenge to researchers and manufacturers to reduce its effects on the electric equipment. In this paper, the severe side effects of using commercial LED lamps on transformers are investigated, analyzed and its circuit is modified to improve the exploitation of transformer capabilities. A new converter circuit for the LED lamps has been designed to minimize harmonics and improve the voltage quality, power factor (PF) and transformer capability utilization. Also, it guarantees a proper operation even the LED input voltage decreased to 40% of its rated value. To assure the effectiveness of the proposed circuit, a prototype is created and tested considering two scenarios: commercial and proposed LED lamp circuits. Comprehensive comparisons between the effects of the two scenarios on the distribution transformers are conducted. The proposed study is applied to Mansoura University campus microgrid electric network in Egypt. The microgrid is simulated via MATLAB Simulink and applied to the two scenarios. The total harmonic distortion (THD), PF, voltage notching, harmonic loss factor, K-factor, factor-K, and the related derating capacities of the network transformers are calculated and compared using the American and European standards for the prototype and simulator. The results ensure that the proposed circuit could effectively minimize the THD and improve the PF, voltage quality, and the utilization of transformer capacities.