Efficiency of converters and amorphous core AC-filters in an LVDC distribution

Effect of network configuration and load profile on efficiency of LVDC distribution network

“…The losses of the filter capacitors are not taken into account in the simulation models because they are considered insignificant compared to the inductor losses. The AC-filter power loss models are also verified by measurements [17].…”

“…at the modulation frequency when the three-phase converter is used, whereas most of the current harmonics occur at twice of the modulation frequency, 20 kHz, when the single-phase full-bridge converters with the unipolar modulation scheme are used. The current harmonics at higher frequency cause increased losses in the LC-filter as shown in [17]. Most of the losses are caused by the load converters and the isolation transformers in the case of single-phase converters when the DC cable length is less than 600 m. In the case of three-phase converters, the cable causes most of the losses instead of the transformer if the DC cable length is over 500 m. According to the results presented in Fig.…”

“…The simulation models of the converter losses take into account the instantaneous current though IGBTs and diodes as presented in [15][16]. The converter power loss models are verified by measurements [17]. The LCL-filters and LC-filters shown in Fig.…”

“…1. The amorphous core AC-filter inductors are used because of the low no-load losses, which is important, because the customer's electricity consumption varies extensively and therefore, the load converter operates most of the time with low load [17]. The losses of the filter capacitors are not taken into account in the simulation models because they are considered insignificant compared to the inductor losses.…”

“…The resistance of the 4*16mm 2 AXMKcable is 1.91 Ω/km at 20°C at DC current, the inductance is 0.29 mH/km and the capacitance is 0.30 μF/km [19]. The cable loss simulation model is verified by measurements [17]. Capacitance value of the two series connected DC capacitors is 1100 μF each in the line and load converters.…”