DC Environment for a Refrigerator With Variable Speed Compressor; Power Consumption Profile and Performance Comparison

 ABSTRACT:

 DC power distribution in residential sector has regained interest among researchers and industrial players as new electronics-based appliances became locally available. However, the compatibility of appliances with DC distribution systems still requires much research effort. This work mainly explores on the power consumption profile of an inverter-driven Variable Speed Controller (VSC-based) refrigerator that has not yet been analyzed as one of the most important household loads. This paper compares the power consumption in two scenarios; 1) using three supply configurations for a VSC-based refrigerator, a Battery-Inverter-Load, a Battery-Load and Grid-Load, and 2) using a same AC power source to supply a VSC-based refrigerator and a same-size conventional refrigerator. This analysis helps toward modeling and energy estimation of PV system applications involving storage batteries. A wireless monitoring circuit has been employed to handle temperature, current and voltage measurements with a high sampling rate to cover the potential surge power. The experimental measurements show a better performance on using DC over AC power source and the power rate consumed has a smooth pattern at the starting-on time until approach a rated power. The measured efficiency of the Battery-Load topology approaches 99% compared to that of the Battery-inverter-load topology, which is approximately 78.5%. It is also found that the tested refrigerator with Battery-Load topology consumes an energy amounting to 1.850 kWh daily, while with Battery-inverterload topology consumes 2.466 kWh daily under the same operating conditions. These results can serve as a model for modeling refrigerators and other appliances that adopt speed controller technology to drive their motors.

KEYWORDS:

1.      Compression refrigeration system

2.      Dc microgrid

3.      Total power consumption

4.      Building energy

5.      Modeling

6.      PV-battery systems

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

In this paper, experimental tests have been conducted to evaluate the performance of a VSC-based refrigerator and the effectiveness of using such refrigerator with the proposed DC level of voltage towards the solar PV applications. Based on the obtained results, the followings can be concluded:

1) Since the power circuit of the new commerciallyavailable inverter-driven refrigerators is already rectifying an AC input, it is possible to efficiently use such refrigerators with the DC voltage level that equivalent to the rectified grid AC without any modification.

2) Using VSC-based refrigerators with the proposed (Battery-Load) has better performance than that with the traditional (Battery-Inverter-Load) configuration of PV systems, which increases system efficiency, prolongs system storage and decreases cost through dispensing the use of inverter.

3) As compared with the traditional, the power consumption pattern of the VSC-based refrigerator does not have any surge power, in which it is possible avoiding the using a very high capacity inverter and batteries even with the traditional configuration Battery- Inverter-Load.

4) The outcome of the conducted experiments for power consumption patterns can serve for further analysis such as; refrigerator consumption modeling, forecasting, and control purposes.

5) It is recommended to use a VSC-based refrigerator for systems that have battery pack within the solar PV scheme as the system would be more efficient and economical.

REFERENCES:

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