ABSTRACT:
In this paper, a new energy control scheme is
proposed for actively controlled hybrid dc microgrid to reduce the adverse
impact of pulsed power loads. The proposed energy control is an adaptive
current-voltage control (ACVC) scheme based on the moving average measurement
technique and an adaptive proportional compensator. Unlike conventional energy
control methods, the proposed ACVC approach has the advantage of controlling
both voltage and current of the system while keeping the output current of the
power converter at a relatively constant value. For this study, a laboratory
scale hybrid dc microgrid is developed to evaluate the performance of the ACVC
strategy and to compare its performance with the other conventional energy
control methods. Using experimental test results, it is shown that the proposed
strategy highly improves the dynamic performance of the hybrid dc microgrid.
Although the ACVC technique causes slightly more bus voltage variation, it
effectively eliminates the high current and power pulsation of the power
converters. The experimental test results for different pulse duty ratios
demonstrated a significant improvement achieved by the developed ACVC scheme in
enhancing the system efficiency, reducing the ac grid voltage drop and the
frequency fluctuations.
KEYWORDS:
1. Hybrid dc microgrid
2. Energy control system
3. Pulse load
4. Supercapacitor
5. Active hybrid power source
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. Schematic diagram of the hybrid dc microgrid under study
EXPECTED SIMULATION RESULTS:
Fig. 2: Experimental test results of
ACVC and CACC technique during constant pulse load operation.
Fig. 3: Experimental test results of
CACC method and ACVC technique when pulse load frequency changes from 0.1-Hz to
0.2-Hz and its duty ratio increased from 20% to 40%.
Fig. 4: Variation of the normalized
average dc bus voltage and the kv in the proposed ACVC technique when
pulse load frequency changes from 0.1-Hz to 0.2-Hz and its duty ratio increased
from 20% to 40%.
Fig. 5: Experimental test results of CACC method and ACVC technique
when pulse load changed from 2-kW to 3-kW.
Fig. 6: Hybrid DC microgrid performance comparison when ACVC, LBVC and
IPC methods are utilized.
CONCLUSION:
In this paper, a new energy
control scheme was developed to reduce the adverse impact of pulsed power
loads. The proposed energy control was an adaptive current-voltage control
(ACVC) scheme based on the moving average current and voltage measurement and a
proportional voltage compensator. The performance of the developed ACVC
technique was experimentally evaluated and it was compared to the other common
energy control methods.
The test results showed that the
ACVC scheme has a similar performance with the continuous average current
control (CACC) method during a constant pulsed power load operation. However,
the transient response of the ACVC technique during pulse load variation was
effectively improved and it prevented any steady state voltage error or
dangerous over voltage.
Also, the performance of the
developed ACVC technique was compared with the limit-based voltage control
(LBVC) and instantaneous power control (IPC) methods for different pulse rates
and duty ratios. The comparative analysis showed that although the maximum dc
bus voltage variation in the case of ACVC scheme was higher than the IPC and
LBVC methods, the proposed ACVC technique required smaller power capacity of
the converter and energy resources. Moreover, the developed ACVC method
effectively eliminated the power pulsation of the slack bus generator and
frequency fluctuation of the interconnected AC grid while the ac bus voltage
drop was well reduced. Additionally, the efficiency analysis for different pulse
duty ratios showed that the developed ACVC method considerably improved the
efficiency of the system since the maximum current of the converter was reduced
and the converter was operating at a relatively constant value.
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