Electric Spring is an emerging smart grid technology, which can provide voltage support to weakly regulated system. This paper studies the effect of load variation on the performance of electric springs. Two different single phase circuits with intermittent power supply have been simulated for the study – with one electric spring and with two electric springs. The loads considered are linear and are identical. Results obtained in MATLAB/Simulink environment show that line voltage is regulated by electric spring irrespective of variation in load. A brief comparative study is done between the simulation results obtained from the two circuits to observe the effect of the additional electric spring. This study tests the effectiveness of electric springs in a circuit designed to be more realistic, i.e., when the loads are not ON all the time and multiple electric springs are distributed all over the grid.
1. Demand Side Management
2. Electric Spring
3. Renewable Energy Sources
Fig. 1. Schematic Diagram of Electric Spring connected with Intermittent Renewable Energy Source
Fig. 2. Block Diagram for Circuit with Two Electric Springs
EXPECTED SIMULATION RESULTS:
Fig. 3. RMS Voltage for Boosting action in single ES circuit
Fig. 4. Active and Reactive power consumption of ES during Boosting action in single ES circuit
Fig. 5. RMS Voltage for Reduction action in single ES circuit
Fig. 6. Active and Reactive power consumption of ES during Reduction action in single ES circuit
Fig. 7. RMS Voltage for Boosting action in double ES circuit
Fig. 8. Active and Reactive power consumption of ES during Boosting action in double ES circuit
Fig. 9. RMS Voltage for Reduction action in double ES circuit
Fig. 10. Active and Reactive power consumption of ES during Reduction action in double ES circuit
This paper demonstrates the effects of load variation on the performance of ES. From the simulation results, it can be noted that, for boosting mode of operation, the ES can regulate the line voltage at the reference value irrespective of variation in load. However, for reduction mode of operation, the load variation causes fluctuations in the line voltage even when the ES is operating. This might be improved by making the circuit more inductive, which will assist the ES for reduction action. The basic single ES circuit was modified by adding an extra ES to it. It was observed that the reactive power consumption of each ES decreased by almost 50% for both modes of operation. Therefore we can conclude that as the number of ES in the circuit increases by a factor of ‘n’, the reactive power consumed by each ES to carry out the same magnitude of regulation decreases by a factor of ‘n’. This decreases the stress on each ES as well as the inverter rating for ES. For this study, the linear and identical loads have been considered, which can be further extended to non-linear and non-identical loads. Also, the random load profile can be replaced with a real time load profile.
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