ABSTRACT:
In
order to solve the influence of nonlinear and unbalanced mixed loads on output
voltage of micro source inverters in microgrid, this paper proposes a
comprehensive strategy which can be used to accurate power distribution,
harmonic suppression, negative-sequence voltage component suppression, and stability
improvement. On one hand, a fundamental control strategy is proposed upon the
conventional droop control; the problem of accurate reactive power distribution
is solved by introducing virtual impedance to inverters, while considering the
aggravating problem of stability because of introducing virtual impedance, a
secondary power balance controller is added to improve the stability of voltage
and frequency. On the other hand, the fractional frequency harmonic control
strategy and negative-sequence voltage control strategy are proposed to solve
the influence of mixed loads, which focus on eliminating specific harmonics
caused by the nonlinear loads and the negative sequence component of the
voltage. The power quality of microgrid can be improved effectively. Finally,
small signal analysis is used to analyze the stability of the multi converter parallel
system after introducing the whole control strategy. The simulation results
show that the strategy proposed in this paper has a great performance on
distributing reactive power, regulating and eliminating harmonic components,
eliminating negative-sequence components and stabilizing output voltage of
inverters and frequency, and improving the power quality of multi inverter-based
microgrid.
KEYWORDS:
1. Microgrid
2. Mixed
loads
3. Power
quality
4. Harmonic suppression
5. Negative
sequence voltage
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
This
paper proposes a comprehensive strategy for accurate power distribution,
harmonic suppression, voltage negative sequence component suppression, and
stability improvement of multi-inverter-based microgrid, with the combination
of virtual impedance droop control and secondary power balance control, the
active and reactive can be distributed accurately, meanwhile the stability of
voltage and frequency are obviously improved, next a harmonic suppression
control strategy is introduced to suppress harmonic components in microgrid.
Furthermore, small signal analysis is used to analyze the stability of the
proposed multi-converter parallel system after introducing the comprehensive
theory. The simulation and experimental of results certify that proposed the
strategy has great performance on accurate reactive power distribution,
harmonic suppression, voltage negative sequence component suppression,
stability improvement.
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