ABSTRACT:
This
paper presents a novel approach by which enhancement in power quality is
ensured along with power control for a grid interactive inverter. The work
presented in this paper deals with modeling and analyzing of a transformer less
grid-connected inverter with active and reactive power control by controlling
the inverter output phase angle and amplitude in relation to the grid voltage.
In addition to current control and voltage control, power quality control is
made to reduce the total harmonics distortion. The distorted current flow can
compensate for the disturbance caused by nonlinear load. The Simulation of the
grid interactive inverter is carried out in MATLAB/SIMULINK environment and
experimental results were presented to validate the proposed methodology for
control of transformer less grid interactive inverter which supplies active and
reactive power to the loads and also makes the grid current to a sinusoidal one
to improve the power factor and reduce the harmonics in grid current. This work
offers an increased opportunity to provide distributed generation (DG) use in
distribution systems as reliable source of power generation to meet the
increased load demand which helps to provide a reasonable relief to the
customers and utilities to meet the increasing load demand
KEYWORDS:
1.
Grid interactive inverter
2.
Voltage Controller
3.
Current Controller
4.
THD improvement
5.
Reactive power compensation
6.
Intelligent power module
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Figure 1: Schematic diagram of
grid connected system
Figure 2: grid tie inverter
Figure 3: Simulation waveforms of current a) when
load is controlled rectifier b) inverter current c) grid current d) the
reference current
Figure 4: Power flow graph.
Figure 5: grid voltage, load current & grid
current
Figure 6: FFT analysis
Figure 7: load current
Figure 8: Injected current
CONCLUSION:
The
simulation of single phase grid interactive inverter has been carried out with
non-linear load and the results obtained from the simulations shows that this
control technique improves the power quality ie THD and the power factor. The
simulation also shows that power transfer of active and reactive power from the
inverter to grid is possible. The reactive power required for the load is
completely provided from the inverter. The hardware implementation of the
interactive inverter has been conducted using real time workshop in the MATLAB
Simulink environment. The half wave rectifier is used as load in the hardware
implementation. The results show that the controller is capable for reactive
power compensation, and maintaining constant voltage at the grid satisfying
standard for grid interconnection. That is the THD is lessthan5% 3.74 and the
power factor is .9977 which is near to unity. Energy conservation by load
management is possible and a reasonable relief to the customer and voltage
profile is maintained at the grid. This work can be extended to cascaded
inverter configuration and reliability analysis has to be made as a better
option for future studies.
REFERENCES:
[1] EPRI-white paper “Integrating Distributed Resources into electric
utility systems ”Technology Review.December2001
[2] Thomas Ackerman “Distributed Generation, a definition’’ Electric
power system research,57(3),2001,pp195-204
[3] G. Joos, B.T Ooi, D. McGill is, F.D. Galiana, and R. Marceau, “The
potential of distributed generation to provide ancillary services,” at IEEE
Power Engineering Society Summer Meeting, 16-20 July 2000, vol. 3, pp. 1762
– 1767
[4] Frede Blaabjerg, Zhechen, Soreren Baekhoej Kjaer “Power electronics
as efficient interface in dispersed power generation system” IEEE
Transactions on Power Electronics vol:19,no.5, sept2004 pp1184-1194
[5] Yong Yang, Yi
Ruan, Huan-qing Shen, Yan-yan Tang and Ying Yang; “Grid-connected inverter for
wind power generation system” Journal of Shanghai University, Page(s):.51-56,
Vol. 13, No 1,Feb,2009.
