ABSTRACT:
This paper deals with a multi objective control
technique for integration of distributed generation (DG) resources to the
electrical power network. The proposed strategy provides compensation for
active, reactive, and harmonic load current components during connection of DG
link to the grid. The dynamic model of the proposed system is first elaborated
in the stationary reference frame and then transformed into the synchronous
orthogonal reference frame. The transformed variables are used in control of
the voltage source converter as the heart of the interfacing system between DG
resources and utility grid. By setting an appropriate compensation current
references from the sensed load currents in control circuit loop of DG, the
active, reactive, and harmonic load current components will be compensated with
fast dynamic response, thereby achieving sinusoidal grid currents in phase with
load voltages, while required power of the load is more than the maximum
injected power of the DG to the grid. In addition, the proposed control method
of this paper does not need a phase-locked loop in control circuit and has fast
dynamic response in providing active and reactive power components of the grid-connected
loads. The effectiveness of the proposed control technique in DG application is
demonstrated with injection of maximum available power from the DG to the grid,
increased power factor of the utility grid, and reduced total harmonic
distortion of grid current through simulation and experimental results under
steady-state and dynamic operating conditions.
KEYWORDS:
1.
Digital signal
processor
2.
Distributed
generation (DG)
3.
Renewable
energy sources
4.
Total harmonic
distortion (THD)
5.
voltage source
converter (VSC)
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.
1. General schematic diagram of the proposed control strategy for DG system.
EXPECTED SIMULATION RESULTS:
Fig.
2. Load voltage, load, grid, and DG currents before and after connection
of
DG and before and after connection and disconnection of additional load into
the
grid.
Fig.
3. Grid, load, DG currents, and load voltage (a) before and after connection
of additional
load and (b) before and after disconnection of additional
load.
Fig.
4. Phase-to-neutral voltage and grid current for phase (a).
Fig.
5. Reference currents track the load current (a) after interconnection of
DG
resources and (b) after additional load increment.
Fig.
6. Load voltage, load, grid, and DG currents during connection of DG
link
to the unbalanced grid voltage.
CONCLUSION:
A
multi objective control algorithm for the grid-connected converter-based DG
interface has been proposed and presented in this paper. Flexibility of the
proposed DG in both steady-state and transient operations has been verified
through simulation and experimental results.
Due to sensitivity of phase-locked loop to noises
and distortion, its elimination can bring benefits for robust control against
distortions in DG applications. Also, the problems due to synchronization
between DG and grid do not exist, and DG link can be connected to the power
grid without any current overshoot. One other advantage of proposed control
method is its fast dynamic response in tracking reactive power variations; the
control loops of active and reactive power are considered independent. By the
use of the proposed control method, DG system is introduced as a new alternative
for distributed static compensator in distribution network. The results
illustrate that, in all conditions, the load voltage and source current are in phase
and so, by improvement of power factor at PCC, DG systems can act as power
factor corrector devices. The results indicate that proposed DG system can
provide required harmonic load currents in all situations. Thus, by reducing
THD of source current, it can act as an active filter. The proposed control technique
can be used for different types of DG resources as power quality improvement
devices in a customer power distribution network.
REFERENCES:
[1]
T. Zhou and B. François, “Energy management and power control of a hybrid
active wind generator for distributed power generation and grid integration,” IEEE
Trans. Ind. Electron., vol. 58, no. 1, pp. 95–104, Jan. 2011.
[2]
M. Singh, V. Khadkikar, A. Chandra, and R. K. Varma, “Grid interconnection of
renewable energy sources at the distribution level with power quality improvement
features,” IEEE Trans. Power Del., vol. 26, no. 1, pp. 307–315, Jan.
2011.
[3]
M. F. Akorede, H. Hizam, and E. Pouresmaeil, “Distributed energy resources and
benefits to the environment,” Renewable Sustainable Energy Rev., vol.
14, no. 2, pp. 724–734, Feb. 2010.
[4]
C. Mozina, “Impact of green power distributed generation,” IEEE Ind. Appl.
Mag., vol. 16, no. 4, pp. 55–62, Jun. 2010.
[5]
B. Ramachandran, S. K. Srivastava, C. S. Edrington, and D. A. Cartes, “An intelligent
auction scheme for smart grid market using a hybrid immune algorithm,” IEEE
Trans. Ind. Electron., vol. 58, no. 10, pp. 4603–4611, Oct. 2011.
