Coordinated Control and Energy Management of
Distributed Generation Inverters in a Microgrid
ABSTRACT:
This paper presents a microgrid consisting of
different distributed generation (DG) units that are connected to the
distribution grid. An energy-management algorithm is implemented to coordinate
the operations of the different DG units in the microgrid for grid-connected
and islanded operations. The proposed microgrid consists of a photovoltaic (PV)
array which functions as the primary generation unit of the microgrid and a
proton-exchange membrane fuel cell to supplement the variability in the power
generated by the PV array. A lithium-ion storage battery is incorporated into
the microgrid to mitigate peak demands during grid-connected operation and to
compensate for any shortage in the generated power during islanded operation. The
control design for the DG inverters employs a new model predictive control
algorithm which enables faster computational time for large power systems by
optimizing the steady-state and the transient control problems separately. The
design concept is verified through various test scenarios to demonstrate the
operational capability of the proposed microgrid, and the obtained results are
discussed.
KEYWORDS:
1. Distributed generation (DG)
2. Energy management
3. Micro grid
4. Model predictive control (MPC).
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. Overall
configuration of the proposed microgrid architecture.
CONCLUSION:
In this paper, a control system that
coordinates the operation of multiple DG inverters in a microgrid for
grid-connected and islanded operations has been presented. The proposed
controller for the DG inverters is based on a newly developed MPC algorithm
which decomposes the control problem into steady-state and transient sub problems
in order to reduce the overall computation time. The controller also integrates
Kalman filters into the control design to extract the harmonic spectra of the
load currents and to generate the necessary references for the controller. The
DG inverters can compensate for load harmonic currents in a similar way as
conventional compensators, such as active and passive filters, and, hence, no
additional equipment is required for power-quality improvement. To realize the
smart grid concept, various energy-management functions, such as peak shaving
and load shedding, have also been demonstrated in the simulation studies. The results
have validated that the microgrid is able to handle different operating
conditions effectively during grid-connected and islanded operations, thus
increasing the overall reliability and stability of the microgrid.
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