ABSTRACT:
In this paper a new variable speed
permanent magnet synchronous generator (PMSG)-based stand-alone wind energy
conversion system (SWECS) is proposed. The interface between the PMSG and the
isolated load is accomplished by a quasi-Z-source inverter (qZSI) with battery
storage system. The battery-assisted qZSI can balance the stochastic
fluctuations of the wind power injected to the load and improve the voltage and
frequency control. In addition to the battery storage, a dump load is used in
the proposed SWECS to better maintain the active power balance and stability of
the dc-link voltage during over-generation condition as well as sudden load changes.
The proposed control system is able to provide an uninterrupted and reliable
supply to sensitive loads under various power generation scenarios of the SWECS
and sudden changes in the load demand. Moreover, the proposed controller
provides maximum power point tracking (MPPT) which is essential for optimum
operation of the SWECS. The validity of the proposed system is proved by
simulation results carried out using MATLAB/ SIMULINK.
KEYWORDS:
1.
Permanent magnet synchronous generator (PMSG)
2.
Stand-alone wind energy conversion
system (SWECS)
3.
Quasi-Z-source inverter (qZSI)
4.
Battery storage system
5.
Dump load
6.
Maximum power point tracking (MPPT)
SOFTWARE: MATLAB/SIMULINK
CONCLUSION:
This paper proposes a new stand-alone
PMSG-based WECS using battery-assisted qZSI. The proposed battery-assisted qZSI
provides the voltage boost and inversion, and energy storage in a single-stage.
By introducing the dynamic model of the qZSI with battery, a closed-loop control
scheme for both dc-side and ac-side of the qZSI was presented. The magnitude
and frequency of the output voltage were effectively controlled through the
proposed control scheme under variable wind profile and load conditions. The
battery storage system located on quasi-Z-source network balances the
stochastic fluctuations of the wind power injected to the load and guarantees
an uninterrupted and stable power supply. On the other hand, using a dump load
in the proposed system can ensure the stability of the dc-link voltage under
over-generation condition of the SWECS. Lack of the dump load makes power balance
difficult and can lead to voltage and frequency instability in the over-generation
condition, especially when the battery reaches its maximum capacity. The
dc-side controller adjusts dsh to manage the battery operation mode and maximum
power extraction from the wind. Simulation results verify the performance of
the proposed control scheme.
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