ABSTRACT
Power fluctuation and fault-related complication are the two major issues for doubly fed induction generator (DFIG)-based wind energy conversion system (WECS). The occurrence of fault leads to the rotor over current, stator over current, and DC-link overvoltage as well. These uncertainties may damage the rotor circuit, converter circuit and force the disconnection of wind system from the grid. To get rid of these issues, a supercapacitor energy storage element along with a passive series dynamic resistor (SDR) is suggested in this paper. Supercapacitor energy storage system (SCESS) is located across the DC-link, which able to handle the power fluctuation and the SDR is placed in rotor circuit, which will reduce the overcurrent possibility. Simulation is carried for a DFIG-based WECS for three phase to ground fault and two phase to ground fault. During symmetrical fault as well as asymmetrical fault, various operational disorders appeared such as rotor overcurrent, stator overcurrent and DC-Link overvoltage are found to be within their permissible limits. The results reveal the effectiveness of the proposed strategy over the conventional vector control scheme and SCESS as well.
Nomenclature
BESS | = | Battery energy storage system |
DFIG | = | Doubly fed induction generator |
FRT | = | Fault ride-through |
LVRT | = | Low-voltage ride-through |
PCC | = | Point of common coupling |
RSC, GSC | = | Rotor side converter and grid side converter |
SCESS | = | Supercapacitor energy storage system |
SDR | = | Series dynamic resistor |
SFCL | = | Superconducting fault current limiter |
VC | = | Vector control |
WECS | = | Wind energy conversion system |
WT | = | Wind turbine |
Symbols
V | = | Wind speed |
A | = | Blade swept area |
ρ | = | Air density |
β | = | Blade pitch angle |
λ | = | Tip speed ratio |
= | Flux linkage | |
, | = | Forced flux and natural flux |
R | = | Resistance per phase |
= | Synchronous angular speed | |
= | Stator voltage | |
Ks | = | Stator coupling coefficient |
E, | = | Induced back EMF in the rotor circuit |
, | = | Power from GSC and RSC |
= | Threshold current | |
ir | = | Rotor current |
, | = | Stator and rotor time constant |
P | = | Percentage of voltage dip |
Subscripts
r and s | = | Rotor and stator quantities |
a, b, c | = | Three-phase variable |
1, 2, 0 | = | Positive, negative and zero sequence |