Control Strategy Study of DFIG with LVRT

Improving fault ride-through capability of DFIG connected wind turbine system: A review

“…Therefore modern grid code requires the wind power plant remains connected during various fault condition.The FRT or LVRT requirement means the ability of all generating plant should remain connected during the fault condition or low voltage within certain limits.German electric transmission operators E.ON and VE-T have first suggestedLow voltage ride through requirements in 2003 [7].This requirement is generally referred as a fault ride through (FRT)/low voltage ride through (LVRT) capability and this is denoted by voltage versus time characteristics shown in fig 3 [1]- [7].Moreover the wind power plant able to provide reactive power during low voltage so as to increase voltage level at the point of common coupling (PCC) and regain the stable system after clearing fault. The disconnection of wind turbines below 80% of the nominal voltage causes to loss of an undesirable portion of power generation [8]. Therefore, Wind turbine now requires that gridconnected wind turbines must not be separated from the grid during three-phase short circuitsor fault-related symmetrical voltage dips as long as the voltageat the Point of Common Coupling (PCC) remains above the Limit Line 1 shown in Fig.…”