Grid Ancillary Services From Doubly Fed Induction Generator-Based Wind Energy Conversion System: A Review <s> D. FREQUENCY CONTROL <s> Increasing levels of wind generation has resulted in an urgent need for the assessment of their impact on frequency control of power systems. Whereas increased system inertia is intrinsically linked to the addition of synchronous generation to power systems, due to differing electromechanical characteristics, this inherent link is not present in wind turbine generators. Regardless of wind turbine technology, the displacement of conventional generation with wind will result in increased rates of change of system frequency. The magnitude of the frequency excursion following a loss of generation may also increase. Amendment of reserve policies or modification of wind turbine inertial response characteristics may be necessary to facilitate increased levels of wind generation. This is particularly true in small isolated power systems. <s> BIB001 </s> Grid Ancillary Services From Doubly Fed Induction Generator-Based Wind Energy Conversion System: A Review <s> D. FREQUENCY CONTROL <s> As wind power penetration increases and fossil plants are retired, it is feared that there will be insufficient kinetic energy (KE) from the plants to support the system frequency. This paper shows the fear is groundless because the high inertias (H cong 4 seconds) of wind turbine-generators (WTGs) can be integrated to provide frequency support during generation outage. <s> BIB002
Unlike the conventional synchronous generators, the increase in wind generators does not increase the system inertia. As a result, wind generation will have an impact on power systems frequency variations during disturbances. Therefore, wind turbines should adjust their inertial response characteristics to support system frequency variations BIB001 . Figure 14 shows a typical power system response after power loss. It can be inferred form this figure that larger systems FIGURE 14. Typical power system response after power loss BIB002 .