Wind power generation has taken its place in its share of electric power generation around the globe. Wind power generation normally utilizes induction generators for power production. In this case, these type of generators do not need synchronization when connecting or reconnecting to the electric grid or to any point of interconnection (POI).
When planning wind power integration, power system stability simulations are conducted to ensure system reliability with the wind power connection. In stability analysis, it is customary to analyze synchronization of generators’ rotor angles in the grid to evaluate system or generator stability. This practice is not applicable to wind power with induction generators based from the above discussion.
For power system stability, it is industry accepted to analyze low voltage ride through (LVRT) of a wind power generation rather than rotor angles. LVRT requires wind power plants to remain connected to the grid in the event of a worst short circuit which maybe nearest to the wind power plant. This is evaluated by observing the voltage at the POI of the wind power plant.
The figure below is a copy of Federal Energy Regulatory Commission (FERC) LVRT requirement. The plot shows the beginning of the voltage sag, the condition for the wind power plant to remain connected to the grid and the condition where the wind power plant is allowed not to remain connected to the grid. The voltage magnitude, plus the time duration, at the POI serves as the barometer if the wind power plant must stay connected or not.
Figure below is an illustration of LVRT requirements of different Transmission Operators and Transmission Owners relating to wind power plant interconnection. This plot is taken from this site. The figure tells us that different grids have different requirements for wind power LVRT. This maybe due to the system stiffness or inertia, system demand or wind power penetration. Moreover, some of the LVRT requirements were benchmarked from actual measured LVRT of wind power plants during system fault events.
Figure below is another interesting LVRT requirement in North America at the Western Electricity Coordinating Council (WECC). This plot is taken from this site. This illustration shows not only LVRT but also high voltage ride through (HVRT). Within the no-trip envelope, the wind power plant must stay connected to the grid but outside this condition the wind power plant can be disconnected from the grid.
The Energy Regulatory Commission in the Philippines has yet to develop voltage ride through requirement for wind power plants. There are existing and proposed or queued wind power generation located in the northern part of Luzon that maybe needed to comply with a developed LVRT. Moreover, LVRT policy can be applied not only to wind power generation but also to conventional power plants. Development of LVRT for wind power plants must be conducted for wind power generation to safeguard the stability and reliability of the power grid.
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