A low-voltage ride-through control strategy based equivalence method for wind farms

Generally, a wind farm is composed of many wind power generating sets of the same type. In the simulation of large-scale power grid the equivalence of wind farms should be carried out to reduce the scale of the simulation and to ensure the accuracy of the simulation. Based on the low-voltage ride-through (LVRT) characteristic of wind power generating set, a method that a wind farm can be equivalent to multi wind power generating sets with identical power output is proposed. In the proposed method the impacts of power outputs of all generating sets in the wind farm, which are different each other, on the equivalence of the wind farm are mainly considered. Based on the active power and reactive power control strategies for doubly fed wind power generating sets and full current conversion generating sets under LVRT, a more reasonable number of equivalent generating sets is determined, and finally a wind farm can be equivalent to a number of multi wind power generating sets with identical power output. Simulation results of actual wind farm show that under different control strategies the optimal number of equivalent generating sets, which is obtained by considering the active and reactive power under different voltage drop levels, is a range, and further the number of equivalent generating sets can be synthetically determined, while both accuracy and conservation are taken into account. Under normal circumstances, the least possible number of generating sets can be determined by off-line simulation, and the least number of generating sets within the range of the number under the optimal active power can be selected by on-line simulation. ©, 2015, Power System Technology Press. All right reserved.