Research On The Reactive Power Control Strategy Of Wind Field Based On Fan Reactive Power Control

At present,the doubly-fed induction generator(DFIG),as the mainstream model in China's wind power industry,has been used on a large scale.In most regions of China,the wind turbines operating in wind farms use power operating modes of unit power factor(power factor is 1).Operation does not take full advantage of the fact that the doubly-fed wind turbines can generate reactive power.Instead,large-capacity reactive power compensation devices are installed in each wind farm.Most current reactive power compensation devices use inverters and controllers.This compensation method is too expensive,and the maintenance costs and damage rates are also high in the later period.Under this background,this paper takes the doubly-fed wind turbines as an example to analyze the power generation principle,reactive power limit,and reactive power compensation strategy of wind farm under the difference of wind speed in the wind farm,and proposes a reactive power compensation control strategy for wind farms with reactive power support capabilities based on this.Firstly,the principle of power generation and power control of doubly-fed induction generator are analyzed,The relationship between the current and voltage of stator side and rotor side and the output of the active power and reactive power is analyzed.Control method of rotor side converter and grid side converter under the coordinate transformation of d/q axis is analyzed.Secondly,according to the relationship between the reactive power limit of the doubly-fed fan and its output active power,a reactive power optimization control strategy based on the reactive power generation of the doubly-fed fan is proposed.The active and reactive decoupling control of the doubly-fed fan is achieved.The calculation of the reactive power limit of the doubly-fed induction generator is based on the relationship between the reactive power limit of the doubly-fed induction generator and the active power,and the variation of the reactive power limit with the change of the active power is obtained,and the reactive power limit of the entire wind farm is calculated.The constraint conditions of active power and reactive power issued by the dispatching department of a doubly-fed wind farm generate the optimal reactive power control strategy for a doubly-fed wind farm.Finally,a wind power system model containing a single doubly-fed wind turbine is established.The main parameters of the doubly-fed wind turbines model are used and the power characteristics of the doubly-fed wind turbines in grid-connected operation are introduced.Based on the characteristics of operation of a single doubly-fed induction generator,a wind power system model with three doubly-fed wind turbines is established.By comparing the conditions,that the three doubly-fed induction generator generate the active and reactive power,using the proposed control strategy and normal strategy,the effectiveness of the proposed control strategy is verified.Applying the control strategy of this paper can make the best use of the reactive power generation capability of the doubly-fed induction generator and reduce the switching capacity of the reactive power compensation device,which has certain engineering applicability.