Reactive power coordination in DFIG based wind farms for voltage regulation & flicker mitigation

Abstract

The deployment of modern DFIG or full converter turbine technologies on a large scale into distribution networks is raising issues for electric utilities with regard to voltage rise and flicker amongst other power quality issues. This paper proposes an real-time reactive power coordination scheme employed with the voltage control technique, the concurrent means for achieving both voltage regulation and flicker mitigation at the wind farm point of common coupling (PCC). Noting that each wind turbine generator (WTG) comprising the wind farm operates in a different state, wind condition dependant, the instantaneous reactive power capabilities of each WTG differ. Based on the estimated real-time instantaneous reactive power available from each WTG, a wind farm Q dispatcher is proposed to fully utilize the DFIG turbine power converter capabilities in order to avoid active power curtailment and maximize energy production. Exploiting the reactive power capabilities of the rotor side converter (RSC) and grid side converter (GSC), the proposed control strategy regulates the voltage level within acceptable bands and reduces the flicker level by up to 90%. The real-time simulation results presented in this paper focus on a 6 MW wind farm being connected to a rural 25 kV distribution feeder, considering the applicable utility grid code requirements.

Advanced Reactive Power Compensation of Wind Power Plant Using PMU Data

“…Change the phasor organism θ into its equivalent Cartesian X by (11) Apply the proposed two-phase modification method in ( 12)- (14) Generate the organism population randomly Publish the results…”

“…It shows that SVC can help to reduce the reactive power demand of the main grid by letting WT participate in the reactive regulation programs. In [13][14], a real-time reactive power control scheme is developed for the voltage fluctuation mitigation at the point of common coupling of WT with the main grid. While these works advocate the use of SVC as a superior and effective approach for reactive power compensation, the results show that it still can not track the high varying nature of the reactive power pattern in the WT.…”

Non stationary‐ARMA flicker model for squirrel cage induction generators based wind farms

“…where, P st,i is the flicker severity due to one wind turbine and n indicates flicker summation factor. In case of wind turbines with same rating, n can be calculated by Equation (14). n = ln (m) ln (P st cum ) − ln (P st ind ) (14) where, P st ind is flicker severity due to standalone operation of each turbine.…”

“…An analytical formulation of the generated aerodynamic torque of a three‐bladed wind turbine including the effects of wind shear and tower shadow is presented in [12]. The proposed model in [12] was utilized in several applications as the volt/var control of power‐electronic interfaced WTGs [13] and reactive power coordination in DFIG based wind farms [14]. A neural network based model for wind turbine flicker emission calculations is presented in [15].…”

“…Estimation of cumulative P st for multiple wind turbines (13) where, P st,i is the flicker severity due to one wind turbine and n indicates flicker summation factor. In case of wind turbines with same rating, n can be calculated by Equation (14). n = ln (m) ln (P st cum ) − ln (P st ind )…”