Transient Control of the Reactive Current for the Line-Side Converter of the Brushless Doubly-Fed Induction Generator in Stand-Alone Operation

In this paper, the transient control algorithm of the reactive current by the line-side converter (LSC) control is proposed when the inductive load is suddenly connected or disconnected from the stator power winding (PW) of the brushless doubly-fed induction generator. In stand-alone operation, the quality of the voltage waveform at the point-of-common coupling (PCC) will be strongly affected due to the reactive power change of load. Moreover, when the amplitude of the PCC voltage is higher than the dc-link voltage, the LSC cannot work normally. To tackle this problem, many control strategies, such as predictive current control, direct voltage control, etc., are usually developed in the machine-side converter to supply the reactive power, but the LSC can also assist in stabilizing the PCC voltage fluctuation by supplying or absorbing reactive current. This paper analyzes the transient state of the load current and the PCC voltage when the load is suddenly connected to the stator PW, and proposes a compensation algorithm which has a good transient-state performance. Then, the controllability of the LSC during the PCC voltage swell is analyzed when the load is disconnected from the stator PW. A high-voltage ride-through control strategy is proposed by using the reactive current of the LSC. The correctness of the proposed method is demonstrated by simulations and experiments.