Improved FBD reactive power and harmonic current detecting method based on voltage sequence decomposition

Current detecting is the key of reactive power and harmonic current compensation, its accuracy and quickness has an important influence on the performance of the compensation. Traditional FBD(Fryze-Buchholz-Dpenbrock) method has a large delay as containing PLL(phase-locked loop) which has a second-order filter. When system voltage drop asymmetric, the phase information would be affected by negative sequence component. A improved FBD reactive power and harmonic current detecting method based on voltage sequence decomposition is proposed using voltage sequence decomposition instead of PLL to improve quickness and accuracy of the compensation current detection. Simulation demonstrates the correctness and effectiveness of the proposed method. Compared with traditional FBD method, it can be shown that fundamental positive sequence active current can be detected faster with modified FBD method and it can be detected more accurately under asymmetric dropped grid voltage.