Improved ip-iq Reactive Current Detection Method Without PLL

Abstract

As the traditional d-q transformation method is not sufficient in detecting the three-phase asymmetric components, a new detection method in which a single phase voltage is input to a differentiator to get an orthogonal differential is proposed. The synchronous rotary angle can be obtained by using the orthogonality relationship based on mathematical relationship. The new detection method is suitable for both asymmetric load and asymmetric supply voltage systems. The effect of time delay caused by phase-locked loop (PLL) is eliminated without using PLL circuit to obtain synchronous rotation angle in the detection process. The phase shifting deviation is solved without shifting the phase of three-phase current. The unbalance degree of input voltage in Static Synchronous Compensator (STATCOM) is effectively reduced by using this method. Simulation and experiment results show that the proposed method is valid and feasible.