A Multi-Objective Current Compensation Strategy for Photovoltaic Grid-Connected Inverter

This paper aims at resolving problems of harmonic, reactive power and current imbalance. In the process of photovoltaic grid connection, a multi-objective control strategy is proposed, in which the three-phase network controller simultaneously controls the harmonic and realizes the reactive power and current balance. The I-p , I-q current detection method, which is based on the current reactive power characteristic theory, can detect the compensation current. In order to reduce the measurement error of PLL, a software PLL based on decoupled double synchronous reference coordinate transformation is introduced, and the principle of multi-objective rule of three-stage network inverter is also given. The simulation and test results show that the harmonic distortion rate decreases from 2.57% to 1.10% with the proposed strategy, and the unbalance between reactive power and current is compensated, which verifies the correctness and feasibility of the strategy.