A Multi-Functional De-Icing Equipment Using Modular Parallel PWM Current Source Converters

Abstract

For transmission line de-icing, a five level specific harmonic elimination (5l-she) modulation method for high-power parallel current source is proposed, which realizes the current balance of DC bridge arm and the suppression of common mode voltage, and ensures the power quality of grid connected current at low switching frequency. In addition the reactive power of the low voltage load can be compensated at the same time. Firstly, the switching states are classified according to the different mode lengths of PWM current, and the common mode voltage corresponding to each switching state is calculated. Secondly, the current sharing control strategy is established based on the analysis of the influence of redundant switching state on the current sharing of DC bridge arm. Then, the 5l-she waveform is constructed based on the switching state with lower common mode voltage, and the redundant switching states is optimized according to the current sharing strategy. Finally, the effectiveness of the proposed method is verified by simulation.