An Improved DC-Link Voltage Control Strategy for Grid Connected Converters

Abstract

This paper presents a robust control strategy to improve dc-link voltage control performances for Grid connected Converters (GcCs). The proposed control strategy is based on an adaptive PI controller and is aimed to ensure fast transient response, low dc-link voltage fluctuations, low grid current THD and good disturbance rejection after sudden changes of the active power drawn by the GcC. The proportional and integral gains of the considered adaptive PI controller are self-tuned so that they are well suited with regard to the operating point of the controlled system and/or its state.

Existing System

Adaptive Neural Network.

Proposed System

This paper proposes an efficient adaptive PI controller for the dc-link voltage control. The adaptive nature of the proposed PI controller guarantees the different control constraints in addition to the reduction of grid current THD during steady state operation, which is mainly caused by dc-link voltage controller’s output signal. The proportional and integral gains of the considered adaptive PI controller are self-tuned according to the operating point of the controlled system and/or its state (i.e. transient or steady state). For that, a band around the dc-link voltage reference is defined. When the measured dc-link voltage is outside this band, the PI gains were selected constants so that a very good dynamic is achieved. Otherwise, the PI gains become variable so that the previously mentioned constrains remain still satisfied. Also, an anti-windup process is added in order to prevent large overshoot after step jumps of the dc-link voltage reference.

Architecture

Grid Connected Inverter