STABILIZE THE DYNAMIC RESPONSE OF DC-LINK VOLTAGE IN DISTRIBUTED GENERATOR USING SLIDING MODE CONTROL

Abstract

With the growing proliferation of DG units using renewable energy sources, stability issues have emerged with regards to the regulation of the DC-link voltage under dynamic behavior. In order to achieve stability of the dynamic behavior of the DC-link voltage in DG systems in the presence of disturbances, renewable energy variations, and parameters uncertainties, a Sliding Mode Control (SMC) approach has been employed. In this regard, a distributed generation model which consisted of a renewable energy source, DC-link capacitor, power converter, and inverter connected to the grid was considered in a simulated form. The performance of the proposed method was analyzed and compared with conventional PI controller based on important dynamic response parameters. From the simulation results, it was found that the proposed SMC controller greatly improved the voltage regulation performance through the reduction of overshoot to 2.1% from 12.5%, settling time to 0.08 s from 0.35 s, and voltage ripple to 2.4 V from 8.6 V. In addition, steady state error was decreased to 0.2% from 1.8% with voltage recovery from any disturbance taking place within 0.08 s. Moreover, the controller could successfully operate under fluctuations in renewable energy sources with maximum voltage deviation of 15 V and recovery time of 0.06 s. It was concluded from the obtained results that the proposed SMC controller method proved to be more robust, responsive to disturbances, and able to respond to transients quickly than conventional controllers. Thus, the proposed approach was determined as reliable and efficient to improve DC-link voltage stability.