Comparative analysis of predictive current control of VSI converters in the connection of renewable energy sources to the power grid

Abstract

This paper analyzes the performance of the predictive current control technique in the operation of Voltage Source Inverters (VSI) used to connect renewable resources to the power grid. VSIs are commonly used to convert DC power from renewable energy sources, such as energy storage units, solar power plants and fuel cells, to AC power with constant magnitude and frequency. For this purpose, a strategy known as PWM was implemented to determine the switching sequence of the converter’s power semiconductors. In addition, the current being injected into the grid must be controlled; thus, an additional control algorithm was required to operate in conjunction with the PWM technique. The main contribution of this paper is demonstrating that predictive current control presents better characteristics than current-oriented control, the most widely used strategy. The first section analyzes conventional PWM techniques and, in the second part, current control techniques are formulated. Predictive control minimizes the future error of the current by defining the best switching state in each period. The two current control techniques present good performance. However, predictive control is preferable due to its simplicity, easy implementation, low harmonic content, as well as reduced response time.

Keywords

• Voltage-source converter
• PWM technique
• Current control
• Oriented control
• Predictive control