Harmonic reduction of three-phase power inverter injection current using virtual admittance

Power inverter plays important and multifaceted roles as an intermediary between renewable energy sources and the grid. One of these important roles is to maintain and improve the quality of power produced by these energy sources under grid different conditions. The purpose of this article is to present a new control scheme that uses the concept of virtual admittance to reduce the injection current harmonics, when the local grid voltage is distorted. The scheme is implemented in the synchronous reference frame (dq) and the method of obtaining the virtual admittance function is simpler and completely different. Although the responsibility for harmonic compensation rests with the virtual admittance, its constituent loop is outside the main control loop of the injection current and uses the local grid voltage feed forwarding. Therefore, an advantage of this method is that it does not interfere with an important issue such as the stability of the inverter control system. Another important issue considered in this article is the possibility of instability of the inverter control system due to the insufficient damping in the inner loop of the low-pass output filter and also the ability to give the inverter to start it soft. For these purposes, an internal voltage control loop with a Proportional-Integral-Derivative controller (PID) and an external current control loop with PI controller are designed in the synchronous reference frame. Finally, in order to validate the proposed control scheme, the simulation results are presented in different conditions.

Automated summary

This article presents a new control scheme that utilizes the concept of virtual admittance to reduce injection current harmonics, aiming to maintain and improve the quality of power produced by renewable energy sources when the local grid voltage is distorted. The method of obtaining the virtual admittance function is simpler and completely different, and its constituent loop is outside the main control loop of the injection current. This approach does not interfere with important issues such as the stability of the inverter control system, making it a promising solution for harmonic compensation.