Control of grid connected converter (GCC) under grid voltage disturbances

Abstract

In this chapter operation of a reliable control method of a Grid Connected Converter (GCC) under grid voltage disturbances is presented. As a GCC authors understand power electronic AC-DC converter with AC side filter and DClink capacitor operating as an interface between the electrical grid and Active Loads (AL). At the beginning short introduction to selected grid voltage disturbances is given. Afterwards, the chosen modeling approach of a GCC is discussed and the example of passive components calculation are provided. In the next sections a brief review of a basic GCC control methods is described. A control method: Direct Power Control with Space Vector Modulation (DPC-SVM) is chosen for further development process. For the basic scheme of DPC-SVM special control modules for voltage dips and higher harmonics compensation are presented. Due to the development of new control modules and its integration with the classical DPC-SVM a new reliable (robust to selected grid voltage disturbances such as dips, higher harmonics) control method is proposed: Robust Direct Power Control with Space Vector Modulation (RDPC-SVM). The term "robust" in the name of proposed control refers to the fact that the RDPC-SVM method is expected to operate in an uncertain environment with respect to the system dynamics. This new control method can assure sinusoidal like and balanced AC current in extremely distorted grid voltage. Based on the case study from series 5-400 kVA of Voltage Source Converters (VSCs) it was verified that the control dynamic and features of the RDPC-SVM fulfill requirements of sinusoidal and balanced currents under uncertain grid voltage distortions. Moreover, the quality of current and power is significantly improved in comparison to classical methods. Hence, the negative impact of the GCC on the grid voltage (through its inner impendence) is significantly reduced i.e.: lower Total Harmonics Distortion (THD) factor of a grid current, control of active and reactive power flow assure good quality of integration with a grid even in case of increased impedance within operation limits. © Springer International Publishing Switzerland 2014.