Control Strategy for a Grid Connected Converter in Active Unbalanced Distribution Systems

Abstract

The development in distributed energy resources technology has led to a significant amount of non-linear power electronics converters to be integrated in the power system. Although this leads to a more sustainable system, it also can have adverse impacts on system stability and energy power quality. More importantly, the majority of the distribution power systems currently are unbalanced (with asymmetrical voltages) due to load unbalance, while the most common fault types are unbalanced grid faults that can have many adverse effects on distributed resource operations. In that regard, proper control of the grid connected converters in active unbalanced distribution systems will become very important. This paper aims to present the behavior of the advanced grid connected converter control technique under different voltage states at the point of common coupling (according to the ABC classification). The main insufficiencies of the classical control technique will be highlighted, while the paper will propose an appropriate solution for mitigation of negative sequence currents under asymmetrical voltages at the point of common coupling. An extensive experimental verification of the proposed techniques is performed using an advanced laboratory prototype for research in grid integration of distributed resources. The experimental verification clearly demonstrates the benefits offered by the advanced control strategy.

Fault Ride-Through (FRT) Behavior in VSC-HVDC as Key Enabler of Transmission Systems Using SCADA Viewer Software

“…The converter control strategy in VSC-HVDC is critical for improving its FRT capability [17][18][19][20][21][22]. The work done in [17] proposed a strategy for reducing the inverter side-overvoltage of the HVDC system in the event of an inverter side Ac system fault.…”

“…The authors of [20] developed a perturbation observer-based sliding-mode control scheme to control VSC-HVDC systems. The authors of [21] proposed a passive control scheme for multi-terminal VSC-HVDC systems to provide reliable and effective integration of electrical power from renewable energy. The authors of [22] proposed the negative sequence controller needed for such asymmetrical conditions in AC grids.…”

“…The authors of [21] proposed a passive control method for multi-terminal VSC-HVDC systems to provide efficient and consistent integration of electrical power from renewable energy. The authors of [22] proposed the negative sequence controller needed for such asymmetrical conditions in AC grids.…”

“…The authors of [22] proposed the negative sequence controller needed for such asymmetrical conditions in AC grids. The passive control scheme was proposed in [21] for multi-terminal VSC-HVDC systems to provide reliable and effective integration of renewable energy. In [22], the authors proposed the negative sequence controller that is required for such asymmetrical conditions in AC grids.…”

Electric Arc Furnaces as a Cause of Current and Voltage Asymmetry

“…The increasing number of devices and installations disturbing the power quality forced the application of various remedial measures. An interesting method allowing to reduce the voltage and current asymmetry is presented in [13]. The applied strategy is particularly effective in smart grids and systems using electricity storage.…”