Abstract
Adopting eco-friendly solutions is the need of the hour in order to downscale carbon emissions and the fast depletion of fossil fuels. Hybrid energy systems provide one such optimistic sustainable solution for power generation in a grid integrated system as well as for stand-alone applications. With grid integrated systems, there are many grid codes to be maintained such as voltage stability, frequency deviation and Fault Ride Through Capability (FRT). In a hybrid system, the propensity of the PV/Wind system to remain connected at the moment of short electric fault is identified as FRT. This paper elucidates the voltage compensation using an Electric Vehicle (EV) charging station or a Flexible AC Transmission System (FACTS) device depending on the intensity of fault that occurs at the Point of Common Coupling (PCC) in grid integrated hybrid systems. When a fault occurs at the PCC, depending on the intensity of the voltage sag either the EV charging station or a FACTS device, namely a Dynamic Voltage Restore (DVR), provides the voltage compensation. The voltage obtained from an EV charging station or DVR is conditioned using power converters and fed to the PCC to even out the discrepancy in the voltage that is effected due to the fault. Even though charges electric vehicles continuously, the EV charging station gives priority to supply voltage for compensation whenever a fault occurs at the grid. If the intensity of voltage sag due to fault is between 0.9 to 0.51 p.u, the EV charging station provides voltage compensation, and for voltage sag between 0.5 to 0.2 p.u, DVR takes over to provide voltage compensation for the continuous sustainability of the grid. The proposed system makes use of an existing source such as an EV charging station as a supplementary device to provide compensation, and also has a backup supplementary device DVR in case of any non-availability of the EV charging station. Thus, the voltage compensation in turn facilitates the parameters such as DC link voltage and the grid voltage to stay within the pertinent limits in the event of a fault at the grid. The system was simulated using MATLAB Simulink and the results were verified.
Highlights
Power quality is a significant consternation in modern day power systems
This paper explores voltage compensation when a fault occurs at Point of Common Coupling (PCC) in hybrid systems
The Dynamic Voltage Restore (DVR) is connected to PCC in series with the grid, thereby injecting the voltage necessary for compensation to recover the voltage sag caused by the fault
Summary
Power quality is a significant consternation in modern day power systems. This concern for the issues in the power quality has prompted the development of certain standards and regulations in grid integrated applications. The proposed technique in this paper involves fuzzy controlled DVR with feedback control and EV charging station to provide voltage compensation to the grid during any event of fault. The charging station for an EV is available in many places, which can be utilized to improve the FRT capability by providing voltage compensation rather than including additional compensating devices Such a coordinative control in charging of plugin hybrid electric vehicles in hybrid AC/DC systems has been developed in [14]. The charging station is directly coupled to that of the grid whose main source is wind and other supplementary energy storage devices in [19] which essentially focuses on reviewing the literature on the contemporary modeling of grid-connected PV based EV system which can be extended to EV hybrid system as proposed in this paper. For fault with higher intensity voltage sag (0.5 to 0.2 p.u), the alternate device DVR takes over to provide voltage compensation by tracking the deficit voltage
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