A Fuzzy Based Improved Control Strategy of Dynamic Voltage Restorer for Low Voltage and High Voltage Ride Through Compensation for Variable Speed Hybrid Energy 

Abstract

In present-day power generation systems, the integration of many renewable energy sources creating more sustainable hybrid energy network can be witnessed. The Hybrid energy system regulates the escalation in the cost of the energy that are linked with currently established energy resources. One such predominantly used Hybrid energy system happens to be Wind / Photo Voltaic (PV) integrated system which is a viable alternative to meet the rising energy demands.Fault Ride Through (FRT) is one of the cardinal essentialities that is perceived as an indispensable grid code because the effect of faults may propagate to a larger geographical area if FRT is not achieved. In a Hybrid system the ability of the generator to remain connected at the time of short electric fault like voltage dip is identified as Low Voltage Ride Through (LVRT) and voltage swell is known as High Voltage Ride Through (HVRT). When fault occurs at the point of the grid, LVRT or HVRT depending on the fault has to be determined and a pertinent compensation should be carried out. This paper proposes a compensation technique based on Dynamic Voltage Restorer (DVR) employing fuzzy controller for LVRT and HVRT in hybrid systems. The disparityin the voltage at PCC is traced and is used to inject the necessary deficit voltage in case of sag or suppress the excessive voltage in case of swell in the hybrid system by means of DVR. This compensation in turn enables the parameters like DC link and stator voltage to stay within the admissible limits in the event of fault at the point of grid.