Improved Low Voltage - Ride Through (LVRT) ‎Performance of an Active Distribution Grid by ‎Providing a Bidirectional Converter to Control DC ‎Bus Voltage Ripple

In  today’s world,  distributed  generation  sources through  grid-connected  inverters  perform  other  roles in addition to generating  the  required  load’s  power. Among these roles, it is possible to perform the function of the inverter  as a virtual synchronous machine in the direction of  frequency stability in the presence of  a  fault, supporting  the network  in  the condition of  voltage  fault  caused  by the presence of  a  fault, and so on. It can be mentioned that doing each of these things, It requires changes in the control system, hardware or new topologies. Supporting the grid  in voltage sag conditions, that  is called  Low Voltage - Ride Through for an  inverter,  has  its  own standards and  requirements, so meeting them  requires new research and designs. In this paper, first, a review of the past work is done and then by presenting a new method, the inverter performance is improved in these conditions. In the presented method, the DC bus ripple will be very low and thus the high order harmonics will be reduced. Also, this  ripple is reduced  by using a two-way converter  and  suitable control of  the  inverter, unlike some of  the presented  methods that  transfer  it on the reactive power  produced or on the voltage of the solar cell side. Furthermore, in these cases, it is tried to reduce the DC bus ripple to the minimum value of the capacitive capacity of this bus. To evaluate the presented method, simulations have been performed in Simulink / MATLAB software and the results have been presented.