Grid Fault Ride Through Capability of Voltage Controlled Inverters for Photovoltaic Applications

Abstract

Fault ride through (FRT) capability is one of the challenges faced in today's large-scale grid photovoltaic (PV) power system.

Solar  PV  systems  are  designed  to  disconnect,  and remain offline  for  5  mints  when  tripped  by  loss  of  grid  voltage. However, The  PV  system,  by  itself,  cannot  differentiate between   transient   and   sustained   grid   voltage   loss.   It behaves   in   the   same   manner   in   the   two   cases,   i.e., disconnect, stay offline for five minutes and then makes re-connection    trial.    Staying    offline    for fiveminutes unnecessarily  wastes  considerable  amount  of  clean  energy from the PV, may affect the power balance of the grid and many other adverse effects of service discontinuity.

This paper presents a new control strategy for grid FRT capability of a large grid connected PV System  to increase the stability and reliability of the PV system, in which a photovoltaic inverter can be controlled to pass transient faults. Our strategy is to control the inverter  so  that  it  disconnects  from  the  grid  when  the  current exceeds  a  specific  value  for  a  specific  time  otherwise,  it  still connected and ride-through the faults to ensure continuous output power under transient fault conditions. A case study of a 100 KW PV  power  system  simulated  to  ensure  the  proposed  control.  The results show the ability of the proposed control method to manage various types of grid faults. A case study of a 100 KW PV power system simulated to ensure the proposed control. The results show the  ability  of  the  proposed  control  method  to  manage  various types of grid faults.