Major Issues Grid integration on Solar pv plant

Short circuit contribution

• 
  Identification of fault current contribution by the RES to the grid 

  
• 
  To ascertain the fault level at grid connection point and within the Solar PV plant is within the short circuit rating
  
• 
  Rated equipment to be used to withstand the maximum subtransient three phase symmetrical short circuit fault levels
  
• 
  Introduction of the proposed Solar PV plant does not cause the fault levels of Transmission substations should not exceed the short circuit breaker rating
  

Frequency variation and regulation

• 
   The frequency of a power system must be preserved near to its nominal value (either 50 Hz or 60 Hz based on the grid). The frequency deviations will only arise when there is a mismatch between generation and load. A stiff power system preserves the frequency subsequent to a contingency even
  
• 
  The frequency of the power system is maintained at the nominal value only when the active power of generation and demand is balanced
  
• 
  If the demand is more than the generation, then the frequency decreases from the nominal value. In the case of surplus generation, the system frequency increases.
  
• 
  As the penetration level of RES increases, the frequency deviations are more frequent. As these RES are connected to the grid through a power electronic inverter, substituting the conventional SG with power electronic inverters will decrease the inertia of the power system.
  
• 
  To handle the frequency stability issues raised from the low inertia and reserve power, new frequency control techniques need Energies to be employed for RES to participate in a frequency regulation process
  

Harmonics & Flickers

• 
  Injection of harmonics lead over heating of equipment’s and insulation failures for transformer, cables, switchgears etc.
  
• 
  The power quality terms and conditions the solar power plant must meet to be eligible to connect to distribution system are as follows: allowed flickers, allowed harmonics currents, voltage fluctuations due to the simultaneous connection and disconnection of the plant, as well as the voltage variation at steady state.
  
• 
  Photovoltaic power plants contribution to the flicker level in the medium voltage energy network. Connecting them to the energy grid may cause frequency variations or fast voltage variations (flicker), significant problems in terms of power quality
  
• 
  Effects of flicker depending on the appearing frequency, voltage fluctuations can have the following consequences for electricity distribution networks: visible changes in light output of lighting sources, a visual discomfort sensation (flicker effect), TV image distortion and faults in radios and electronic installations operation.
  
• 
  Flicker measurement is performed using a flicker-meter. This instrument measures the voltage fluctuation level and simulates both the response of the light source and the reaction of the human eye.
  

CEA GUIDELINES: The limits of voltage harmonics by the distribution licensee in its electricity system, the limits of injection of current harmonics by bulk consumers, point of harmonic measurement, i.e., point of common coupling, method of harmonic measurement and other related matters, shall be in accordance with the IEEE 519-2014 standards, as amended from time to time & Measuring and metering of harmonics shall be a continuous process with meters complying with provisions of IEC 61000-4-30 Class A.