Paper Certificate Frequency Variations of Power System Due to Switching of Renewable Energy Sources

Abstract

Power  systems  mainly  containing  intermittently  operating   renewable   sources   require   load/frequency   control   which  is  performed  at  the  AC  transmission  and  distribution  levels.  This  frequency  control  can  be  achieved  by  employing  short-  and  long-term  storage  plants  buffering  and  complemen-ting  renewable  energy  sources.    A  representative  grid  consists  of  a  natural-gas-fired  plant  serving  as  frequency  leader,  long-term storage plant, wind-power farm with associated short-term storage  plant  for  energy  buffering,  photovoltaic  farm  with  associated  short-term  storage  plant  interconnected  by  a  long  transmission  line  to  two  load  circuits.    Transient  analysis  is  performed  with  Mathematica  solving  the  differential  equation  system   for   frequency   variation.   Power   flow   through   the   transmission  line  is  limited  by  its  impedance.  The  long  trans-mission  line  must  be  segmented  to  achieve  stability  and  the  voltage must be controlled between segments of an 800km line. The   renewable   plants   must   be   operated   together   with   the   storage  plants  in  order  to  minimize  frequency  variations  by  smoothing  the  power  output  of  renewable  plants,  achieving  a  step-wise control of the transmission-line power.