The reason why {HEAD ~ the maximum supply power} is different between {TAIL ~ summer} and winter is that a periodic test for the power stations is carried out in winter with less power demand in preparation for summer with more power demand 
is different between
The reason why { HEAD ~ the maximum supply power } is different between { TAIL ~ summer } and winter is that a periodic test for the power stations is carried out in winter with less power demand in preparation for summer with more power demand
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH