from tkinter import *
import _thread, time

def liigu():
  global x, y, d
  while y<200:
   y=y+1
   ala.coords(ovaal, x, y, x+d, y+d)
   time.sleep(0.1)

aken=Tk()
ala=Canvas(aken, width=400, height=300, bg='white')
ala.pack()

x=10
y=100
d=15

ovaal=ala.create_oval(x, y, x+d, y+d, fill="blue")
_thread.start_new_thread(liigu, ())

aken.mainloop()