You can use VBA for this...

Sub blankrowevery30()
    Dim i      As Long
    Dim LR     As Long
    LR = Range("A" & Rows.Count).End(xlUp).Row
    For i = 31 To LR Step 30
        Rows(i).Insert
    Next i
End Sub
Paste code in a Normal module
  • Where to paste code
  • Highlight macro to copy >> Ctrl + C >> Open your workbook
  • Alt + F11 >> opens the Visual Basic Editor (VBE)
  • Ctrl + R >>opens the Project Explorer (if not already open on left side of screen)
  • Insert menu >> Module or Alt + I, M >> activates the Insert menu and inserts a Standard Module
  • Paste code >> Ctrl + V (right side of screen)
  • Alt + Q >> exits VBE and returns to Excel
  • Back in Excel >> Alt + F8 >> Macro Dialog Box >> Highlight macro >> Run