High order IIR Comb Notch Filter with small Bandwidth - Low atenuation of harmonics
An order-200 IIR filter? You're playing with fire you know that? High-order IIR filter are prone to instability and/or misleading behavior even if they are stable.

If I understand correctly, you designed a 50-Hz notch filter, then a 100-Hz notch filter and so on?

Do you really need to filter out every harmonic? Do you know how high your harmonics are?

Solution #1 : Why not filter only the fundamental and the other major harmonics.  Usually even harmonics are not a problem and typically harmonics higher than 11 or 15 are small enough that you can simply ignore them. This would change your filter from an order 200 to a more manageable order 12 IIR filter.

Solution # 2 : Instead you could use a 200-tap moving-average that would allow you to extract the 50-Hz component and its harmonics. You could subtract the output of the moving-average from your signal and you would get rid of the 50-Hz component and its harmonics as long as they don't change too fast.