"i have put hashrates to dev pools,but there are a lot of HW,and i think it happens because of changing of N-factor."

If you are not using the yacminer try that. It is very stable and 0 hw for me. I always had problems with the cgminer for this coin.
Just try the config generator, if still having problems give ThirtyBird a pm, he da man!

Here the config link:
http://ultracoin.net/configgen_raw.html