fit <-auto.arima(diff(vv), d =1, D =0, max.p = 2, max.q = 1,max.P = 1, max.Q = 1,
       stationary = TRUE, ic ="aic",stepwise=FALSE,trace=FALSE,
       test = c("kpss", "adf", "pp"),seasonal.test = c("ocsb", "ch"))