The adverb 一连 emphasizes the repetition of the same events one after another.
一连 is placed either before a verb used as a predicate or before a classifier which indicates a number of repetitions. The classifier can be either a precise number or the pronoun 几 .
It has been raining here for days
zhèlǐ yìlián hǎo jǐ tiān dōu shì yǔtiān
Four or five lots were shipped in a row today
jīntiān yìlián yùndàole sìwǔ pī huò
He went to bed and finally got somegood sleep after three nights of insomnia
tā shàng le chuáng, zài yìlián sān tiān sān yè méi shuìhǎo yǐhòu zhōngyú néng shūshufúfu de shuìshàng yí jiào le