Meaning of the phrasal verb draw up is to come to a halt and it is used the following way
The train drew up at the station.
He drew up his car outside my house.
But I found a sentence in which it is used as
The train drew up to the station.
I think it is wrong.
Help me understand this.
Actually "drew up to" is the more correct form for this meaning. This usage goes back to the days of horse-drawn carriages, when a carriage would draw up to a specified spot such as a door way or entry way. This use ultimately derives from the way in which a horse would draw the vehicle.
"Draw up at" has an essentially identical meaning.
"Draw up" with neither "to" nor "at" would be unusual. Except in the sense of "draw up a document" or other unrelated senses.
The term draw in a larger sense means simply to move something by pulling on it.
One common sense of the phrase came from pulling on the reins of a horse or team of horses to cause them to stop. Now, "draw up" has expanded to mean bringing any vehicle to a stop.
From its original meaning, also, "draw up" can also convey the sense of pulling something more tightly together, as in "draw up close to me" or "draw up a chair."
The first two sentences you gave are examples of the first meaning, simply to bring a vehicle to a stop ("the train stopped at the station" and "he stopped his car outside my house").
Your third sentence actually invokes the second meaning, evoking the idea that the train was pulled in close to the station (although, in this case, it did also happen to be a vehicle that came to a halt).
Note that it's not even required to come to a stop to "draw up" to something. For example, "I was driving on the highway and a large truck drew up alongside me."
