This is often a dream of neglect, fitting in, or seeking to act with benevolent power in the world. Much of the meaning to be derived from this sort of dream depends on how you locate yourself within the orphan scenario of the dream.
If you find yourself working in an orphanage, seeking to adopt a child from an orphanage, or just visiting an orphanage, you may be seeing yourself as an agent of justice in the world-this is worthy of consideration. You may be trying to fight against injustice, or trying to compensate for acts of unfairness you have committed in your waking life.
If you appear as a child in an orphanage, the connectivity of your waking relationships is worth examining. Do you have a sense of belonging and rootedness in the world or a sense of trying to find your place?