Does the courts decide if you are charged violation of probation or does the probation Dept have the power even if your not charged by the courts

Your Probation officer decides if he or she believes you have violated your probation. They will then present the judge will a order to have your violated and arrested.
Then you will go before the judge to prove your case ( or they prove theirs) Remember a probation violation does not have to be something illegal to be arrested for. It can be hanging out with the wrong people, not paying fines, not taking a class ordered and more