System and method for adjusting voltage of power conversion system for primary side adjustment

The invention relates to a system and a method for adjusting voltage of a power conversion system for primary side adjustment. An embodiment system controller comprises a first sampling component, a signal processing component and an error amplifier, the first sampling component samples sensing signals and determines compensating signals at least partially based on the sensing signals, the sensing signals are associated with first current of a primary winding flowing through the power conversion system, the signal processing component receives feedback signals and the compensating signals and generates first signals at least partially based on the feedback signals and the compensating signals, the feedback signals are associated with an auxiliary winding of a secondary winding coupled on the power conversion system, and the error amplifier receives the first signals and reference signals and generates amplifying signals at least partially based on the first signals and the reference signals.