A high-voltage power supply system (1) for powering an electrostatic precipitator, ESP (10) is disclosed. The system has an AC supply circuit (2) configured to generate a first and a second AC supply voltage, and two supply circuits (5, 6) connected between the AC supply circuit and the ESP. One of the supply circuits is a DC supply circuit (5) configured to transform and convert the first AC supply voltage to a DC base voltage for the ESP, while the other is a pulse supply circuit having a pulse forming circuit (12) configured to generate and forward high-voltage pulses to the ESP. The AC supply circuit is configured such that each of the AC supply voltages are in the mid frequency range, i.e. in the range of 100 Hz to 5000 Hz. Hereby, a cost effective, low weight and compact high-voltage power supply system is presented.