A power supply system for an alternating current, AC, load, comprising: a DC/AC converter (12, 22, 32, 42), an AC side of that being coupled to an AC grid and the AC load through an AC bus; and a power supply device (11, 21, 31A, 31B, 41) coupled to a DC side of the DC/AC converter through a DC bus (13, 23, 33, 43) and configured to output DC electric energy to the DC bus; wherein the power supply device comprises: an energy storage circuit (111, 211, 311, 411) comprising a first energy storage circuitry (1111,2111,3111,4111) and a second energy storage circuitry (1112, 2112, 3112, 4112); and a controller (112, 212, 312, 412) configured to control a conversion operation of the first energy storage circuitry to output a low-frequency component in an output power of the energy storage circuit, and configured to control a conversion operation of the second energy storage circuitry to output a high-frequency component in the output power of the energy storage circuit; wherein the controller (112, 212, 312, 412) comprises: a calculation circuit, configured to calculate the output power of the energy storage circuit; a power extraction circuit, coupled to the calculation circuit and configured to extract the low-frequency component in the output power of the energy storage circuit; a current source control circuit, coupled to the power extraction circuit and configured to adjust an output power of the first energy storage circuitry according to the low-frequency component; characterized in that the calculation circuit is configured to calculate the output power of the energy storage circuit according to a voltage signal of the DC bus and a current signal of the energy storage circuit; and in that the controller (112, 212, 312, 412) further comprises: a voltage source control circuit, configured to adjust an output voltage of the second energy storage circuitry according to a voltage reference value of the DC bus, causing the second energy storage circuitry to output the high-frequency component. a DC/AC converter (12, 22, 32, 42), an AC side of that being coupled to an AC grid and the AC load through an AC bus; and a power supply device (11, 21, 31A, 31B, 41) coupled to a DC side of the DC/AC converter through a DC bus (13, 23, 33, 43) and configured to output DC electric energy to the DC bus; wherein the power supply device comprises: an energy storage circuit (111, 211, 311, 411) comprising a first energy storage circuitry (1111,2111,3111,4111) and a second energy storage circuitry (1112, 2112, 3112, 4112); and a controller (112, 212, 312, 412) configured to control a conversion operation of the first energy storage circuitry to output a low-frequency component in an output power of the energy storage circuit, and configured to control a conversion operation of the second energy storage circuitry to output a high-frequency component in the output power of the energy storage circuit; an energy storage circuit (111, 211, 311, 411) comprising a first energy storage circuitry (1111,2111,3111,4111) and a second energy storage circuitry (1112, 2112, 3112, 4112); and a controller (112, 212, 312, 412) configured to control a conversion operation of the first energy storage circuitry to output a low-frequency component in an output power of the energy storage circuit, and configured to control a conversion operation of the second energy storage circuitry to output a high-frequency component in the output power of the energy storage circuit; wherein the controller (112, 212, 312, 412) comprises: a calculation circuit, configured to calculate the output power of the energy storage circuit; a power extraction circuit, coupled to the calculation circuit and configured to extract the low-frequency component in the output power of the energy storage circuit; a current source control circuit, coupled to the power extraction circuit and configured to adjust an output power of the first energy storage circuitry according to the low-frequency component; a calculation circuit, configured to calculate the output power of the energy storage circuit; a power extraction circuit, coupled to the calculation circuit and configured to extract the low-frequency component in the output power of the energy storage circuit; a current source control circuit, coupled to the power extraction circuit and configured to adjust an output power of the first energy storage circuitry according to the low-frequency component; characterized in that the calculation circuit is configured to calculate the output power of the energy storage circuit according to a voltage signal of the DC bus and a current signal of the energy storage circuit; and in that the controller (112, 212, 312, 412) further comprises: a voltage source control circuit, configured to adjust an output voltage of the second energy storage circuitry according to a voltage reference value of the DC bus, causing the second energy storage circuitry to output the high-frequency component.