Photovoltaic power system and control method thereof

A method for controlling a photovoltaic power system, the method comprising:

• performing a maximum power point tracking (MPPT) control on n DC/DC converter circuits in the photovoltaic power system that comprises a plurality of photovoltaic strings, a controller, a direct current-to-alternating current (DC/AC) inverter circuit, and N DC/DC converter circuits located at a previous stage of the DC/AC inverter circuit, wherein each DC/DC converter circuit is connected to at least one of the plurality of photovoltaic strings, wherein N is a positive integer greater than or equal to 2, wherein the DC/AC inverter circuit is connected to the N DC/DC converter circuits and the controller, and wherein the photovoltaic power system is connected to a power grid through an output end of the DC/AC inverter circuit;
• performing summation and averaging operations on maximum output active-power parameters of the n DC/DC converter circuits to obtain a maximum output active-power average value;
• using the maximum output active-power average value as a first control parameter;
• and
• controlling, based on the first control parameter and an active-power reserve parameter, N−n DC/DC converter circuits to operate in a constant power generation (CPG) mode, wherein n is a positive integer greater than or equal to 1 and less than or equal to N−1.

A controller, comprising:

• a processor;
• and
• a memory coupled to the processor and storing instructions, which when executed by the processor, cause the processor to perform operations of controlling a photovoltaic power system, wherein the photovoltaic power system comprises a plurality of photovoltaic strings, a controller, a direct current-to-alternating current (DC/AC) inverter circuit, and N DC/DC converter circuits located at a previous stage of the DC/AC inverter circuit, wherein each DC/DC converter circuit is connected to at least one of the plurality of photovoltaic strings, wherein N is a positive integer greater than or equal to 2, wherein the DC/AC inverter circuit is connected to the N DC/DC converter circuits and the controller, and wherein the photovoltaic power system is connected to a power grid through an output end of the DC/AC inverter circuit, the operations comprising:
• performing a maximum power point tracking (MPPT) control on n DC/DC converter circuits;
• performing summation and averaging operations on maximum output active-power parameters of the n DC/DC converter circuits to obtain a maximum output active-power average value;
• using the maximum output active-power average value as a first control parameter;
• and
• controlling, based on the first control parameter and an active-power reserve parameter, N−n DC/DC converter circuits to operate in a constant power generation (CPG) mode, wherein n is a positive integer greater than or equal to 1 and less than or equal to N−1.