# US 12,113,356 B2 · Photovoltaic power generation system and method for controlling power balance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,113,356 B2 - Document ID: US12113356B2 - Status: Granted - Kind: B2 - Application number: 17/703,742 - Filed: 2022-03-24 - Published: 2022-11-24 - Granted: 2024-10-08 - Earliest claimed: 2021-05-24 - Assignees: Sungrow Power Supply Co., Ltd. - Applicants: Sungrow Power Supply Co., Ltd. - Inventors: Jiacai Zhuang; Wei Liu; Jun Xu - Web page: https://patentgrep.com/patent/US12113356B2 ## CPC - H02J 1/106: {for load balancing, symmetrisation, or sharing} - H02J 3/381: {Dispersed generators} - H02J 1/12: Parallel operation of DC sources having power converters with further DC sources without power converters - H02S 40/30: Electrical components - H02J 2101/24: Photovoltaics - Y02E 10/56: Power conversion systems, e.g. maximum power point trackers - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - H02S: GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES (obtaining electrical energy from radioactive sources G21H1/12; light sensitive inorganic semiconductor devices H10F; light sensitive organic semiconductor devices H10K30/00; thermoelectric devices H10N10/00; pyroelectric devices H10N15/00) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A photovoltaic power generation system and a method for controlling power balance are provided. The system includes at least two photovoltaic arrays, at least one power balance circuit and a power converter. Each of input ports of the power balance circuit is connected with at least one photovoltaic array, and an output port of the power balance circuit is connected with the power converter. The power balance circuit performs power transfer based on a difference between output powers of the two photovoltaic arrays to control a difference between powers of two output terminals of the power balance circuit to be within a preset range. ## Claims ### Claim 1 A photovoltaic power generation system, comprising at least two photovoltaic arrays, at least one power balance circuit, and a power converter, wherein each of the photovoltaic arrays comprises at least two photovoltaic strings connected in parallel; each of two input ports of the power balance circuit is connected to at least one photovoltaic array, wherein the two input ports of the power balance circuit are connected to different photovoltaic arrays; an output port of the power balance circuit is connected to the power converter; the power balance circuit is configured to, in response to determining that a mismatching degree of the photovoltaic arrays respectively connected to the two input ports exceeds an allowable range, perform power transfer based on a difference between output powers of the photovoltaic arrays connected to the power balance circuit to control a difference between powers of two output terminals of the power balance circuit to be within a preset range. ### Claim 2 (depends on 1) The photovoltaic power generation system according to claim 1, wherein a neutral point of the power balance circuit is grounded via an impedance circuit. ### Claim 3 (depends on 2) The photovoltaic power generation system according to claim 2, wherein the power balance circuit further comprises a first switching circuit connected in series with the impedance circuit. ### Claim 4 (depends on 3) The photovoltaic power generation system according to claim 3, wherein a second switching circuit is connected in series between the output port of the power balance circuit and the power converter. ### Claim 5 (depends on 2) The photovoltaic power generation system according to claim 2, wherein a second switching circuit is connected in series between the output port of the power balance circuit and the power converter. ### Claim 6 (depends on 1) The photovoltaic power generation system according to claim 1, wherein each of the input ports of the power balance circuit is connected to at least two photovoltaic arrays connected in parallel; or each of the input ports of the power balance circuit is connected to an output terminal of a DC/DC converter, and an input terminal of the DC/DC converter is connected to at least one photovoltaic array; or each of the input ports of the power balance circuit is connected to at least two DC/DC converters of which output terminals are connected in parallel, and an input terminal of each of the DC/DC converters is connected to at least one photovoltaic array. ### Claim 7 (depends on 1) The photovoltaic power generation system according to claim 1, wherein the photovoltaic power generation system comprises two or more power balance circuits; and input ports of the power balance circuits are connected to different photovoltaic arrays, and output ports of the power balance circuits are connected in parallel. ### Claim 8 (depends on 1) The photovoltaic power generation system according to claim 1, wherein, a first input port of the power balance circuit comprises a first input terminal and a second input terminal, a second input port of the power balance circuit comprises a third input terminal and a fourth input terminal, and the output port of the power balance circuit comprises a first output terminal and a second output terminal, and the first input terminal is connected to the first output terminal, and the fourth input terminal is connected to the second output terminal; a series switching branch is connected between the first output terminal and the second output terminal, and the series switching branch comprises at least two control switches; the second input terminal and the third input terminal are connected, and then are connected to a common point of the two control switches in the series switch branch via an inductive impedance; and a common point of the second input terminal and the third input terminal serves as the neutral point of the power balance circuit. ### Claim 9 (depends on 1) The photovoltaic power generation system according to claim 1, wherein, a first input port of the power balance circuit comprises a first input terminal and a second input terminal, a second input port of the power balance circuit comprises a third input terminal and a fourth input terminal, and the output port of the power balance circuit comprises a first output terminal and a second output terminal, and in a case that the power balance circuit comprises a DC/DC converter, the second input terminal and the third input terminal are respectively connected to two input terminals of the DC/DC converter, a positive output terminal of the DC/DC converter is connected to the first output terminal of the power balance circuit, the first input terminal is connected to the first output terminal, the fourth input terminal is connected to the second output terminal, and the positive input terminal of the DC/DC converter serves as the neutral point of the power balance circuit; or the second input terminal and the third input terminal are respectively connected to two input terminals of the DC/DC converter, a positive output terminal of the DC/DC converter is connected to the second output terminal of the power balance circuit, the first input terminal is connected to the first output terminal, the fourth input terminal is connected to the second output terminal; and a negative output terminal of the DC/DC converter serves as the neutral point of the power balance circuit. ### Claim 10 A method for controlling power balance, comprising: detecting a mismatching degree of photovoltaic arrays respectively connected to two input ports of a power balance circuit; and in response to determining that the mismatching degree exceeds an allowable range, activating the power balance circuit and controlling the power balance circuit to perform power transfer based on a difference between output powers to control a difference between powers of two output terminals of the power balance circuit to be within a preset range. ### Claim 11 (depends on 10) The method according to claim 10, wherein a neutral point of the power balance circuit is grounded via an impedance circuit and a first switching circuit that are connected in series, and the method further comprises: maintaining a first switching circuit in a closed state before closing a second switching circuit; and controlling the first switching circuit to be opened after closing the second switching circuit.