WO2021232691A1 - High-voltage photovoltaic power generation system - Google Patents

High-voltage photovoltaic power generation system Download PDF

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WO2021232691A1
WO2021232691A1 PCT/CN2020/126256 CN2020126256W WO2021232691A1 WO 2021232691 A1 WO2021232691 A1 WO 2021232691A1 CN 2020126256 W CN2020126256 W CN 2020126256W WO 2021232691 A1 WO2021232691 A1 WO 2021232691A1
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photovoltaic
voltage
electrical isolation
module
power generation
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PCT/CN2020/126256
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French (fr)
Chinese (zh)
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彭文博
郑建涛
李晓磊
高虎
刘大为
田鸿翔
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中国华能集团有限公司
中国华能集团清洁能源技术研究院有限公司
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Publication of WO2021232691A1 publication Critical patent/WO2021232691A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S10/00—PV power plants; Combinations of PV energy systems with other systems for the generation of electric power
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/66—Regulating electric power
    • G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/34—Electrical components comprising specially adapted electrical connection means to be structurally associated with the PV module, e.g. junction boxes
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

Definitions

  • the invention belongs to the technical field of photovoltaic power generation, and specifically relates to a high-voltage photovoltaic power generation system.
  • Increasing the DC voltage level of the photovoltaic system can help reduce line losses and reduce system costs.
  • Conventional photovoltaic systems can obtain a larger DC voltage level by connecting components in series, such as 1000V or 1500V DC voltage, but while obtaining 1000V DC voltage and 1500V DC voltage, the photovoltaic modules in the string are required to have 1000V or 1500V insulation resistance. Pressure level. As there are currently no photovoltaic modules with a withstand voltage above 1500V and no relevant technical standards, this restricts the development of photovoltaic systems to higher DC voltage levels.
  • the purpose of the present invention is to provide a high-voltage photovoltaic power generation system, which can achieve a higher DC voltage level without increasing the withstand voltage level of photovoltaic modules, and at the same time avoid the series connection caused by long strings. Mismatch risk improves the efficiency of the photovoltaic system while significantly reducing system costs.
  • the invention discloses a high-voltage photovoltaic power generation system.
  • Several photovoltaic modules are connected in series to form a photovoltaic sub-string, each photovoltaic sub-string is connected with an electrical isolation controller, and all the electrical isolation controllers are connected in series with a photovoltaic inverter;
  • the electrical isolation controller includes a maximum power point tracking module and an electrical isolation module, and the maximum power point tracking module is connected to the electrical isolation module.
  • the number of photovoltaic modules in the photovoltaic sub-string x 1 ⁇ x ⁇ [V/V oct ], where [] is the rounding symbol, V is the DC voltage level of the photovoltaic module, and V oct is the local limit of the photovoltaic module Maximum open circuit voltage at low temperature.
  • the number of electrical isolation controllers y 2 ⁇ y ⁇ [V/V oct ], where [] is the rounding symbol, V is the DC voltage level of the photovoltaic module, and V oct is the photovoltaic module’s local extreme low temperature Maximum open circuit voltage.
  • the ground voltage of any photovoltaic component in the photovoltaic sub-string is not higher than the input voltage of the electrical isolation controller connected to it.
  • the maximum power point tracking module is an MTTP controller.
  • the electrical isolation module is an isolation circuit.
  • the present invention has the following beneficial technical effects:
  • the invention discloses a high-voltage photovoltaic power generation system.
  • the photovoltaic modules are not directly connected in series to form a string, but a plurality of photovoltaic modules are connected in series to form a photovoltaic sub-string, and each photovoltaic sub-string is connected with a maximum power tracking and
  • the electrical isolation controller with electrical isolation function the electrical isolation controller is then connected in series to form a photovoltaic string with a higher voltage, and the photovoltaic string is then connected to the inverter for grid-connected power generation.
  • the input side and output side of the electrical isolation controller are decoupled to ground potential, that is, the accumulation of ground potential on the output side of the electrical isolation controller due to the mutual series connection does not affect the ground potential of any substring on the input side of the electrical isolation controller.
  • the maximum power point tracking module can track the maximum power point of the input photovoltaic sub-string to ensure the maximum output of the photovoltaic module and eliminate the series mismatch between the self-strings.
  • the electrical isolation module can realize the ground potential of the output side and the input side. At the same time, the accumulation of voltage to ground on the output side will not raise the voltage to ground on the input side.
  • the invention can achieve a higher DC voltage level without increasing the withstand voltage level of the photovoltaic module, and at the same time avoids the risk of series mismatch caused by long strings, improves the efficiency of the photovoltaic system and significantly reduces the system cost. Application prospects.
  • the number of photovoltaic modules in the photovoltaic sub-string depends on that the sum of the open circuit voltages under extreme low temperature conditions is not higher than the maximum input voltage on the DC side of the inverter. Therefore, as the DC side voltage increases, the number of photovoltaic modules in the photovoltaic string will increase in response, and at the same time, the open circuit voltage of the modules will increase as the ambient temperature decreases.
  • the number of electrical isolation controllers can be one for one module or one for a photovoltaic sub-string composed of multiple photovoltaic modules, depending on whether the voltage of any photovoltaic sub-string is not higher than the photovoltaic module Withstand voltage level, while considering cost factors.
  • Fig. 1 is a schematic diagram of the structure of a photovoltaic system according to embodiment 1 of the present invention
  • Figure 2 is a schematic structural diagram of a photovoltaic system according to Embodiment 2 of the present invention.
  • Figure 3 is a schematic diagram of the structural principle of the electrical isolation controller of the present invention.
  • 1 is a photovoltaic module
  • 2 is an electrical isolation controller
  • 21 is a maximum power point tracking module
  • 22 is an electrical isolation module
  • 3 is a photovoltaic inverter.
  • a number of photovoltaic modules 1 are connected in series to form a photovoltaic sub-string, and the number of photovoltaic modules 1 in the photovoltaic sub-string x: 1 ⁇ x ⁇ [V/V oct ], where [] is a rounding symbol , Directly take the integer part.
  • V is the DC voltage level of photovoltaic module 1
  • V oct is the maximum open circuit voltage of photovoltaic module 1 at the local extreme low temperature.
  • Each photovoltaic sub-string is connected to an electrical isolation controller 2.
  • the ground voltage of any photovoltaic component 1 in the photovoltaic sub-string is not higher than the input voltage of the electrical isolation controller 2 connected to it; all electrical isolation controllers 2 Connected to photovoltaic inverter 3 after series connection, the number of electrical isolation controller 2 y: 2 ⁇ y ⁇ [V/V oct ], where V is the DC voltage level of photovoltaic module 1, and V oct is the local limit of photovoltaic module 1. Maximum open circuit voltage at low temperature.
  • the electrical isolation controller 2 includes a maximum power point tracking module 21 and an electrical isolation module 22, and the maximum power point tracking module 21 is connected to the electrical isolation module 22.
  • the output positive and negative poles of the photovoltaic module 1 are connected to the positive and negative poles of the input side of the electrical isolation controller 2.
  • the electrical isolation controller 2 includes two major functional modules: DC/DC, that is, a maximum power point tracking module (MPPT) 21 function module and an electrical isolation module 22.
  • MPPT maximum power point tracking module
  • the maximum power point tracking module 21 optimizes the maximum power output point of the connected photovoltaic module 1 through DC/DC conversion, and then optimizes the output to the electrical isolation module 22.
  • the electrical isolation module 22 realizes voltage isolation between the output and the input side, that is, the positive and negative potentials of the input side and the output side are related, but the ground potentials of the electrodes on the input side and the output side are independent of each other. Therefore, the decoupling of the ground potential at the output end of the photovoltaic module 1 and the total voltage of the photovoltaic string is achieved.
  • the internal electric energy flow can be from the input side to the maximum power point tracking module 21 to the electrical isolation module 22 and then to the output side, or from the input side to the electrical isolation module 22 to the maximum power point tracking module 21 and then to the output side.
  • the maximum power point tracking module 21 may adopt an MTTP controller.
  • the electrical isolation module 22 may adopt an isolation circuit.
  • each photovoltaic module 1 is individually connected to an electrical isolation controller 2.
  • the electrical isolation controllers 2 are connected in series to form a high voltage, which is input to the DC side of the photovoltaic inverter 3.
  • the electrical isolation controller 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. Take an example of the voltage isolation capability of input test and output test. For example, the maximum output voltage of each photovoltaic module 1 is 40V, and the maximum output voltage is 45V after being tracked by the electrical isolation controller 2MPPT.
  • a photovoltaic sub-string contains 50 photovoltaic modules 1, and each photovoltaic module 1 is first connected to an electrical isolation controller 2, a total of 50 electrical isolation controllers 2.
  • the negative input side of the second electrical isolation controller 2 (the negative output side of photovoltaic module 1) has a ground voltage of 0V
  • the positive input side (the positive output side of photovoltaic module 1) has a maximum voltage to ground. It is 40V.
  • the maximum voltage between the negative pole and ground of the nth electrical isolation controller 2 is (n-1)*45V
  • the maximum voltage between the positive pole and ground is n*45V.
  • the negative input side of the first electrical isolation controller 2 (the negative output side of photovoltaic module 1) has a voltage of 0V to ground, and the maximum voltage of the positive input side (the positive output side of photovoltaic module 1) to ground is 0V. It is 40V. Therefore, under this system architecture, no matter how many electrical isolation controllers 2 are connected in series, the voltage to ground on the input side of each electrical isolation controller 2 will not accumulate. Therefore, a higher string DC voltage can be achieved while maintaining a lower DC voltage. Low voltage withstand requirements of the photovoltaic module 1.
  • the electrical isolation controller 2 since the electrical isolation controller 2 has an independent maximum power point tracking function, no matter how many photovoltaic modules 1 are included in the string, the current mismatch between the photovoltaic modules 1 will also be eliminated by the electrical isolation controller 2 to avoid long strings The series mismatch problem.
  • the electrical isolation controller 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. Take an example of the voltage isolation capability of input test and output test.
  • the maximum output voltage of each photovoltaic module 1 is 40V
  • 20 photovoltaic modules 1 are connected in series to form a photovoltaic sub-string with a maximum output voltage of 800V, after being tracked by the electrical isolation controller 2MPPT
  • the output voltage is 900V.
  • a total of 3*20 photovoltaic modules 1 are connected to 3 electrical isolation controllers 2 respectively, and three electrical isolation controllers 2 are connected in series to form a string with a voltage of 2700V.
  • the voltage of the first electrical isolation controller 2 from the negative pole to ground on the negative output side is 0V, and the maximum voltage on the positive output side to ground is 900V.
  • the negative input side of the first electrical isolation controller 2 (the negative output side of the photovoltaic sub-string) has a voltage of 0V to ground, and the positive input side (the positive output side of the photovoltaic sub-string) is to ground
  • the maximum voltage is 800V, and the maximum withstand voltage requirement of any photovoltaic module 1 in this photovoltaic sub-string does not exceed 800V.
  • the maximum voltage of the second electrical isolation controller 2 to ground is 900V, and the maximum voltage of the anode to ground is 1800V.
  • the negative input side of the second electrical isolation controller 2 (the negative output side of the photovoltaic sub-string) has a voltage of 0V to ground, and the positive input side (the positive output side of the photovoltaic sub-string) is to the ground
  • the voltage is 800V, and the maximum withstand voltage requirement of any photovoltaic module 1 in this photovoltaic sub-string does not exceed 800V.
  • the withstand voltage level of the photovoltaic module 1 connected under each electrical isolation controller 2 does not exceed the maximum output voltage of a single photovoltaic module 1 * the number of series, and maintain a low withstand voltage requirement of the photovoltaic module 1.
  • the electrical isolation controller 2 since the electrical isolation controller 2 has an independent maximum power point tracking function, no matter how many photovoltaic modules 1 are included in the string, the current mismatch between the photovoltaic modules 1 will also be eliminated by the electrical isolation controller 2 to avoid long strings The series mismatch problem.

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Abstract

Disclosed is a high-voltage photovoltaic power generation system, belonging to the technical field of photovoltaic power generation. A plurality of photovoltaic assemblies are connected in series to form photovoltaic subgroup strings, each photovoltaic subgroup string is connected to an electrical isolation controller, and all the electrical isolation controllers are connected in series and are then connected to a photovoltaic inverter; and the electrical isolation controller comprises a maximum power point tracking module and an electrical isolation module, and the maximum power point tracking module is connected to the electrical isolation module. According to the present invention, a higher direct-current voltage level can be realized under the condition that the voltage-withstand level of a photovoltaic assembly is not improved, and at the same time, the series mismatching risk caused by long strings is avoided, the system cost is remarkably reduced, while the efficiency of the photovoltaic system is improved, and a good use prospect is achieved.

Description

一种高压光伏发电系统A high-voltage photovoltaic power generation system 技术领域Technical field
本发明属于光伏发电技术领域，具体涉及一种高压光伏发电系统。The invention belongs to the technical field of photovoltaic power generation, and specifically relates to a high-voltage photovoltaic power generation system.
背景技术Background technique
提高光伏系统直流电压等级有助于减少线损和降低系统成本。常规光伏系统通过组件串联能够获得较大的直流电压等级，如1000V或1500V直流电压，但是在获得1000V直流电压和1500V直流电压的同时，要求组串中的光伏组件同时具有1000V或1500V的绝缘耐压水平。由于目前没有1500V以上耐压等级光伏组件，也没有相关技术标准，因此限制了光伏系统往更高直流电压等级发展。Increasing the DC voltage level of the photovoltaic system can help reduce line losses and reduce system costs. Conventional photovoltaic systems can obtain a larger DC voltage level by connecting components in series, such as 1000V or 1500V DC voltage, but while obtaining 1000V DC voltage and 1500V DC voltage, the photovoltaic modules in the string are required to have 1000V or 1500V insulation resistance. Pressure level. As there are currently no photovoltaic modules with a withstand voltage above 1500V and no relevant technical standards, this restricts the development of photovoltaic systems to higher DC voltage levels.
同时，在光伏组件耐压等级达到高压要求的情况下，获得更好的直流母线电压意味着需要更多光伏组件串联，而更多的串联意味着更大的串联失配几率，如此则不利于系统电量的提高。At the same time, when the PV module withstand voltage level meets the high voltage requirements, obtaining a better DC bus voltage means that more PV modules need to be connected in series, and more series connection means a greater chance of series mismatch, which is not conducive to Increase of system power.
发明内容Summary of the invention
为了解决上述现有问题，本发明的目的在于提供一种高压光伏发电系统，在不提高光伏组件耐压等级的条件下实现了更高的直流电压等级，同时避免了长组串带来的串联失配风险，提升光伏系统效率的同时显著降低系统成本。In order to solve the above existing problems, the purpose of the present invention is to provide a high-voltage photovoltaic power generation system, which can achieve a higher DC voltage level without increasing the withstand voltage level of photovoltaic modules, and at the same time avoid the series connection caused by long strings. Mismatch risk improves the efficiency of the photovoltaic system while significantly reducing system costs.
本发明通过以下技术方案来实现：The present invention is realized through the following technical solutions:
本发明公开了一种高压光伏发电系统，若干光伏组件串联组成光伏子组串，每个光伏子组串连接有一个电气隔离控制器，所有电气隔离控制器串联后与光伏逆变器连接；The invention discloses a high-voltage photovoltaic power generation system. Several photovoltaic modules are connected in series to form a photovoltaic sub-string, each photovoltaic sub-string is connected with an electrical isolation controller, and all the electrical isolation controllers are connected in series with a photovoltaic inverter;
电气隔离控制器包括最大功率点追踪模块和电气隔离模块，最大功率点追踪模块与电气隔离模块连接。The electrical isolation controller includes a maximum power point tracking module and an electrical isolation module, and the maximum power point tracking module is connected to the electrical isolation module.
优选地，光伏子组串内光伏组件的数量x：1≤x≤[V/V oct]，其中[]为取 整符号，V为光伏组件的直流电压等级，V oct为光伏组件在当地极限低温下的最大开路电压。 Preferably, the number of photovoltaic modules in the photovoltaic sub-string x: 1≤x≤[V/V oct ], where [] is the rounding symbol, V is the DC voltage level of the photovoltaic module, and V oct is the local limit of the photovoltaic module Maximum open circuit voltage at low temperature.
优选地，电气隔离控制器的数量y：2≤y≤[V/V oct]，其中[]为取整符号，V为光伏组件的直流电压等级，V oct为光伏组件在当地极限低温下的最大开路电压。 Preferably, the number of electrical isolation controllers y: 2≤y≤[V/V oct ], where [] is the rounding symbol, V is the DC voltage level of the photovoltaic module, and V oct is the photovoltaic module’s local extreme low temperature Maximum open circuit voltage.
优选地，光伏子组串内任一光伏组件的对地电压不高于与其连接的电气隔离控制器的输入电压。Preferably, the ground voltage of any photovoltaic component in the photovoltaic sub-string is not higher than the input voltage of the electrical isolation controller connected to it.
优选地，最大功率点追踪模块为MTTP控制器。Preferably, the maximum power point tracking module is an MTTP controller.
优选地，电气隔离模块为隔离电路。Preferably, the electrical isolation module is an isolation circuit.
与现有技术相比，本发明具有以下有益的技术效果：Compared with the prior art, the present invention has the following beneficial technical effects:
本发明公开的一种高压光伏发电系统，光伏组件不直接串联形成组串，而是由若干个光伏组件先串联形成光伏子组串，每一光伏子组串接入一个带有最大功率跟踪和电气隔离功能的电气隔离控制器，电气隔离控制器再串联形成更高电压的光伏组串，该光伏组串再接入逆变器进行并网发电。电气隔离控制器输入侧与输出侧对地电势解耦，即电气隔离控制器输出侧由于相互串联所增加的对地电势累积不影响任一电气隔离控制器输入侧的子组串对地电势。最大功率点追踪模块能够对输入的光伏子组串进行最大功率点跟踪，保证光伏组件最大出力，并消除自组串间的串联失配，电气隔离模块能够实现输出侧和输入侧对地电位上的解耦，同时输出侧对地电压的累积不会抬高输入侧的对地电压。本发明可在不提高光伏组件耐压等级的条件下实现更高的直流电压等级，同时避免了长组串带来的串联失配风险，提升光伏系统效率的同时显著降低系统成本，具有良好的应用前景。The invention discloses a high-voltage photovoltaic power generation system. The photovoltaic modules are not directly connected in series to form a string, but a plurality of photovoltaic modules are connected in series to form a photovoltaic sub-string, and each photovoltaic sub-string is connected with a maximum power tracking and The electrical isolation controller with electrical isolation function, the electrical isolation controller is then connected in series to form a photovoltaic string with a higher voltage, and the photovoltaic string is then connected to the inverter for grid-connected power generation. The input side and output side of the electrical isolation controller are decoupled to ground potential, that is, the accumulation of ground potential on the output side of the electrical isolation controller due to the mutual series connection does not affect the ground potential of any substring on the input side of the electrical isolation controller. The maximum power point tracking module can track the maximum power point of the input photovoltaic sub-string to ensure the maximum output of the photovoltaic module and eliminate the series mismatch between the self-strings. The electrical isolation module can realize the ground potential of the output side and the input side. At the same time, the accumulation of voltage to ground on the output side will not raise the voltage to ground on the input side. The invention can achieve a higher DC voltage level without increasing the withstand voltage level of the photovoltaic module, and at the same time avoids the risk of series mismatch caused by long strings, improves the efficiency of the photovoltaic system and significantly reduces the system cost. Application prospects.
进一步地，光伏子组串内光伏组件的数量，取决于其在极端低温情况下开路电压之和不高于逆变器直流侧最大输入电压。因此随着直流侧电压的增加，光伏组串内的光伏组件数量会响应增加，同时，组件开路电压随环境温度降低 而升高。Further, the number of photovoltaic modules in the photovoltaic sub-string depends on that the sum of the open circuit voltages under extreme low temperature conditions is not higher than the maximum input voltage on the DC side of the inverter. Therefore, as the DC side voltage increases, the number of photovoltaic modules in the photovoltaic string will increase in response, and at the same time, the open circuit voltage of the modules will increase as the ambient temperature decreases.
进一步地，电气隔离控制器的数量，电气隔离控制器的数量既可以一块组件一个，也可以多个光伏组件组成的光伏子组串一个，取决于任一光伏子组串电压不高于光伏组件耐压等级，同时考虑成本因素。Further, the number of electrical isolation controllers, the number of electrical isolation controllers can be one for one module or one for a photovoltaic sub-string composed of multiple photovoltaic modules, depending on whether the voltage of any photovoltaic sub-string is not higher than the photovoltaic module Withstand voltage level, while considering cost factors.
附图说明Description of the drawings
图1为本发明实施例1的光伏系统的结构示意图；Fig. 1 is a schematic diagram of the structure of a photovoltaic system according to embodiment 1 of the present invention;
图2为本发明实施例2的光伏系统的结构示意图；Figure 2 is a schematic structural diagram of a photovoltaic system according to Embodiment 2 of the present invention;
图3为本发明电气隔离控制器的结构原理示意图。Figure 3 is a schematic diagram of the structural principle of the electrical isolation controller of the present invention.
图中：1为光伏组件，2为电气隔离控制器，21为最大功率点追踪模块，22为电气隔离模块，3为光伏逆变器。In the figure: 1 is a photovoltaic module, 2 is an electrical isolation controller, 21 is a maximum power point tracking module, 22 is an electrical isolation module, and 3 is a photovoltaic inverter.
具体实施方式Detailed ways
下面结合附图和具体实施例对本发明做进一步详细描述，其内容是对本发明的解释而不是限定：The following describes the present invention in further detail with reference to the accompanying drawings and specific embodiments, the content of which is to explain rather than limit the present invention:
本发明的高压光伏发电系统，若干光伏组件1串联组成光伏子组串，光伏子组串内光伏组件1的数量x：1≤x≤[V/V oct]，其中，[]为取整符号，直接取整数部分。V为光伏组件1的直流电压等级，V oct为光伏组件1在当地极限低温下的最大开路电压。每个光伏子组串连接有一个电气隔离控制器2，光伏子组串内任一光伏组件1的对地电压不高于与其连接的电气隔离控制器2的输入电压；所有电气隔离控制器2串联后与光伏逆变器3连接，电气隔离控制器2的数量y：2≤y≤[V/V oct]，其中V为光伏组件1的直流电压等级，V oct为光伏组件1在当地极限低温下的最大开路电压。 In the high-voltage photovoltaic power generation system of the present invention, a number of photovoltaic modules 1 are connected in series to form a photovoltaic sub-string, and the number of photovoltaic modules 1 in the photovoltaic sub-string x: 1≤x≤[V/V oct ], where [] is a rounding symbol , Directly take the integer part. V is the DC voltage level of photovoltaic module 1, and V oct is the maximum open circuit voltage of photovoltaic module 1 at the local extreme low temperature. Each photovoltaic sub-string is connected to an electrical isolation controller 2. The ground voltage of any photovoltaic component 1 in the photovoltaic sub-string is not higher than the input voltage of the electrical isolation controller 2 connected to it; all electrical isolation controllers 2 Connected to photovoltaic inverter 3 after series connection, the number of electrical isolation controller 2 y: 2≤y≤[V/V oct ], where V is the DC voltage level of photovoltaic module 1, and V oct is the local limit of photovoltaic module 1. Maximum open circuit voltage at low temperature.
如图3，电气隔离控制器2包括最大功率点追踪模块21和电气隔离模块22，最大功率点追踪模块21与电气隔离模块连接22。光伏组件1输出正负极接入电气隔离控制器2的输入侧正负极。电气隔离控制器2包含DC/DC即最大功率点追踪模块(MPPT)21功能模块和电气隔离模块22两大功能模块。首先最大功 率点追踪模块21通过DC/DC变换对接入的光伏组件1最大功率输出点进行寻优，寻优输出至电气隔离模块22。电气隔离模块22实现输出和输入侧的电压隔离，即输入侧和输出侧的正负极电势差相关，但是输入侧和输出侧的电极的对地电势相互独立。因此实现了光伏组件1输出端对地电势与光伏组串总电压解耦。其内部的电能流向，可以是输入侧到最大功率点追踪模块21到电气隔离模块22再到输出侧，也可以是输入侧到电气隔离模块22到最大功率点追踪模块21再到输出侧。最大功率点追踪模块21可以采用MTTP控制器。电气隔离模块22可以采用隔离电路。As shown in FIG. 3, the electrical isolation controller 2 includes a maximum power point tracking module 21 and an electrical isolation module 22, and the maximum power point tracking module 21 is connected to the electrical isolation module 22. The output positive and negative poles of the photovoltaic module 1 are connected to the positive and negative poles of the input side of the electrical isolation controller 2. The electrical isolation controller 2 includes two major functional modules: DC/DC, that is, a maximum power point tracking module (MPPT) 21 function module and an electrical isolation module 22. First, the maximum power point tracking module 21 optimizes the maximum power output point of the connected photovoltaic module 1 through DC/DC conversion, and then optimizes the output to the electrical isolation module 22. The electrical isolation module 22 realizes voltage isolation between the output and the input side, that is, the positive and negative potentials of the input side and the output side are related, but the ground potentials of the electrodes on the input side and the output side are independent of each other. Therefore, the decoupling of the ground potential at the output end of the photovoltaic module 1 and the total voltage of the photovoltaic string is achieved. The internal electric energy flow can be from the input side to the maximum power point tracking module 21 to the electrical isolation module 22 and then to the output side, or from the input side to the electrical isolation module 22 to the maximum power point tracking module 21 and then to the output side. The maximum power point tracking module 21 may adopt an MTTP controller. The electrical isolation module 22 may adopt an isolation circuit.
实施例1Example 1
如图1，每一光伏组件1单独连接一台电气隔离控制器2。电气隔离控制器2间相互串联形成高电压，输入光伏逆变器3直流侧。该电气隔离控制器2具备最大功率点跟踪功能和输入侧与输出侧电压隔离能力。举例说明输入测和输出测的电压隔离能力，如每一光伏组件1的最大输出电压为40V，经电气隔离控制器2MPPT跟踪后最大输出电压为45V。一个光伏子组串中包含50个光伏组件1，每一光伏组件1均先接入一台电气隔离控制器2，共50台电气隔离控制器2。50台电气隔离控制器2串联后总电压提升至2250V。假设组串负极接地，则从负极起第一台电气隔离控制器2负极输出侧对地电压为0V，正极输出侧对地最大电压为45V。同时由于输出侧与输入侧电气隔离，第一台电气隔离控制器2负极输入侧(光伏组件1负极输出侧)对地电压为0V，正极输入侧(光伏组件1正极输出侧)最大对地电压为40V，第二台电气隔离控制器2负极对地最大电压为40V，因此正极最大对地电压为90V。同时由于输出侧与输入侧电气隔离，第二台电气隔离控制器2负极输入侧(光伏组件1负极输出侧)对地电压为0V，正极输入侧(光伏组件1正极输出侧)对地最大电压为40V。以此类推第n台电气隔离控制器2负极对地最大电压为(n-1)*45V，正极最大对地为n*45V。同时由于输出侧与输入侧电气隔离，第一台电气隔离控制器2负极 输入侧(光伏组件1负极输出侧)对地电压为0V，正极输入侧(光伏组件1正极输出侧)对地最大电压为40V。因此在这种系统架构下，无论串联多少电气隔离控制器2，每一电气隔离控制器2输入侧的对地电压是不会累积的，因此可实现较高组串直流电压的同时，保持较低的光伏组件1的耐压要求。同时由于电气隔离控制器2均具有独立的最大功率点跟踪功能，因此无论组串中包含多少光伏组件1，光伏组件1间的电流失配也将被电气隔离控制器2消除，避免长组串的串联失配问题。As shown in Figure 1, each photovoltaic module 1 is individually connected to an electrical isolation controller 2. The electrical isolation controllers 2 are connected in series to form a high voltage, which is input to the DC side of the photovoltaic inverter 3. The electrical isolation controller 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. Take an example of the voltage isolation capability of input test and output test. For example, the maximum output voltage of each photovoltaic module 1 is 40V, and the maximum output voltage is 45V after being tracked by the electrical isolation controller 2MPPT. A photovoltaic sub-string contains 50 photovoltaic modules 1, and each photovoltaic module 1 is first connected to an electrical isolation controller 2, a total of 50 electrical isolation controllers 2. After 50 electrical isolation controllers 2 are connected in series, the total voltage Increase to 2250V. Assuming that the negative pole of the string is grounded, the voltage of the first electrical isolation controller 2 from the negative pole to the ground on the negative output side is 0V, and the maximum voltage on the positive output side to ground is 45V. At the same time, since the output side is electrically isolated from the input side, the negative input side of the first electrical isolation controller 2 (the negative output side of photovoltaic module 1) has a voltage to ground of 0V, and the positive input side (the positive output side of photovoltaic module 1) has a maximum voltage to ground. The maximum voltage of the second electrical isolation controller 2 to ground is 40V, so the maximum voltage of the anode to ground is 90V. At the same time, because the output side is electrically isolated from the input side, the negative input side of the second electrical isolation controller 2 (the negative output side of photovoltaic module 1) has a ground voltage of 0V, and the positive input side (the positive output side of photovoltaic module 1) has a maximum voltage to ground. It is 40V. By analogy, the maximum voltage between the negative pole and ground of the nth electrical isolation controller 2 is (n-1)*45V, and the maximum voltage between the positive pole and ground is n*45V. At the same time, since the output side is electrically isolated from the input side, the negative input side of the first electrical isolation controller 2 (the negative output side of photovoltaic module 1) has a voltage of 0V to ground, and the maximum voltage of the positive input side (the positive output side of photovoltaic module 1) to ground is 0V. It is 40V. Therefore, under this system architecture, no matter how many electrical isolation controllers 2 are connected in series, the voltage to ground on the input side of each electrical isolation controller 2 will not accumulate. Therefore, a higher string DC voltage can be achieved while maintaining a lower DC voltage. Low voltage withstand requirements of the photovoltaic module 1. At the same time, since the electrical isolation controller 2 has an independent maximum power point tracking function, no matter how many photovoltaic modules 1 are included in the string, the current mismatch between the photovoltaic modules 1 will also be eliminated by the electrical isolation controller 2 to avoid long strings The series mismatch problem.
实施例2Example 2
如图2，若干个光伏组件1先串联后接入一台电气隔离控制器2。电气隔离控制器2间再相互串联形成更高电压，输入光伏逆变器3直流侧。该电气隔离控制器2具备最大功率点跟踪功能和输入侧与输出侧电压隔离能力。举例说明输入测和输出测的电压隔离能力，如每一光伏组件1的最大输出电压为40V，20块光伏组件1串联形成最大输出电压800V的光伏子组串，经电气隔离控制器2MPPT跟踪后输出电压为900V。共3*20个光伏组件1，分别接入3台电气隔离控制器2，三台电气隔离控制器2串联形成2700V电压的组串。在这个系统中，假设组串负极接地，则从负极起第一台电气隔离控制器2负极输出侧对地电压为0V，正极输出侧对地最大电压为900V。同时由于输出侧与输入侧电气隔离，第一台电气隔离控制器2负极输入侧(光伏子组串负极输出侧)对地电压为0V，正极输入侧(光伏子组串正极输出侧)对地最大电压为800V，在这个光伏子组串内任一光伏组件1的最大耐压要求都不超过800V。第二台电气隔离控制器2负极最大对地电压为900V，正极最大对地电压为1800V。同时由于输出侧与输入侧电气隔离，第二台电气隔离控制器2负极输入侧(光伏子组串负极输出侧)对地电压为0V，正极输入侧(光伏子组串正极输出侧)对地电压为800V，在这个光伏子组串内任一光伏组件1的最大耐压要求都不超过800V。以此类推，在这种系统架构下，无论串联多少电气隔离控制器2，每一 电气隔离控制器2输入侧的对地电压是不会累积的，因此可实现较高组串直流电压的同时，在每一电气隔离控制器2下接入的光伏组件1的耐压等级均不超过单一光伏组件1最大输出电压*串联数，保持较低的光伏组件1的耐压要求。同时由于电气隔离控制器2均具有独立的最大功率点跟踪功能，因此无论组串中包含多少光伏组件1，光伏组件1间的电流失配也将被电气隔离控制器2消除，避免长组串的串联失配问题。As shown in Figure 2, several photovoltaic modules 1 are connected in series and then connected to an electrical isolation controller 2. The electrical isolation controllers 2 are connected in series with each other to form a higher voltage, which is input to the DC side of the photovoltaic inverter 3. The electrical isolation controller 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. Take an example of the voltage isolation capability of input test and output test. For example, the maximum output voltage of each photovoltaic module 1 is 40V, and 20 photovoltaic modules 1 are connected in series to form a photovoltaic sub-string with a maximum output voltage of 800V, after being tracked by the electrical isolation controller 2MPPT The output voltage is 900V. A total of 3*20 photovoltaic modules 1 are connected to 3 electrical isolation controllers 2 respectively, and three electrical isolation controllers 2 are connected in series to form a string with a voltage of 2700V. In this system, assuming that the negative pole of the string is grounded, the voltage of the first electrical isolation controller 2 from the negative pole to ground on the negative output side is 0V, and the maximum voltage on the positive output side to ground is 900V. At the same time, because the output side is electrically isolated from the input side, the negative input side of the first electrical isolation controller 2 (the negative output side of the photovoltaic sub-string) has a voltage of 0V to ground, and the positive input side (the positive output side of the photovoltaic sub-string) is to ground The maximum voltage is 800V, and the maximum withstand voltage requirement of any photovoltaic module 1 in this photovoltaic sub-string does not exceed 800V. The maximum voltage of the second electrical isolation controller 2 to ground is 900V, and the maximum voltage of the anode to ground is 1800V. At the same time, because the output side is electrically isolated from the input side, the negative input side of the second electrical isolation controller 2 (the negative output side of the photovoltaic sub-string) has a voltage of 0V to ground, and the positive input side (the positive output side of the photovoltaic sub-string) is to the ground The voltage is 800V, and the maximum withstand voltage requirement of any photovoltaic module 1 in this photovoltaic sub-string does not exceed 800V. By analogy, in this system architecture, no matter how many electrical isolation controllers 2 are connected in series, the ground voltage on the input side of each electrical isolation controller 2 will not accumulate, so it can achieve higher string DC voltage at the same time. , The withstand voltage level of the photovoltaic module 1 connected under each electrical isolation controller 2 does not exceed the maximum output voltage of a single photovoltaic module 1 * the number of series, and maintain a low withstand voltage requirement of the photovoltaic module 1. At the same time, since the electrical isolation controller 2 has an independent maximum power point tracking function, no matter how many photovoltaic modules 1 are included in the string, the current mismatch between the photovoltaic modules 1 will also be eliminated by the electrical isolation controller 2 to avoid long strings The series mismatch problem.
需要说明的是，以上所述仅为本发明实施方式之一，根据本发明所描述的系统所做的等效变化，均包括在本发明的保护范围内。本发明所属技术领域的技术人员可以对所描述的具体实例做类似的方式替代，只要不偏离本发明的结构或者超越本权利要求书所定义的范围，均属于本发明的保护范围。It should be noted that the above description is only one of the embodiments of the present invention, and equivalent changes made according to the system described in the present invention are all included in the protection scope of the present invention. Those skilled in the art to which the present invention pertains can make similar substitutions to the specific examples described, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, it belongs to the protection scope of the present invention.

Claims (6)

  1. 一种高压光伏发电系统，其特征在于，若干光伏组件(1)串联组成光伏子组串，每个光伏子组串连接有一个电气隔离控制器(2)，所有电气隔离控制器(2)串联后与光伏逆变器(3)连接；A high-voltage photovoltaic power generation system, characterized in that several photovoltaic modules (1) are connected in series to form photovoltaic sub-strings, each photovoltaic sub-string is connected with an electrical isolation controller (2), and all electrical isolation controllers (2) are connected in series Then connect with the photovoltaic inverter (3);
    电气隔离控制器(2)包括最大功率点追踪模块(21)和电气隔离模块(22)，最大功率点追踪模块(21)与电气隔离模块连接(22)。The electrical isolation controller (2) includes a maximum power point tracking module (21) and an electrical isolation module (22), and the maximum power point tracking module (21) is connected to the electrical isolation module (22).
  2. 根据权利要求1所述的高压光伏发电系统，其特征在于，光伏子组串内光伏组件(1)的数量x：1≤x≤[V/V oct]，其中[]为取整符号，V为光伏组件(1)的直流电压等级，V oct为光伏组件(1)在当地极限低温下的最大开路电压。 The high-voltage photovoltaic power generation system according to claim 1, wherein the number of photovoltaic modules (1) in the photovoltaic sub-string x: 1≤x≤[V/V oct ], where [] is a rounding symbol, V Is the DC voltage level of the photovoltaic module (1), and V oct is the maximum open circuit voltage of the photovoltaic module (1) at the local extreme low temperature.
  3. 根据权利要求1所述的高压光伏发电系统，其特征在于，电气隔离控制器(2)的数量y：2≤y≤[V/V oct]，其中[]为取整符号，V为光伏组件(1)的直流电压等级，V oct为光伏组件(1)在当地极限低温下的最大开路电压。 The high-voltage photovoltaic power generation system according to claim 1, wherein the number of electrical isolation controllers (2) y: 2≤y≤[V/V oct ], where [] is a rounding symbol, and V is a photovoltaic module (1) DC voltage level, V oct is the maximum open circuit voltage of the photovoltaic module (1) at the local extreme low temperature.
  4. 根据权利要求1所述的高压光伏发电系统，其特征在于，光伏子组串内任一光伏组件(1)的对地电压不高于与其连接的电气隔离控制器(2)的输入电压。The high-voltage photovoltaic power generation system according to claim 1, wherein the voltage to ground of any photovoltaic component (1) in the photovoltaic sub-string is not higher than the input voltage of the electrical isolation controller (2) connected to it.
  5. 根据权利要求1所述的高压光伏发电系统，其特征在于，最大功率点追踪模块(21)为MTTP控制器。The high-voltage photovoltaic power generation system according to claim 1, wherein the maximum power point tracking module (21) is an MTTP controller.
  6. 根据权利要求1所述的高压光伏发电系统，其特征在于，电气隔离模块(22)为隔离电路。The high-voltage photovoltaic power generation system according to claim 1, wherein the electrical isolation module (22) is an isolation circuit.
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