模块化多电平光储一体化并网逆变器拓扑研究

03Research on Topology of Modular Multilevel Optical Storage Integrated Grid Connected Inverters

目前大规模光伏并网的系统结构较为单一,多为低压直流输出逆变升压至中压交流汇集并网,其结构冗杂、转换环节较多,导致后期运维复杂、运维成本相对较高。对于百兆瓦级大型集中式光伏电站,不论是现有交流汇集还是直流汇集方案,均难以实现电网主动支撑能力。文章采用模块化多电平(MMC)技术路线,构建新型光储一体化大容量换流技术,将分散式接入方案,改为集中式接入方式,大幅降低并网逆变器数量,构建易于实现电网主动支撑功能的新一代并网系统。提出分散式直流接入的光储一体化换流器拓扑结构、光伏阵列、储能装置与光储一体化换流器连接、并网主接线拓扑,形成适用于百兆瓦级光伏电站并网的换流器及系统主回路设计方案。对其中的关键技术进行研究,分析了两种储能分散接入系统耦合方式的MMC拓扑设计方式,为模块化多电平光储一体化逆变器的设计奠定基础。

At present,the system structure of large-scale photovoltaic grid connection is relatively single,mostly consisting of low-voltage DC output inverter boost to medium voltage AC collection grid connection.Its structure is complex and there are many conversion links,resulting in complex later operation and maintenance,and relatively high operation and maintenance costs.For large-scale centralized photovoltaic power plants with a capacity of 100 megawatts,both existing AC and DC collection schemes are difficult to achieve active support capabilities of the power grid.This article adopts the modular multilevel(MMC)technology route to construct a new type of integrated high-capacity converter technology for optical storage.The decentralized access scheme is changed to a centralized access method,significantly reducing the number of grid connected inverters and constructing a new generation of grid connected systems that are easy to achieve active support functions for the power grid.Propose a topology structure,photovoltaic array,connection between energy storage devices and integrated photovoltaic energy storage converters for decentralized DC access,and a grid connected main wiring topology to form a converter and system main circuit design scheme suitable for grid connection of 100 MW level photovoltaic power plants.Research was conducted on the key technologies involved,and two MMC topology design methods for energy storage coupling in decentralized measurement and access systems were analyzed,laying the foundation for the design of modular multi-level optical storage integrated inverters.