MMC结构的分布式光伏系统功率不平衡优化方案

Power Imbalance Optimization Scheme of Distributed PV System With MMC Structure

模块化多电平变换器(modular multilevel converter,MMC)由于其模块化结构,已成为大规模光伏(photovoltaic,PV)并网逆变器的研究热点。然而,在不同光照强度和温度下,PV组件之间发电功率不同,导致MMC内部出现桥臂、相间功率不均衡。因此,该文先分析MMC-PV系统在功率不均衡下的表现机理,后提出一种基于MMC结构的光储电能路由,其控制策略在满足交、直流端口功率需求的同时,实现桥臂间和相间的功率自均衡,提高PV利用率和系统稳定性。同时,受桥臂内子模块功率传输极限的影响,对PV和ESS的配置约束作详细分析,最后,通过仿真以及实验验证所提拓扑及控制策略的正确性和有效性。

The modular multilevel converter(MMC)has become the research hotspot of large-scale grid-connected photovoltaic(PV)inverter because of its modular structure.However,under different light intensity and temperature,the power generation between PV modules is different,leading to the imbalance of power between bridge arm and phase in MMC.Therefore,this paper first analyzes the performance mechanism of MMC-PV system under power imbalance,and then proposes an optical energy storage routing based on MMC structure.Its control strategy not only satisfies the power requirement of AC and DC ports,but also realizes power self-balancing between bridge arms and phases,which improves PV utilization rate and system stability.At the same time,the configuration constraints of PV and ESS are analyzed in detail due to the influence of power transmission limit of submodules in the bridge arm.Finally,the correctness and effectiveness of the proposed topology and control strategy are verified by simulation and experiments.