高压直挂电池储能系统(battery energy storage system,BESS)采用H桥电路串联的方法升高电压后接入电网,将电池簇分散接入级联 H 桥变换器的直流侧,具有高度模块化的结构,对比低压方案具有单机容量大、效率高、响应速度快等明显优势.高压直挂BESS若能兼具无功补偿能力,实现系统四象限运行,将具有更大的成本优势和经济效益.电池簇接单相 H 桥变换器的结构,使得系统运行在高比例无功补偿工况时,电池簇电流在一个二倍基频的周期中会出现两次反向,导致电池运行在高频充放电的工况,这会对电池寿命和电池状态监测造成较大的影响.为解决这一问题,提出一种基于零序电压注入的高比例无功补偿控制方法,避免了二倍基频脉动电流对电池进行高频充放电,再通过优化零序电压的幅值和相位,最大程度上降低对电池的影响.
Four Quadrants Operation Control of High-voltage Transformerless Large-capacity System Integrating Battery Energy Storage and Reactive Power Compensation
The high-voltage transformer-less battery energy storage system(BESS)adopts the concept of cascading H-bridge circuits to connect the high voltage power grid.A large number of battery cells are separated equally into numerous clusters at the DC side of H-bridge submodules,and a high degree of modularity features the BESS.Compared with the low-voltage solution,it has obvious advantages such as larger capacity of single-machine,higher efficiency,and faster response speed.If the high-voltage transformer-less BESS also has reactive power compensation capabilities and can realize the four-quadrant operation of the system,greater cost advantages and economic benefits will be obtained.When the system operates at a high proportion of reactive power compensation,the structure of the battery cluster connected to the single-phase H-bridge converter results in that the battery current will reverse in a cycle of twice the fundamental frequency.The battery is charged and discharged with high frequency,which will have a great impact on battery life and battery status monitoring.To solve this problem,this paper proposes a high-proportion reactive power compensation control based on zero-sequence voltage injection and the charged and discharged current with twice the fundamental frequency is removed.Besides,the amplitude and phase of the zero-sequence voltage are optimized to minimize the impact on the battery.
high-voltage transformer-lessbattery energyreactive power compensationzero-sequence voltagepower factorfour quadrants
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