电力电子组网系统中构网型换流器间的协同限流研究

Cooperative Current Limiting Control between Grid Forming Converters in Power Electronic Equipment System

新能源快速发展下带来的100%电力电子设备组网独立运行的场景逐渐增多,由于缺乏传统同步发电机的惯性和阻尼,当基于不同控制类型的构网型换流器为系统提供电压和频率支撑时,其对外部干扰较敏感,负荷大扰动情况下,系统存在明显的过流问题。针对该问题,首先对单端构网型换流器设计了一种基于电流饱和算法的过电流抑制方法,以限制端口换流器的暂态过电流。其次,在多端口换流器协同限流方面,提出了一种基于不同控制类型的构网型换流器间协同限流控制方法,解决了不同构网型换流器组网时由于扰动造成的输出过电流问题,并实现限流控制与正常工作模式间的平滑切换。同时,建立系统的小信号模型,利用根轨迹分析主要控制参数对系统稳定性的影响。最后,搭建了控制器级硬件在环测试平台,对理论分析和所提方法进行了硬件在环测试,验证了所提方法的有效性和优越性。

With the rapid development of new energy,the scenarios of 100%power electronic equipment networking and independent operation are gradually increasing.Due to the lack of inertia and damping of traditional synchronous generator,they are sensitive to external interference when the grid forming converters based on different control types provide voltage and frequency support for the system.Under the condition of large load disturbance,the system has obvious overcurrent problems.To solve this problem,firstly,we devised an overcurrent suppression method based on Current Saturation Algorithm for single grid forming converter to limit its transient overcurrent.Secondly,we proposed a cooperative current limiting control method based on different control types for multi-port converters,which solved the problem of excessive output current caused by disturbance when networking composed of grid forming converters and realized the smooth switching between current limiting control and normal working mode.At the same time,we built a small signal model of the system and used the root locus to analyze the influence of the main control parameters on the system stability.Finally,we built a controller-level-hardware-in-the-loop test platform and performed hardware-in-the-loop tests on the theoretical analysis and the proposed method to verify the effectiveness and superiority of the proposed method.