基于直流环流注入的MMC储能系统相间功率均衡控制策略

发布时间：2018-07-18 10:12

【摘要】：在网压不平衡工况下,模块化多电平储能系统(modular multilevel converter energy storage system,MMCESS)如果以并网电流平衡为控制目标,虽然可以保证交流系统安全运行,但是会引起各相放电速度不同,导致子模块储能电池荷电状态(state of charge,SOC)的不均衡。为解决上述问题,首先对比分析了传统MMC和MMC-ESS的内部环流特性;然后分析了以并网电流平衡为目标的不平衡网压控制对电池SOC的影响;针对这一问题,提出了利用注入直流环流的控制策略,有效地实现了相间功率均衡,并论述了直流环流控制器参数对系统稳定性的影响;以各相电压跌落度为变量,绘制各相注入的直流环流占额定桥臂电流比例的三维图,针对不同跌落度分析了各相桥臂电流的变化,为设备器件选型提供了依据;最后,通过仿真和实验验证了理论分析的正确性及控制策略的可行性。
[Abstract]:Under the condition of unbalanced grid voltage, if the modularized multilevel energy storage system (modular multilevel converter energy storage system is controlled by grid-connected current balance, it can ensure the safe operation of AC system, but it will cause different discharge speed of each phase. This results in the imbalance of (state of charge SOC in the charge state of the sub-module storage battery. In order to solve the above problems, the internal circulation characteristics of traditional MMC and MMC-ESS are compared and analyzed, and then the influence of unbalanced grid voltage control aiming at grid-connected current balance on the SOC of the battery is analyzed. The control strategy of injecting DC circulation is put forward to realize the power equalization between phases effectively, and the influence of DC circulation controller parameters on the stability of the system is discussed. The three dimensional graph of DC current ratio of each phase injection to rated bridge arm current is drawn. The variation of current of each phase bridge arm is analyzed according to different drop degrees, which provides the basis for device selection. The correctness of the theoretical analysis and the feasibility of the control strategy are verified by simulation and experiments.
【作者单位】：国家能源主动配电网技术研发中心(北京交通大学);北京电动车辆协同创新中心(北京交通大学);
【基金】：国家能源应用技术研究及工程示范项目(NY20150301)~~
【分类号】：TM46

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