This study deals with a new control strategy for flying capacitor (FC) based multilevel converter, in order to attain the desired reference value for five-level output voltage in active neutral point clamped (ANPC) converter. The balancing of capacitor voltages is one of the crucial aspects of grid-tied photovoltaic (PV) fed ANPC converter. The accurate reference voltage for FC is required to experience minimum power pulsation and capacitor voltage imbalance. An offset injection-based FC voltage regulator is implemented to track the desired voltage reference for FC. A simple proportional–integral controller generates the offset signal, which is added to the sinusoidal modulating wave to eliminate the FC imbalance. Moreover, neutral point voltage (NPV) balancing is achieved with the help of DC component injection control. The DC–AC power transfer, FC balance, NPV balance and unity power factor operation are achieved simultaneously. The performance of the closed-loop controller for grid-tied PV-fed ANPC converter is analysed at constant and variable irradiances. The system is modelled in MATLAB/Simulink for offline simulation. Furthermore, offline simulation results are validated using real-time controller hardware in loop (HIL) test bench. Moreover, active power is injected into the AC grid seamlessly and results are found compliant with the IEEE 519 standard.

中文翻译：

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实时HIL中PV阵列馈电有源中性点钳位转换器的飞跨电容器电压平衡和中性点电压调节

这项研究针对基于飞电容（FC）的多电平转换器提出了一种新的控制策略，以便在有源中性点钳位（ANPC）转换器中获得五电平输出电压的理想参考值。电容器电压的平衡是并网光伏（PV）供电的ANPC转换器的关键方面之一。要获得最小的功率脉动和电容器电压不平衡，就需要精确的FC参考电压。实现了基于偏移注入的FC电压调节器，以跟踪FC所需的参考电压。一个简单的比例积分控制器生成偏移信号，该信号被添加到正弦调制波中，以消除FC不平衡。此外，借助直流分量注入控制可实现中性点电压（NPV）平衡。DC-AC电力传输，同时实现FC平衡，NPV平衡和单位功率因数操作。分析了并网光伏馈电ANPC转换器的闭环控制器在恒定和可变辐照度下的性能。该系统在MATLAB / Simulink中建模，用于离线仿真。此外，离线仿真结果使用实时控制器硬件在环（HIL）测试台进行了验证。此外，有功功率可以无缝地注入交流电网，其结果符合IEEE 519标准。离线仿真结果使用实时控制器硬件在环（HIL）测试平台进行验证。此外，有功功率可以无缝地注入交流电网，其结果符合IEEE 519标准。离线仿真结果使用实时控制器硬件在环（HIL）测试平台进行验证。此外，有功功率可以无缝地注入交流电网，其结果符合IEEE 519标准。