In this work, Distributed Energy Resources (DER) (like large scale Photovoltaic (PV) and Battery Energy Storage (BES)) are used with the cells of Modular multilevel Converter (MMC). However, integrating DER with the cells of MMC causes power unbalance issue within the converter. The power unbalanced due to PV system can happen from different rated PVs, dust layer, partial shading, etc. At the same time power unbalance in MMC with batteries can happen due to different rated battery, different State of Charge (SoC), etc. The power unbalance in the MMC results in an increase in circulating current (CC) leading to additional loss and over current issue. This paper investigates a novel control technique, solving the power unbalance issue without using circulating current. The novel control technique comprises of (i) independent arm control technique and (ii) the zero-sequence voltage (ZSV) injection technique. The independent arm control technique is used to solve the power mismatch between arms of same leg, thereby reducing the fundamental frequency AC circulating current. Whereas the zero-sequence voltage (ZSV) injection technique to solve the power unbalance between different legs. Furthermore, the overmodulation caused due to ZSV injection is counter with BES. Hence, a wider range of power unbalance can be solved without CC. A MATLAB-simulation model and scaled down experimental laboratory prototype is used to verify the power balancing method.
Operation of Modular Multilevel Converter with Distributed Energy Resources during Unbalanced Power Generation
31.07.2024
2078793 byte
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
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