PHOTOVOLTAIC BASED MODULAR MULTILEVEL CONVERTER FOR BATTERY ENERGY STORAGE SYSTEM

This paper proposes another arrangement and it's control procedures for the photovoltaic Based Modular Multilevel Converter battery energy storage system. The existing system had various disadvantages such as when the application requires more voltage than 2.7 volts that a single cell can provide the floating capacitors are stacked in a series of 2 and more. In order to prevent the leakage current from causing damage to other cells via over voltage it is important to balance each cell. One of the other problems faced by the existing system is that it cannot be used in AC & high frequency circuits. In order to solves these problems a new system is proposed where every PV module is connected from it's DC to various PV generators utilizing DAB (DC-DC converter). A BES framework installed into every converter (from the arm part) which is attached to the DC of the battery energy storage sub module using more than one Dual Active Bridge converter. It will help in smoothing the power output. It will also help to limit the power given to the grid. This paper also proposes the elimination of the mismatch of the power by exchanging the power in between the converter and the inner flow of modular multilevel converter. By eliminating the power mismatch and using current that is differential to reduce mismatch of power and to transfer the power among the legs and the arms of the converter .This power smoothing using the battery energy storage system and elimination technique is demonstrated in the paper. Our proposed system uses semiconductors that can be switched on and off autonomously, the converter can supply reactive power, it can operate with a delay and advance power factor and it can be used in isolated systems. We can further see from our simulation that a more smooth output has been obtained.