Battery Energy Storage System Operational Control for Distribution Transformer Overload Management

A distribution transformer is an important asset whose failure causes huge financial loss to a utility and scarcity of power for end consumers. One of the prime causes for failure of Distribution Transformers (DTs) is overloading. A Battery Energy Storage System (BESS) can reduce the stress on a DT by discharging itself during peak demand periods. An effective energy management methodology for BESS at DT level has been presented in this paper. A novel method for battery charging & discharging is proposed based on real-time net power flow measurements from DT and from load-side, considering penetration of rooftop solar Photovoltaic (PV) power at consumer end. BESS will be charged and discharged during off peak and peak demand periods respectively. The designed BESS has a bi-directional converter and solar PV with boost converter that are connected at the DC-link of their respective individual three-phase converters. The control logic for battery charging/discharging is developed in such a way that the power flow from distribution transformer shall not exceed 80 % of its rated capacity. The charging is performed under two modes of operation. Current control mode charging is preferred till battery SoC is 80%. Subsequently, voltage control mode of charging is performed up to 95% SoC level. The modeling and simulation is carried out in MATLAB
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and results are presented to showcase the effectiveness of proposed control logic for different modes of operation. The proposed methodology will be tested and validated on real-time HIL testing platform for pre-pilot implementation validation.