Electrical and Electronic Engineering, Renewable Energy, Sustainability and the Environment, Control and Systems Engineering, Artificial Intelligence
5
Scopus Publications
Scopus Publications
Dynamic phase shift-controlled SST-MLI for grid-connected battery storage Krishna Molli, A. Hemachander, P. Ajay D. Vimal Raj International Journal of Ambient Energy, 2026 Energy storage systems are vital for maintaining the balance between power consumption and generation in renewable energy-based microgrids. Recently, modular multilevel inverters (MLIs) have become increasingly prominent in medium- and high-voltage grid integration applications. This research presents the integration of a large-scale battery energy storage (BES) system into a microgrid using a 25-level solid-state transformer (SST) based on a T-type MLI topology. A novel Dynamic Phase Shift Controller (DPSC) is developed to enhance the performance of the BES system. The DPSC effectively regulates active and reactive power while ensuring the longevity and health of the battery. Simulation results demonstrate that the proposed controller achieves a fast-dynamic response with a settling time of 0.1 s, minimal overshoot (<1.2%), and no undershoot under step power variations. Experimental validation using a 600 VA, 25-level prototype confirms efficiency up to 95.23% during charging and 93.38% during discharging. The dynamic performance of the proposed BES system is evaluated through MATLAB/Simulink simulations under varying load conditions and further validated using a low-power experimental prototype.
SST-Based 25-Level T-Type MLI for Integration of Microgrids Krishna Molli, P. Ajay D Vimal Raj IEEE Journal of Emerging and Selected Topics in Industrial Electronics, 2024 The demand for independent dc sources and switching components is increasing and turned to be the primary challenge with multilevel inverters (MLIs) for integrating renewable energy sources. As a result, the component reduction is crucial in these systems. The introduction of cascaded MLIs based on solid-state transformers (SSTs) has significantly reduced the requirement for dc sources. This article proposes a novel SST-based MLI with a single dc source and two capacitors to generate 25 levels at the output. Two medium-frequency isolation transformers with different rated voltages make up the proposed MLI. A cascaded H-bridge (CHB) connects the primary windings of each transformer, and the secondary windings are connected in series with the load. The proposed SST-based MLI uses a simple nearest level control switching methodology to generate the nearest level. A laboratory prototype was built to assess the proposed SST-based MLI performance. The power loss analysis of the system is also discussed. The proposed SST topology is also compared with other recent topologies of similar type.
Transformer Based 25-Level T-Type MLI for Renewable Energy Integration Krishna Molli, P. Ajay D Vimal Raj, N. P. Subramaniam IEEE Journal of Emerging and Selected Topics in Industrial Electronics, 2022 The primary challenge with cascaded H-bridge multilevel inverters (MLI) is the need of a large number of switching components and distinct dc-sources for integration of renewable energy to medium voltage grid. As a result, in these types of systems, component minimization is crucial. With the advent of transformer cascaded multilevel inverters (TCMIs), multiple dc sources in cascaded H-Bridge (CHBs) are no longer required for operation. According to the findings of this research, a novel transformer cascaded MLI with 25 levels and 12 switches can be implemented using a single dc source. The proposed MLI is comprised of two different rated isolated transformers. The proposed MLI topology offers the structural advantage of fewer semiconductor components, provides self-galvanic isolation, and generates uniform voltage levels for all turn's ratio. Furthermore, the MLI employs a switching mechanism known as nearest level control, which reduces device power loss and, hence, enhances the systems overall efficiency. To assess the performance of the proposed TCMLI, a laboratory prototype was built and simulations in the MATLAB/Simulink environment were run. In addition, a study of the systems power loss analysis has been presented. A comparison of the proposed topology to other recent topologies of a similar nature is also provided.
Stabilized Power Management in the Microgrid Using Unified Delta Controller Journal of Electrical Systems, 2021
