Balasubramanian Indu Rani

Bio: Balasubramanian Indu Rani is an academic researcher from National Institute of Technology, Tiruchirappalli. The author has contributed to research in topics: Power module & Power optimizer. The author has an hindex of 1, co-authored 1 publications receiving 95 citations.

Control Strategy for Power Flow Management in a PV System Supplying DC Loads

Abstract: The growing concern for energy saving has increased the usage of LED-based street lights, electronic chokes, compact fluorescent lamps, and inverter-fed drives. Hence, the load profile seen by the electrical grid is undergoing a notable change as these devices have to operate from a dc source. Photovoltaics (PV) being a major energy source, the aforementioned loads can be connected directly to the dc bus. A grid-connected PV system involves a power source (PV array), a power sink (load), and two power sources/sink (utility and battery), and hence, a power flow management system is required to balance the power flow among these sources. One such system is developed for selecting the operating mode of the bidirectional converter by sensing the battery voltage. The viability of the scheme has been ascertained by performing experimental studies on a laboratory prototype. The control strategy is digitally implemented on an Altera Cyclone II Field Programmable Gate Array (FPGA) board, and the algorithm is verified for different modes of operation by varying the load. Experimental results are presented to bring out the usefulness of the control strategy.

Energy management strategies in hybrid renewable energy systems: A review

Abstract: Variability and intermittency are some of the main features that characterize renewable energy sources. Intermittency usually includes both predictable and unpredictable variations. The many drawbacks of intermittency of renewable sources can be overcome by considering some special design considerations. Integrating more than one renewable energy source and including backup sources and storage systems are among the few measures to overcome these drawbacks. These additional design considerations usually increase the overall cost of the renewable system. Furthermore, the presence of more than one energy supply/storage system requires the control of energy flow among the various sources. Therefore, optimizing the size of the components and adopting an energy management strategy (EMS) are essential to decreasing the cost of the system and limiting its negative effects. The energy management strategy is commonly integrated with optimization to ensure the continuity of load supply and to decrease the cost of energy production. Therefore, energy management is a term that collects all the systematic procedures to control and minimize the quantity and the cost of energy used to provide a certain application with its requirements. The energy management strategy usually depends on the type of energy system and its components. Various approaches and techniques have been used to develop a successful energy management strategy. In this paper, a comprehensive review of the approaches proposed and used by authors of many papers is conducted. These approaches include both the standalone hybrid renewable energy systems and the grid-connected hybrid renewable systems. More attention is focused on popularly used techniques to address the features of each system. The selected papers in this review cover the various configurations of the hybrid renewable energy systems for electric power generation only.

Microgrid supervisory controllers and energy management systems: A literature review

Abstract: Microgrids (MGs), featured by distributed energy resources, consumption and storage, are designed to significantly enhance the self-sustainability of future electric distribution grids. In order to adapt to this new and revolutionary paradigm, it is necessary to control MGs in intelligent and coordinated fashion. To this aim, a new generation of advanced Microgrid Supervisory Controllers (MGSC) and Energy Management Systems (EMS) has emerged. The aim of this paper is to summarize the control objectives and development methodologies in the recently proposed MGSC/EMS. At first, a classification of control objectives is made according to the definition of hierarchical control layers in MGs. Then, focusing on MGSC/EMS related studies, a detailed methodology review is given with emphasis on representative applications and research works. Finally, the conclusions are summarized and the proposals of future research directions in this area are given.

An Energy-Stored Quasi-Z-Source Inverter for Application to Photovoltaic Power System

Abstract: The quasi-Z-source inverter (qZSI) with battery operation can balance the stochastic fluctuations of photovoltaic (PV) power injected to the grid/load, but its existing topology has a power limitation due to the wide range of discontinuous conduction mode during battery discharge. This paper proposes a new topology of the energy-stored qZSI to overcome this disadvantage. The operating characteristic of the proposed solution is analyzed in detail and compared to that of the existing topology. Two strategies are proposed with the related design principles to control the new energy-stored qZSI when applied to the PV power system. They can control the inverter output power, track the PV panel's maximum power point, and manage the battery power, simultaneously. The voltage boost and inversion, and energy storage are integrated in a single-stage inverter. An experimental prototype is built to test the proposed circuit and the two discussed control methods. The obtained results verify the theoretical analysis and prove the effectiveness of the proposed control of the inverter's input and output powers and battery power regardless of the charging or discharging situation. A real PV panel is used in the grid-tie test of the proposed energy-stored qZSI, which demonstrates three operational modes suitable for application in the PV power system.

Dynamic Energy Management of Renewable Grid Integrated Hybrid Energy Storage System

Abstract: In this paper, a unified energy management scheme is proposed for renewable grid integrated systems with battery–supercapacitor hybrid storage. The intermittent nature of renewable-energy resources (RES), coupled with the unpredictable changes in the load, demands high-power and high-energy-density storage systems to coexist in today's microgrid environment. The proposed scheme dynamically changes the modes of renewable integrated systems based on the availability of RES power and changes in load as well. The participation of battery–supercapacitor storage to handle sudden/average changes in power surges results in fast dc link voltage regulation, effective energy management, and reduced current stress on battery. In addition, the proposed energy management scheme enables the real power transfer along with ancillary services such as current harmonic mitigation, reactive power support, and power factor improvement at the point of common coupling. The proposed scheme is validated through both simulation and experimental studies.

A Power Management Strategy for PV/Battery Hybrid Systems in Islanded Microgrids

Abstract: In this paper, a power management strategy for PV/battery hybrid systems in islanded microgrids is proposed. The control strategy enables the photovoltaic (PV)/battery unit to operate as a voltage source that employs an adaptive droop control to share the load with other sources while charging the battery. Also, the PV/battery unit can track and supply the maximum PV power to the microgrid as long as there is sufficient load. Otherwise, the hybrid unit will autonomously follow the changing load while storing the excess energy in the battery. The control strategy is designed to modify the PV operating point to match the load autonomously whenever the available PV power is higher than the load and the battery is fully charged. In addition, the battery can provide the operational functions that a separate storage unit may provide in an islanded microgrid, such as regulating voltage and frequency, and supplying deficit power in the microgrid. This is achieved by utilizing multi-loop control and multi-segment adaptive droop control without relying on communications or a state machine. Small-signal models of the proposed control loops are developed to investigate system stability. The system performance is validated using experimental results from a 3-KVA prototype microgrid.