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Current controlled operation of cascaded H-bridge converter for fast SoC balancing in grid energy storage

2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019

Hussain, Amir; Raj, Krishna; Rajashekara, Kaushik; Krishnamoorthy, Harish; Atcitty, Stanley A.

In grid energy storage systems based on batteries, the interface converter topology plays a significant role in the optimized operation of the system. Among different types of multi-level converters, cascaded H-bridge converter (CHBC) provides the advantage of utilizing isolated battery pack (BP) with a lower number of series-connected cells and can perform state of charge (SoC) balancing by controlling the power flow to/from each BP. However, the rate of SoC balancing is limited due to low balancing current when the amount of power exchange is low. This paper proposes a new power control method using hybrid modulation strategy with extended operating region (HMSEOR) which enables the CHBC to perform fast SoC balancing at constant current irrespective of the amount of power exchange between the battery system and the grid. The HMSEOR allows power flow from a BP with a higher SoC to a BP with a lower SoC without compromising power exchange with the grid. The performance of the proposed SoC balancing method is validated through real-time hardware-in-the-loop (HIL) simulation and compared with the conventional SoC balancing at unity power factor operation.

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TYPE Conference Poster YEAR 2019
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A Voltage Droop-Based State of Charge Control among Split Batteries in Modular Multilevel Converter for Grid Energy Storage Interface

2019 IEEE Industry Applications Society Annual Meeting, IAS 2019

Hussain, Amir; Raj, Krishna; Rajashekara, Kaushik; Krishnamoorthy, Harish; Atcitty, Stanley A.

In grid energy storage systems based on batteries, the interface converter topology plays a significant role in the optimized operation of the system. Among the different types of transformer-less high-power converters, the split battery type modular multilevel converter (SBMMC) has become a promising technology for interfacing the storage system with a medium voltage grid which can also perform battery management. This paper proposes a droop-based control for state of charge (SoC) balancing among the battery packs in SBMMC for a grid-connected battery energy storage system (BESS). First, steady-state analysis of the SBMMC is performed which forms the basis for SoC balancing scheme. Consequently, the droop-based control is applied to balance SoCs among the arms and submodules (SM) by controlling the reference voltages. For SoC balancing among the three phases of the upper and lower arms, appropriate zero sequence voltage (ZSV) is injected to the respective reference voltages of each arm. The proposed SoC balancing method has been validated through simulation results.

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TYPE Conference Poster YEAR 2019
ScopusOSTI
Results 51–75 of 280
Results 51–75 of 280