Subir Karmakar

To address grid instability caused by intermittent renewable energy, this work proposes utility‐scale battery energy storage (BES) integration using a hybrid multilevel and multipulse voltage source converter (VSC) topology, which overcomes the limitations of conventional converters in efficiency, scalability and harmonic performance for high‐power, high‐voltage applications. VSC employs 13‐level H‐bridge converters and 30‐pulse high voltage converters to mitigate voltage harmonics. By combining multipulse technique with selective harmonics elimination, low total harmonic distortion is achieved for VSC output voltage and grid currents. Utilising multiple cascaded H‐bridge (CHB) converters and transformers increases VSC power and energy capacity for BES plant to deliver energy at a 400‐kV voltage level to grid. A 1000‐MW VSC with a 6000‐MWh BES plant is simulated in MATLAB and implemented on a real‐time platform to study its steady‐state, harmonics and dynamic performances.

This article presents a 120 MW capacity solar photovoltaic (PV) plant with a battery energy storage (BES). This plant has utilized high-power 72-pulse voltage source converters (VSCs), developed using six multi-winding transformers and twelve three-level neutral-point-clamped (NPC) converters. 72-pulse operation of the VSC is realized by suitably selecting the transformers phase-shifting and NPCs switching phase-displacement angles. The multi-MPPT approach is applied in the VSC to optimize energy generation from the solar PV array. This solar PV plant has utilized DC-coupled BES, which is distributed along with the solar PV array field in the plant area. The excess PV energy is stored in the BES locally and dispatched the same during nighttime when PV array is not generating using the same solar VSC and DC and AC electrical equipments. Thus, it offers a saving on investment cost. Additionally, the VSC is utilized to provide reactive power to the grid. A developed MATLAB model of the solar PV and BES plant is presented along with the OPAL-RT real-time implementation strategy, and steady-state, harmonics and dynamic responses are obtained.

This paper presents a cascaded transformer based multilevel converter (CTMLC) for high capacity battery energy storage (BES) plant. In this CTMC voltage source converter (VSC), each cell is configured with back-to-back connected fundamental switched H-bridges with transformer isolation. A conventional cascaded multilevel converter (MLC) configuration suffers a voltage balancing issue due to unequal energy contribution from different H bridge battery cells. The presented CTMLC and switching modulation strategy significantly minimize the H bridge battery cells voltage balancing issue. Moreover, battery utilization increased, and for the same DC battery capacity, the CTMC has higher power and energy capacity at the plant level as compared to conventional MLC. A 432MW/1728MWh (with four-hour backup) BES plant is modeled in MATLAB-Simulink to demonstrate its steady state, harmonics, and dynamic performance.

In this paper, a fundamental switched area equalization modulation strategy (AEMS) is presented for a multilevel converter (MLC) used in large-scale battery-energy storage (BES) system. In this AEMS, the switching angles are computed online by equalizing the area under the reference voltage signal and carrier signal. In this BES system, the AEMS provides simple and reasonably good voltage harmonics performance for MLC. MATLAB/Simulink model of a 13-level cascaded H-bridge (13-level CHB) with storage is developed and implemented in real-time using OPAL-RT to validate the concept. Various performance results under steady-state and dynamic conditions are obtained and presented in detail.

This article presents a solar photovoltaic plant with dc-coupled battery energy storage (BES) system configured with a high-power 54-pulse voltage source converter (VSC) and distributed maximum power point tracking boost dc–dc converters. Dc-coupled BES allows storing excess solar energy and dispatching the same during nonsolar hours, thus improving VSC utilization and reducing the payback period. The 54-pulse VSC is configured with three sets of identical 18-pulse VSCs, which are developed with two-level converters and a medium voltage (MV) transformer. The MV transformer is configured with series-connected different phase-shifted zigzag and star primary windings and delta secondary windings. The VSC configuration has lower voltage and current harmonics, and reduces switching losses. The 54-pulse VSC is operated with 90–110% of voltage variation to provide 0–100% of nominal reactive power (capacitive and reactive) support to the grid. The solar PV-BES plant is simulated in MATLAB-Simulink and then real-time implementation is done in OPAL-RT to evaluate its steady state, harmonics, and dynamic responses.

The incident solar irradiance on the solar photovoltaic (PV) modules fluctuates due to moving clouds in the sky, resulting in rapid changes in the solar PV plant generated power. The current work presents a solar PV plant power smoothening algorithm that is suitable for both cloudy and sunny weather conditions. The smoothening algorithm optimizes the battery usage, keeps the battery state-of-charge (SOC) within a predefined reference operating range, and reduces BES charge-discharge losses. In the power conditioning system (PCS) of BES, a thirteen-level cascaded H-bridge voltage source converter (VSC) with fundamental switching of MW size is used. The simulated steady-state, harmonics and dynamic response of 20MW solar PV plant with 10MW/5MWh BES configuration are presented in detail.

The demand for high-power converters for use in large-scale solar photovoltaic (PV) plants increases as the plant size continues to grow. The multipulse voltage-source converter (VSC) configurations are the viable option for high-power solar PV converter applications because they improve conversion efficiency due to low switching losses and allow direct integration with a medium-voltage (MV) grid. In this article, a 48-pulse VSC based on the fundamental frequency switching (FFS) three-level neutral point clamp (NPC) converter with a start–delta transformer configuration is used for large-scale solar PV plant application. It is also used as a PV-static synchronous compensator (STATCOM) to provide the required reactive power support to the grid to regulate the voltage. The solar PV plant configuration for a 100-MW capacity is modeled in MATLAB and implemented in the real-time OPAL-RT platform to verify its design and controls. The harmonics, static, and dynamic performances are demonstrated in detail.