| Reactive Power Control For A Single Phase Grid Connected Transformerless DC/AC PV Inverter | |
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MSRDG International Journal of Computer Scientific Technology & Electronics Engineering
© 2025 by MSRDG IJCSTEE Journal Volume 1 Issue 4 Year of Publication: 2025 |
Paper Download Article ID MSRDG-IJCSTEE-V1I4P103 |
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Abstract: The design, modelling, and implementation of a reactive power control strategy for a single-phase grid-connected transformerless DC/AC photovoltaic (PV) inverter. The elimination of the isolation transformer, while reducing cost and improving efficiency, introduces challenges related to ground leakage current suppression and precise control of reactive power exchange with the utility grid. The proposed system employs a full-bridge H-bridge inverter topology coupled with an LCL output filter and a proportional-resonant (PR) current controller operating in the stationary reference frame. Reactive power regulation is achieved through a dedicated outer-loop controller that modulates the phase angle between the injected current and the grid voltage, enabling flexible operation across leading, lagging, and unity power factor conditions. A phase-locked loop (PLL) algorithm ensures robust grid synchronisation under practical voltage disturbances. Common-mode voltage clamping techniques are incorporated to limit ground leakage current to levels compliant with the IEC 62109-2 standard. Simulation results validate steady-state accuracy and dynamic performance, demonstrating reactive power step-response settling times below 15 ms, current total harmonic distortion (THD) of 1.6%, and peak efficiency exceeding 97.8% at rated load. The findings confirm the viability of reactive power ancillary services from residential-scale PV installations without requiring a galvanic isolation stage. |
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| Keywords: Reactive power control; Transformerless PV inverter; PR controller; LCL filter; Grid-connected inverter; Power factor correction; Leakage current; Phase-locked loop | |
