Syahrul Ashikin Azmi
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Preferred name
Syahrul Ashikin Azmi
Official Name
Syahrul Ashikin, Azmi
Alternative Name
Azmi, Syahrul Ashikin Binti
Azmi, S. A.
Azmi, Syahrul A.
Affandi Saidi, S.
Main Affiliation
Scopus Author ID
54928364200
Researcher ID
X-2468-2019

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  • Publication
    Current control of grid connected three phase current source inverter based on medium power renewable energy system
    ( 2021-01-01)
    Syahrul Ashikin Azmi
    ;
    Adam G.P.
    ;
    Rahim S.R.A.R.
    ;
    Williams B.W.
    Current source inverter (CSI) features simple converter structure and inherent voltage boost capability. In addition, it provides low instantaneous rate of voltage change with respect to time in comparison to voltage source inverter (VSI) and multilevel inverter (MLI). Nonetheless, CSI does not outshine as grid interfacing unit in photovoltaic (PV) generation system. This is because of requirement of large sizing of dc-link inductor and sluggish performance during light load condition. Contemplating both advantages and disadvantages of CSI, this work is aimed to investigate and analyze the superiority of CSI in PV system. The proposed system employs direct regular-sampled pulse width modulation (DRSPWM) as modulator and multi-loop proportional-integral (PI) in synchronous frame as the controller. The grid-connected CSI system is further evaluated along with photovoltaic maximum power point tracking (PV-MPPT) control. Simulation verification highlighted that the option of using CSI as medium power PV grid integration unit in exchanging active-reactive power with grid network is very satisfactory. In addition, balanced sinusoidal output currents with acceptable harmonic limit are successfully achieved; like other topologies in PV grid integration. The proposed CSI system is proved to be able to track the references in event of varying input condition from PV array. The theoretical equations and modeling are described, and the simulation are conducted in MATLAB / Simulink platform.
      24  3
  • Publication
    Grid integration of multiple PV inverters with reduced number of interfacing transformers— A dedicated controller for elimination of DC current injection
    ( 2023-03-01)
    Syahrul Ashikin Azmi
    ;
    Adam G.P.
    ;
    Williams B.W.
    ;
    Rahim N.A.
    ;
    Siti Rafidah Abdul Rahim
    The injection of dc current offset into ac networks may impacted the lifespan of the distribution system equipment including isolation transformers and measurement devices and in serious event may cause equipment's malfunction. This paper intents to eliminate dc current offsets in the output currents using a combinational of proportional-integral (PI) and proportional resonance (PR) controls embedded in one inverter unit. Resultant output currents of this method are sinusoidal and clean from dc offset before entering the point of common coupling. This method gives advantages for transformerless option for group of interfacing inverters in the medium-scale solar farm or in arrangement of inverters restricted in a small locale. Moreover, the use of expensive and high-accuracy measurement sensor nor complex transformer can be omitted, whilst indirectly give positive impact to the operational cost of the farm. The simulation verifications proved the usefulness of the proposed method by introducing varying unknown dc offset levels in the phase currents, and a dedicated dc offset suppressor inverter able to successfully eliminate the dc offset to zero. The validity of the proposed method is demonstrated in simulation using MATLAB/Simulink.
      30  1