Research Output
Articles
Publication Date: 2026
Electric Power Systems Research (03787796)251
An increase in the current of the converter's switching valves beyond their rated value and fluctuations in the DC-link voltage during unbalanced fault conditions are among the most significant challenges in voltage source converter-based high voltage direct current (VSC-HVDC) systems. These issues can significantly reduce the reliability of the system. Existing methods to address these problems tend to increase the complexity of the control system and involve high computational demands. Additionally, their performance may not be suitable for all common transformer configurations in VSC-HVDC systems. In unbalanced fault scenarios, this work proposes a straightforward way to manage the current and minimize DC-link voltage variations. The suggested approach successfully regulates the current across all typical transformer winding connections to the appropriate value. The studied system is simulated under double line-to-ground and single line-to-ground fault conditions in PSCAD/EMTDC. The results confirm the effectiveness of the proposed control method across all common transformer configurations in both two-terminal and multi-terminal VSC-HVDC systems. © 2025 Elsevier B.V.
Publication Date: 2025
Electrical Engineering (14320487)107pp. 10433-10444
This paper presents a 0.7-MW high-current variable-voltage inductive load that is connected by a 12-pulse thyristor rectifier to the distribution system. In order to compensate at the point of common coupling over the load current range, a parallel hybrid filter (PHF) is used comprising two single-tuned passive filters for 11th and 13th harmonic and a second-order high-pass passive filter for 23th harmonic and DSTATCOM. According to the load reactive power variation, the DSTATCOM is used only to improve the displacement power factor (DPF) while passive filters are incapable of keeping DPF in acceptable values (greater than 0.98). Because of the distribution system voltage variation, it is assumed that voltage varies ± 5% of the network line voltage. A new comprehensive method is presented for the PHF design with simple equations based on accurate equalization of DSTATCOM maximum lead and lag currents (minimum rating and cost) in the fixed and variable network voltage. This equalization not only reduces the rating of DSTATCOM, but also the total power of passive filters. A network current TDD optimization is according to the PSO algorithm carried out with modeling of the system (presenting system equations) and using network harmonics current constraints in PSO loops which puts all network current harmonics in acceptable amounts. What’s more, harnessing PSO algorithm considerably reduces network current TDD in comparison with previous studies. MATLAB simulation results comprising DSTATCOM current and reactive power, network current TDD and harmonics, and other simulation results are presented to verify the better reactive power and harmonic performance of proposed method compared with other method. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
Publication Date: 2024
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025
This paper focuses on the parameter estimation of induction motors. It introduces a new approach for stator resistance identification, which is practical for industry applications such as electrical railway transportation systems. Furthermore, the total leakage inductance and the rotor side resistance are identified by a single test with high accuracy, without the need for AC injection and phase angle detection. The proposed method is simpler compared to other methods, also benefiting from lower computational requirements. Finally, the magnetizing inductance is estimated using a novel approach with a PR controller. Since there is no need to measure the phase difference between voltage and current, the accuracy of the introduced method is high. © 2024 IEEE.
Publication Date: 2023
Electric Power Systems Research (03787796)214
Voltage sags is one of the most important issue of power quality, which can disrupt industrial process and impose huge costs on industrial plants. For improving disturbance ride-through capability of voltage source converter based on high voltage direct current (VSC-HVDC) supplying industrial plant, an auxiliary frequency controller is proposed to control output voltage frequency at inverter station. Since industrial loads are more sensitive to voltage drops compared to frequency deviations, output voltage frequency is slightly deceased based on DC-link voltage changes during disturbances in proposed control scheme in order to prevent voltage collapse and provide desirable voltage quality for industrial plants; hence, the continuity of industrial process will be ensured. The case study is a part of a real industrial plant and variations of DC-link voltage, AC buses voltages, induction motors speed, and performance of adjustable speed drive are investigated when the proposed method is used during faults. In proposed method, voltage drop across industrial plant during a severe fault is less than other methods and dynamic performance of system is improved. The case study is simulated under balanced three-phase fault, double line-to-ground fault, and single line-to-ground fault in PSCAD/EMTDC, and results verify the validity of the proposed control scheme. © 2022
