With the growing integration of Modular Multilevel Converters (MMCs) in Multi-Terminal Direct Current (MTDC) transmission systems, there is a growing need for control strategies that balance economic efficiency with robust dynamic performance. This paper presents an enhanced Optimal Power Flow (OPF)-based framework for hybrid AC-MTDC systems, incorporating a novel droop control strategy that jointly coordinates DC-voltage and AC-frequency regulation. By embedding frequency control loops into the MMCs, the method enables system-wide coordination that enhances power sharing and improves resilience under disturbances. The proposed strategy dynamically adjusts converter operating points to minimize generation costs and DC-voltage deviations, balancing economic objectives with system stability. A modified Nordic test system integrated with a four-terminal MTDC grid is used to validate the approach. Optimization is performed using Julia, while the system's dynamic performance is evaluated through electromagnetic transient simulations with the EMTP software. Case studies across multiple scenarios demonstrate that the proposed droop control achieves markedly improved frequency and voltage robustness over active power control, while incurring lower generation costs than the adaptive droop benchmark. The results highlight the ability of the proposed strategy to deliver cost-effective operation without compromising performance, offering a promising solution for the coordinated control of future hybrid AC-DC transmission networks.

The pandemic has severely affected the quality of education worldwide, especially regarding actual hands-on experience with the laboratory. Therefore, a remote laboratory is the solution to this issue. Controlling the speed of DC motors is included in the control systems laboratory courses syllabus in many universities worldwide. This study aims to develop a real-time remote DC motor control suitable for use in a remote laboratory. The speed control is implemented using TMS320F28379D ControlCard DSP and MATLAB/Simulink. The DC motor is connected to a host computer. Students can control the DC motor remotely on their computers and connect to the host computer using the TeamViewer. Unlike other remote laboratories, where most provide a simulation environment, the proposed platform can give actual hands-on experience. The proposed platform is tested experimentally and compared with the simulation results.

The modular multilevel converter (MMC) uses many power electronic components in the high voltage direct current (HVDC) application. One of the major concerns in half-bridge MMC is the fault in the converter submodules. It raises the question of whether the reliability and high-quality performance of the MMC can be increased significantly as the active device controls the power flow between the AC- and DC-sides. During the SM fault within the MMC leg, the unbalance is introduced in-side the MMC converter. The unbalanced voltage within the leg of the MMC will continuously introduce an AC-current component on the DC-side of the converter. Thus, the hybrid proportional-internal (PI) control and proportional-resonant control (PR) is introduced in controlling the power flow within the internal MMC to eliminate the AC-current component and ensure pure DC-current in the internal MMC. This study investigates the internal power flow control of a three-phase rectifier MMC with symmetric and asymmetric SM fault conditions. Compared with conventional control methods, the proposed control can tolerate SM faults and eliminate the AC-current component within the converter, increasing the converter's performance. Simulation results are included and discussed to verify the proposed control.

As the world transitions to renewable electrification to reduce CO2 emissions, remote island electrification remains a challenge. Although some islands are connected to the grid, many still rely on fossil fuels for electricity generation. Several studies indicate that renewable energy sources, such as wave energy, have the potential to make these islands self-reliant because of their substantial power potential. However, research on the control of power electronics converters for these systems remains limited. This paper proposes isolated grid-forming control for island electrification to address this gap using a wave energy converter and an energy storage system. Resistive loading control is implemented to optimize the power absorption of the generator. The result illustrates the establishment of the required AC voltage and 50 Hz frequency in the island load, ensuring harmonics compliance with the recommended standards. Experiments were conducted to test and validate the operation of different converter controls. The results also demonstrate the converter's ability to black-start the island load and automatically transition the load current with varying loads in a few milliseconds. Furthermore, the power quality produced by the wave energy converter presents one of its significant challenges. Therefore, the performance of two distinct converter technologies was compared. The performance of the IGBT converter was evaluated against that of the SiC-based converter in terms of power quality. The study demonstrates that the use of SiC enhances power quality in all switching frequencies tested, achieving the most significant reduction of 78% in current THD and 92% in voltage THD at the 25 kHz switching frequency, thus validating its advantages for wave energy converter applications.

Reactive control is a popular method for maximizing wave energy absorption in wave energy converters (WECs). This technique involves adjusting the damping and stiffness coefficients of the WEC to align its natural frequency with the frequency of incoming waves. Unfortunately, wave variability and complex hydrodynamics have posed challenges in accurately determining these coefficients. This paper proposes a model-independent approach for reactive control based on a variable step size maximum power point tracking (MPPT) algorithm. The MPPT algorithm tunes the WEC's damping and stiffness coefficients toward maximum generated power. Furthermore, a power curtailment control (PCC) strategy is integrated, based on a proportional-integral (PI) controller that modifies the MPPT control force to follow power generation references below its maximum generation capacity. This capability is essential for grid integration, where power generation must match demand. Finally, a hardware-in-The-loop experimental setup was constructed to evaluate the proposed control strategies under monochromatic and polychromatic wave conditions. An analysis comparing MPPT and damping control under various polychromatic wave conditions revealed that MPPT achieves substantially higher electrical power, outperforming damping control by 55.4% to 70.6%. The experimental results demonstrated the efficacy of the PCC strategy in reducing the WEC power output to track specific power setpoints.