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In high voltage direct current (HVDC) systems, the occurrence of short circuits results in a rapid rise in line current, adversely affecting the interconnected alternating current (AC) grid. Particularly in voltage source‐based multimodular converter (MMC) HVDC networks, such transients pose a significant threat to power converter units. Traditional relaying algorithms prove inadequate for safeguarding AC‐DC‐linked HVDC networks. Both the direct current (DC) and alternating current (AC) segments of such networks demand robust protection mechanisms. Signal processing‐based techniques offer valuable insights during fault events, yet challenges such as noise interference, mode missing, and harmonics generation during faults persist, leading to erroneous conclusions. To address this, we introduce Synchro Squeezed Transform (SST) in this study to mitigate ambiguity in relaying algorithm decisions. SST facilitates the extraction of amplitude and effective instantaneous frequency of AC signals. The proposed method employs the Rényi entropy of time‐frequency representation (TFR) as the primary logic, followed by the estimation of the spectrum‐based Teager–Kaiser Energy Operator (TKEO) for DC signals as the secondary logic. These combined logics enable the identification of various AC and DC faults in Voltage Source Converter (VSC)‐based bipolar HVDC networks. Simulation results, including comparisons with existing approaches, demonstrate the efficacy of the proposed methodology in enhancing fault detection and classification accuracy in AC‐DC‐linked HVDC networks. [ABSTRACT FROM AUTHOR]

This paper presents the torque ripple analysis of a brushless DC (BLDC) motor. This torque ripple is generated by generating the ripple in the stator current. For reducing the ripple, a phase-modulated model predictive current control strategy has been implemented in an MMC-fed BLDC motor. The performance of the torque ripple of the BLDC motor is enhanced by using the proposed phase-modulated model predictive control (PMMPC) technique as compared to the model predictive control (MPC) and proportional-integral (PI) controller. Moreover, the performance of the torque ripple is enhanced by increasing the switching frequency for all controllers. A comparative analysis of the torque ripple of the BLDC motor is depicted for different current control and different switching frequency. A harmonic distribution is also shown for all control techniques at switching frequencies of 1, 5, and 10 kHz. The harmonic content is minimum for the PMMPC technique when compared to the other mentioned control technique. The experimental validation of simulation results has also been done here. [ABSTRACT FROM AUTHOR]

This paper investigates the optimal guaranteed cost (GC) control problem for uncertain discrete-time (DT) systems with state saturation nonlinearities via static-state feedback. The parameter uncertainties in the system state and input matrix are considered to be norm bounded. Utilizing Lyapunov theory and sector-based characterization of saturation nonlinearities, a novel criterion for the existence of GC controllers is proposed. The criterion is expressed in the framework of linear matrix inequalities (LMIs) and is thus computationally tractable. The proposed GC controllers make the closed-loop (CL) system asymptotically stable and ensure an adequate level of performance for all admissible parameter uncertainties. To design an optimum GC controller, a convex optimization problem with LMI constraints is formulated. The effectiveness of the proposed approach is illustrated by examples. [ABSTRACT FROM AUTHOR]

High level of photovoltaic (PV) integration into the distribution network (DN) may have a negative impact in terms of voltage variations across the limits. As such thorough analysis is required to ensure voltage within limits, mainly at feeder‐end buses. In this study, the PV integration problem is addressed in a more comprehensive way, considering the unbalance DN, impedance characteristic, and interaction of load against available PV output. The approach applies to both the planning and operational stage in the assessment of allowable PV hosting capacity (HC). In the planning stage, the local impedance index is computed at constant load and power factor conditions. The entire network is partitioned into areas and the most suitable area for PV integration is determined, which can allow maximum PV integration, without/minimum voltage violations. In the operation stage for allowable PV hosting capacity, further voltage analysis is performed, wherein peakness of PV output and load conditions do not match each other. Towards, voltage regulation via PV inverter, the power factor profile is adjusted as a function of PV output. The study is demonstrated for transient solar radiation, with emphasis on maintaining the voltage at feeder‐end buses. The simulation is carried out on interfacing GridPV in MATLAB and OpenDSS toolbox. The proposed scheme for allowable HC and further voltage regulation in the network using PV inverter is also compared with those approaches, applying optimised and centralised placement of PVs. [ABSTRACT FROM AUTHOR]

The problem of guaranteed cost (GC) control using static-state feedback controllers for uncertain linear discrete time-delayed systems subjected to actuator saturation is studied in this paper. The stability analysis of closed-loop systems is carried out using a Lyapunov-Krasovskii functional. Conditions for the existence of state-feedback GC controllers are developed using a linear matrix inequality (LMI)-based criterion. The approach ensures a sufficient performance bound over all the acceptable parameter uncertainties. The scheme of the optimal GC controller problem is framed as a convex optimization problem with LMI constraints. The design of GC controllers for discrete-time systems subjected to actuator saturation without considering the effect of state-delay is also discussed. The effectiveness of the proposed approach is illustrated using suitable examples. [ABSTRACT FROM AUTHOR]