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Controlled power converters have found many applications in the power industry during the last decade. Virtual synchronous generator (VSG) is a truly good example of these converters that can be used to induce desired dynamics to the network. Despite the excellent performance of VSGs in balanced conditions, they do not carry the flexibility to suppress unbalanced components. To deal with this conflicting issue, a decoupled double synchronous reference frame-based VSG is proposed in this paper. Applying this method to the VSG structure under unbalanced voltage conditions by decoupling the positive and negative components, the oscillating terms are mostly eliminated, and DC values are extracted with the aim that the controllers can perform better. The benefits of the proposed scheme include higher accuracy, better controllability, effective component separation, and robust performance under heavy load conditions. The simulation results prove the validity and effectiveness of the proposed strategy against traditional VSG and previous techniques presented to enhance VSGs under unbalanced conditions in an islanded microgrid. [ABSTRACT FROM AUTHOR]

This study focuses on the selection of the most effective location of direct current power system stabiliser (DC-PSS) in multi-terminal high-voltage direct current (MT-HVDC) grids that is applied to voltage source converter (VSC) to voltage stability enhancement and oscillation damping. Due to the adverse interaction between having multiple number of DC-PSS, it is necessary to select the best location for installing DC-PSS in MT-HVDC grid. In this study, the participation factor (PF) method is used. This method assists to find which power converters are more sensitive and have a major impact on the instability of the entire system. In this approach, the whole of the system is modelled as a multi-input multi-output (MIMO) dynamic system. PFs related to each power converter are intended by the oscillatory mode sensitivity analysis against the components of the MIMO matrix of the system. The PF analysis determines which VSC station is more participating in the small-signal instability of the system. In order to endorse the efficiency of the proposed method, time-domain MATLAB simulations are conducted in Cigré MT- HVDC grid benchmark. [ABSTRACT FROM AUTHOR]

In this study, by using the electromagnetic field analysis, the design of brushless DC generator with a novel construction and controller, appropriate for variable speed applications, is proposed. In the proposed machine, unlike the conventional structure, an assisted DC field coil is employed instead of permanent magnet excitation to provide a regulated voltage. Results of the electromagnetic field analysis show that including the DC field coil increases the controllability of the flux in different machine parts which provide a regulated terminal voltage in a wide speed range appropriate for variable speed applications. Moreover, the maximum power point tracking is achieved by controlling the DC field current along with producing optimal turn‐on and turn‐off angles for stator winding using the electromagnetic analysis based on optimal finite element analysis. Also, an appropriate controller is designed to control the DC field coil current. To verify the actual performance of the proposed configuration, a 1.5 Kw machine is manufactured and tested followed by the discussion on results. The obtained experimental results are in good agreement with the results of the electromagnetic analysis which confirm the maximum power trackability and robust output voltage regulation of the proposed conversion system under different shaft speeds and load conditions. [ABSTRACT FROM AUTHOR]