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The transition of the European electrical energy system leads to rising installations of renewable energy sources (RES). Average transmission distances and active and reactive power losses increase, because RES are mainly installed at sites with a high yield of primary energy. This development affects the voltage stability of the system. To address these challenges, a meshed high voltage direct current...
A mathematical analysis is developed in this paper to estimate the value of short-circuit currents in HVdc links. The study allows to calculate the evolution of the fault currents, their maximum values and the time they are reached. Thus, it can help to select adequate protection systems for HVdc grids. The mathematical study is verified by means of PSCAD simulations where the theoretical and simulated...
Modular multilevel converters generate high voltage ripple in the floating capacitors which increases the harmonic content of arm voltages and currents and consequently the losses and can degrade the control performance. In order to reduce this voltage ripple, a large capacitance is usually employed, but the size and cost of the submodules and the whole converter are increased. In this paper the voltage...
The detailed real-time simulation of MMC-based HVDC links is one of the most challenging tasks in power system validation today, requiring the combined use of CPU and FPGA technologies. The inclusion of surge arresters in the real-time fault tests further increases the difficulties because of the highly non-linear characteristics of such protective devices. In this paper, the OPAL-RT digital real-time...
A nonlinear H-infinity (optimal) control method is proposed for the problem of control of the VSC-HVDC transmission system (Voltage Source Converter - High Voltage DC transmission system). Approximate linearization, round a local operating point, is performed for the dynamic model of the VSC-HVDC transmission system. This local equilibrium consists of the present value of the state vector of the VSC-HVDC...
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