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The impact of aerosols on electromagnetic environment of HVDC power lines has become an emerging research issue. In order to investigate the effect of aerosol's charged characteristics, suspended aerosols were produced by burning incense in a square plexiglass box. The morphology and elemental composition of the experimental aerosols were characterized by Scanning electron microscopy (SEM) and energy...
When the probe of field mill is directly mounted on the ground under the high voltage direct current (HVDC) transmission lines, the ionized field near the probe is distorted. In order to reduce the ionized field distortion on the top surface of the field mill probe, an electrode with semi-circular edge is added flush with the top surface of the probe. Finite element method is utilized to calculate...
One of the constraints to further DC distribution system development is the lack of practical fast DC circuit breaker. In the paper, DC distribution system and breaker protection coordination is discussed. Feasible strategies and methods of protection coordination are proposed. At the same time, based on the actual system with different voltage levels and the circuit breaker prototype test results,...
This paper proposes a VSC-MTDC transmission line protection scheme based on polarity comparison of superimposed current and resistive-type superconducting fault current limiter (R-SFCL). R-SFCLs utilize a current-driven transition from the superconducting state to the normal state to limit the short circuit current. Thus, DC circuit breakers can be used to break the fault current in the event of a...
This paper proposes a fault ride-through strategy for fully rated converter wind turbines connected to the grid via MMC-HVDC transmission. During grid fault, a voltage drop in the wind farm network is made by the wind-farm-side MMC. On detecting the voltage drop, grid-side voltage sourced converters of wind turbines decrease their output active currents immediately. Therefore, the power output from...
This paper conducts a detailed analysis on the dc side interaction of a modular multilevel converter based HVDC system. The dc side is modelled as a cable system with a voltage controlled remote converter. To implement such research, detailed small-signal models of a point-to-point MMC-HVDC system with consideration of the internal harmonic dynamics are established, based on the concept of “dynamic...
As one of the main effective equipment to deal with the grid harmonic problem, Active Power Filter (APF) becomes large-scale industrial application gradually. With the increasing requirements of high-capacity APFs in industries, multi-module parallel connected APF becomes an important developmental direction and research hotspot for its flexible capacity and high reliability. A redundant strategy...
The insulation of transmission lines phase-ground and phase-phase air gaps decrease significantly under forest fire condition, which causing transmission lines trip and threatening the operation safety of EHV and UHV transmission lines. In order to attain a simulation method to test the gaps discharge characteristics under forest fire condition, wooden cribs were applied to study the flame heights...
In multi-terminal VSC-HVDC system, The most important prerequisite to ensure stable operation of the system is to maintain stability of the DC voltage, a coordinated power control strategy applies to multi-terminal VSC-HVDC system is proposed in this paper. The proposed control strategy can make the converter stations controlled by multiple fixed-point DC voltage distribute the power reasonably according...
Oil-paper insulation system is an extraordinarily essential system of converter transformers as well as HVDC oil-impregnated paper capacitance graded bushings. Due to a few researches in surface and interface charge behaviour of supporting materials, there are still some problems in charge accumulation, thus affecting the application of HVDC bushings and the safety of entire grid. This paper studies...
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