Abstract: A method, an apparatus and a device for suppressing a first HVDC commutation failure under an AC system fault are provided. The method includes: obtaining a three-phase voltage of a converter bus, and calculating a zero-sequence component amplitude and an ?? component amplitude; calculating a first trigger-angle command for a single-phase fault and a second trigger-angle command for a three-phase fault selecting a smaller one of the first trigger angle command and the second trigger angle command as a trigger-angle command for an extinction-angle controller; and adjusting a trigger angle of the HVDC transmission system by using the trigger-angle command as an upper limit value for an output of the extinction-angle controller of the HVDC transmission system.

Abstract: A method for identifying video signal source is provided. The method includes the following steps. A first identification code is assigned to a first transmitter device by a receiver control unit of a receiver device. A first video data is transmitted by the first transmitter device. The first video data and a first identification image corresponding to the first identification code are combined as a first combined video data by the receiver control unit. The first combined video data is outputted to a display device by the receiver control unit.

Abstract: A voltage source converter based DC deicer and its control method are provided. The voltage source converter based DC deicer includes a connecting reactor, a modular multilevel voltage source converter based on a full H-bridge submodule, smoothing reactors, deicing disconnectors, a deicing bus, and a deicing AC line. The AC side of the modular multilevel voltage source converter is connected to an AC side bus through the connecting reactor, an isolation disconnector and a breaker. The DC side of the modular multilevel voltage source converter is connected to the deicing AC line through the smoothing reactors, the deicing disconnectors, and the deicing bus.

Abstract: A multi-functional automatic switching circuit for direct current ice melting and a switching method thereof are provided. The automatic switching circuit comprises at least one sub-switching circuit. The sub-switching circuit comprises a six-pulse current converter (R) with no saturable reactor, six reactors (L1a, L1b, L1c, L2a, L2b, and L2c), three three-phase knife switches (Sac1, Sac2, and Sac3), and five single-phase knife switches (SV1, SV2, SV3, SV4, and SV5). The sub-switching circuits in series connection or parallel connection, four direct current side switching knife switches (Sdc1, Sdc2, Sdc3, and Sdc4), an isolation knife switch (K), a breaker (QF) and a control and protection system (CP) may form an automatic switching circuit for six-pulse or twelve-pulse direct current ice melting.

Abstract: A voltage source converter based DC deicer and its control method are provided. The voltage source converter based DC deicer includes a connecting reactor, a modular multilevel voltage source converter based on a full H-bridge submodule, smoothing reactors, deicing disconnectors, a deicing bus, and a deicing AC line. The AC side of the modular multilevel voltage source converter is connected to an AC side bus through the connecting reactor, an isolation disconnector and a breaker. The DC side of the modular multilevel voltage source converter is connected to the deicing AC line through the smoothing reactors, the deicing disconnectors, and the deicing bus.

Abstract: A multi-functional automatic switching circuit for direct current ice melting and a switching method thereof are provided. The automatic switching circuit comprises at least one sub-switching circuit. The sub-switching circuit comprises a six-pulse current converter (R) with no saturable reactor, six reactors (L1a, L1b, L1c, L2a, L2b, and L2c), three three-phase knife switches (Sac1, Sac2, and Sac3), and five single-phase knife switches (SV1, SV2, SV3, SV4, and SV5). The sub-switching circuits in series connection or parallel connection, four direct current side switching knife switches (Sdc1, Sdc2, Sdc3, and Sdc4), an isolation knife switch (K), a breaker (QF) and a control and protection system (CP) may form an automatic switching circuit for six-pulse or twelve-pulse direct current ice melting.