Hybrid Multifunctional DC High Current Ice Melting Device

Abstract

The present invention relates to the high-voltage transmission and distribution system technology field, the structure is simple, and the usage is convenient. The full-bridge MMC converter of the mixed-type multifunctional direct current large-current ice melting device and the alternating current side of a thyristor direct current ice melting device are connected with the alternating current bus of a power supply; the positive electrode and the negative electrode of the direct current side of the thyristor direct current ice melting device are connected with the direct current buses of the positive electrode and the negative electrode through a disconnecting link K4 and a direct current smoothing reactor; the positive electrode of the direct current side of the full-bridge MMC converter is connected with the positive electrode direct current bus through a disconnecting link K1, and the direct current side negative electrode of the full-bridge MMC converter is connected with the negative direct current bus through a disconnecting link K2; a disconnecting link K3 is crossed between the positive electrode direct current bus and the negative electrode direct current bus, two ends of a disconnecting link K6 are respectively connected with nodes between the disconnecting link K4 and the direct current smoothing reactor and between a disconnecting link K5 and the direct current smoothing reactor; and the positive electrode direct current bus and the negative electrode direct current bus are connected with two phases of the power transmission line being subjected to ice melting through a disconnecting link K7 and a disconnecting link K8, and the tail ends A, B and C phases of the power transmission line being subjected to ice melting are in short connection.

Description

technical field [0001] The invention belongs to the technical field of high-voltage power transmission and distribution systems, and in particular relates to a hybrid multifunctional DC high-current ice-melting device based on a full-bridge MMC converter and a thyristor rectifier. Background technique [0002] At present, accidents of high-voltage transmission line disconnection, tower collapse, and tower collapse due to icing and snow accumulation on transmission lines occur from time to time. The accidents of high-voltage transmission line disconnection and tower collapse have seriously affected the safe operation of the power grid, resulting in large-scale power outages ACCIDENT. In order to prevent the occurrence of such accidents, the icing and snow on the wires must be melted in time. At present, two major types of ice-melting methods, mechanical (vibration) and electric heating, are mainly adopted. Mechanical (vibration) ice melting, that is, the method of vibrating ...

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Problems solved by technology

However, the above two types of devices need to be equipped with a large number of passive filters based on capacitors and reactors, so there are problems such as large footprint, large reactive power changes during ice melting, and easy generation of harmonic resonance.

Chinese patent 201110362882.2 discloses a dual-function DC ice-melting device based on a voltage source converter. This invention combines the ice-melting function with the STATCOM function. However, this invention has the following disadvantages: 1) The device requires a cooling 2) Because of the limitation of the circuit structure, the DC voltage adjustable range of the device of this invention is small, thereby requiring that the length of all power transmission lines melted by ice is roughly the same, but often the length of power transmission lines of a substation are not roughly the same, so the inventive device cannot deice all the transmission lines of the substation

However, since this technology uses IGBT as a power device, its ice-melting current is limited to a certain extent.

In addition, the existing DC ice-melting devices in my country have to carry out ice-melting drills with transmission lines every year in winter to ensure the normal operation of the equipment. This drill brings two problems: 1) due to the need to stop the transmission line during the drill , reducing the safety and reliability of the power grid; 2) causing a lot of waste of electric energy (every drill will consume tens of thousands to hundreds of thousands of kilowatt-hours of electricity)

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