Direct-current high-current ice-melting device with STATCOM function

Abstract

The invention belongs to the technical field of the high-voltage power transmission and distribution system, in particular relates to a direct-current high-current ice-melting device with a STATCOM function. The direct-current high-current ice-melting device with the STATCOM function is characterized by comprising two STATCOMs with same circuit configurations and one ice-melting commutation switch matrix, wherein one ends of the two STATCOMs are connected with a three phase alternating-current buses, the other ends of the two STATCOMs are connected with the ice-melting commutation switch matrix, the ice-melting commutation switch matrix is composed of six isolation switches which are matched with the two STATCOMs and are divided into two groups correspondingly, and two ends of each group of the isolation switches are respectively connected with the STATCOMs and an A phase, a B phase and a C phase of a line to be de-iced. According to the direct-current high-current ice-melting device with the STATCOM function, disclosed by the invention, a large number of passive filters based on capacitors and electric reactors is not required to be arranged at an alternating-current side, therefore the floor space of the whole device is greatly reduced, no pulse width modulation technology is needed, the switching loss of an IGBT (Insulated Gate Bipolar Translator) is reduced, and the output current is enhanced.

Description

technical field [0001] The invention belongs to the technical field of high-voltage power transmission and distribution system devices, and in particular relates to a DC high-current ice-melting device with a STATCOM function. 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 such accidents, the icing and snow on the wires must be melted in time. At present, there are two main methods of melting ice, mechanical (vibration) and electric heating. Mechanical (vibration) ice melting, that is, the method of vibrating wires to make ice and snow fall off, is characterized by simple operation and no need to w...

AI Technical Summary

Problems solved by technology

Mechanical (vibration) ice melting, that is, the method of vibrating wires to make ice and snow fall off, is characterized by simple operation and no need to waste electric energy, but its disadvantage is that it must be carried out step by step, the speed is slow, and the ground is frozen and snow is serious. In some cases, it is often impossible to operate because of traffic problems that cannot reach the transmission line on the mountain

Electrothermal ice melting technology, that is, using the high current generated by short-circuiting the end of the line to heat the wire to achieve the purpose of melting ice. Compared with the mechanical (vibration) ice melting method, the advantage of the electric heating ice melting technology is the melting speed. Faster, not affected by icing and snow on the road surface, but it needs to consume a certain amount of electric energy and configure related supporting devices

Nowadays, electrothermal ice-melting technology is widely used, including AC high-current ice-melting technology and DC high-current ice-melting technology. In comparison, the advantage of AC high-current ice-melting technology is that each substation has AC power supplies of different voltage levels. , so the power supply is relatively easy to obtain, but its disadvantage is that under the same ice-melting current, a higher power supply voltage is required, because the AC inductive reactance of the general transmission line is much larger than its resistance, thus melting ice requires a large power supply capacity And a large reactive power, the impact on the system is greater when melting ice, which may cause system voltage stability problems; another disadvantage is that the voltage of the AC power supply cannot be adjusted, so the ice melting current cannot be controlled

The advantage of DC high-current ice-melting technology is that under the same ice-melting current, only a lower power supply voltage is required, because the DC inductance of the transmission line is 0, so the impact on the system is very small when melting ice; the disadvantage is that it requires additional Equipped with rectification and filtering units, and because severe icing of lines is uncommon, these units are less utilized

Patents 200810060026.X and 200810120372.2 disclose two types of devices that can combine DC high-current ice-melting technology and static var compensation technology (SVC), which effectively improves equipment utilization. However, both types of devices in the above inventions require Configure 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.

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 four disadvantages: 1) The device requires a cooling Transformer, which increases loss and cost; 2) Because the device uses pulse width modulation (PWM) technology, it increases IGBT switching loss and electromagnetic interference; reduces the ability of output current; 3) Since the device uses pulse width modulation (PWM ) technology, it is necessary to install a filter on the AC side; 4) Due to the limitation of the circuit structure, the adjustable range of the DC voltage of the device of the invention is small, so that the length of all the power transmission lines to be melted is required to be approximately the same, but often the power transmission of a substation The lengths of the lines are not approximately the same, so the inventive device cannot de-ice all the transmission lines of the substation

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