A hybrid DC ice-melting device with continuously adjustable output voltage and current

Abstract

The invention discloses a hybrid DC ice-melting device with continuously adjustable output voltage and current, which includes a large-capacity adjustable-speed ice-melting transformer, a small-capacity transformer, a primary non-controlled rectifier, a secondary non-controlled rectifier, a chopping voltage regulation module and Output knife switch, the secondary side of the large-capacity adjustable ice-melting transformer is connected to the AC side of the main uncontrolled rectifier, the secondary side of the small-capacity transformer is connected to the AC side of the secondary uncontrolled rectifier, and the chopper and voltage regulation module is located in the secondary uncontrolled rectifier The DC side of the controlled rectifier constitutes a secondary rectifier, and the DC side of the secondary rectifier is connected in series with the DC side of the main uncontrolled rectifier as the main rectifier, and then connected to the input end of the output switch. The invention can continuously adjust the ice-melting voltage and current in a wide range, is suitable for 220kV and above voltage level transmission lines, has low cost, good ice-melting performance, strong fault tolerance, high ice-melting reliability, and grid-connected harmonics The current is small, and the additional low-order filter banks of the thyristor phase-controlled rectification circuit are not required.

Description

technical field [0001] The invention relates to electrical engineering technology, in particular to a hybrid DC ice-melting device with continuously adjustable output voltage and current. Background technique [0002] Ice and snow disasters occur frequently in southern China. Ice-covered power transmission lines are likely to cause disconnection and downturning, which seriously threatens the safe and stable operation of the power grid and the reliability of power supply. Especially in the catastrophic ice disaster in 2008, large-scale and long-term power outages occurred in many provinces in East China and Central my country, which caused huge losses to the national economy and the production and life of the people. [0003] In order to cope with ice and snow disasters, various types of DC ice melting devices have been developed in China to implement DC ice melting on ice-covered lines. These devices can be divided into three types: uncontrolled rectification based on diode...

AI Technical Summary

Problems solved by technology

Among them, the input and output technical performance of the PWM rectification type ice-melting device is very good, but the cost of multiple sets of fully-controlled switching devices with a relatively expensive unit price is too high to be popularized and applied; the output voltage of the phase-controlled rectification type is continuously adjustable, but An additional large-capacity low-order harmonic set is required to meet the grid-connected harmonic requirements, resulting in a large footprint and high cost for the entire device; the uncontrolled rectification type can realize different line types, The ice melting of lines with different lengths has become the mainstream of the market due to its advantages of simple structure, low cost, and high reliability of ice melting.

However, since the output voltage and current of the uncontrolled rectification type can only be adjusted in discrete levels, it is impossible to achieve fine control of the ice-melting current and ice-melting time.

The document "Icing device that can reduce input-side harmonics and adjust output voltage" (High Voltage Technology, Issue 5, 2013) proposes an agricultural distribution network that combines a diode uncontrolled rectifier circuit and a DC chopper circuit The topological structure of the ice melting device requires only one full-control switching device to realize continuous adjustment of the output DC voltage and current, but the voltage and current capacity of the topological full-control switching device cannot be lower than the rated output voltage and rated current of the device

For a high-voltage and large-capacity ice-melting device, the required full-control switching device has a large capacity and high cost, and is limited by the withstand voltage level of the current fully-controlled switching device. Multiple switching devices are required to be used in series and combined, and voltage equalization is difficult. Large, complex control, low reliability

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