Alternating current electrified railway in-phase continous power supply system based on multi-port direct current transmission

Abstract

The invention discloses an alternating current electrified railway in-phase continous power supply system based on multi-port direct current transmission. The system comprises more than one three-phase high-voltage alternating current power supply, direct current converters used for converting three-phase high-voltage alternating current into high-voltage direct current, a high-voltage direct current transmission loop used for transmitting the high-voltage direct current to a loop of each traction transformer, alternating current converters used for converting the high-voltage direct current into low-voltage single-phase alternating current, and a contact network system connected with an output end of the alternating current converter, wherein the contact network system is divided into an alternating current bus and a return line which takes power by a locomotive and then flows back from a steel rail. The system has the advantages that the system is simple in structure principle, high in safety and reliability, and easy to realize and popularize.

Description

technical field [0001] The invention mainly relates to the field of rail transit-based power supply systems, in particular to an AC electrified railway in-phase power supply system based on multi-terminal direct current transmission. Background technique [0002] As far as the transmission line project is concerned, under the same conditions, the investment of DC lines is far less than that of AC lines, and the impact on the environment is small. For long-distance DC transmission projects, the overall project investment is more economical due to the long line length and the same converter station. AC transmission and grid connection need to regulate the two AC grids, that is, unified synchronous operation and voltage regulation and frequency regulation. The two ends of the AC grid connected by the DC transmission line do not require synchronous operation, and the DC transmission itself does not have stability problems, and the transmitted power is not limited by the stabili...

AI Technical Summary

Problems solved by technology

In addition, it does not affect the power flow distribution of each catenary, which makes it difficult to set the relay protection parameters

[0005] my country's current electrified railway adopts the method of power supply in different phases and segments, and its excessive phase separation is unavoidable. When the locomotive is in excessive phase separation, it needs to be blocked first, and then restarted after the residual magnetism of the traction transformer is eliminated. This is equivalent to, During this period, the locomotive is running by inertia, so the speed and traction of the train are lost, reducing the capacity of the line

At the same time, the existing traction power supply network has low power factor, serious harmonics and negative sequence, which lead to prominent problems such as reactive power compensation, high-frequency resonance, low-frequency oscillation, and three-phase imbalance

For the above problems, some solutions have been applied at home and abroad, such as using vehicle-mounted over-phase or ground automatic over-phase devices to eliminate the influence of over-phase; using SVC, SVG, APF or RPC devices to solve reactive power, harmonics, and voltage. fluctuations, negative sequence and other power quality problems, but because of the single function, these problems cannot be solved at the same time, so it is often necessary to invest in a variety of compensation and conversion devices in the traction substation, which not only increases the investment and management costs, but also increases the share. land and operational risk

[0006] In addition, each traction station takes power from the nearest local backbone network. Due to the differences in capacity and load of each backbone network, the background system capacity and power supply quality of each traction substation, and the capacity of each substation cannot be communicated.

In recent years, my country's electrified railway has developed rapidly, and the single-unit capacity and operating density of electric locomotives have been significantly improved. However, the development of my country's power grid lags behind, so the background capacity of traction substations is relatively small, which makes the electric energy brought by the locomotive Quality problems are becoming more and more obvious, and this power supply capacity has limited the further development of electrified railways

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