Power quality integrated management device of electrified railway traction supply network

Abstract

The invention discloses a power quality integrated management device of an electrified railway traction supply network. The power quality integrated management device comprises an APF branch circuit and an HPF branch circuit. The APF branch circuit comprises a connecting electric reactor, a controller, more than one set of APF converter and more than one set of charging circuit corresponding to the APF converter. After being connected with the charging circuits, the APF converters are connected to a contact network through the connecting electric reactor in a hanging mode. The APF converters are cascaded through more than two power units, the controller is connected with the APF converters and sends a control signal to switch components of the power units, single-phase uniform amplitude alternating-current PWM output voltage is generated, and an expected current injection contact network is obtained through the connecting electric reactor. According to the HPF branch circuit, a second-order resonance circuit is composed of a resistor, an electric reactor and a capacitor. The power quality integrated management device can provide idle work support for an electric railway traction power supply system, the power factor is improved and meanwhile negative sequence components, harmonic waves, voltage fluctuations and voltage flickers in the system are effectively restrained.

Description

technical field [0001] The invention relates to an electric energy management device, in particular to an electric energy quality comprehensive treatment device applied to an electrified railway traction power supply network. Background technique [0002] As an important infrastructure of the national economy, railway plays an important role in my country's comprehensive transportation system. In accelerating the construction of a conservation-oriented society, railways shoulder important responsibilities. On the one hand, as a key energy-consuming industry, it has great potential to be tapped in terms of energy conservation and consumption reduction, and improvement of comprehensive energy application efficiency. On the other hand, electrified railways have long-term problems such as low power factor, high harmonic content, and negative sequence, which seriously affect the power quality of the public grid. The characteristics of my country's electrified railway traction l...

AI Technical Summary

Problems solved by technology

[0005] (3) Due to its structural asymmetry, the current returned to the system contains a large amount of negative sequence current;

[0007] (5) Large reactive current and low power factor

[0012] High-order harmonic current interferes with communication; low-order harmonics cause increased power loss in the grid, reduced efficiency of AC motors, increased current in parallel compensation capacitors, resonance, and failure of relay protection, etc.

[0013] (3) Reactive current

However, there are still some problems: each locomotive compensation device has a large capacity, and the investment cost is considerable; limited by the conditions of the locomotive, the installed compensation capacity and the number of groups cannot fully meet the compensation requirements; it is stipulated that when the rated power exceeds 50%, the compensation device is used, but all Line locomotives operate under 50% power most of the time (such as light load, downhill or low-speed operation), and the comprehensive power factor reflected in the substation is generally only about 0.8, which cannot effectively compensate reactive power; the operating environment is harsh, and the device high reliability requirements

The existing problem is: due to the randomness of the switching time of the switch, there is a large current impact when it is switched on, and there is a high overvoltage when it is cut off, which may easily cause damage to the switch and capacitor equipment. Therefore, it is generally not easy to switch on the compensation device. Otherwise, it is easy to cause overcompensation or undercompensation; the total compensation capacity cannot be set too large, otherwise the compensation effect will not be good, and overcompensation will cause the bus voltage to rise, which is not conducive to the operation of the locomotive

In this way, the device cannot compensate the harmonic source of the electric railway traction network on the spot, and the high-order harmonic impedance of the harmonic source increases sharply with the growth of the line, seriously endangering the electrical equipment on the traction network line; on the contrary , if the voltage source converter and passive filter are installed in the marshalling station, it can facilitate the local compensation of the harmonic source of the traction network, but it is not conducive to effectively reflect the three-phase unbalance and voltage fluctuation of the traction power supply system. Control effect of power quality problems such as flicker

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