United electric energy quality controller based on series multiplex of transformer and chain type construction

Abstract

The invention relates to a unified power energy quality controller based on the serial-connection multiplicity of transformers and a chain structure, which belongs to the technical filed of flexible AC transmission and distribution of an electric power system and the power electronic. The unified power quality controller comprises a single-phase serial-connection multiple transformer bank and a single-phase chain H bridge converter, wherein the transformer bank consists of m single-phase transformers which form the serial-connection multiple transformer bank together with n voltage source converters connected with n secondary windings of m single-phase transformers respectively; the single-phase chain H bridge converter is provided with n chains and is formed by connecting n DC voltage supporting units and n power source converters, and an AC port of the n-chain single-phase chain H bridge converter is directly connected with the electric fence through a reactor, m and n are signless integrals equal to or more than 2, and m is less than or equal to n. The invention can realize accurate current control, has high dynamic responding speed, and can solve the problems of the traction substation of an electrified railway that the three-phase voltage is unstable and fluctuates, the power factor is low and the harmonic pollution exists, and the like.

Description

technical field [0001] The invention belongs to the technical field of flexible AC power transmission and distribution in power systems and power electronics, and relates to large-capacity power electronic devices and the treatment of user power quality problems. In particular, it provides a single-phase transformer series multiplexing and A unified power quality controller (Unified Power Quality Controller, UPQC) device for a chain-type H-bridge converter. Background technique [0002] As a large-capacity single-phase load, electric locomotives will inject negative sequence current into the power supply system of electrified railways (referred to as electric railways), and cause power quality problems such as three-phase unbalanced voltage and voltage fluctuations in the power supply system. China's current electric railway power supply system is a different-phase power supply mode. The phase sequence rotation technology and balance transformer technology commonly used in t...

AI Technical Summary

Problems solved by technology

However, the use of single-phase multi-winding transformers will bring a series of disadvantages: the processing technology of single-phase multi-winding transformers is relatively complicated, and it is difficult to achieve the equivalent leakage reactance between the primary and secondary windings and the secondary windings. To overcome the uneven current of each winding; in addition, the mutual impedance between the secondary windings of the single-phase multi-winding transformer is relatively small, and when there is a small difference in the parallel voltage of the secondary side, a large circulating current will be generated, even if the split type The connection method can only increase the equivalent leakage reactance between the secondary windings to a certain extent, and it may still cause a large circulating current between the windings when the phase-shift carrier PWM strategy is adopted.

Only using ordinary DC capacitor units obviously does not have this effect

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