Feed-forward voltage compensation-based direct-current side oscillation suppression method for metro traction converter

Abstract

The invention discloses a feed-forward voltage compensation-based direct-current side oscillation suppression method for a metro traction converter. Proper damping parameters are selected according toa stability criterion condition. Meanwhile, based on the principle that the ratio of effective vectors is maximum and the disturbance is minimum, a feed-forward voltage compensation parameter of a dqshaft is calculated. According to the principles of equal effective action vectors and power conservation, a reference voltage vector after the amplitude-limiting adjustment is obtained through calculation. As a result, the direct-current side stability control of a metro traction transmission system under the compensation over-modulation condition is ensured. According to the invention, the dynamic compensation for the feed-forward voltage is adopted, and the oscillation of the direct-current side voltage and the direct-current side current during the operation process of the traction transmission system is suppressed. The stability of the voltage at the direct-current network side is ensured. Meanwhile, the over-modulation condition caused by voltage compensation is considered, so thatthe effectiveness of the oscillation suppression method under the over-modulation condition is ensured. The condition that existing reference current compensation schemes are easily limited by currentloop bandwidth is avoided, so that the faster dynamic response is achieved.

Description

Technical field [0001] The invention relates to the technical field of subway traction drives, in particular to a method for suppressing the DC side oscillation of a subway traction converter based on feedforward voltage compensation. Background technique [0002] The subway traction drive system is mainly composed of DC side filter, traction converter, asynchronous motor and traction control unit DCU. At present, urban rail transit is continuously put into operation in major cities in China, and the stability of the subway traction drive system has become the key to safe operation and has received extensive attention. In recent years, China’s self-developed traction converters have found in ground tests and on-site tests that the AC / DC side voltage, current and motor output torque of the traction drive will follow the The increase in the output power of the converter often causes continuous oscillation in certain specific frequency bands, which directly affects the stability of...

AI Technical Summary

Problems solved by technology

However, limited by many factors such as the space, weight and harmonic suppression of the vehicle-mounted converter, the selection of filter inductors and supporting capacitors on the DC side is often difficult to meet the needs of system stability.

In addition, the negative impedance caused by constant power control on the load side will greatly weaken the system damping, making the system sensitive to external disturbances

At the same time, the complexity of the distribution parameters of the traction substation and the traction network makes it difficult to match the parameters of the train network. With the increasingly complex operating environment such as multi-vehicle multi-working conditions and short-interval departures, under specific operating frequency bands and working conditions, subway traction transmission The system is prone to DC side LC resonance, and further causes DC power supply network voltage oscillation, which greatly reduces the reliability of the system

[0004] In order to improve the stability of the subway traction drive system and avoid the occurrence of oscillation between the train and the power supply network, a corresponding current loop compensation control scheme has been proposed, in which the torque loop current setting is adjusted proportionally according to the need for stability control of the DC grid side. The "multiplicative" compensation scheme of the value is prone to overcompensation, which will affect the dynamic performance of the system

At the same time, according to the system stability criteria, the "additive" control scheme that adds compensation on the basis of the reference torque current has certain limitations, and is easily limited by the bandwidth of the current loop. When the DC side voltage oscillation frequency is high , there will be a situation where oscillation suppression fails

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