Subsynchronous oscillation suppression method based on grid-connected converter control

Abstract

The invention provides a subsynchronous oscillation suppression method based on grid-connected converter control. The method comprises the steps that three-phase alternating current voltage VPCC and current IPCC of a PCC point of a grid-connected converter are acquired; coordinate transformation is carried out on VPCC and IPCC to acquire active and reactive components id and iq of the current in arotating coordinate system; an active current control signal Ed is acquired according to an active current reference value idref, id and a voltage feed-forward control signal; according to a reactivecurrent reference value iqref, iq, an additional reactive current command optimization control signal Utcq and the voltage feed-forward control signal, a reactive current control signal Eq is acquired; a three-phase alternating current internal potential eabc is acquired from Eq, Ed and theta; and pulse width modulation is carried out on eabc to acquire a switching control signal to suppress thesubsynchronous oscillation of the shaft of an adjacent synchronous machine. According to the invention, the electrical damping of the synchronous machine and the suppression effect of the subsynchronous oscillation of a synchronous generator are increased by adding a control branch at the reactive current command of the grid-connected converter without increasing the system capacity and changing the parameters of a PI controller.

Description

technical field [0001] The invention belongs to the field of power system stability control, and more specifically relates to a method for controlling the electrical damping of a synchronous machine based on an additional reactive current command of a grid-connected converter. Background technique [0002] The subsynchronous oscillation of the synchronous generator belongs to the system oscillation instability. According to its mechanism, it can be divided into two problems. One is the subsynchronous resonance problem of the power system caused by the series capacitance compensation in the AC transmission system. caused by subsynchronous oscillation problems. Because grid-connected converters respond very sensitively to power and speed changes within the sub-synchronous range. [0003] The suppression of the subsynchronous oscillation of the synchronous generator is mainly to study the electrical damping characteristics of the synchronous generator, and realize the optimiza...

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Problems solved by technology

[0007] Aiming at the defects of the prior art, the purpose of the present invention is to realize subsynchronous oscillation suppression by providing an additional reactive current command control based on the grid-connected converter when the electrical distance between the grid-connected converter and the synchronous machine is relatively close. While increasing the system capacity and not changing the parameters of the PI controller, only add a damping compensation branch at the reactive current command of the current loop of the grid-connected converter to improve the electrical damping of the synchronous machine and increase the suppression effect of suppressing the subsynchronous oscillation of the synchronous generator , aiming to solve the technical problems of using synchronous generator speed feedback error and serious lag, unable to effectively invest in the oscillation suppression device in a timely manner, and adding additional suppression equipment to the grid-connected converter to increase the device cost and control complexity

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