Method and system for suppressing subsynchronous oscillation of new energy unit based on phase modifier

Abstract

The invention discloses a method and system for suppressing subsynchronous oscillation of a new energy unit based on a phase modifier, and belongs to the technical field of subsynchronous oscillation.The method comprises the following steps: adding a subsynchronous oscillation damping control link to an excitation system of a phase modifier arranged in a new energy enrichment area; obtaining a corresponding relation from the damping control link of the excitation system to a stator side output current; adding a subsynchronous frequency electric quantity adjusting link in the excitation system, and determining the transmission characteristics of subsynchronous current / voltage between a phase modifier rotor and a stator winding; and controlling the phase modifier to output reverse voltage or current to a power grid according to a preset damping control strategy when it is monitored that the terminal voltage or current of the phase modifier has a sub-synchronous frequency band oscillation component so as to complete subsynchronous oscillation suppression of the new energy unit. According to the invention, the phase modifier is adopted to inhibit subsynchronous oscillation of the newenergy unit, and a better effect is predicted in economy and controllability.

Description

technical field [0001] The present invention relates to the technical field of subsynchronous oscillation, and more specifically, to a method and system for suppressing subsynchronous oscillation of new energy units based on a condenser. Background technique [0002] The application of series compensation technology, high-voltage direct current transmission (HVDC) technology and large-scale new energy access in the power system may cause subsynchronous oscillation problems. With the rapid development of new energy power generation in my country, subsynchronous oscillation has gradually become a new energy delivery system. One of the stability problems. At present, the new energy weak access system and the doubly-fed wind power centralized transmission system through AC series compensation that use the power electronic converter interface to connect to the grid have experienced multiple synchronous oscillations. Using the converter interface to connect to the grid If direct-dri...

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Problems solved by technology

[0003] At present, the domestic industry is carrying out research on suppression measures for new energy subsynchronous oscillations. Unlike traditional steam turbine unit fixed-frequency point subsynchronous oscillations, the frequency of new energy subsynchronous oscillations may drift within a wider frequency band, showing the characteristics of broadband oscillations. Therefore, the use of steam turbine units The fixed parameter subsynchronous oscillation damping control strategy may not achieve the purpose of improving the damping. At present, the research on the stability mechanism, analysis methods and solutions of diversified power electronic equipment connected to more complex power systems has lagged behind the power electronicization of power systems. Due to the lack of systematic research, operators cannot predict the occurrence of unknown oscillations in advance, the guidance of control methods is insufficient, and the control ability of power electronic equipment cannot be fully utilized. Temporary control measures such as supplementary capacitors ensure system safety

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