Voltage-controlled virtual synchronization method for doubly-fed wind turbines

Abstract

The invention discloses a voltage control type virtual synchronizing method of a double-feed wind power generator set. Through simulating inertia and a frequency-modulating and voltage-modulating characteristic of a synchronizer, the set can be different from a characteristic of no electric grid frequency change response in a traditional current control type, thereby possessing capability of supporting voltage and frequency of a weak power grid based on the voltage control type through virtual inertia. The method provides and realizes a VCT-DFIC virtual synchronous control structure of which an inner ring is controlled by an improved double-feed generator stator voltage rotor current double-closed-loop structure based on adaptive stator virtual impedance and transmission line sag voltage feedforward compensation in a control manner which includes crossed control between stator voltage and rotor current and furthermore an outer ring is controlled by a virtual synchronous realizing algorithm. The method realizes output power control in VCT-DFIG grid integration operation in a weak grid condition with any actual impedance and effective decoupling, and furthermore a designed control structure realizes higher inertia and frequency supporting capability of the double-feed generator.

Description

technical field [0001] The present invention focuses on the technical field of new energy power generation and researches a doubly-fed generator control method, relates to a voltage-controlled strategy for parallel operation with a weak grid, and in particular relates to a voltage-controlled virtual synchronization method for a doubly-fed wind power generating set. Background technique [0002] With the continuous development of grid-connected operation of renewable energy, the application of new energy with high penetration rate and large capacity makes the power grid present the characteristics of low inertia and weak damping. In addition, energy utilization based on distributed forms and long-distance transmission lines also cause The non-negligible line impedance, so when distributed new energy such as photovoltaic and wind power is generated and the weak grid is running, there are a series of "weak" (low inertia, weak damping, high line impedance and low short-circuit ca...

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Problems solved by technology

[0011] Based on the existing research, the present invention focuses on the low inertia, weak damping and line impedance characteristics of the weak grid and its influence on the performance of the doubly-fed wind turbine integrated into the weak grid. The main purpose is to solve the Problems such as power coupling and oscillation under interaction, realize doubly-fed generators supporting weak grids and grid-connected active and reactive power control

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