Offshore wind turbine group grid-connected resonance stability discrimination method based on impedance modeling

Abstract

The invention relates to an offshore wind turbine group grid-connected resonance stability discrimination method based on impedance modeling, and the method comprises the following steps 1) constructing a linearized state space model of a large-scale offshore wind turbine group based on a double-fed wind turbine generator through an AC grid-connected system; 2) establishing an equivalent impedancemodel of the doubly-fed wind turbine generator; 3) establishing an offshore wind turbine group submarine cable single-machine grid-connected equivalent model, and obtaining submarine cable single-machine grid-connected equivalent impedance; and 4) according to the offshore wind turbine group submarine cable single-machine grid-connected equivalent model and the impedance model of the doubly-fed induction fan, judging the stability of the offshore wind turbine group submarine cable single-machine grid-connected equivalent model by adopting a Nyquist stability criterion and a Bode diagram, andwhen the single-machine grid-connected equivalent model tends to be stable, considering that the original offshore wind turbine group grid-connected system tends to be stable. Compared with the priorart, the method has the advantages of simplified judgment, accurate judgment and the like.

Description

technical field [0001] The invention relates to the technical field of wind power grid-connected operation, in particular to a method for judging the grid-connected resonance stability of a large-scale offshore wind power group based on impedance modeling. Background technique [0002] In recent years, global warming has become an important and widely discussed topic, and the current core issue is how to reduce carbon dioxide emissions. For the power system sector, increasing renewable energy generation seems to be the best and most practical way to solve this problem Among the new energy sources, wind power generation technology is relatively mature, and wind power resources are abundant, which can be widely used around the world. According to the report of the European Wind Energy Association, by the end of 2020, Europe will install about 230GW of wind power units, which will provide The European Union provides 14-17% of electricity. [0003] Since the 21st century, the n...

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Problems solved by technology

[0004] At present, some studies have used the impedance-based stability criterion to judge such interconnected systems. The criterion shows that the output impedance of the generator and the grid impedance must meet the Nyquist stability criterion, so that the entire system can remain stable. For such unstable problems, existing methods require detailed inverter control models, transformers and transmission cable models, and coupling grid-connected equipment with other cables, and the calculation model is complex

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