A Dynamic Equivalence Method of DFIG Based on Equivalent Power Angle Coherence

Abstract

The invention discloses a dynamic equivalence method for double-fed wind turbines on the basis of equivalent power angle co-modulation. The method comprises the following steps of 1, processing statorand rotor voltage flux linkage equations of all the double-fed wind turbines in a wind farm, ignoring stator voltage drop and constructing equivalent transient internal potentials of the double-fed wind turbines; 2, using the included angles between the equivalent transient internal potentials and terminal voltage as equivalent power angles of the double-fed wind turbines, using the equivalent power angles as determining criteria on co-modulation among the double-fed wind turbines, and comparing disturbed trajectories of the equivalent power angles between every two double-fed wind turbines to determine division of co-modulation units of the wind farm; 3, using active power output by the double-fed wind turbines as weights, obtaining equivalent transient internal potentials of equalizers,and connecting transient internal potential buses of the same group of double-fed wind turbines to equivalent transient internal potential buses of the equalizers through complex-ratio phase shiftingtransformers respectively; 4, calculating equivalent parameters of the equalizers, and connecting equivalent transient internal potential buses of the equalizers to the equalizers through equivalentdouble-fed wind turbine impedors.

Description

technical field [0001] The invention relates to the field of equivalent modeling of wind farms in new energy power generation technology, in particular to a dynamic equivalent method for double-fed wind generators based on equivalent power angle coherence. Background technique [0002] With the rapid development of the modern power industry, large-scale AC and DC interconnected power systems have emerged, and the characteristics of multi-machines (thousands of machines) and large power grids (thousands of lines and thousands of busbars) have become more and more prominent, which makes the power system The calculation of planning, design and operation mode has become extremely cumbersome and complicated. On the one hand, it takes a lot of time and space to complete these calculations in detail. On the other hand, due to the limitation of simulation scale and hardware equipment, the above calculations are difficult to realize in practice. To this end, some reasonable simplifi...

AI Technical Summary

Problems solved by technology

At present, there are few relevant literatures on how to distinguish the coherent characteristics of wind farms. The relevant literatures propose a method of coherent grouping according to the characteristic quantity, but this kind of method has the problem of whether the selection of the characteristic quantity is complete, and the universality of this method is an obstacle. The bottleneck of its application

The similarity grouping based on disturbed trajectories is a common method for multi-machine system grouping, and the power angle of the generator is often used as the observation value. Unlike the synchronous motor, due to the existence of power electronic equipment in the doubly-fed fan, the Its external dynamic characteristics are quite different from those of traditional synchronous generators. Therefore, when performing coherence discrimination on wind turbines, there is no consensus on which variable disturbed trajectories to use for comparison.

In addition, since the doubly-fed wind turbine adopts decoupling control, it does not reflect the inertia externally, and its impact on the system is only characterized by the amount of output power. At present, there are few relevant literatures on the method of wind turbine parameter aggregation.

Images