Research On Reduced Order Model Of Doubly-fed Wind Generator

As increasing of the requirement from the grid to the wind parallel operation ability, the control optimization of wind power system is more and more important, and the analysis of the wind generator system modeling is becoming more and more indispensable. This article carried out the research from several aspects as:the principle and model of doubly-fed wind generaror, order reduction method, comparision of the simplified models, and dynamic equivalence of wind farm based on the simplified model.Based on the establishment of the mathematical model and the control technology of doubly-fed wind generator, this paper discusses the order reduction method of the doubly-fed wind generator; then this paper introduces the process from the whole order electromagnetic model to the simplified model and end to electromechanical transient model. On the one hand, it simplifies the Motor Side Converter model and the Grid Side Converter with a controlled voltage source inverter respectively, to simulating the exciation voltage as well as the network side voltage of the Grid Side Converter.By using this method to build the electromagnetic simplifed model. Then taking the simplification of the generator model in consideration, using a controlled current source instead of the whole generator-converter model to simulate the external characteristic of wind machine, it can build the electromechanical transient model.This paper makes detail comparisions with those of the whole order model and simplified models from three aspeces:including the main structural and parameters differences, running characteristics under normal working condition with a stepped wind speed and low voltage condition with constant wind speed, as well as the calculation speed. Based on the differences coparisions, this paper discusses the reasons contributed to all of those results.This article introduces main steps of dynamic equivalence of wind farm based on the simplified model, including generator group identified, equivalent of parameters, equivalent of input and so on; then, taking a example of a wind farm consists of1lwind generators for example, by comparing the simulation reslts of the equivalence model with the whole order detail model, to verify the validity of the proposed wind dynamic equivalent method.