Study On Frequency Oscillation Of Power Systems Caused By Wind Power Integration

In recent years,wind power has been connected to the power grid in large quantities.Wind power generation has brought some new problems and challenges while making the grid become more and more green and clean.One of the typical and outstanding problems is the oscillation problem.At present,the oscillation problem caused by the integration of wind power has occurred from time to time,which greatly threatens the safe and stable operation of the power system and also affects the access of wind power.This issue has received great attention from the theoretical and engineering circles.It has not been effectively solved so far,and it is both a hot issue and an open issue.This paper starts some research on this,and the main work is as follows:1.The paper sorts out the typical viewpoints about the oscillation caused by wind power grid connection,summarizes the existing problems and shortcomings,and puts forward the research ideas.This paper believes that there are three questions that need to be answered in this field:(1)When the oscillation occurs(2)How to suppress the oscillation(3)How to use the damping controller.In order to answer these three questions,this paper used a combination of time domain simulation and eigenvalue analysis to discuss.2.The simulation platform was built based on the DigSILENT/PowerFactory software.First,the models of the main components were analyzed,including the doubly-fed induction fan(DFIG),the thermal power generator shaft system,and the synchronous generator.Secondly,based on the IEEE first standard model,a simulation platform was built,including five simulation models,that is,single wind farm connected to large power grid;wind and thermal power through different access points connected to the grid;wind and thermal power connected to the same point and connected to the grid;double wind farms and thermal power connected to the grid;four wind farms and thermal power units connected to the grid3.The factors that may affect the frequency oscillation of the wind power grid were analyzed,and how to construct the oscillation and how to suppress the oscillation were specifically studied.The influencing factors analyzed include wind farm distribution,thermal power unit output,transmission line length,series-compensated reactor parameters,rotor-side converter parameters,and fan shafting parameters.By setting different single influencing factors,multiple influencing factors and other operating conditions,three typical oscillation scenarios were constructed,and the structure and operating point of the system when the oscillation occurs were analyzed.The research results show that the probability of oscillation is small,and it is difficult to construct oscillation.Various measures for suppressing oscillations were studied for the constructed oscillation scene.The results show that many measures can suppress oscillation from the perspective of planning.Based on this,this paper gives some guidance and suggestions at the planning level.4.At the operating level of the power system,an additional damping controller for the converter of the fan is a typical suppression oscillation measure.To this end,this paper discussed some related problems of the additional damping controller,including the effect and use of the additional damping controller in the multi-oscillation mode without oscillation.The analysis indicated that the damping controller can be shielded when there is no oscillation,and multiple sets of different parameters should be set in multi-modality.