VSC并网逆变器振荡的频率耦合导纳建模及影响因素分析

Frequency-coupled Admittance Modeling of VSC Grid-connected Inverter Oscillation&Influencing Factors Analysis

随着双高电力系统的发展,并网逆变器与交流电网之间的振荡问题频发。近年来,此类振荡问题逐渐表现出振荡频率互相耦合的特性,正负序解耦的导纳模型不再适用于这种情况下的振荡分析。频率耦合的导纳模型以及不同因素是如何影响频率耦合的,尚需进一步研究。首先建立了考虑频率耦合的并网逆变器导纳模型,随后基于灵敏度方法分析了不同因素对于频率耦合的影响,并给出了1个可以定量描述系统频率耦合程度的参数。对影响较大的锁相环带宽进行了优化设计,最后通过仿真验证了影响因素的灵敏度分析以及优化设计的正确性。

With the development of power system with high proportion of renewable energy and power electronic equipment,the oscillation problem between three-phase grid-connected inverters and AC grid becomes prominent.In recent years,such type of oscillation problem gradually shows the feature of mutual of different oscillation frequencies,the positive and negative sequence decoupled admittance model is no longer suitable for this oscillation analysis.Therefore,the admittance model of frequency coupling and how the different factors affect the frequency coupling require further study.Firstly,the admittance model of grid-connected inverter considering frequency coupling is established.Then the impacts of different factors on the frequency coupling are analyzed based on sensitivity method,and the parameter that can quantitatively describe the degree of system frequency coupling is given.Optimal design for PLL bandwidth that has high impact on frequency coupling is carried out,Finally,the correctness of analysis of influence factors and optimal design are validated by simulation.