基于分布式潮流控制器的海上风电系统谐波治理方法和控制策略

Harmonic Mitigation Method and Control Strategy of Offshore Wind Power System Based on Distributed Power Flow Controller

由于电力电缆的电容效应,海上风电经电缆汇集系统极易出现谐波谐振放大的现象,造成电能质量的下降。分布式潮流控制器属于基于电压源换流器的装置,在进行潮流调节的同时也能进行谐波治理。文中首先构建了海上风电系统的频域相关模型,基于该模型分析了谐波谐振放大的原因;随后,采用了将分布式潮流控制器串入海上风电系统的谐波治理方式,推导并得到了含分布式潮流控制器的海上风电系统的谐波特性。基于该谐波特性,设计了一种控制策略。该策略通过控制分布式潮流控制器实时跟踪使并网点谐波电压幅值为零的谐波补偿电压,从而降低并网点的谐波电压含量。仿真结果表明,所提出的基于分布式潮流控制器的海上风电系统谐波治理方法和控制策略能够有效地降低并网点的谐波电压,改善电能质量。

Due to the capacitive effect of power cables,the phenomenon of harmonic resonance amplification tends to occur in the offshore wind power collection system via power cables,which leads to decline in power quality.The distributed power flow controller(DPFC)is a device based on the voltage source converter,which can regulate power flow and control harmonics at the same time.In this paper,the frequency-domain correlation model of the offshore wind power system is constructed,and the reason for harmonic resonance amplification is analyzed based on this model.Then,the harmonic mitigation method of connecting the DPFC to the offshore wind power system is proposed,and the harmonic characteristics of the offshore wind power system with the DPFC are derived.Based on the these characteristics,a control strategy is designed,which reduces the harmonic voltage content of the grid-connected point by controlling the DPFC to track the harmonic compensation voltage that makes the harmonic voltage amplitude at the grid-connected point zero in real time.The simulation results show that the proposed harmonic mitigation method and control strategy of the offshore wind power system based on DPFC can effectively reduce the harmonic voltage at the gridconnected point and improve the power quality.