基于全局同步脉宽调制的电容高次谐波电流抑制方法

摘要

With the steady penetration of inverters,the switching harmonics caused by power electronic devices will bring about adverse effect to the microgrid.When many inverters are connected in parallel,the high harmonics can either be injected into its own AC filter capacitor or into AC filter capacitors of other inverters.The high harmonics will accumulate randomly for lack of coordinated control among pulse width modulation (PWM) signals.And the high order harmonics can reduce the lifetime of AC filter capacitors.An attenuation method of high harmonic current for filter capacitors based on global synchronous pulse width modulation is proposed.Firstly,the high harmonics injection principle of AC filter capacitors is deeply analyzed and the basic principle of attenuation method of high harmonic current for capacitors based on global synchronous pulse width modulation is proposed.Secondly,the general formulas of calculating high harmonics flowing into capacitors are derived.Thirdly,mathematical expressions are chosen appropriately and the optimal solution of phase shift angles among distributed inverter is obtained.Finally,simulation results are presented to verify the performance of the proposed method.%随着微电网中逆变器渗透率的不断提高,由电力电子器件产生的高次谐波对微电网设备造成了不利影响,其中,当多台逆变器并联运行时,其产生的高次谐波除了注入逆变器自身的交流滤波电容外,还会注入其他并联逆变器的交流滤波电容产生高次谐波电流随机叠加现象,影响电容寿命.提出一种基于全局同步脉宽调制技术的逆变器电容电流谐波抑制方法.首先,对多并联运行逆变器的电流谐波注入电容机理进行了分析,并提出了利用全局同步脉宽调制方法抑制电容高次谐波电流的基本原理和方法.其次,推导出适用于各种运行状态下电容电流谐波和脉宽调制波相位差之间的数学表达式.然后,根据逆变器类型选择适当的数学模型,对数学模型进行求解并获得脉宽调制最佳相位差.通过仿真分析对所提方法进行了验证.