数字控制LCL型并网逆变器的宽频谐波谐振阻尼策略

Considering the low power loss and simple structure, an equivalent impedance model of digitally controlled LCL-type inverter with a widely deployed capacitor-current active damping feedback structure is built first. Then, according to the obtained model, the effects of digital time delay of control system and equivalent grid impedance on active damping performance of inverter, including effective damping region and harmonics resonance characteristics mainly, are investigated in detail. In order to improve the damping performance of digitally controlled LCL-type inverter under the action of digital time delay and grid impedance, a wide-band harmonic resonance damping strategy is proposed based on capacitor-voltage active damping structure finally.