弱电网且谐波畸变背景下分布式电源并网系统谐振抑制

分布式可再生能源接入配电网远端场景下，并网逆变器系统可能同时受到弱电网较大内阻抗及其背景谐波的影响，而仅优化并网逆变器的控制设计却不易有效解决这一问题。提出一种弱电网且谐波畸变背景下分布式电源并网系统谐振抑制方法。该方法将并网逆变器电网电压全前馈控制与并联接入的有源阻尼器相融合，利用前者抑制谐波电压畸变的影响，利用后者重塑并网系统的输出导纳，抑制并网系统与弱电网间的谐振。同时，给出有源阻尼器虚拟电阻阻值的设计方法以及提升并网系统的截止频率的方法。基于Matlab/Simulink的时域仿真结果表明，所设计的并网系统既能够有效抑制谐波电压畸变引发的并网电流畸变，也能够抑制因网侧导纳存在而引起的谐波谐振。

Resonance suppression of a distributed power grid-connected system in a weak grid and with harmonic distortion background

When distributed renewable energy is connected to the remote end of the distribution network, the grid-connected inverter system may be affected by the large internal impedance and background harmonics of the weak grid at the same time. However, the optimization of the control design of the grid-connected inverter is not easy to achieve effectively. A novel resonance suppression method for distributed power grid-connected systems with a weak power grid and harmonic distortion is proposed. In this method, the grid voltage feedforward control of the grid-connected inverter is combined with the active damper connected in parallel. The former is used to suppress the influence of harmonic voltage distortion, and the latter is used to reshape the output admittance of the grid-connected system to suppress the resonance between that system and the weak grid. The design method of the virtual resistance value of the active damper and the method of increasing the cut-off frequency of the grid-connected system are given. The time-domain simulation results based on Matlab/Simulink show that the designed grid-connected system can not only effectively suppress the grid-connected current distortion caused by harmonic voltage distortion, but also suppress harmonic resonance caused by the presence of net side admittance.

This work is supported by the National Key Research and Development Program of China (No. 2021YFB2400900).