三相LCL并网逆变器的单电流双环控制策略

为了抑制LCL并网逆变器系统的谐振尖峰,提出了一种单电流双环控制策略。该策略只对并网电流进行采样：内环采用并网电流的二次微分反馈,以配置系统开环传递函数极点,增加系统阻尼;外环对并网电流直接反馈,以跟踪输出电流,提高系统精度。同时,外环采用准比例谐振（QPR）控制器来补偿电流,以减小稳态误差,消除特定次谐波。通过该单电流策略与传统的电容电流内环,并网电流外环策略的对比,以及采用QPR与比例积分（PI）控制器的对比,结果表明本文所采用方法的性能较优。仿真结果验证了该策略能有效抑制并网电流谐波,提高系统的动态性能和稳定性。

Single Current Dual-loop Control Strategy for Three-phase Grid-connected Inverter With LCL Filter

In order to restrain resonant peak of the LCL grid inverter system, a single current double loop control strate- gy is proposed. The strategy only needs to sample grid-side cur- rent. The inner loop uses feedback of quadratic differential of the grid current to set poles for open loop transfer function, and can increase the system damping; The outer loop uses feedback of the grid current directly to track output current and improve the system accuracy. In the meantime, it uses a quasi proportion- al resonant （QPR） controller to compensate current for outer loop, can effectively reduce the steady-state error, eliminate spe- cific harmonies. Compare the single current strategy with the traditional strategy, and QPR controller with proportional inte- gral （PI） controller, the results demonstrate that the method which this paper adopts has a better performance. The simula- tions demonstrate that the control strategy can restrain grid cur- rent harmonics effectively, and improve dynamic performance and stability of the system.