基于SOGI及功率权重占空比前馈控制的单相级联型光伏并网逆变器功率平衡控制

针对于大型级联光伏并网逆变器各级联单元在光照不均匀及光伏阵列之间不匹配时采用集中MPPT存在较大功率损失的问题，本项目提出一种基于二阶广义积分器（SOGI）及功率权重占空比前馈控制的单相级联型光伏并网逆变器的功率平衡控制策略。研究内容主要包括：(1)通过对各级联单元进行独立MPPT控制以实现输出功率最大化，最大限度地利用太阳能；(2)利用改进的电压、电流双闭环控制实现并网逆变器的直流侧电压稳定、并网电流零稳态误差和单位功率因数运行等性能；(3)采用可满足电压外环和电流内环近似解耦的功率权重占空比前馈控制策略，以实现直流侧光伏阵列的最大功率与级联型并网逆变器交流侧的输出功率相平衡；(4)利用SOGI锁相环技术准确而快速地进行同步锁相控制。最后通过仿真和实验研究对理论分析及控制策略进行验证。本项目对以级联型为拓扑的大规模光伏并网发电提供了一种新的控制思路，具有较强的理论意义和实际应用价值。

There are a lot of power losses in the cascaded photovoltaic grid connected inverter when the illumination is not uniform and the photovoltaic array does not match. A power balanced controlling strategy of single phase cascaded photovoltaic grid-connected inverter based on second order generalized integrator and power weight duty ratio feed-forward is proposed. The research mainly includes: (1)the independent MPPT control is used to achieve maximum output power and the use of solar energy; (2)the double closed loop control of voltage outer loop and current inner loop is used to achieve the stability of dc side voltage, grid-connected current zero steady-state error and unit power factor running control performance; (3)the power balanced controlling strategy of the power weight duty ratio feed-forward is able to meet the approximate decoupling of voltage outer loop and current inner loop, which achieves the Output power of AC side of photovoltaic grid connected inverter is balance with the maximum power of DC side photovoltaic array ; (4)using SOGI phase locked loop technology realizes synchronous phase lock control accurately and quickly. Finally, the theoretical analysis and control strategy are verified by simulation and experiment. This project provides a new control method for large-scale grid connected photovoltaic power generation, which has strong theoretical and practical value.