The accurate detection of harmonics and reactive currents and the generation of photovoltaic active current reference are essential for the control of three-phase grid-connected photovoltaic power conditioner system. In order to get the photovoltaic active current with same frequency and phase as the positive-sequence fundamental voltage of grid,the influence of parameter K in the amplitude integral positive-sequence fundamental extraction on the phase deviation of output positive-sequence fundamental voltage is analyzed and the relationship between K and frequency/phase deviation of positive-sequence fundamental voltage is derived. The positive-sequence fundamental voltage can be accurately extracted when K is set properly. Synchronous sine or cosine signals can be obtained without PLL. Based on ip-iq method,two standard selectors are applied, which combine randomly the photovoltaic active current with the harmonic or reactive current to form the grid-connection reference current for realizing the random functional combination of active power injection,harmonic restraint and reactive power compensation. Results of the simulation with MATLAB/Simulink and the experiment based on RT-LAB verify the correctness of theoretical analysis.%三相光伏并网功率调节系统控制的关键之一是谐波、无功电流的准确检测和光伏有功电流指令信号的形成.为得到与电网电压正序基波同频同相的光伏有功电流,分析了幅值积分正序基波提取方法中参数K对输出正序基波电压相位偏移的影响,推导出K与频率偏差和正序基波电压相位偏移的关系式,合理取K值可准确提取正序基波电压.该系统无需锁相环可得到同步正、余弦信号.在ip-iq法基础上,引入2个标准选择器,使光伏有功电流与谐波、无功电流任意组合形成并网指令电流,实现有功注入与谐波抑制、无功补偿的任意组合性功能.MATLAB/Simulink仿真和RT-LAB实验结果验证了理论分析的正确性.
展开▼
