一种利于DSP实现的改进型电网电压软锁相环的研究

摘要

Soft phase-locked loop (SPLL) gets more and more applications in the field of modern industrial control, especially in grid voltage phase locking. This paper analyzes the basic structure and working principle of the SPLL and designs an improved grid SPLL according to the shortcomings of traditional SPLL which has large amount of computations and is difficult to achieve on the chip of digital signal processor (DSP). On one hand, the control algorithm is simplified based on the locked nature of the phase angle by reverse thinking. And these builds on the very understanding of the relationship of three-phase voltage coordinate transformation. On the other hand, the PI parameters are calculated dynamically (not the constant PI parameters) which makes phase locking function work dynamically and the control algorithm is more simple. The theoretical analysis and simulation analysis show that the modified SPLL is simple, possesses better performance in dynamic phase tracking, harmonic suppression and detection of unbalanced voltage, etc. , can deal with fault such as power down, and is very appropriate to implement on the DSP.%　　软锁相环(Soft Phase-locked Loop，SPLL)在现代工业控制尤其是电网电压相位锁定中得到越来越多的应用。分析了SPLL 的基本结构和工作原理，针对传统 SPLL 运算量大、不利于在数字处理器(Digital Signal Processor，DSP)上实现的缺点，设计了一种改进型电网电压SPLL。根据电网电压SPLL工作原理，结合坐标变换关系，从结果出发，通过相角已锁定的性质来做逆向思考简化控制算法。动态计算SPLL的PI参数，以使锁相功能动态响应更好、控制算法运算量更少。理论分析、仿真研究都表明改进后的SPLL算法简单，动态响应快，能够抑制电网电压三相不平衡及谐波干扰，能够应对电网突然掉电等故障，非常利于在DSP中实现。