同步相位与瞬时对称分量的检测新方法

Novel Method for Detecting Synchronous Phases and Instantaneous Symmetrical Components

电网不对称故障时,快速、准确地检测同步相位和对称分量,是基于电压源逆变器的灵活交流输电系统(FACTS)装置实现控制与保护的关键问题之一。在分析传统三相锁相环工作原理和负序分量影响锁相环(PLL)检测性能的基础上,设计了一种同步相位与对称分量的一体化实时检测新方法。该方法在正负序同步坐标系下采用电压前馈补偿实现对称分量的检测,用测得的基波正序电压q轴分量作为锁相环的输入,用锁相环的输出相位作为同步坐标变换的参考相位。并分析了该方法实现的机理,给出了检测电路的实现框图,同时进行了实验验证。结果表明,该方法既能在电网电压不对称时准确检测同步相位和对称分量,又能消除交流系统频率变化对检测同步相位和对称分量的影响。

Under AC power system fault conditions, detecting synchronous phase and instantaneous symmetrical components quickly and accurately is an important part of the control and protection system of voltage source inverter （VSI） based FACTS（ Flexible AC Transmission）. Consequently, based on the analysis of the working principle of phase lock loop （PLL） and the influence of negative sequence voltage components on the PLL＇s detecting perform- ance, a novel integrated method for detecting synchronous phase and instantaneous symmetrical components was proposed. A feed-forward voltage compensating method based on dual synchronous frame was adopted in the meth- od, q axis component of the fundamental positive voltage was used as input of the PLL and the output of PLL was used as reference phase of synchronous frame transform. Moreover, the implementation mechanism of the proposed method was analyzed, and the block diagram of the detecting circuit is given and verified by experimental research. Experimental results show that the proposed method can not only detect synchronous phase and instantaneous sym- metrical components accurately under unbalanced source voltage but also eliminate the influence of frequency diversi- fication on detecting synchronous phase and instantaneous symmetrical components.