对称双芯移相器的接入对距离保护的影响及改进措施研究

对称双芯移相变压器(Phase Shifting Transformer, PST)作为潮流调控设备，能实现输电线路传输功率的调节。然而，PST接入线路后将改变线路阻抗分布、电压和电流信号，可能导致距离保护的误动或拒动。为了消除PST接入对常规距离保护造成的影响，根据PST对各序网故障分量的移相特性、PST序网等效阻抗以及接地、相间测量阻抗算法，推导出PST安装位置、PST移相角、故障位置均会对距离保护产生影响。基于距离保护受PST接入的影响机理，利用对称分量反变换、同步相量测量技术，提出了基于相角补偿和相量测量单元(Phasor Measurement Units, PMUs)的自适应距离保护。在此基础上，利用Matlab/Simulink搭建了PST的模型，并通过仿真验证了PST接入对距离保护影响机理推导的正确性以及所提出的自适应距离保护改进措施的有效性，为未来PST的深入研究和工程应用提供了理论支撑。

Influence of a symmetrical dual core PST on distance protection and improvement measures

As a piece of power flow control equipment, the symmetrical dual core phase shifting transformer (PST) can realize the control of transmission power of a transmission line. However, after the PST is connected to the line, the line impedance distribution, voltage and current signals will be changed. This may lead to misoperation or refusal of distance protection. In order to eliminate the influence of PST access on conventional distance protection, given the phase-shifting characteristics of a PST on fault components of each sequence networks, the equivalent impedance of PST sequence networks and the algorithm of grounding and phase-to-phase measurement impedance are used. It is deduced that the PST installation position, PST phase-shifting angle and fault position will affect distance protection. Based on the influence mechanism of distance protection by PST access, an adaptive distance protection based on phase angle compensation and phasor measurement units (PMUs) is proposed. This uses symmetrical component inverse transformation and synchronous phasor measurement technology. The PST model is built using Matlab/Simulink, and the correctness of the derivation of the influence mechanism of PST access on distance protection and the effectiveness of the proposed adaptive distance protection improvement measures are verified by simulation. This provides theoretical support for the in-depth research and engineering application of a PST in the future. This work is supported by the National Natural Science Foundation of China (No. 51567005).