基于提升距离保护适应性的改进VSG控制策略研究

Improved VSG Control Strategy to Enhance the Adaptability of Distance Protection

随着新能源的大规模并网,新能源虚拟同步发电机(VSG)控制技术得到广泛应用。针对现有VSG控制下传统距离保护动作失效的问题,提出1种基于提升距离保护适应性的改进VSG控制策略。首先,对传统距离保护失效的原理进行分析;然后,以减小故障点两侧电流相位差为控制目标,通过定量设计VSG内环控制中的虚拟阻抗值,实现对换流器输出故障电流特性的主动控制;最后,在Matlab/Simulink中搭建新能源并网交流线路发生短路故障时的仿真模型。仿真分析表明,所提改进VSG控制策略能有效支撑传统距离保护的动作可靠性。

With the large-scale grid integration of new energy,virtual synchronous generator(VSG)control is supposed to be widely used.Aiming at the failure of traditional distance protection action under the existing VSG control,an improved VSG control strategy based on improving the adaptability of distance protection is proposed.Firstly,the mechanism of distance protection invalidation is analyzed.Then,with the reduction of current phase difference between the two sides of the fault point as control target,the active control of converter output fault current characteristics is realized by quantitatively designing the virtual impedance value in VSG inner loop control.Finally,the simulation model of short circuit fault when new energy grid is connected with AC line is built in Matlab/Simulink.The simulation results indicate that the proposed control strategy can effectively support the operational reliability of conventional distance protection.