Title: A Novel Decoupled LVRT Control Strategy for Transient Voltage Stability Enhancement of IBRs Using Voltage-Angle Coupling Analysis Show Chinese title

Title: 一种基于电压角度耦合分析的新型解耦LVRT控制策略，用于增强IBRs的暂态电压稳定性

Abstract: With the fast-increasing penetration of inverter-based resources (IBRs), the voltage support capability of the grid following (GFL) IBRs under low voltage ride through (LVRT) control significantly influences the transient voltage stability of the power system. The existing LVRT adjusts the q-axis current to regulate reactive power injection. However, under a large disturbance, the phase-locked loop (PLL) error invalidates the proportional relationship between the q-axis current and reactive power, consequently causing deviation in the actual reactive power injection of the IBR. Besides, the variation of IBR current, determined by the PLL phase and LVRT, also directly influences the transient voltage. To address this issue, the specific influence of PLL error on active and reactive power injection is first analyzed under LVRT control. In addition, by combining the LVRT and PLL dynamics, the mechanisms of three voltage problems caused by voltage angle coupling are revealed. overvoltage, low voltage, and DC-side overvoltage. The specific scenarios in which these voltage stability problems occur are also obtained by the voltage-vector-triangle graphic. Furthermore, a power angle decoupled LVRT control is proposed to eliminate the influence of voltage angle coupling. Finally, the mechanism analysis and effectiveness of the decoupled LVRT are verified in the case study. Show Chinese abstract

Abstract: 随着基于逆变器的资源（IBRs）的快速渗透，电网跟随（GFL）IBRs在低电压穿越（LVRT）控制下的电压支持能力显著影响电力系统的暂态电压稳定性。 现有的LVRT通过调整q轴电流来调节无功功率注入。 然而，在大扰动下，锁相环（PLL）误差会破坏q轴电流与无功功率之间的比例关系，从而导致IBR的实际无功功率注入出现偏差。 此外，由PLL相位和LVRT决定的IBR电流变化也会直接影响暂态电压。 为了解决这个问题，首先在LVRT控制下分析了PLL误差对有功和无功功率注入的具体影响。 此外，通过结合LVRT和PLL动态，揭示了由电压角度耦合引起的三种电压问题的机制：过电压、低电压和直流侧过电压。 通过电压矢量三角形图，也获得了这些电压稳定性问题发生的特定场景。 此外，提出了一种功率角度解耦的LVRT控制，以消除电压角度耦合的影响。 最后，在案例研究中验证了解耦LVRT的机制分析和有效性。