Analysis of the influence of impedance ratio on critical short circuit ratio of new energy grid connection points

Abstract The short-circuit ratio is widely recognized as an effective indicator for assessing the voltage support strength of AC/DC systems. However, when a specific base value is selected, the short-circuit ratio is merely a parameter defined by the modulus of the system’s equivalent impedance. In real-world systems, the stability of AC/DC power systems is influenced not only by the modulus of Thevenin’s equivalent impedance but also by the phase angle of the impedance. Understanding the relationship between the critical short-circuit ratio and impedance ratio is crucial for guiding new energy integration projects. This paper explores the connections between the impedance ratio, maximum transmission power, and AC system parameters, deriving the relationship between the critical short-circuit ratio and impedance ratio. The study offers valuable insights into using the impedance ratio as an auxiliary criterion for evaluating the strength of the power grid in engineering applications.