逆 变 型 电 源 场 站 故 障 稳 态 电 流 实 用 化 计 算 方 法

The single-unit multiplication method is commonly used for fault steady-state modeling of inverter-interfaced generator stations to simply estimate the short-circuit current level. But its calculation accuracy needs to be improved. First, the decisive effect of active power output and voltage dips on the steady-state current output of the power generation unit under the constraints of the low voltage ride-through control strategy is analyzed in this paper. Then, the output characteristic curve of the fault steady-state current is derived. Based on this, the effects of the differences in electrical distance and active power output of the station on the calculation error of single-unit multiplication method are analyzed. On the basis of error analysis, an improved single-unit multiplication method considering the distribution characteristics of power generation units is proposed. The method uses the equivalent impedance to equate the electrical distance between the power generation unit and point of common coupling in the calculation of the voltage at the access point of the power generation unit. The station grouping is equated into two units for reducing the impact of the difference in active power output between the power generation units on the short-circuit characteristics. Simulation analysis in different scenarios shows that the improved method has a large improvement in the calculation accuracy compared with single-unit multiplication method. The method proposed has good engineering practicality as it can achieve station grouping and short-circuit current aggregation with simple calculations.