逆变型电源场站故障稳态电流实用化计算方法

Practical Calculation Method for Fault Steady-state Current in Inverter-interfaced Generator Stations

单机倍乘法常用于逆变型电源场站的故障稳态建模,可简单估算场站短路电流水平,但计算精度有待提升。文中首先分析了低电压穿越控制策略约束下,有功出力、电压跌落程度对发电单元输出的稳态电流的决定性作用,得出故障稳态电流输出特性曲线,基于此分析了场站电气距离及有功出力差异对单机倍乘法计算误差的影响。在误差分析的基础上,提出了计及发电单元分布特性的改进单机倍乘法。该方法在发电单元接入点电压计算中,利用等值阻抗来等效发电单元与并网点的电气距离;将场站分群等值为两台机组,减小发电单元间有功出力差异对短路特性的影响。不同场景下的仿真分析表明,改进方法计算精度较单机倍乘法有着较大的提升。所提方法仅需通过简单计算即可实现场站分群和短路电流聚合,有较好的工程实用性。

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 steadystate 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.