基于暂态过电压约束的新能源并网系统电压支撑强度量化分析方法

Quantitative Analysis of System Strength of Renewable Energy Generation Grid-connected System Based on Transient Overvoltage Constraint

在新能源并网系统中,具有动态无功支撑能力的新能源机组是引发工频暂态过电压的重要无功源,新能源并网系统电压支撑强度对暂态过电压水平有着重要影响。该文计及新能源并网系统多馈入支路之间的相互影响,采用短路比指征电压支撑强度,建立量化电压支撑强度对暂态过电压影响程度的数学关系模型。首先,针对单馈入系统,分析暂态过电压发生时刻并网点电压与无功功率、短路容量之间的关系,建立单馈入系统暂态过电压数学分析模型。然后,采用电压相量法分析多馈入系统中各支路之间的相互作用对暂态过电压的影响,建立多馈入系统的暂态过电压数学分析模型;以短路比作为电压支撑强度的表征指标,依据该模型量化分析电压支撑强度与暂态过电压之间的关系,系统短路容量越小,无功盈余越多,暂态过电压越严重。其次,以1.3pu作为暂态过电压问题的安全约束,提出满足该约束下交流系统最小短路容量以及新能源并网系统最大无功规模的计算方法。最后,分别建立多个场景的算例,验证暂态过电压数学分析模型的准确性以及系统最小短路容量及最大无功规模计算方法的有效性,为新能源并网规划与运行提供参考。

The strength of system with renewable energy generation(REG)has an important impact on the severity of transient overvoltage.A quantification method is proposed by using the short-circuit ratio(SCR)as the system strength index and considering the interaction in multi-infeed systems.First,the relationship is analyzed among the voltage,reactive power,and short-circuit capacity at the transient overvoltage moment.Furthermore,the interaction in multi-infeed systems is analyzed by using voltage phase method,and the mathematical model for multi-infeed system is established.The correlation between the system strength and the transient overvoltage is analyzed by combining SCR and this model.Meanwhile,a quantitative method of REG maximum scale is proposed by taking 1.3pu as the constraint due to the transient overvoltage,and the calculation method of minimum short-circuit capacity is proposed to improve system strength.Finally,the correlation between system strength and transient overvoltage is verified by examples.