高比例新能源电力系统功角摇摆-暂时工频过电压耦合机理

Coupling Mechanism Analysis of Rotor Angle Swing and Temporary Power Frequency Overvoltage in Power Systems With High Proportion of Renewable Energy

在高比例新能源和大容量直流工程大量投运的背景下,扰动冲击引发的暂态电压安全问题给新能源机组带来的脱网风险亟需开展深入研究。文中旨在研究同步电源功角摇摆与新能源暂时工频过电压的耦合机理。首先,基于两机等值系统,结合等面积定则和电压向量分析功角摇摆过程电压幅值波动特性,理论推导新能源接入系统前后机端电压峰值的解析表达式;其次,提取影响机端电压峰值的关键因素,利用预设最大峰值约束给出各影响因素极限值的求解方法,并结合工程实际辨析极限值解析计算的保守性;最后,给出新能源机端过电压的改善建议,用于指导大规模新能源外送系统实现电力安全可靠送出,光伏火电打捆系统和实际电网的时域仿真结果验证了理论分析的有效性。

With high share of renewable energy sources and large capacity of DC transmission projects,it is urgent to conduct further research on the potential off-grid-risk of renewable energy raised by the transient voltage safety.This paper is to study the coupling mechanism of rotor angle swing and renewable energy temporary power frequency overvoltage.First,for a double-machine equivalent system,the voltage fluctuation characteristics of rotor angle swing process is analyzed by equal area criterion and voltage vector method,and analytic expression of the machine-terminal peak voltage is derived before and after renewable energy connecting to the system.Then,the key factors which affects the peak voltage are extracted,the preset maximum peak value constraint is utilized to obtain the limit value considering the affected factors,and conservatism of the limit value calculation is analyzed combined with practical engineering.Finally,the countermeasures are proposed to improve the overvoltage level of renewable energy,and these suggestions are used to conduct the safe and reliable of power delivery.The theoretical analysis is validated by the time domain simulation on the photovoltaic-thermal-bundled system and the practical system.