以现代雷达为代表的毫秒级脉冲负载会对独立电力系统电能质量造成严重影响,需要系统分析电能质量问题成因,为改善电能质量提供理论依据。文中以柴油发电机组带脉冲负载系统(DGS_PLS )为研究对象,系统研究了脉冲负载工作特性对系统电能质量的影响问题。首先,建立柴油发电机组调速系统模型,并分析转速在周期性脉冲扰动作用下的响应结果;其次,基于脉冲负载的开关函数模型,分析脉冲负载的谐波源特性;然后,通过分析脉冲负载的工作方式,解释功率三相不平衡原因,给出针对DGS_PLS 改进的稳态功率计算方法以量化分析。研究表明,脉冲负载会造成系统频率持续波动;同时会向系统注入大量的间谐波电流,间谐波电流以整数次谐波为中心对称分布,进而造成电压严重畸变;同时脉冲负载稳态功率不能在三相中平均分配,会造成系统三相不平衡问题。最后,通过脉冲负载实验装置对谐波特性分析和三相不平衡问题分析结果的正确性进行验证,总结脉冲负载工作模式对系统电能质量的影响规律。

The millisecond pulse load represented by modern radar will have a serious impact on the power quality of the independent power system, so it is necessary to analyze the cause of the power quality problem in order to provide a theoretical basis for improving power quality. The diesel generator set with pulse load system (DGS_PLS) is taken as the research object, and the influence of the pulse load operating characteristics on the system power quality is systematically analyzed. Firstly, the speed regulation system model of the diesel generator set is established, and the response result of the speed under periodic pulse disturbance is analyzed. Secondly, based on switching function model of pulse load, the characteristics of the harmonic source of the pulse load are analyzed. Then, by analyzing the working mode of the pulse load, the reason of the power three-phase unbalance is explained, and the improved steady-state power calculation method for DGS_PLS is given for quantitative analysis. Studies have shown that pulsed load can cause continuous frequency fluctuations; at the same time, a large amount of inter-harmonic current will be injected into the system. The inter-harmonic current is symmetrically distributed with integer harmonics as the center, which causes severe voltage distortion; Moreover, the steady-state power of the pulse load cannot be evenly distributed among the three phases, which will result in a serious three-phase imbalance in the system. Finally, the results of harmonic characteristic analysis and three-phase unbalance analysis are verified by pulse load experimental device, and the influence law of pulse load working mode on power quality of the system is summarized.

TM721.1