民用谐波源负荷的谐波测量与随机性分析

发布时间：2019-04-27 11:42

【摘要】：非线性家用电器的广泛使用,使得居民负荷产生的谐波对电网的危害日趋严重,它们的谐波发射水平已不容忽视。我国居民负荷分布广泛,如果使用监测设备去评估谐波发射水平,成本无疑是巨大,且不利于谐波治理。因此亟须建立起能有效评估民用谐波源负荷的模型。目前针对民用谐波源负荷的有关的定量研究相对较少,相关模型没有考虑到供电电压对谐波发射水平的影响,系统电压对单个谐波源和特定谐波源组合的影响程度是明确的的,但对于由各种各样家用电器组成的民用负荷来说,系统电压对各次谐波电流的影响很难从理论上去确定,因此论文从实测数据出发,分析了谐波变化规律和系统电压对各次谐波电流的影响程度,然后针对居民谐波源负荷的特点,建立了以单个家用电器为基本单元的从下到上的谐波评估模型。论文主要研究内容如下:(1)对常见民用谐波源负荷的工作电流进行了采样分析,发现它们的谐波电流以3、5、7次为主,且谐波次数越高幅值越低;各次谐波之间的相位分布差异不大。结合主要谐波源的频域模型分析,家用电器的谐波特征和自身结构和参数相关,同时会受到系统电压的影响。在实际的配电网中,供电电压会使非线性家用电器的谐波发射水平降低,对不同次数的谐波作用效果不同;对谐波相位也有影响;(2)对单个住户、单个单元、供电变压器低压侧和高压侧四个测试点的电压电流进行了连续多天采样,分析了功率、各次谐波电流幅值相位等的变化规律,发现并不是所有负荷都对系统中谐波电流有贡献,非线性负载是主要的谐波源,线性负载对住户的发射的谐波影响较小;各次谐波和功率之间的线性相关度不同,3次最高,5次最低,7次呈现出负的线性相关度;系统电压对各次谐波的影响不同,3次谐波相位比较稳定,5、7次谐波相位对系统电压比较敏感;电压畸变率对5次谐波的变化影响较大,电压幅值对7次谐波的变化影响较大;(3)针对由实测数据得出的民用负荷的谐波特点,建立以非线性家用电器为基本单元的民用负荷谐波评估模型。大部分家用电器的使用和居民生活习惯密切相关,因此可以利用相关"时间使用"的统计数据得到家用电器的使用概率,通过蒙特卡罗仿真确定居民谐波源负荷的开关状态,结合家用电器的谐波电流源模型及各次谐波电流的校正系数,计算出单个住户的谐波发射水平。5次谐波电流的校正系数由供电电压畸变率确定;7次谐波电流的校正系数由供电电压幅值电压确定。然后将此刻其他住户的各次谐波电流累加起来,最终确定民用谐波源负荷的集总谐波发射水平。
[Abstract]:With the widespread use of non-linear household appliances, the harmonic generated by household load is becoming more and more harmful to the power grid, and their harmonic emission level can not be ignored. The load is widely distributed in our country. If the monitoring equipment is used to evaluate the level of harmonic emission, the cost is undoubtedly huge, and it is not conducive to harmonic control. Therefore, it is necessary to establish a model which can effectively evaluate the load of civil harmonic source. At present, the quantitative research on civil harmonic source load is relatively few, and the influence of power supply voltage on harmonic emission level is not taken into account. The influence degree of system voltage on the combination of single harmonic source and specific harmonic source is clear, and the correlation model does not take into account the influence of power supply voltage on harmonic emission level. However, for the civil load composed of various household appliances, the influence of the system voltage on each harmonic current is difficult to be determined theoretically, so the paper starts from the measured data. Based on the analysis of the law of harmonic variation and the influence of system voltage on the harmonic current, a bottom-to-top harmonic evaluation model with single household appliance as the basic unit is established according to the characteristics of the harmonic source load. The main contents of this paper are as follows: (1) sampling and analyzing the working current of the common civil harmonic source load, it is found that the harmonic current is mainly 3,5,7 times, and the higher the harmonic number is, the lower the amplitude of the harmonic current is; There is little difference in phase distribution among the harmonics. Combined with the frequency domain model analysis of the main harmonic sources, the harmonic characteristics of household appliances are related to their own structure and parameters, and are affected by the system voltage at the same time. In the actual distribution network, the power supply voltage will reduce the harmonic emission level of the nonlinear household appliances, and have different effects on the harmonic effect of different times, and the harmonic phase will also be influenced by the power supply voltage, and the harmonic emission level of the nonlinear household appliances will be reduced. (2) the voltage and current of single household, single unit, low-voltage side and high-voltage side of power supply transformer are sampled continuously for many days, and the variation rule of power, amplitude and phase of each harmonic current is analyzed. It is found that not all loads contribute to the harmonic current in the system, the nonlinear load is the main harmonic source, and the linear load has little effect on the household harmonic emission. The linear correlation between harmonics and power is different, three times are the highest, five times are the lowest, seven times show negative linear correlation. The third harmonic phase is stable, the 5th and 7th harmonic phase is sensitive to the system voltage, the voltage distortion rate has a greater effect on the fifth harmonic change, and the voltage amplitude has a greater influence on the seventh harmonic change. (3) according to the harmonic characteristics of civil load obtained from the measured data, a harmonic evaluation model of civil load based on non-linear household appliances is established. The use of most household appliances is closely related to the residents' living habits, so the probability of using household appliances can be obtained by using the relevant statistical data of "time use", and the switching state of the residents' harmonic source load can be determined by Monte Carlo simulation. Combined with the harmonic current source model of household appliances and the correction coefficient of each harmonic current, the harmonic emission level of a single household is calculated, and the correction coefficient of the fifth harmonic current is determined by the distortion rate of the power supply voltage. The correction coefficient of the seventh harmonic current is determined by the supply voltage amplitude voltage. Finally, the lumped harmonic emission level of the civil harmonic source load is determined by adding up the harmonic currents of other households at the moment.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM711;TM935

【相似文献】