三相四线制低压配电网谐波和瞬时无功电流检测方法的改进

发布时间：2018-10-23 17:35

【摘要】：随着电力工业以及半导体工业的迅速发展,换流设备也随着得到广泛的应用。与此同时,大量非线性负荷增加,电压畸变谐波污染严重,无功功率消耗严重等问题严重影响了供电质量和电网的安全稳定运行。谐波的有效抑制和无功功率的动态补偿已成为我国电力事业工作人员的一大急需解决的课题。三相四线制供电方式是我国低压配电网最主要的供电方式,而现在最为流行的无功补偿装置SVG在三相四线制电网中的应用还不是很广泛。本文着重分析了 SVG的工作原理,工作特性,电流控制方式等,分析了 SVG在三相四线制电网中的主电路拓扑结构,并对他们做出分析对比,选择了最适合本论文设计的拓扑结构。解决谐波污染问题的一个重要方面是将变流器自身改进成为单位功率因数变流器,而SVG变流装置的主拓扑结构电路采用多重化技术和PWM技术配合来减低谐波污染就是对这一原理的应用,采用这样控制技术的变流装置其自身的高频次谐波极易被过滤,低次数谐波也容易被消除。无功电流检测的准确与否直接制约了无功补偿装置的补偿性能,本文主要分析对比了 SVG最常用最快捷的两类谐波和无功电流检测方法,并探讨了这三种检测方法建立的功率理论依据。通过公式推导和仿真分析指出:dq检测方法能够直接应用于三相四线制电网的无功电流检测当中。在这点上,ip-iq检测方法和pq检测方法未能超过dq检测法,需要进行零序电流分离环节才可以适用在三相四线制电网中。本文还分析了上述三种谐波和无功电流检测方法在电网不平衡运行情况的无功电流检测性能,通过仿真分析得出结论在电网电压不平衡的情况下,由于锁相环的未能准确提取电网正序基波电压,严重影响了受检测的无功电流的准确性和和检测的快速性。本文针对传统方法的不足提出了一种瞬时无功电流检测方法的改进方法,针对ip-iq法不能直接应用于三相四线制电网中这个缺点,提出了零序电流分离环节;针对锁相环对检测方法带来的误差,用本文设计的幅值积分器来将其替代,其各个环节分别是:正序电压获得环节,幅值积分器过滤交流分量环节。在ip-iq法的基础上对改进方法进行了simulink仿真模拟,通过和传统方法的对比验证了新方法检测的准确性和实时性。
[Abstract]:With the rapid development of power industry and semiconductor industry, converter equipment has been widely used. At the same time, a large number of nonlinear load increases, voltage distortion harmonic pollution is serious, reactive power consumption and other problems seriously affect the quality of power supply and the safe and stable operation of the power network. The effective suppression of harmonics and the dynamic compensation of reactive power have become an urgent task for electric power workers in China. Three-phase four-wire power supply system is the most important power supply mode in low-voltage distribution network in China, but the most popular reactive power compensation device SVG is not widely used in three-phase four-wire power network. In this paper, the working principle, working characteristics and current control mode of SVG are analyzed, and the main circuit topology of SVG in three-phase four-wire power network is analyzed and compared. The topology which is most suitable for the design of this paper is selected. An important aspect of solving the problem of harmonic pollution is to improve the converter itself into a unit power factor converter. And the main topology circuit of SVG converter adopts the cooperation of multi-heavy technology and PWM technology to reduce harmonic pollution, which is the application of this principle. The high frequency and order harmonics of the converter with such control technology are easily filtered. Low-order harmonics are also easily eliminated. The accuracy of reactive current detection directly restricts the compensation performance of reactive power compensator. This paper mainly analyzes and compares the two kinds of harmonic and reactive current detection methods most commonly used and most quickly in SVG. The power theory basis of these three detection methods is also discussed. Through formula derivation and simulation analysis, it is pointed out that dq detection method can be directly applied to reactive current detection of three-phase four-wire power grid. At this point, the ip-iq detection method and the pq detection method can not exceed the dq detection method, and the zero-sequence current separation link is needed in order to be suitable for three-phase four-wire power network. This paper also analyzes the reactive current detection performance of the above three harmonic and reactive current detection methods in the unbalanced operation of the power network, and draws a conclusion through the simulation analysis that the power grid voltage is unbalanced. Due to the failure of PLL to accurately extract the fundamental voltage of the positive sequence of the power grid, the accuracy of the detected reactive current and the speed of detection are seriously affected. In this paper, an improved method of instantaneous reactive current detection is proposed to overcome the shortcomings of traditional methods. Aiming at the shortcoming that ip-iq method can not be directly applied to three-phase four-wire power grid, a zero-sequence current separation link is proposed. In view of the error caused by PLL to the detection method, the amplitude integrator designed in this paper is used to replace it. Each link is: positive sequence voltage acquisition link, amplitude integrator filter AC component link. Based on the ip-iq method, the improved method is simulated by simulink, and the accuracy and real-time performance of the new method are verified by comparing with the traditional method.
【学位授予单位】：沈阳农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM930

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