【作者】 袁绍军；

【导师】 孙同景；

【作者基本信息】 山东大学 ， 控制理论与控制工程， 2008， 硕士

【摘要】 随着电力电子技术的快速发展,电力系统的谐波污染日益严重,电能质量问题受到高度重视。一方面,发电厂和变电站的高压电能计量关系到发电、送电、用电三方的利益,这就对电能计量的准确度提出了更高的要求;另一方面,对电网电能质量和使用情况的在线监测对于电网的安全稳定运行和合理收费具有重要意义,可以根据监测结果进行相关分析,减少大量现场校验工作。本文以TMS320F2812 DSP为核心处理器,结合FIR数字滤波和FFT算法,并应用以太网通信技术,设计并实现了电能在线计量与分析系统。本文的主要工作有:首先介绍了目前国内外电能计量分析算法的研究现状,详细分析了本系统的性能指标,提出了以FIR数字抗混叠滤波和FFT相结合的算法。在硬件电路设计上,根据算法的要求选择TI的TMS320F2812 DSP并设计其外围电路。信号调理电路将高压互感器二次侧输出的三相电压电流信号转换为0～5V的信号。应用硬件锁相环技术实现对信号的频率跟踪和同步采样控制。A/D采样电路应用ADS8364对电压电流信号进行同时采样。通信电路采用外扩以太网控制芯片RTL8019AS的形式,实现现场数据的实时远程上报和管理。充分考虑器件选型、信号采样方式、PCB布线、现场屏蔽和接地等相关技术对系统精度的影响,为信号采样和计量分析精度提供了保证。在软件算法上,采用基于DSP捕捉锁相环倍频信号和算术平均滤波算法实现对频率的精确测量;根据锁相环的倍频信号控制ADS8364对信号进行同步采样。采用零点实时校准方法跟踪地通道的纹波,改善采样参数的计量精度。采样后的数字信号通过FIR数字抗混叠滤波器滤除其中含有的高次谐波(32阶以上)分量,再运用FFT算法进行谐波含量和各种电能参数的分析计算;为提高定点DSP浮点运算的速度和精度,采用IQmath函数进行基于Q格式定标的数学运算。对完整的TCP/IP协议进行裁剪,实现其中的ARP协议、IP协议、ICMP中的ping回送应答协议和UDP协议,成功实现与上位机的实时通信。本文所设计的电能在线计量与分析系统在山东电力研究院计量中心测试运行期间工作可靠稳定。本系统能够实现对电能的高精度计量和分析,其中对电压、电流的有效值和有功功率的计量精度达到了0.05级,对谐波含量的分析结果比较精确。更多还原

【Abstract】 With the fast development of power electronics technology, harmonic pollution of power system becomes serious day by day and power quality is attached more importance. On the one hand, it puts forward a higher request to the accuracy of high-voltage power measurement, which relates the interests of power plants, power supply departments and power consumers; on the other hand, online monitor of power quality and using condition, which can reduce a great deal of field check work using the monitored results, has a great significance to power girds’ safely running and reasonable charging.Using TMS320F2812 DSP as its core processor as well as combining FIR digital anti-aliasing filter algorithm, FFT algorithm and Ethernet communication technology, this paper designs and implementes a system which is online power metering and analysing.The main work of this paper as follows:First of all, it introduces the research status of power metering and analysing algorithm, analyzes the technical indicators of this system in detail, and then proposes the FIR digital anti-aliasing filter and FFT algorithm applied in this paper.On design of hardware, TI’s TMS320F2812 DSP is chosen and its peripheral circuits are designed according to requirements of algorithm. Processing circuit converts three phases voltage and current on the second side of high-voltage transformers to 0-5V signals. This paper uses PLL technology to track signal frequency and control synchronous sampling, samples the converted voltage and current synchronously by use of ADS8364. As for communication circuit, it uses Ethernet control chip RTL8019AS to complete real-time field datas report and remote management. What’s more, this system takes fully account of the influence from device selection, sampling methods, PCB routing technology, scene shielding&grounding, and other relating technology to the system’s accuracy, which provides a guarantee to the sampling and metering accuracy.On design of software, this paper achieves accurate measurement of frequency based on DSP capturing multiplied signal of PLL and arithmetic average filter; The multiplied signal of PLL is responsible for controlling the action of ADS8364. This paper puts forward a real-time zero calibration method to track the ripple of ground and improve the accuracy of sample results effectively. FIR DF filter out high harmonics of digital signals after A/D converting, then FFT algorithm analyses the harmonic content of the power grid and waveform’s distortion rate. This paper adopts Q format calibration to improve fixed-point DSP’s floating-point calculation speed and accuracy by use of IQmath functions. At last, this paper cuts the integrated TCP/IP protocol and realizes ARP, IP, ping function of ICMP and UDP protocol, and finally completes real-time communication with PC.Online power metering and analyzing system runs stably during test operation in Shandong Elctric Power Research Institute. This system can achieve high accuracy of power metering and analyzing, it can promise a 0.05 grade metering accuracy of voltage RMS, current RMS and active power, as well as accurate results of harmonic analysis.更多还原