【作者】 马玉龙；

【导师】 刘连光；

【作者基本信息】 华北电力大学 ， 电力系统及其自动化， 2001， 硕士

【摘要】 我国电能质量国家标准主要规定了五个指标—频率、谐波、电压偏差、电压三相不平衡及电压波动与闪变。本论文的目标就是研制能实时监测上述五项电能质量指标的数字式装置，它是电能质量监测系统的厂站装置，负责为远方监控中心提供现场监测结果。 本文选用FFT来计算电压偏差、三相不平衡度和谐波含量。频率的测量选用过零点检测法。 在国内还没有很好的电压波动与闪变的数字处理方法。本文的一项重要工作就是依据IEC标准和电压波动与闪变国家标准，在对电压波动与闪变仿真的基础上研究电压波动与闪变测量的数字化实现方法，仿真结果表明所提方法能很好地满足IEC所提的精度要求。 在硬件系统设计上，选用ISA总线的工控机结构。为解决谐波测量和闪变测量在采样频率和计算周期上的矛盾，采用主从式CPU结构。为减小FFT分析过程中出现的频谱泄漏现象，硬件电路设计上采用了锁相环倍频技术，可以实现每周波128点同步采样。工控机还自带有液晶、硬盘、面模键盘等必要的辅助设备，可以实现监测结果的就地显示、存盘等功能。作为电能质量监测系统的厂站装置，还设置了通信端口，可以将厂站装置的测量结果上传到远方监测中心。 根据所选定的电能质量测量方法和硬件电路结构，用VisualC++6.0编写了实现上述目标的软件代码。更多还原

【Abstract】 AbstractFive items, with frequency, harmonics, voltage deviation and voltage fluctuation and flicker respectively, are included in the state standards of energy quality. The main work of this paper is to study a new digital device according to these standards, which is the remote terminal of the supervisory and measuring system of energy quality.FFT is used to get the basic characteristic value, such as the amplitude and phasor of the harmonics. Once the amplitude and phase is attained, three of the five items of state energy quality including harmonics, voltage deviation and three-phase unbalance, is derived. Zero-crossing algorithm is used to get the system frequency. To avoiding the disadvantageous influence of distorting waveform to the zero-crossing point, filter around working frequency is added.The analog system of the IEC flickermeter is simulated. Then the algorithm of digital system is studied and the digital design result is presented subsequently. Simulation result proved that the algorithm and method presented to be correct and acceptable. This makes it possible to continue the supervisory and measuring device.Hardware is designed with a system of industrial controlling structure. Structure of ISA bus and two CPU is adopted. The two CPU’s task is allocated as following: the auxiliary CPU only performs the task of flicker-measuring and frequency-measuring, and the main CPU performs the evaluation of harmonics and other tasks such as saving result. Another disadvantage of DFT or FFT is the leakage of frequency spectrum when synchronous sampling is not satisfied. To avoid this, synchronous sampling method is adopted which is composed with a phase-locking ioop and frequency-multiplying circuit.Finally, the software corresponding to the above algorithm is developed, which can implement the design aims such as evaluating displaying and saving.更多还原