基于幅值线性变化模型的频率测量新算法

A Novel Frequency Measuring Algorithm for the Power System Based on a Linear Amplitude Model

基于短时间内电流幅值线性变化模型,提出了一种用于精确测量电力系统瞬时频率的新算法,为系统提供实时状态变量。算法假设连续4个采样点对应电流的幅值线性变化,经过严格的数学推导,再结合泰勒展开和数学等比定理计算系统的瞬时频率。定性分析了幅值线性变化模型带来的误差,给出了泰勒展开和A/D转换引起的频率测量误差。该算法具有实现简单和测频速度快等优点,不需要采用数字滤波技术。该测频算法用于系统正常运行、没有振荡的单一频率情况时,理论误差接近于0。仿真结果表明,不论系统是否振荡、振荡是否剧烈,该测频算法都有很高的测量精度,且对电流中的随机噪声具有很好的适应性。

A novel frequency measuring algorithm for the power system is presented based on a model with linear current amplitude during a brief time. The frequency measuring algorithm provided is used to obtain accurate instantaneous parameters for the power system. In the algorithm, the amplitudes of four consecutive sampling currents are supposed to be linear. After rigorous mathematical deduction, including Taylor series expansion and the geometric proportion theorem, the instantaneous frequency can be derived. The errors due to the linear amplitude model are analyzed qualitatively and those of the A/D converter and Taylor series expansion are considered. By the proposed technique, without any digital filters, the measured frequency can be derived easily, quickly and accurately. The simulation results show that swing or not, gentle or violent, the algorithm proposed is highly accurate and easily adapted tO the random noise in the current.