矿用智能供电系统高精度测频算法的研究

Study on the high precision frequency measurement algorithm in the mine intelligent power supply system

为解决矿用供电系统在频率时变条件下测频算法误差大的问题,提出一种改进的软件过零点算法。该算法建立了系统电压的相位角、时间和频率的关系式,根据相邻两个同方向的过零点相位相差2π的关系,推导出频率变化率非零条件下过零点处的实时频率与周期的关系式,综合运用牛顿三次插值多项式、牛顿迭代法和秦九韶算法得出周期计算公式,精确求解出实时频率和频率变化率。MATLAB仿真结果表明,该算法在供电系统待测信号中不含谐波、含有谐波和随机噪声以及系统频率在故障时快速下滑等情况下均可精确测量频率和频率变化率,在测量精度、实时性和计算量等方面优于传统过零点测频算法,完全适用于矿山智能供电系统中保护和测控类装置以及相关自动化设备的实际应用。

To solve the problem of the error of frequency measurement algorithm with time-varying frequency in mine power supply system,an improved software zero-crossing algorithm is proposed. The relationship among the phase angle,the time and the frequency of the voltage of the system is established. The relation formula between the real-time frequency and the period of zero-crossing point is derived when rate of frequency variation is not zero according to the relationship between two adjacent with the direction of the zero-crossing phase difference of 2π. The exact calculation formula of the period is obtained by using the Newton three interpolation polynomial,the Newton iteration method and the Qin Jiushao algorithm. Hence,the frequency and rate of frequency variation can be obtained. A variety of situations,including signals without harmonics,signals with harmonics and random noise,as well as the frequency rapid decline process in system failure,are simulated using MATLAB,The simulation results show that the algorithm of this paper can accurately measure the real-time frequency of the system and rate of frequency variation in above situations,and this method is superior to conventional zerocrossing algorithm in measurement accuracy,instantaneity and computation. This algorithm is suitable for application of protection,control and monitoring devices and automation equipment in mine intelligent power supply system.