Power grid instantaneous frequency measuring and tracking method based on orthogonal sub-band

Abstract

The invention discloses a power grid instantaneous frequency measuring and tracking method based on an orthogonal sub-band. The method comprises the steps that discrete sampling is carried out on an analog input signal; the signal after discrete sampling is filtered by a constructed orthogonal filter group, and is divided into two sine sub-band signals with the phase difference of 90 degrees; the mathematical relationship among three random and continuous sampling points in the sine sub-band signals is used to respectively calculate the instantaneous angular frequency of each sub-band; linear optimization integration based on a Gaussian noise model is carried out on the measurement results of two sub-bands, so as to acquire an instantaneous angular frequency measurement value with small error variance; Kalman filter estimation is carried out on the measurement value; and the instantaneous frequency of a power grid is tracked. According to the method provided by the invention, measuring and tracking accuracy is not affected by a non-periodic noise signal, power grid voltage / current amplitude variation and a harmonic signal; the method has the advantages of short data window and simple algorithm calculation; and the instantaneous frequency of a power grid fundamental wave can be accurately measured and tracked in real time.

Description

technical field [0001] The invention belongs to the field of power system application technology, and more specifically relates to a method for measuring and tracking the instantaneous frequency of a power grid based on orthogonal subbands. Background technique [0002] Frequency is one of the main physical parameters of the power system, and it is also an important parameter reflecting the operating state of the power system. Measuring and tracking the frequency of the power system is a prerequisite for ensuring the normal operation, control and regulation of the power system. [0003] In the actual monitoring process, the power signal of the power grid is often affected by factors such as electromagnetic transients, harmonic loads, high and low frequency electromagnetic interference, and nonlinear equipment. The frequency changes with time, and it is a non-stationary signal. Certain limitations. The instantaneous frequency can describe the frequency characteristics of the...

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Problems solved by technology

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art, provide a power grid instantaneous frequency measurement and tracking method based on orthogonal sub-bands, and effectively solve the problem of large errors in some sampling intervals of the traditional instantaneous frequency measurement method through the linear optimal fusion method At the same time, only three sampling point data are used to calculate the key frequency, which effectively reduces the amount of calculation and greatly improves the real-time performance; it also has good anti-interference performance, is less affected by harmonic components, and is not limited by the problem of synchronous sampling. Accuracy and practicality are greatly improved

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