Method for measuring harmonic waves of power system rapidly

Abstract

The invention relates to a method for measuring harmonic waves of a power system rapidly. The method comprises the following steps that an oversampling ADC oversamples signals to obtain original sampling data; the original sampling data output by the oversampling ADC is down-sampled and stored; windowing FFT is carried out on the down-sampled data; a fundamental wave frequency is calculated; a quasi-synchronization sampling rate is calculated and stored; the calculated quasi-synchronization sampling rate is used to carry out interpolation on the original sampling data output by the oversampling ADC; the data after interpolation is down-sampled and stored; rectangular window FFT is used to process the data; and FFT spectral amplitudes after rectangular window FFT are multiplied by a compensation coefficient, amplitude compensation is carried out, and a result is output. The method can be used to improve the signal to noise ratio of in-band signals via an oversampling technology, on the premises that the frequency and resolution are ensured, the computing complexity is reduced greatly, the accuracy of fundamental wave frequency calculation is improved, and less buffer memory is occupied by down-sampling.

Description

technical field [0001] The invention belongs to the field of electricity, and in particular relates to a method for calculating and analyzing harmonics of a power grid. Background technique [0002] In recent years, with the rapid growth of my country's electricity demand, there are more and more electrical loads, and all non-linear loads, such as switching mode power supplies, electronic fluorescent lamp ballasts, variable speed drives, uninterruptible power supplies, magnetic iron core equipment And household appliances such as TVs will generate harmonics, which will reduce the quality of power grid power supply. Therefore, it is becoming more and more important to carry out harmonic analysis on the voltage and current signals of the power supply grid, so as to perform grid compensation and purification. In order to perform power grid compensation and purification as quickly and accurately as possible, the real-time and accuracy requirements of harmonic analysis are gettin...

AI Technical Summary

Problems solved by technology

However, this method needs to store the original data obtained by the oversampling of the analog-to-digital converter in the cache, because the oversampling rate is very high, resulting in a very large cache, and when using a filter to filter the original sampling data, the filtering result must also be stored In the cache for the next operation of extracting the fundamental period, in the embodiment of the patent, when the analog-to-digital converter uses a sampling rate of 50*128*40=256KHz, if the bit width of the analog-to-digital converter If it is 16 bits, the buffer size required to save a fundamental cycle signal is 128*40*16=81920bit, when the sampling rate of the filter is 50*128*2=12.8KHz, the buffer required to save the filtered data The size is 128*2*16=4096bit, then a total of 81920+4096=86016bit cache is required

The area occupied by the buffer in the integrated circuit will be very large; on the other hand, this method calculates the fundamental wave period by calculating the time difference between two zero-crossing points, so it is very susceptible to noise interference, resulting in inaccurate period calculation

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