CN204008852U - Based on Harmonic Measurer device between DSP - Google Patents

Abstract

The utility model relates to a DSP-based inter-harmonic detection instrument, the structure of which is that the three-phase voltage and the three-phase current are respectively connected to a filter circuit through a voltage transformer and a current transformer; the output terminals of the filter circuit are respectively connected to a zero-crossing comparison circuit and A/D sampling circuit; the output end of the zero-crossing comparison circuit is connected to the phase selection closing circuit, the output end of the phase selection closing circuit is connected to the phase-locked frequency multiplication circuit, and the output end of the phase-locked frequency multiplication circuit is connected to the A/D sampling circuit, A/D The output end of the D sampling circuit is connected to the DSP chip. The utility model can test the inter-harmonic of the power grid, and the test is accurate and fast, achieves the expected goal, plays a role in preventing equipment from being damaged by the inter-harmonic, and provides a basis for the treatment of the inter-harmonic.

Description

DSP-based inter-harmonic detection instrument

technical field

The utility model relates to a power system detection instrument, in particular to a DSP-based inter-harmonic detection instrument, which belongs to the technical field of intelligent substations.

Background technique

With the widespread use of nonlinear components such as power electronic devices in the power grid, in addition to the harmonics of integer multiples of the fundamental frequency, the power grid may also generate interharmonics of non-integer multiples of the fundamental frequency, such as 1/2, 1/3, 1/4 power frequency harmonics. Interharmonics will bring some new problems to the grid, such as subsynchronous oscillation, voltage fluctuation and flicker.

Inter-harmonics can cause overheating and reduced service life of electrical equipment; cause filter resonance, overload, and communication interference; can also cause malfunction of digital relays that work at zero crossing; inter-harmonics can cause noise and vibration of motors and transformers increase; inter-harmonics can cause voltage transformers to resonate in frequency divisions, leading to explosion accidents of transformers or arresters.

In the prior art, the methods for detecting interharmonics mainly include FFT method, wavelet analysis method, AR method and neural network method, etc. FFT method is relatively common, but it is prone to spectrum leakage; wavelet analysis method is prone to frequency mixing, and AR The method and the neural network method are relatively subject to external interference. Explosion accidents of voltage transformers and lightning arresters often occur in substations, which are suspected to be caused by frequency division resonance caused by inter-harmonics. However, the existing intermediate harmonic detection instruments cannot extract inter-harmonic signals of any frequency, so it is impossible to use the instrument to further authenticating.

Utility model content

The utility model aims at the problems existing in the above-mentioned prior art, and provides a DSP-based inter-harmonic detection instrument, which uses HHT (Hilbert-Huang Transform, HHT) transformation for inter-harmonic detection, and solves the problems in the prior art. The problem of not being able to extract interharmonic signals of arbitrary frequencies.

The technical scheme of the utility model is as follows:

The three-phase voltage and three-phase current are respectively connected to the filter circuit through the voltage transformer and the current transformer; the output terminals of the filter circuit are respectively connected to the zero-crossing comparison circuit and the A/D sampling circuit; the output terminals of the zero-crossing comparison circuit are connected to the phase selection closing circuit , the output end of the phase selection closing circuit is connected to the phase-locked frequency multiplication circuit, the output end of the phase-locked frequency multiplication circuit is connected to the A/D sampling circuit, and the output end of the A/D sampling circuit is connected to the DSP chip.

The A/D sampling circuit is selected ADS1178 chip.

Described DSP chip is TMS320VC5509A chip.

The output end of the DSP chip is connected to the RS232 interface, the keyboard input port and the display.

The advantages and effects of the utility model are as follows:

The utility model has accurate and fast test, effectively reduces monitoring errors, and reduces power consumption.

The core processor of this device is TMS320VC5509A. This chip is a l6 bit fixed-point DSP chip with high cost performance. It has a good inheritance from C54x, inheriting its low power consumption and low cost development trend, but compared with it, it has higher performance and lower power consumption. But lower. Faster processing speed, dual-core structure, processing speed 400MIPS.

The A/D conversion circuit uses the ADS1178 chip, which is a high-speed 8-channel, 16-bit data acquisition system chip, which can simultaneously sample 4-way voltage and 4-way current signals, and can eliminate the signal phase caused by sampling problems Delay, effectively reduce the monitoring error.

Description of drawings

Fig. 1 is a structural schematic block diagram of the utility model.

Detailed ways

Example

The three-phase voltage and three-phase current are respectively connected to the filter circuit through the voltage transformer and the current transformer; the output terminals of the filter circuit are respectively connected to the zero-crossing comparison circuit and the A/D sampling circuit; the output terminals of the zero-crossing comparison circuit are connected to the phase selection closing circuit , the output end of the phase selection closing circuit is connected to the phase-locked frequency multiplication circuit, the output end of the phase-locked frequency multiplication circuit is connected to the A/D sampling circuit, and the output end of the A/D sampling circuit is connected to the DSP chip.

The A/D sampling circuit is selected ADS1178 chip.

Described DSP chip is TMS320VC5509A chip.

The output end of the DSP chip is connected to the RS232 interface, the keyboard input port and the display.

The utility model carries out the interharmonic test in the 66kV substation, and the test is accurate and fast, and the expected goal is achieved. The above are specific embodiments of the utility model and the applied technical principles. Any equivalent transformation based on the technical solution of the utility model falls within the scope of protection of the utility model.

Claims (2)

1. based on Harmonic Measurer device between DSP, it is characterized in that three-phase voltage is connected filtering circuit by voltage transformer (VT) summation current transformer respectively with three-phase current; The output terminal of filtering circuit connects respectively zero passage comparator circuit and A/D sample circuit; The output terminal of zero passage comparator circuit connects phase selection circuit, and the output terminal of phase selection circuit connects phase-locking frequency multiplication circuit, and the output terminal of phase-locking frequency multiplication circuit connects A/D sample circuit, and the output terminal of A/D sample circuit connects dsp chip; Described A/D sample circuit is selected ADS1178 chip; Described dsp chip is TMS320VC5509A chip.

2. according to claim 1 based on Harmonic Measurer device between DSP, it is characterized in that described dsp chip output terminal connects RS232 interface, keyboard input port and display.