Short circuit detection and protection system based on DSP

Abstract

The invention discloses a short circuit detection and protection system based on DSP, which is composed of an analog channel processing unit, an A / D converter, a clock unit, a DSP central processing unit, a photoelectric isolation unit I, a photoelectric isolation unit II, a switching value input unit and a switching value output unit. The invention has the advantages that the short circuit detection and protection system overcomes the phenomenon that other fault current waveforms are easy to affect a short circuit current signal when the short circuit current signal is processed, thus improving the detection accuracy of the system; the short circuit detection and protection system takes DSP as a central processing chip, so that the system has great data processing amount, high instantaneity and precision, simple system structure and high cost performance, and the system rapidity is improved.

Description

(1) Technical field: [0001] The invention relates to a short-circuit detection and protection system, in particular to a short-circuit detection and protection system based on DSP (Digital Signal Processing—Digital Signal Processor). (two) background technology: [0002] Due to the development of the power system, the increase of the load, the investment of large-capacity units, power plants and substation equipment, especially the emergence of large power plants in the load center and the interconnection of the power system, the capacity of the transmission and distribution network has been greatly increased, and the short-circuit current If the short-circuit fault is not removed in time, it will have a great impact on the original substation equipment in the system, and even cause severe voltage instability, frequency collapse and other vicious accidents, which will bring economic losses to power plants and users. pose a serious threat to life safety. Therefore, especiall...

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Problems solved by technology

[0004] 1. Based on the overcurrent protection technology that detects the magnitude of the short-circuit current, this overcurrent protection is set according to the principle of avoiding the maximum starting current of the motor. When the power supply line is long and the end of the line is short-circuited, the short-circuit current is small and the sensitivity of the protection is small. restricted

[0005] 2. The short-circuit protection technology based on the principle of phase sensitivity has been studied more at home and abroad, and it is relatively mature. Although it solves the problem of protection sensitivity, this technology can only protect three-phase short-circuit, and two-phase short-circuit does not operate.

[0006] 3. Short-circuit protection technology based on the principle of carrier frequency. This kind of protection has strict requirements on line parameters (cable cross-section, length, power transformer, etc.), and it is prone to malfunction and poor reliability when line parameters change.

Use sudden changes in short-circuit current waveforms to identify faults. Current mutations are the key to identification. There are often various disturbances in the power supply system, such as the start of motors, the start and stop of large equipment, frequency control, system operations, etc. There are many disturbances Under normal circumstances, it will affect the current waveform of the detection point, and the interference current waveform is generally in the form of a sudden change, which may cause false identification in the detection

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