Analysis Of The Saturated Characteristics Of The Current Transformer And Rebuilding Of The Waveform Based On DSP

With the rapid development of the power industry, the rated voltage and current of the electrical appliances in power system is increasing. In order to keep the security and economical efficiency of the system, it is necessary for us to detect the parameters of the electrical appliances. Because of this, we can do a lot of work, including supervising, measuring and protecting. And the current transformer is one of the most important appliances which can do measuring and protecting in the power system.This issue is based on the relaying protection system, and is used to solve the problem about the saturation of the current transformer. When CT is saturated, the primary current will not be correctly reflected by the secondary one. Owing to this, we have a great trouble in measuring. Meanwhile, the circuit breaker will not move at the perfect time when we want. So how to restore the short current to the original state is the key of the project. This paper mainly discusses about current transforms, specially current transforms for protect purpose. Aimed at the saturation phenomenon we have already observed in the application, we have done a lot of research and analysis, and mainly dress the following aspects:1. Introduced basic theory of transformers and its T-form equivalent circuit which is based on the transient functions.2. Fitting of the excitation curve and How to build our saturated current transformer emulation model based on the T-form equivalent circuit.3. How to emulate the current transforms on the model we have built.4. Analyze some of the possible saturation waveform we may observe when a current transformer run in power system based on the emulation model, and then lodged and analyzed the precision of an arithmetic for correction.5. Designed an error correction system based on the arithmetic using a TMS320F2812 chip.The essay holds up a practical and simple method to analyze the transient characteristic of the current transformer, we prove it effective through simulating. Meanwhile, we analyze the anti-saturated algorithm deeply, supporting an effective method to do research on the current transformer.