Advantages: Compared with the traditional electromagnetic induction current transformer, the photoelectric current transformer has the following advantages:
(1) has excellent insulation performance and low cost. The insulation structure of electromagnetic induction current transformer is complex, and its cost increases exponentially with the voltage level. In the photoelectric current transformer, the information on the high voltage side is transmitted to the low voltage side through the glass fiber made of insulating material. Its insulation structure is simple, and its cost generally increases linearly with the increase of voltage level.
(2) There is no iron core, and there are no problems such as magnetic saturation and ferromagnetic resonance. The photoelectric current transformer has good transient response and stability, which ensures the high reliability of the system operation.
(3) The secondary circuit of the electromagnetic induction current transformer cannot be opened, and the low voltage side is in danger of high voltage. Because there is only optical fiber connection between the high voltage and the low voltage of the photoelectric current transformer, the optical fiber has good insulation performance, which can ensure that the high voltage loop and the secondary loop are completely electrically isolated, and there is no danger of high voltage caused by open circuit at the low voltage side. At the same time, because there is no magnetic coupling, the influence of electromagnetic interference on transformer performance is eliminated.
(4) Large transient response range and high measurement accuracy. During the normal operation of the power grid, the current flowing through the current transformer is not large, but the short-circuit current is increasing. Due to the problem of magnetic saturation, it is difficult for electromagnetic induction current transformer to achieve large-scale measurement and meet the needs of single channel high-precision measurement and relay protection. The photoelectric current transformer has a wide dynamic range, the rated current of the measuring channel can be measured from tens of amperes to thousands of amperes, and the over-current range can reach tens of thousands of amperes. Therefore, it can not only meet the needs of measurement and relay protection, but also avoid the complex structure of multi-measurement channels of electromagnetic induction current transformer.
(5) Wide frequency response range. The frequency response of the sensing head of photoelectric current transformer depends on the transit time of optical fiber on the sensing head, and the actual measurable frequency range mainly depends on the electronic circuit. The structure of modern photoelectric current transformer can already measure the harmonics on high voltage power lines. The work of electromagnetic induction current transformer in these aspects is more difficult.
(6) There is no inflammable and explosive danger caused by oil filling. The insulation structure of photoelectric current transformer is simple, which can avoid oil insulation, so the danger in this aspect can be avoided in structural design.
(7) Small size and light weight. The weight of the sensing head of photoelectric transformer is generally less than 1KG.
(8) Adapt to the trend of digitalization, computerization and automation of power measurement and protection. Photoelectric current transformer generally outputs digital signals, which can best adapt to the trend of microcomputer protection, digitization and automation of electric power measurement.
The development of digital transformers in Germany is relatively mature internationally. In recent years, with the appearance of foreign photoelectric transformers and the installation and trial of foreign photoelectric transformers in China, the development of photoelectric transformers has attracted the attention of industrial departments and enterprises. According to the analysis of relevant data, the market potential of China's photoelectric transformer industry can reach more than 2 billion yuan per year, but there is no enterprise that can provide regular products in China at present. However, with the power development in China Diangu and other places, we will certainly catch up with the world power technology peak.