Sensor passive combination will become the development trend of electronic transformer

The emergence of electronic transformers was hailed as a revolution in the high voltage electrical manufacturing industry at the beginning of this century. Its digital output and networked wiring make the power grid more secure, more environmentally friendly, and more conducive to the intelligence of primary equipment and even the entire transmission and distribution system. Compared with traditional transformers, electronic transformers have the following features:

Small signal transmission instead of high power output, transformer miniaturization, low power can make the original tens of kilograms or even tons of weight reduced to a few kilograms. Optical isolation instead of oil and gas insulation. Independent high-voltage transformers use digital optical fiber connections between optical and electrical devices one after another. Optical isolation replaces complex and expensive oil-gas insulation systems. This is a revolutionary change. The higher the voltage, the higher the cost-effectiveness of transformers. The digital output replaces the analog output, which facilitates subsequent network connection and intelligent processing. It adopts optical fiber transmission and is more resistant to electromagnetic interference. Network data sharing replaces multi-winding parallel wiring. The single-point measurement data of the electronic transformer can be transmitted via industrial Ethernet and thus shared, and a large number of parallel cables can be omitted at the power station.

According to application statistics, China currently has about 100 units engaged in tentative research and development of new electronic transformers. The preliminary supply capacity is about 10 or so, and the categories are relatively complete. Currently, there are 3~ 5 homes. The product involves 10 ~ 800 kV, current, voltage, free-standing, combined appliances and other different varieties. Since 2004, active electronic transformers have entered the market before the optical transformers. The high voltage side of the active electronic transformer converts the current signal into a digital signal and transmits it to the ground potential through optical fiber. Like the optical sensing scheme, it realizes Optical isolation between high and low voltage insulation, combined with ease of industrial mass production, has become the dominant transformer category.

In the same period, China developed a more practical "self-excited source" technology, thereby transforming it into a "quasi-passive" structure. This solution can greatly simplify the transformers and fundamentally improve the reliability and life cycle.

Soon, an "equipotential cavity" partial pressure structure suitable for electronic low-power partial pressure appears in China. It has very high insulation safety and measurement accuracy, and thus can replace the traditional transformers relying on oil and gas insulation. This technology is particularly suitable for the dry-type of high-voltage, UHV voltage divider structure, is a new type of electronic voltage transformer from China. In order to overcome the measurement performance susceptible to temperature, vibration stress, at present, the optical program has been improved from a ring-shaped magneto-optical glass to a fiber-optic sensor, making the optical program on a new technology platform, closer to practical requirements. The electronic transformers of the so-called optical fiber type have been used for a small number of trials and need to further overcome the problems of complicated structure and high cost.

The main problems faced by the application of electronic transformers have changed the original assembly application methods. For example, microelectronic devices have been moved to the outdoor environment near high-voltage lines, isolation barriers, circuit breakers and other strong interference sources, must withstand severe weather conditions and not Due to the rule of strong electromagnetic interference, the main problems faced in the current research and development of electronic transformers are: electromagnetic interference protection, communication error control, reliable power supply methods, and adaptation to outdoor environments. If improper measures are taken, signal failures and protection errors are easily caused. Judgment, rust aging, etc. To solve these problems, we need to improve the test as soon as possible, test relevant standards, and promote the next step in the development of electronic transformers to the high reliability, high stability direction.

In the future R&D direction sensing passivation: Since passive sensing methods have technological advantages, stand-alone ECT sensing components will tend to be passivated. This includes active sensors that will be self-powered by escaping external sources of dependence. To quasi-passivation, the average life cycle of electronic transformers will reach more than 10 years. The optical sensor is practical by improving its measurement performance, simplifying the system structure, lowering the cost.

Structural composition: Utilizing the advantages of electronic micro power and miniaturization, transformers are more modularly combined in transformers, fully-enclosed combination appliances, isolated knives, etc. to reduce the area and cost, and can also be promoted through functional reuse. The miniaturization and intelligence of an electric appliance itself. Various programs will exert their advantages while also combining with each other's advantages. In addition to various independent and enclosed current-voltage combination transformers, LPCT/ROG-CT and optics are expected to appear in the next few years. Combined current transformers.

Function Reuse: Make full use of the advantages of data sharing, single-point test, multi-point sharing, and transformers provide different types of digital interfaces such as Goose, RS485, and MU, which can be shared by a variety of measurement and control devices to reduce multi-point repeated installation of transformers. , Make the device configuration more compact.

Standardization of parts: The standardization of transformer parts makes it universal and interchangeable. It can be used as a standard accessory for “plug-in” installation in various primary devices. The transformers of different manufacturers can be replaced and interchanged.