1 Introduction

With the development of national economy and the improvement of living standards, people's demand for electricity is increasing day by day, and at the same time, higher requirements are put forward for the reliability and quality of power supply. Feeder automation is the most direct and effective technical means to improve the power supply reliability of distribution network system. In recent years, the country has stepped up the transformation of urban and rural power grids, and the investment of major power supply bureaus in China in distribution automation is also increasing. In the process of realizing the automation of distribution network, we find that the communication problem is a difficult problem. Here, I only talk about some knowledge and experience from the application of optical fiber communication in distribution network automation.

2 distribution automation requirements for communication

Like dispatching SCADA system, distribution automation system also needs an effective communication network, and it has its own characteristics: the number of terminals is very large. The system has a large distribution network, which is monitored by opening and closing, distribution transformers and circuit breakers. These devices need some FTU and TTU, and FTU is installed with distribution equipment, with wide geographical distribution and scattered communication nodes.

The scale, complexity and automation level of distribution automation system determine that the communication system should meet the following requirements:

(1) Reliability:

Many communication equipment distribution network systems are exposed to the outdoor environment, so they must be able to resist natural attacks such as high temperature, cold, sun exposure, rain and snow, hail and lightning. At the same time, try to avoid all kinds of electromagnetic interference, ensure long-term stable and reliable work, and require that the communication system can still work normally when the line is out of power.

(2) Economy:

Considering the overall economy of distribution system and communication system, the investment should not be too large, and strive to make full use of the existing communication resources of the main network, and make overall planning for the main and distribution networks to avoid repeated investment.

(3) large addressing:

The communication system should not only consider the current and future data requirements, but also consider the upgrade requirements.

(4) Two-way communication:

In order to realize telemetry, remote communication and remote control in distribution network automation, it is necessary to have two-way communication ability.

(5) Easy to operate and maintain.

According to the above requirements, with the decline of optical fiber price, optical fiber communication system is widely used in electric power at present.

3 optical fiber communication

Since the advent of laser and low-loss optical fiber, optical fiber communication system has risen rapidly with its unparalleled technical and economic advantages and swept the world. The system is a communication system that uses optical fiber as transmission medium and light as signal carrier to transmit information. The applied wavelength of light is1.0 ~1.0 μ m. The whole system is composed of electric terminal, light, cable and repeater. Optical fiber can be divided into single-mode fiber (SMF), multimode fiber (MMF), long-wavelength low-drive bulk fiber (LMF), polarization maintaining fiber (PMF), plastic fiber (POF) and many others. Commonly used in single-mode and multimode fiber, multimode fiber is a variety of light transmission modes, while single-mode fiber only transmits one light wave mode. The transmission distance of single-mode fiber is longer than that of multimode fiber. Generally speaking, optical signals can be transmitted about 6 kilometers in multimode fiber and 30 kilometers in single-mode fiber. Therefore, the price of single-mode optical devices is higher than that of multimode optical devices. Practical optical fiber is usually composed of reinforced core, protective material and fixing material.

Optical fiber communication has the advantages of large communication capacity, low attenuation, lightning resistance, electromagnetic interference resistance, corrosion resistance, good confidentiality, high reliability and convenient installation, but the investment cost is relatively high, especially for the optical fiber laying of buried optical cable lines in the city, the construction cost will be even higher.

6 conclusion

In the actual distribution automation communication system, it is necessary to establish a low-cost and high-efficiency two-way communication system to realize the extremely high performance of information flow with acceptable reliability and cost. In addition, because the functions of distribution automation system are completed by too many complicated systems, it is unrealistic and uneconomical for a single communication system to meet the needs of all functions. Therefore, the distribution automation system should apply a variety of communication modes and choose their best combination according to the comprehensive economic and technical indicators. A variety of communication methods commonly used in power system include digital microwave wireless data transmission, wireless spread spectrum, green cable, post and telecommunications local network, carrier wave, spread spectrum carrier wave, etc., which can be selected for networking.