Application of Ring Main Unit in Power Distribution System


In recent years, with the development of China's market economy and the progress of science and technology, China's electric power enterprises have also carried out reforms in the spring breeze of reform and opening up. However, as far as the automation development of the distribution network system is concerned, China is still at the primary stage of development. As the distribution network construction is compared with the construction of the main network, the investment of power enterprises is less, which leads to the low level of automation of the power system distribution network of power enterprises. As a result, China's current domestic power supply quality cannot be compared with that of advanced countries in the world, and the gap between them is still worrying. After comparing the performance of most of the current distribution network equipment technologies in China, the speed of power supply recovery after failure is slow, causing frequent accidents. This situation has a very serious impact on the normal life, production, learning and other activities of our people, especially on the rapid growth of our national economy. Under the influence of the market economy, China's electric power enterprises are gradually developing towards the direction of market-oriented economy. The weak links of the distribution network are becoming increasingly prominent. The serious disharmony between the power demand and the allocation of power grid facilities has affected the construction of China's power grid. Therefore, the implementation of intelligent ring network cabinet in the distribution network system is not only conducive to promoting the development of distribution network automation, but also plays a positive role in promoting social progress and economic development in China.

1. Advantages analysis of ring main unit

At present, the ring network cabinets used in China's power market mainly include SF6 ring network cabinets and FBA vacuum ring network cabinets. These two types of ring network cabinets are widely used and have been used for a long time. In addition, the production technology of these two types of ring network cabinets has become mature in China, with high performance indicators. With the development of science and technology, and two kinds of ring network cabinets play a positive role in ensuring the safety of power workers.


1.1 Effectively prevent staff from misoperation

With the continuous development of science and technology, the number of ring main unit (RMU) products in China's current power market is gradually increasing. However, the quality of products is uneven, which has affected the improvement of the power system. If some ring network cabinet equipment adopts vacuum load switch, it has the high-voltage function of three positions, namely grounding, isolation and closing. In this equipment, the interface between the disconnector and the grounding switch is very clear, and its load switch and disconnector have the function of automatic linkage. When the vacuum load switch is disconnected, the disconnector will also be disconnected, and the fracture is very clear; When the vacuum load switch is closed, the isolating switch will automatically close. These all put forward higher requirements for the mechanical interlocking between the load switch and the grounding switch. Only in this way can we more effectively prevent the danger caused by the misoperation of employees in the work, so as to provide a strong guarantee for the safety of the operating personnel.

1.2 High performance indicators

In the use of the power system, SF6 ring network cabinet and FBA vacuum ring network cabinet are operated frequently, and the number of times of closing and opening the fixed active load is up to 100 times, more than 10 times that of common load switches such as compressor type and gas generating type. In addition, these two ring network cabinets have strong breaking capacity and high current tolerance.

1.3 High maintainability

Since the ring network cabinet is installed in the power distribution room, it can effectively avoid various interferences caused by human factors. In addition, due to the closed conditions, it can also effectively prevent the impact on the operation caused by the external weather changes. For example, some ring network cabinets have made innovations in the design of the cabinet surface, and have marked various wiring methods on the cabinet surface. It can be seen that this relatively humanized design method has brought a guiding role to the operation of operators. In addition, on some products, some precautions that are easy to occur in operation are also marked and explained, which greatly reduces the error rate of operators due to operation errors. At present, most of the ring network cabinets produced in China have basically been installed with a device to detect the status of the main circuit with points, and the concealed installation of this device can more humanize some of the conditions with points. In order to prevent the occurrence of misoperation, some products also install closing handle doors in combination with electromagnetic locks. In the product, a transparent, visible glass observation window will be installed at the front door. The operator of the power system can directly see the state of the switch inside the observation window, which greatly increases the convenience of use. It should be reminded that during the maintenance process, attention must be paid to the design of lightning protection devices. If possible, they should be inspected and tested once a year to ensure the normal working performance of lightning protection devices.

1.4 Strong flexibility

With the acceleration of the modernization process, the development of the ring network cabinet is gradually moving towards the direction of expandable ring network cabinet. Modular and compact ring network cabinets have developed rapidly. The current ring network cabinets can be flexibly applied to various distribution network design schemes, and can be combined and matched at will according to specific conditions. In addition, even if the road surface is not very flat, soft connection can be achieved by cable bridging, and partial discharge will not occur.

2. Application of ring main unit in power distribution system

In China, the appearance of ring network cabinets is not long. With the development of China's socialist market economy and the deepening of reform and opening up, Chinese enterprises and institutions have also been rapidly developed and expanded, which has greatly improved the application scope of ring network cabinets. From the perspective of power distribution in power enterprises: for some relatively simple distribution networks, in order to ensure that the power supply of the power supply system is unstable and unsafe, ring network cabinets can be used to complete; In those more complex distribution networks, the ring network cabinet has the advantages of simple structure and low operating cost, which is more obvious than those switch cabinets with short circuit to some extent. With the rapid development of modern science and technology, the ring network cabinet products currently used not only have excellent performance, but also gradually develop towards the direction of modularization, intelligence and systematization. In a word, with the improvement of people's living standards, various household appliances have flooded into people's lives, which also puts forward higher requirements for the power supply system of China's electric power enterprises. In order to ensure people's daily life needs, and to ensure the safety and stability of electricity use, there must be power supply equipment with strong stability, excellent performance, and easy operation. The emergence and application of ring network cabinets solve these problems, And it will play an increasingly important role in the future development of distribution network system.