Power distribution is the link in the power system that is directly connected to users and distributes electric energy to users. The power distribution system consists of distribution substations, high-voltage distribution lines, distribution transformers, low-voltage distribution lines and corresponding control and protection equipment.
A power distribution system is a power network system composed of a variety of power distribution equipment (or components) and power distribution facilities that converts voltage and directly distributes power to end users.
Here we only look at the distribution network structure of the main equipment:
• The 10kV switch in the substation is the beginning of the distribution network.
• Access to the medium-voltage ring network cabinet, power supply N-1 equipment, and hand-in-hand network. The previous radioactive lines and economically disadvantaged places did not have this.
• Access to the switching center is only available to rich people. It also serves the purpose of N-1 and isolating faults.
• Connect to the distribution station or overhead transformer to convert 10kV to 220V. This is usually the end of the story for dedicated users. Residential users look down.
• Low-voltage lines are connected to low-voltage cabinets, cable branch boxes and other equipment.
• After receiving the meter box at your door or downstairs, the power distribution ends.
In short, the basic distribution network is composed of transmission equipment, transformer equipment, control equipment, redundant equipment, and quality control equipment. There are many differences in network equipment between those with money and those without money, and the reliability is completely different.
The main function of the distribution network is to distribute the electric energy received from the transmission network according to demand. That is, the high voltage is reduced to various voltages required by users to provide power to various users.
Compared with power transmission, which specializes in “transmission”, power transformation specializes in “transformation”, and power distribution does both “transmission and transformation”. Sometimes they also do some customer marketing work, completing all the work of small power grids, so the transmission, transformation and distribution network are also It’s called “main distribution network”.
The distribution network equipment points are many and wide, and the value of a single device is low, so the investment in maintenance is also small, and the demand for small intelligence is large.
Distribution network indicators
The distribution network is closely connected with the majority of users, so it is very important whether the distribution network is qualified.
There are four main indicators for judging distribution network:
Power supply reliability: Power supply reliability refers to the reliability of continuous power supply to users.
Network loss rate: The network loss rate can be defined as the ratio of the power loss of the power network to the total power supply, usually expressed as a percentage.
Voltage fluctuations and voltage flicker: Voltage fluctuations refer to rapid changes in grid voltage or periodic changes in the voltage envelope. Voltage flicker refers to the main perception of light flickering by the human eye, which causes flickering and fluctuating voltage of the light, which is called flicker voltage.
Voltage qualification rate: The voltage qualification rate refers to the percentage of the total time that the voltage at a certain point in the power system is qualified within the statistical time.
Smart distribution network
Intelligent distribution network uses modern electronic technology, communication technology, computer and network technology to integrate online data and offline data of distribution network, distribution network data and user data, power grid structure and geographical graphics to realize the normal operation and maintenance of distribution system. Intelligent monitoring, protection, control, power consumption and distribution management in case of accidents. Including distribution automation system, distribution network detection and protection, switching appliances, etc.
Feature of Smart Distribution Network
1) High power supply reliability
Smart distribution networks can resist external damage, avoid large-scale power outages, limit external damage to a certain range, and ensure power supply for important users.
2) Better power quality
The smart distribution network can monitor and control power quality in real time to ensure the normal operation of user equipment without affecting its service life.
3) Higher operating efficiency
Intelligent distribution network can monitor the temperature and insulation level of distribution equipment in real time, improve transmission capacity and utilization efficiency of distribution network equipment under the premise of safety and reliability.
4) Support large-scale access to distributed power sources
The distribution network is the main platform for the access of distributed power sources such as photovoltaics, wind turbines, fuel cells, and micro gas turbines. When the main grid is out of power, microgrids can be used to ensure power supply for important users.
5) Support interaction with users
On the one hand, the smart distribution network uses communication information technology to realize two-way real-time interaction of power consumption information between the power grid company and users; on the other hand, a large number of demand-side response resources can fully participate in the operation of the distribution network through the power market. According to electricity prices or incentives Policies adjust electricity consumption behavior.