The basic provisions of distribution network planning include

The basic provisions of distribution network planning include safety; Economy; Reliability.

Distribution network planning;

The power grid planning of distribution network is to determine when and where to build what type of lines and how many lines to build, to achieve the required transmission capacity during the planning period and to minimize the system cost on the premise of meeting various technical indicators. The content of distribution network planning is to determine the transmission mode in the city, select the grid voltage, determine the layout and scale of substations, and determine the network structure.

Distribution network structure mode:

1.220kV network

Most 220kV substations are built near cities. Considering that it is beneficial to urban construction and economic operation of power grid, it is appropriate for the substation to be about 3 minutes away from the edge of the city. The voltage level of 220kV substations is mostly 220/1135kV (10). The110kV side is responsible for supplying power to the whole city, and its low voltage side supplies power to the nearby urban areas.

The 220 kV network should be centered on the 500 kV substation or other large power supply points to form a single-ring network and gradually build a double-ring network. The closed-loop operation mode can improve the reliability of power supply during normal operation.

2. 1 10 kV power grid

The layout of the newly-built 1 10kV substation should comprehensively consider factors such as load density and power supply radius, and the secondary equipment in the substation should give priority to integrated automation devices, laying a good foundation for unattended operation. For substations with conventional secondary equipment, the four or five remote functions and communication channels of RTU can be improved and gradually transformed into unattended substations.

1 100 kV network takes 220kV substation as the center, forming a structure with single-ring network (under normal circumstances, the line runs in open loop or the bus runs in sections) as the main part, supplemented by double-ring single radiation.

3.35 kV power grid

In places or mountainous areas where there are few 1 100 kV substations, we will vigorously build miniaturized 35kV unattended substations. The layout of the 35kV substation is centered on the 220kV substation and goes deep into the load center of the planning area. There are at least two power supply lines in the 35kV substation, which can be introduced from different sections of the 35kV bus in the same 1 10kV substation, or from two 1 10kV substations.

In places or mountainous areas where 1 10kV substations are densely distributed and local conditions are ripe, the 1 10kV step-down system and 20kV distribution network can be gradually adopted, and the voltage levels of 35kV and 10kV are cancelled.