Comprehensive Analysis and Countermeasures of Line Loss in County-level Rural Power Grid

In the past few years since the implementation of the rural power grid reconstruction project in Mulan County Bureau, the line loss rate of rural high and low voltage power grids has been significantly reduced, which can basically meet the requirements of national agricultural network transformation. However, there are some high-voltage lines and low-voltage station areas where the line loss rate is not obvious. It meets the requirements of the national agricultural network transformation, and even higher than the national agricultural network transformation requirements.

(1) The layout of the transmission and distribution power grid is not completely scientific and reasonable:

At present, Mulan County Bureau has four 63kV substations and 19 10kV distribution lines, which are responsible for power supply for 14 townships in the county. Due to the small number of substations and distribution lines, the townships and villages are scattered and the load distribution is uneven. The layout of the transmission and distribution grids is not completely scientific and reasonable. The power supply radius of some high-voltage distribution lines exceeds the requirements of the regulations. The maximum power supply radius is up to 36.1. Km. Although the cross-sectional area of ​​the wire is increased, the line loss is still large.

(2) High and low voltage power grids have large reactive losses:

In the reconstruction of rural power grid, no reactive power compensation for high and low voltage power grids was considered. No reactive power compensation capacitors were installed on high voltage distribution lines, power distribution transformers and low voltage power equipment. The system used for electrical equipment was not reactive. To compensation, the grid power factor is low, causing the line loss rate to rise.

(3) Single-phase ground faults in high and low voltage power grids:

Single-phase ground faults often occur during high and low voltage line operation. After a single-phase ground fault occurs, a large amount of power will be lost at the fault point, thereby increasing the line loss of the high and low voltage lines.

(4) Low grid load rate:

Mulan County's electric load is mainly based on residential electricity consumption and township enterprises. The load rate is only about 50%. The peak and trough load changes are relatively large, and the seasonal load changes are also relatively large. When the load of the distribution network is operated at the economic load rate, the network loss rate is the lowest. If the load rate is too low, the grid peak-to-valley difference is too large, which will increase the line loss.

(5) Other:

The accuracy of the meter is unqualified, the wiring of the electric energy meter and the transformer is wrong, and the estimation, the missing copy, the wrong copy, and the like. These are also important reasons for the high line loss rate.

(1) Further improve the layout of the transmission and distribution grid:

According to the design principle of "small capacity, dense point, short radius", the substation and distribution line should be appropriately increased to make the layout of the county-level transmission and distribution grids more perfect, achieving scientific and reasonable standards and meeting the requirements of national agricultural network transformation.

(2) Increase the reactive power compensation of high and low voltage power grids:

Reactive power compensation should be applied to high and low voltage power grids. According to the calculation results, reactive power compensation capacitors are installed on the high-voltage distribution lines, distribution transformers and low-voltage power equipment. The reactive power is mainly based on local compensation, supplemented by centralized and decentralized compensation, and the reactive power consumed by the electrical equipment is obtained. Compensation, improve the grid power factor, thereby reducing the line loss rate of high and low voltage grids.

(3) Reduce the single-phase ground fault of high and low voltage power grids:

During the operation of the line, regular irregular inspections of the equipment are carried out to prevent the short-circuit between the wires and the trees, and the damaged porcelain pieces are replaced in time to prevent the single-phase grounding failure of the lines caused by the breakdown. After a single-phase ground fault occurs, personnel should be quickly identified to find the fault point and eliminated in time to reduce power loss.

(4) Improve the grid load rate:

The main practice of the Mulan Bureau is to install peak and valley and time-sharing electric energy meters for users of 100kVA and above, to implement peak-to-valley time-sharing electricity prices, and to increase the load rate of the power grid by economic means.

(5) Other:

Grasping the theoretical calculation of line loss, strengthening the management of electricity consumption, finding out the main reasons for the increase of line loss, implementing unified indicators, tiering responsibility, grading assessment, phasing out high-energy-consuming equipment, eliminating the phenomenon of stealing electricity; strengthening measurement management, on electric energy The table is regularly checked, the old type electric energy meter is eliminated, the accuracy of the transformer and meter is improved, the meter and the transformer are prevented from being incorrectly wired, the meter and the meter box are centrally managed, the standard meter reading procedure is strengthened, and the meter reading is strictly performed. The system eliminates "run, run, drip, leak" to prevent human and other unknown losses from occurring and reduce the line loss rate.

The above is a brief analysis and introduction for the actual situation of the rural power grid line loss of the Mulan Bureau. After the implementation of the above-mentioned countermeasures by the Mulan Bureau, the line loss rate of the rural power grid has decreased, and good results have been achieved, and large economic benefits have been obtained.

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