In recent years, China's distribution network construction investment has continuously increased, and the development of distribution network has achieved remarkable results. However, there is still a gap between the level of electricity consumption and the international advanced level. The development of urban and rural areas is not balanced, and the quality of power supply needs to be improved.
Outstanding features of the distribution network
1. China's distribution network has many points, wide area, long line, single power supply and low automation;
2. Due to the restriction of funds during the transformation of urban and rural power grids, the distribution capacity is small, the medium and low voltage main line and the feeder line have small cross sections, and the medium and low voltage power supply has a large radius;
3. The rural distribution network has a long transformation period, and the load growth is fast, and the electricity consumption period is relatively concentrated.
Low voltage classification basis
1 occurrence location
Reasonable power supply load distance
Reasonable power supply load distance
2 occurrence area
Substation and its subordinate areas
10kV feeder and its area below
Taiwan area and its subordinate areas
Low voltage user
3 time period
Short time
Periodic (seasonal, phased, daily load fluctuations)
Long-term
4 causes
Insufficient capacity of grid equipment
Concentrated electricity load
Long distance power supply
Three-phase load imbalance
Insufficient reactive power compensation
The pressure regulating equipment is not adjusted in time.
Technical level
1, the main factor of voltage drop
2. The power supply radius of some medium and low voltage lines is too long, and the power supply quality assurance capability is weak.
3. Insufficient regulation voltage capability of distribution network
(1) Some of the main transformers become unloaded type main transformers, and the no-load voltage regulating transformers have weak voltage regulation according to load conditions, and it is difficult to meet the voltage adjustment requirements.
(2) The substation reactive power compensation capacity configuration is unreasonable, and the substation reactive power compensation voltage adjustment capability is not fully utilized.
(3) Insufficient long-circuit regulation capability
4. Low-voltage user side reactive power compensation ability is weak
5, reactive power compensation is low
Typical method of rural low voltage management
Substation line distribution voltage three-set joint adjustment technology
Based on the voltage of the resident's client, comprehensive utilization of modern communication technology, automatic control technology, short-term and ultra-short-term load forecasting, etc., to achieve coordinated control of substation, line, distribution transformer and user reactive power compensation equipment and voltage regulator.
County-level power grid reactive power optimization compensation technology
Reactive power compensation mode
Voltage reactive information system construction technology: application information automatic acquisition, computer technology, etc., real-time monitoring, acquisition, calculation and analysis of voltage and reactive power management related data of distribution network, and the technology of voltage reactive power optimization configuration and optimal operation scheme.
Reactive power supply construction and transformation technology: According to the optimization calculation results, the technology of reactive power supply construction and transformation, including equipment selection and installation location selection, compensation capacity and compensation mode selection.
Reactive power optimization compensation and control technology: According to the voltage reactive power optimization scheme, the technology of optimal matching of voltage reactive devices is realized by automatic or manual control means.
35kV distribution construction
The 35kV distribution technology mainly includes three parts: 35kV distribution substation, 35kV distribution line and 35/0.4kV direct distribution area.
The o35kV distribution substation is designed to meet the needs of remote rural social and economic development, transitional or emergency response to disasters, and follows the technical principles of miniaturization, low cost, and low maintenance. The voltage level is 35kV and the main transformer capacity is 3150kVA. The following 10kV outlets are substations designed for 2~3 times.
The o35kV distribution line is erected with 12-15m reinforced concrete poles, and is insulated with a ceramic cross arm or a composite cross arm to achieve a light-weight design of 35kV lines.
The o35/0.4kV direct distribution area refers to the distribution area where the 35kV line is deepened into the load center and powered by a 35/0.4kV distribution transformer.
Medium and low voltage line regulator application technology
In medium and low voltage lines with large voltage fluctuations or large voltage drops, the quality of the supply voltage on the user side is improved by adopting an automatic voltage regulator device installed at the rear end of the line. The pressure regulation range is wide, up to about 20%.
Wide-load unloaded voltage distribution transformer application
According to the working principle of the transformer, when ignoring the internal impedance drop of the transformer, there is
Single three-phase hybrid power supply mode application
The medium-voltage line is deep into the load center, and the low-voltage single-phase power distribution method is generally divided into a single-phase two-wire system and a single-phase three-wire system.
Adjustment and distribution and application of mother and child
On-load adjustment and distribution includes the on-load capacity transformer body, the on-load capacity adjustment switch, the on-load capacity control system and the supporting equipment.
In addition, grid companies need to cooperate with the government to coordinate the development of urban and rural power grids. According to the characteristics of rural climate and living conditions in various regions, we will sort out the weak links of power grids and insufficient power supply capacity, in accordance with the “selection of conductor sections, once in place of corridors, and in the construction of substations. The principle of “one-time construction†proposes solutions to improve the power supply capacity of rural distribution networks in accordance with differentiated needs;
For the "low voltage" problem in rural areas, it is necessary to organize a comprehensive census, establish a normal monitoring and governance mechanism, optimize operational control, strengthen power grid construction, and combine multiple measures and preventive measures;
At the same time, it is necessary to carry out general survey of low-voltage equipment, increase the transformation of old equipment, promote the application of residual current action protectors, low-voltage compensation devices and smart meters, and gradually eliminate the problems of bottlenecks of low-voltage power grids, prominent safety hazards, and power supply.Cbd Vape Products Oem,D8 Vape Pen Oem,Cbd Disposable Vape Pen Oem,China Cbd Vape Products Oem
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