Is the rural power grid transformation voluntary or compulsory?

Most rural power grids in China were built in 1960s and 1970s. Due to technical and material reasons, many power grids have not adapted to the needs of modern economic development. With the development of society, the scale of township and individual economy is huge, and the transmission and distribution power of rural power grid is also increasing rapidly. Many lines have been seriously overloaded, and with the aging of power grid equipment, the quality and safety of power supply cannot be guaranteed. As a direct result, the electricity price of rural power grid generally exceeds the price limit, and some of them are as high as 3 ~ 4 yuan/kWh, so farmers dare not use electricity. There is also a big gap between the electricity prices of users in the same place. Therefore, it is imperative to transform the rural power grid. However, the transformation of rural power grid is a systematic project, and the power sector will directly manage the end of rural power grid, that is, every household in rural areas. At the same time, the power department will unconditionally bear the loss of 10KV line. How to manage the rural 10KV power grid well, reduce the line loss, supply power reasonably and improve the economic benefits of power enterprises has become a serious issue for power enterprises.

On April 20 1 June/0/day, the national energy administration issued the notice of "technical principles for the new round of rural power grid transformation and upgrading", which did not say that it was mandatory transformation, but that the parts that did not meet the principles were transformed according to the principles. In addition to being uneconomical, there are security risks.

The following is the full text of this principle:

Technical principles of the new round of rural power grid transformation and upgrading

Chapter I General Principles

1. 1 This technical principle is formulated to guide the implementation of a new round of rural power grid transformation and upgrading project and build a modern rural power grid.

1.2 The transformation and upgrading of rural power grid should adhere to the overall planning of urban and rural areas, unified planning and unified standards, implement the concept of power supply reliability and asset life cycle, promote intelligent upgrading, and carry out standardization construction to meet the medium and long-term development requirements of rural economy.

1.3 The rural power grid should be upgraded according to local conditions. According to the economic and social development level, user nature and environmental requirements of different regions, the corresponding construction standards should be reasonably selected to meet the regional development and the electricity demand of various users, and improve the acceptance capacity of distributed new energy.

1.4 the technical regulations and norms of the state and industry on design, construction and acceptance shall be strictly implemented in the rural power grid transformation and upgrading.

Chapter II General Requirements

2. 1 The rural power grid transformation and upgrading plan should be incorporated into urban and rural development planning and land use planning, so as to realize the synchronous planning and construction of power grid and other infrastructure. The transformation sequence of distribution facilities should be connected with village planning and construction, coordinated with the environment, scientifically laid out, beautiful and durable.

2.2 The transformation and upgrading of rural power grid should be coordinated with the planning and construction of transmission grid, and a grid structure with sufficient capacity, strong adaptability, safety and reliability should be built to enhance the load transfer and mutual support among power grids at all levels.

2.3 The rural power grid transformation and upgrading should be planned and constructed in accordance with the principle of "selecting conductor sections at a time, putting corridors at a time and completing substation (room) construction at a time" to improve the adaptability to load growth. The selection of conductor section should be based on the saturated load value, comprehensive economic current density, allowable voltage drop, mechanical strength and other factors in the planned area.

2.4 For newly planned villages, medium and low voltage distribution lines and distribution transformers should be built in place at one time according to saturated load; For villages that are included in the upgrading and reconstruction plan of old villages, the construction and reconstruction of distribution facilities should give priority to distribution network, and promote the transformation of low-voltage lines in a timely manner in combination with the improvement of village living environment; For the villages and settlements that are clearly to be relocated in the plan, the upgrading of distribution facilities will be suspended.

2.5 Rural power grid transformation and upgrading should actively adopt "three links and one standard" (general design, general equipment, general cost and standard technology), unify construction standards and ensure project quality. Apply new technologies, new products and new processes to improve the equipment level. Adhere to green development, and the dismantled and recycled materials will be gradually used for power grid construction and transformation after passing the inspection.

2.6 The transformation and upgrading of rural power grid should adapt to the trend of intelligent development, promote the construction of distribution automation, intelligent wireless radio distribution area and rural electricity information collection, meet the demand of decentralized access to new energy, and serve the new urbanization and beautiful countryside construction.

2.7 Without the consent of the power supply enterprise, it is forbidden to hang radio, telephone, cable TV and other weak current lines unrelated to electricity on the overhead line towers.

2.8 In cities and towns with a high level of urbanization, power grid construction can refer to DL/T599 "Technical Guidelines for Transformation of Urban Medium and Low Voltage Distribution Networks".

Chapter III High-voltage Distribution Network

3. 1 Strengthen the connection between the county power grid and the main network. Generally, there should be at least two 1 10(66)kV high-voltage lines for power supply in the county power grid.

3.2 County backbone generally adopts ring or chain structure.

3.3 Overhead lines should be adopted for high-voltage lines, and the conductor cross section of10kV overhead lines should not be less than 150mm2, 66kV and 35kV should not be less than 120 mm2.

3.4 On the premise of meeting the design requirements, reinforced concrete poles are preferred for 35kV lines, and iron towers or steel tube towers can be selected for special needs.

3.5 Substation site selection should meet the requirements of urban and rural planning and power grid planning, and be close to the load center area.

3.6 Newly built substations should be built in unattended mode, and existing substations should be gradually transformed into unattended substations. Conditional areas can pilot smart substations or assembled substations.

3.7 Substations should be arranged semi-outdoors, and users can build their own substations or combined electrical appliances (GIS, HGIS) in towns and heavily polluted areas where site selection is difficult.

3.8 According to the final design, the number of main transformers in the substation should be no less than two. For on-load voltage regulation, energy-saving transformers of S 1 1 and above are used, SF6 circuit breakers or vacuum circuit breakers are used for high-voltage distribution devices of 35kV and above, and vacuum circuit breakers are used for 10kV distribution devices arranged in users.

3.9 The capacity-to-load ratio of high-voltage power grid should be controlled between 1.8 ~ 2. 1, and higher values should be taken in areas with rapid load growth.

3. The building of10 substation should be in harmony with the environment, conform to the principle of "safety, economy, beauty, energy saving and land saving", and be built at one time according to the final scale.

Chapter IV Medium Voltage Distribution Network

4. 1 medium voltage distribution network should be rationally laid out, and the connection mode should be flexible and concise. In principle, public lines should be powered by sections, and the power supply ranges should not overlap.

4.2 When the number of 10kV outgoing lines in the substation is insufficient or the line corridor conditions are limited, a switching station can be built.

(1) The wiring of the switching station should be simplified as much as possible, and the single bus or single bus sectional wiring mode should be adopted.

(2) The switchyard should be unattended, and the redistribution capacity should not exceed 10000kVA.

4.3 The trunk line of medium-voltage distribution network should be segmented according to the line length and load distribution, and segmented switches should be installed, and branch switches should be installed for important branch lines.

4.4 Urban medium-voltage distribution network should adopt multi-section moderate wiring mode, and wires and equipment should meet the requirements of load transfer. Rural medium-voltage distribution network should adopt multi-section single radiation connection mode, and multi-section, moderate connection or multi-section single (terminal) connection can also be adopted if conditions permit.

4.5 The wiring of medium-voltage distribution network shall determine the reasonable power supply radius according to DL/T5 13 1. The power supply radius of urban medium-voltage distribution network lines should not exceed 4 kilometers; The power supply radius of rural medium-voltage distribution network lines should not exceed 15km.

4.6 For the 10kV line with low load density and long power supply time, a line voltage regulator can be installed to adjust the terminal voltage in the line. In remote areas with light load and 35kV lines passing through, power can be supplied by building 35/ 10kV distribution station or 35/0.4kV direct distribution station.

4.7 The conductor section selection of the medium-voltage distribution network trunk line should refer to the saturated load value of the power supply area and be selected according to the economic current density. The cross section of urban power grid overhead trunk line should not be less than 150mm2, and rural power grid trunk line should not be less than 95mm2.

4.8 The tower of medium-voltage distribution network in cities and towns should be 12m and above, and in rural areas it should be 10m and above. Prestressed concrete poles should not be used on the roadside to prevent cars from crashing.

4.9 urban line spacing should not exceed 50m, and rural line spacing should not exceed 70m. Special sections should be selected according to the design requirements.

4. 10 lightning-prone areas and overhead insulated lines should be equipped with lightning protection devices to prevent lightning-induced disconnection.

4. 1 1 medium voltage distribution lines should be overhead, and overhead insulated conductors should be used in towns, forest areas and densely populated areas. Cable can be used in the following situations:

(1) The corridor is narrow and it is difficult for overhead lines to pass;

(2) Coastal areas vulnerable to tropical storms;

(3) Economic development zones with high requirements and conditions for power supply reliability;

(4) Road sections passing through key scenic tourist areas;

(5) the special needs of power grid structure or safe operation.

4. The12 distribution station area should be constructed and reconstructed according to the principles of "dense points, short radius" and "first distribution, then capacity expansion".

(1) The transformer shall be arranged in the load center, generally installed on the column, and the height from the bottom of the transformer to the ground shall not be less than 2.5m

(2) For densely populated areas with high safety requirements, box-type substations or distribution stations can be used for power supply.

4. 13 The newly installed and replaced distribution transformers shall be S 13 or above energy-saving distribution transformers or amorphous alloy core distribution transformers. Dry-type transformers should be used for distribution transformers installed in high-rise buildings, basements and special fire protection requirements.

4. 14 distribution transformer station should be built at one time according to the final scale, and the capacity of distribution transformer should be reasonably selected according to the planned load in the near future. The capacity of on-column distribution transformer shall not exceed 400kVA, the capacity of box-type substation transformer shall not exceed 630kVA, and the capacity of single transformer in distribution room shall not exceed 800kVA.

4. 15 For stations with large seasonal load fluctuation, high overload capacity distribution transformers or on-load capacity regulating distribution transformers can be selected.

4. 16 In areas where residents mainly use electricity in their daily lives, single-phase and three-phase hybrid power supply can be adopted, and the capacity of single-phase transformer should not exceed 50kVA.

4. 17 When selecting the capacity of rural public distribution transformers, factors such as rural electrification level, climate characteristics, power load characteristics and synchronization coefficient should be comprehensively considered.

4. 18 The incoming and outgoing lines of the distribution transformer shall be insulated wires or power cables, and the high and low voltage terminals of the distribution transformer shall be equipped with insulating sheaths.

4. 19 The high-voltage side of the distribution transformer on the column is protected by fuses, the distribution transformer in the box substation is protected by load switch-fuse combination appliances, the distribution transformer in the distribution room is protected by circuit breakers, and the low-voltage side is protected by plastic case circuit breakers or fuses.

4.20 The low-voltage distribution device of distribution transformer should have the functions of lightning protection, overcurrent protection, metering, measurement, information collection and so on. The box should be made of strong anti-corrosion and flame retardant materials.

4.2 1 The newly-built or reconstructed distribution station area should be built according to the intelligent distribution station area, and the location for installing intelligent distribution transformer terminal and centralized meter reading device should be reserved in the low-voltage distribution device of distribution transformer.

4.22 In areas with frequent natural disasters such as typhoons and floods, there should be no distribution room or switch station in the basement, and flood control and drainage measures should be taken for those who really do not have the conditions; The foundation design of distribution room, box-type substation and meter box should raise the foundation and take good drainage and waterproof measures.

4.23 Necessary anti-theft measures should be taken for transformers and other facilities located in remote areas.

Chapter V Low-voltage Distribution Network

5. 1 Low-voltage distribution network adheres to the principle of district power supply, and should be simple in structure, safe and reliable, and generally adopts single-power radiation wiring.

5.2 Power supply radius of low-voltage lines: no more than 250m in towns and 500m in villages. In areas where users are particularly dispersed, the power supply radius can be appropriately expanded, but the terminal voltage quality should be checked.

5.3 The conductor section of the low-voltage trunk line should refer to the saturated load value of the power supply area and be selected according to the economic current density. The conductor section of urban low-voltage trunk lines should not be less than120m2, and that of rural low-voltage trunk lines should not be less than 70mm2.

5.4 Overhead insulated wires should be used for low-voltage lines in densely populated areas of cities and towns, and low-voltage cables can be used for the reconstruction of historical and cultural villages, traditional villages and houses recognized by the Ministry of Housing and Urban-Rural Development, and areas with special requirements for environment and safety.

5.5 Low-voltage overhead lines in densely populated areas of towns and villages should use concrete poles of 12m and above, with a micro-diameter of not less than190mm; ; In other areas, concrete poles of 8m and above should be adopted, with a slight diameter not less than 150mm. Considering the demand of load development, poles of 10kV line can be selected, and passages are reserved for the extension of 10kV line.

5.6 Low-voltage lines can be erected on the same pole with 10kV distribution lines of the same power supply. When 10kV distribution lines are segmented, low-voltage lines erected on the same pole should not cross the segmented area.

5.7 TT wiring mode is adopted [the neutral point on the low-voltage side of the distribution transformer is directly grounded (working grounding), and the exposed conductive parts of all electrical equipment in the low-voltage power grid are connected to independent grounding bodies with protective grounding wires (PE wires), and there is no direct electrical connection between working grounding and protective grounding. ] In the area of distribution station, residual current action protector should be installed at the low voltage outlet of distribution box.

Chapter VI Low-voltage Household Table

6. 1 Weather-resistant insulated wires shall be used for low-voltage grounding wires. The conductor section should be determined according to the user's load. Generally, the aluminum core and copper core of the cross section of the insulated conductor are not less than 16 mm2 and 6 mm2 respectively.

6.2 Household metering should adopt the metering method of "one household and one meter". The watt-hour meter should be reasonably configured before the farmers' electricity load, and the maximum allowable working current of the watt-hour meter should not be less than 40 A.

6.3 Smart watt-hour meters shall be selected for household electric meters, and centralized meter reading devices shall be installed, so as to comprehensively build a user electricity consumption information collection system.

6.4 The main switch shall be installed at the incoming line side of the centralized metering box. A household switch should be installed at the outlet of the electric energy meter, and the user should be able to operate it.

6.5 The electric energy meter shall be installed in the meter box. Outdoor meter box shall be flame retardant, weatherproof and long-life meter box. Metal meter box should be reliably grounded.

Chapter VII Automation and Information Communication

7. 1 the county-level dispatching and distribution automation system should be built or reformed in an integrated mode, with basic functions such as power grid operation monitoring, remote control security constraints, and online status monitoring of operating equipment.

7.2 Newly-built or reconstructed automation systems should coordinate the requirements of various automation systems, and plan and design the data acquisition platform in a unified way.

7.3 The construction and transformation of distribution automation should be based on the requirements of regional power supply reliability, primary power grid and distribution equipment.

(1) Local feeder automation should be adopted for urban overhead lines and centralized feeder automation should be adopted for cable lines;

(2) Remote fault indicators should be used in rural lines to realize rapid fault diagnosis and location.

7.4 The transformation and upgrading of rural power grid should be carried out simultaneously with the planning and construction of communication network, so as to ensure the communication bandwidth and capacity margin, and improve the support capacity for related businesses.

7.5 The rural power grid communication system should meet the needs of comprehensive information transmission such as data, voice and image required by power grid automation system, management information system and other businesses. The communication trunk lines of substations and power supply stations should adopt the optical fiber communication mode, the area with conditions can adopt the optical fiber communication ring network link mode, and the distributed communication points of medium and low voltage power grids can adopt the optical fiber, wireless, carrier and other communication modes. The main and standby dual-channel mode can be adopted in important unattended substations.

Chapter VIII Reactive Power Compensation and Voltage Control

8. 1 The optimal compensation scheme should be determined according to the compensation strategies of combining centralized compensation with decentralized compensation, combining high voltage compensation with low voltage compensation, and combining voltage regulation with loss reduction.

8.2 Reactive power compensation in rural power grid should choose economical and practical reactive power optimization compensation methods according to local conditions, and actively adopt new technologies and equipment such as dynamic compensation and smooth regulation.

8.3 The construction of reactive power optimization compensation in rural power grid should be carried out from the aspects of voltage and reactive power information collection, reactive power optimization calculation, device configuration, control management and so on. The voltage and reactive power control (VQC) and automatic voltage control (AVC) systems in substations are actively applied to realize the comprehensive and optimal control of voltage and reactive power.

8.4 The reactive power compensation capacity of the substation can be configured according to 10-30% of the capacity of the main transformer.

The reactive power compensation device of distribution transformers of 8.5 100 KVA and above shall be an automatic device with comprehensive control functions such as voltage, reactive power and power factor, and the compensation capacity shall be determined according to the load rate of distribution transformer and the power factor of low voltage side.

8.6 For substations with serious harmonic pollution, reactive power compensation devices combining reactive power compensation and filtering should be selected.

Chapter IX Supplementary Provisions

9. 1 The National Energy Administration is responsible for the interpretation of this technical principle, and it will be implemented as of the date of promulgation. The original Technical Principles for Rural Power Grid Transformation and Upgrading (Guo Neng Xin Neng [2010] No.306) will be abolished.