What are the technical principles for the construction and transformation of rural power networks in medium and low voltage cities?

Notice of the State Planning Commission on Forwarding the Technical Principles of Rural Power Grid Construction and Transformation (Ji Ji [1999] No.555)

Technical principles of rural power grid construction and transformation

Chapter I General Provisions

1. 1 The Technical Principles for Rural Power Grid Construction and Transformation are formulated in order to do a good job in rural power grid construction and transformation (hereinafter referred to as rural power grid transformation), achieve the purpose of advanced technology, safety, reliability and energy saving, meet the needs of rural power consumption growth, and improve the quality of power supply and the modern management level of rural power distribution network.

1.2 The equipment selected for rural power network transformation must be domestic equipment that has passed the provincial and ministerial appraisal, and the products recommended by the State Economic and Trade Commission and the State Power Company are preferred.

1.3 All localities should adopt new technologies, new products and new processes according to local conditions on the premise of ensuring the safety, economy and reliability of electricity consumption.

The technical regulations and specifications of 1.4 on design, construction and acceptance shall be strictly implemented in rural power grid reconstruction.

Chapter II General Requirements

2. 1 The rural power grid reconstruction project should pay attention to the optimization of the overall layout and network structure, and bring the rural power grid reconstruction into the unified power grid planning.

2.2 The power supply radius of rural power lines shall generally meet the following requirements:

400V line is not more than 0.5km；; 10kV line is not more than15km; ; 35kV line is not more than 40km；; 1 10kV line is not greater than150km; ;

2.3 In areas with long power supply radius or economically developed areas, it is suggested to increase the distribution of substations to shorten the power supply radius. The long-term goal is one substation in each township to ensure the quality of power supply and meet the development. In areas with low load density, the power supply radius of 10kV line can be appropriately extended on the premise of ensuring voltage quality and moderately controlling line loss.

2.4 In economically developed and conditional areas, power grid transformation should be combined with dispatching automation, distribution automation, unattended substations and reactive power optimization. Temporary and unconditional conditions should also be considered in structural layout and equipment selection.

2.5 rural power grid transformation should achieve:

2.5. 1 The comprehensive high-voltage line loss rate of rural power grid is reduced to below 10%, and the low-voltage line loss rate is reduced to below 12%.

2.5.2 The power factor of substation 10kV side reaches 0.9 and above, that of power users 100kVA and above reaches 0.9 and above, and that of agricultural users reaches 0.8 and above.

2.5.3 The qualified rate of user terminal voltage is above 90%, and the allowable deviation value of voltage should reach: allowable deviation value is 220v+7% ~-10%; 380V allowable deviation+7 ~-7%; 10kV allowable deviation+7% ~-7%; 35kV allowable deviation+10% ~- 10%.

2.5.4 The reliability rate of urban 10kV power supply shall meet the standards proposed by the Reliability Center of State Power Corporation.

2.5.5 The ratio of main transformer capacity to distribution transformer capacity in rural power grid is 1:2.5, and the ratio of distribution transformer capacity to electrical equipment capacity is 1: 1.5 ~ 1.8.

2.6 When selecting the transmission line path and substation site, flood storage areas, swamps and low-lying areas should be avoided, and the approved general design or typical design should be adopted.

2.7 rural power grid reconstruction project should make full use of existing available facilities.

Chapter III 1 10kV Power Transmission and Transformation Project

3. 1 1 10kV power transmission and transformation project construction should meet the needs of electricity development from 10 to 15.

3.2 The project construction must strictly implement the current relevant national laws and regulations, and the design must meet the specified design depth requirements.

3.3 Substation construction should proceed from the overall interests, combine the national conditions, conform to the characteristics of rural power grids, adopt moderately applicable standards, strictly control the floor space and building area, and refrain from luxury decoration.

Chapter IV 35kV Power Transmission and Transformation Project

4. 1 The construction of rural substations should adhere to the principle of "dense point and short radius" and develop in the direction of "outdoor, miniaturization, low cost, safety and reliability, advanced technology", and consider unattended design.

4.2 The design standard can consider the load development requirement of 10 year, and generally two main transformers can be considered.

4.3 The incoming and outgoing lines of the substation should be connected twice or more as far as possible, and the lines should be looped and operated in open loop, or radial single connection mode should be adopted according to the situation.

4.4 If a new fuse is used as the main transformer protection mode on the high voltage side, the corresponding 10kV side protection should be equipped with inverse time reclosing.

4.5 Microcomputer protection devices should be adopted for the protection of newly-built substations, and the integrated centralized console should be cancelled.

4.6 New energy-saving transformers must be adopted for new main transformers, and all high-energy-consuming transformers should be replaced within three years.

4.7 Equipment selection should meet the general requirements, and cities and economically developed areas should choose products that are automatic, intelligent, free of refueling and less maintenance.

4.8 The conductor adopts steel core stranded wire, and the conductor section is selected according to the economic current density, and the development allowance is 10 years, but not less than 70mm2. In areas with heavy loads, it is recommended to use rare earth conductors.

4.9 Prestressed concrete poles should be the first choice for line towers, and some iron towers can be used in areas where transportation and construction are difficult.

4. 10 standard fittings adopt national finalized products, and non-standard fittings must adopt standard steel and be galvanized.

10kV distribution network chapter 5

5. 1 Rural distribution substations should be constructed and reconstructed according to the principle of "small capacity, dense points and short radius". Low-loss distribution transformers should be selected for new construction and reconstruction stations (at present, S9 type and a small amount of amorphous alloy distribution transformers are mainly used). Series 64 and 73 high-energy distribution transformers should be completely replaced.

5.2 The transformer capacity is based on the existing load and has appropriate redundancy. Add a household power transformer, and the capacity of a single transformer generally does not exceed 1 10kVA.

5.3 Distribution transformers with a capacity of 3 15kVA and below shall be installed on poles, and distribution transformers with a capacity of 3 15kVA and above shall be installed on the floor. Multi-functional power distribution cabinets should be selected, and it is not suitable to build a power distribution room.

5.4 The new and modified distribution transformer units shall meet the following safety requirements:

5.4. 1 The distance between the bottom of column and household transformer and the ground shall not be less than 2.5m

5.4.2 Fences (bars) shall be set around the floor-standing transformer, the height of the fences (bars) shall not be less than 1.8m, the clear distance between the fences (bars) and the outer contour of the transformer shall not be less than 0.8m, and the foundation of the transformer base shall be higher than the local maximum flood level, but not less than 0.3m.. ..

5.5 The high-voltage side of distribution transformer should adopt the new fuse and metal oxide arrester which are finalized by the state.

5.6 The cross section of the low-voltage side lead shall not be less than 35 square millimeters (aluminum wire). The main switch shall be an automatic air switch and equipped with a leakage protector.

5.7 Urban distribution network should adopt the structure of ring network layout and open network operation, rural distribution network should be dominated by single radiation, long trunk lines or branch lines should be equipped with sectional or branch switchgear, and the use of automatic reclosers and automatic sectionalizers should be actively promoted, leaving room for the development of distribution network automation.

5.8 The conductor adopts steel-core aluminum stranded wire, and the conductor section is selected according to the economic current density, with a development allowance of not less than 5 years, but not less than 35 square millimeters, and the section at the end of the line with less load can be selected as 25 square millimeters. Bare wires are generally used, and insulated wires can be used in towns or complex areas.

5.9 The distribution mode of single-phase transformer or single-phase and three-phase mixed power supply can be adopted in areas with low load density, few load points and conditions.

5. 10 Prestressed cement poles of 10 meters and above are generally selected in rural areas, and prestressed cement poles of 12 meters and above are generally selected in cities and towns.

5. 1 1 Without the consent of the electric power enterprise, other lines such as broadcasting, telephone and cable TV shall not be erected on the same pole.

5. 12 Standard fittings shall adopt national standard products, and non-standard fittings shall adopt standard steel and be hot galvanized.

Chapter VI Low-voltage Distribution Facilities

6. 1 The layout of low-voltage distribution lines should be combined with the rural development planning, considering the housing planning of villages and towns, and the construction and transformation should be carried out in strict accordance with the requirements of the Technical Specification for Rural Low-voltage Power.

6.2 The conductor section of low-voltage trunk line shall be selected according to the maximum working current, but it shall not be less than 35 square millimeters, and the branch line shall not be less than 25 square millimeters (aluminum stranded wire). Single strand, broken strand and iron wire are prohibited.

6.3 Line erection shall meet the requirements of relevant regulations. Generally, concrete poles of not less than 8m are used for poles, and bare wires should be used for trunk lines. However, in towns and villages, in order to ensure the safety of electricity use, insulated wires can be used through economic and technical comparison. Insulating porcelain bottles shall be installed for pole stay.

6.4 Buried wires are recommended for the well line of irrigation and drainage machinery.

6.5 The phase line, zero line or protection line of the household connection line shall be led out from the same pole, and the span shall not be greater than 25m. More than, should increase the household pole.

6.6 Insulated wires should be used for household connecting wires, and the cross section of the wires should not be less than 6 square millimeters. After entering the home, control circuit breakers, fuses and leakage protectors should be installed, and the home connection lines must be separated from communication lines and broadcast lines. Hard insulating pipes should be installed when entering the line and passing through the wall, and dripping bends should be made outdoors.

6.7 Without the consent of the electric power enterprise, other lines such as broadcasting, telephone and cable TV shall not be erected on the same pole.

Chapter VII Reactive Power Compensation

7. 1 The reactive power compensation of rural power grid adheres to "overall planning, rational layout, grading compensation and local balance" and "combination of centralized compensation and decentralized compensation, with decentralized compensation as the main one; High-voltage compensation is combined with low-voltage compensation, mainly low-voltage compensation; The principle of combining voltage regulation with loss reduction and giving priority to loss reduction.

7.2 Dense capacitance compensation should be adopted in substation, and compensation should be made according to reactive power planning. If there is no plan, it can be configured according to 10- 15% of the main transformer capacity.

7.3 1 10 kva and above distribution transformers shall be compensated by electric tracking.

7.4 Actively promote reactive power compensation microcomputer monitoring and automatic switching devices. Assembled and self-healing capacitors with reliable performance and advanced technology should be adopted.

7.5 The reactive power compensation of the distribution transformer can be configured according to 10- 15% of the capacity of the distribution transformer, and the line reactive power compensation capacitor should not be erected on the same stage as the distribution transformer.

Chapter VIII Low-voltage metering device

8. 1 Farmers' electricity consumption must be charged by one meter per household, and township public facilities must be charged by separate meters.

8.2 It is forbidden to use the national eliminated and invalid watt-hour meter. Wide-range watt-hour meters should be used and calibrated regularly.

8.3 The electric energy meter should be reasonably configured according to the farmers' electricity load. Economically developed areas generally think that it is not less than 2kW/ household.

Chapter IX Supplementary Provisions

9. 1 Electric power companies in all provinces (autonomous regions and municipalities) provide actual conditions and formulate corresponding technical standards.

9.2 This principle shall be solved by the State Power Company.

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Technical principles of construction and transformation of urban low-voltage distribution network in Guangxi

1 range

1. 1 This guideline specifies the main technical principles and requirements that should be followed in the planning, design, construction and transformation of urban (district) distribution networks managed by Guangxi Power Grid Corporation.

1.2 Requirements of this technical principle: the grid structure is firm, with distinct levels, reliable equipment, advanced technology, land saving, green and energy saving, and reasonable cost; The main facilities should be built at one time to meet the development needs of 10.

1.3 The scope of application of this guideline is all units (including escrow) owned by Guangxi Power Grid Corporation. Users accessing the distribution network system of Guangxi Power Grid Corporation can refer to this guideline.

1.4 The contents of the country, industry, local and China Southern Power Grid Corporation have been clearly defined in this guideline, so they are not repeated here. The content of the clause is not clear enough or the existing clause is modified, and the clause is clearly defined or emphasized.

2 normative reference documents

3 Terms and definitions

The following terms and definitions apply to this standard, where the voltage level from 3. 1 to 3.8 is 10kV.

3. 1 indoor distribution station

Transformers and their low-voltage distribution devices are located in buildings (including underground), which convert the voltage of 10kV into the working voltage of 0.38kV and receive and distribute power, and are referred to as indoor distribution stations (rooms) for short.

For residential quarters, businesses, entertainment and offices, the simultaneous rate of electrical equipment K 1 is multiplied by the average load rate K2 of electrical equipment, that is, K= K 1×K2.

4 General provisions and technical requirements

4. 1 nominal system voltage

Medium voltage 10kV, low voltage 0.22/0.38kV. The power quality must comply with relevant state regulations.

4.2 Short-circuit current

Medium-voltage power grid: The short-circuit current of the system should generally be limited to 16kA or below. When the project is difficult to implement, it can be increased appropriately after demonstration, but the maximum amount should not exceed 20kA. In new construction and renovation projects, electrical equipment should be selected according to 20kA, and electrical equipment near 220kV substation should be inspected.

5 medium voltage power grid planning and construction principles

5. 1 grid construction principle

6 Medium voltage equipment configuration

7 overhead line

8 cable line

9 low voltage line

10 distribution automation

10. 1 The function of distribution network automation should be coordinated with the primary system of urban network, and the scheme and equipment selection should follow the principle of economy and application, and pay attention to its cost performance. It is implemented on the basis of relatively stable distribution network structure, reliable equipment and certain supporting capacity of primary system.

10.2 the construction and transformation of distribution network should comprehensively consider the situation of distribution lines, communication networks and switch cabinets, choose an economical and practical automatic construction method, make full use of existing resources, and make full use of the original primary equipment, distribution master station, distribution terminal, distribution electronic station and communication channel through inheritance or appropriate transformation according to the requirements of equipment life cycle management. The primary school system should not be reformed on a large scale.