When building new power lines, transformer substations or reconstructing, expanding, re-equipping with new technical means, electrical networks are first designed. Drawings, plans, load calculations are carried out taking into account current standards. The rules provide for requirements that ensure the reliable operation of networks, auxiliary units and structures, reliable supply of consumers, improvement of technical indicators and quality of generated electrical energy. Electric networks include lines from which urban and agricultural consumers are supplied with energy, including communal facilities, enterprises and organizations in the industrial, domestic and cultural spheres.
Requirements for electrical grids for agricultural consumption
The direction of development of power grids for rural consumers mainly contains the issues of installation of lines with a voltage of 35-110 kW. They are based on sectional lines with one main voltage circuit and mutual reserve, operating from integrated transformer substations. Lines with mutu althe reserve is fed from the inputs of various substations. If the power is supplied from one transformer, then the norms of technological design of electrical networks allow connection to different systems of one substation. Backup power is connected automatically if necessary.
New substations under construction are connected to the outdoor switchgear of a working substation in the cut of power lines or by a branch scheme, taking into account the throughput of the existing network. If the new and old lines run in parallel, then the issue of transferring the existing transformer to increased voltage is being considered.
Requirements for transformer substations
Substations of transformer equipment are envisaged for use as complete sections of industrial production and closed type, made of bricks, reinforced concrete panels and blocks.
The project is based on unified designs and standard units, it is allowed to design devices that are subject to industrial development if they are delivered by the time the installation begins. The design of electrical networks implies an indication of the delivery time in the documentation. A wide variety of standard sizes of used building structures is not allowed, a minimum number is used.
Decisions are made based on the parameters of power grids, economical design schemes after comparing several options. Preference is given to the design that provides the lowest cost. The technical parameters of electrical networks are selected inaccording to power flows in all operating modes.
Calculated losses are taken based on the allowable values of voltage losses at the input of the electrical receiver and the allowable voltage indicator in the central power system. If there are no technical data for calculating allowable losses, then for the calculation of utility networks, voltage consumption of 8% is taken, production lines - 6.5%, livestock complexes - 4% of the nominal indicator.
Loads are determined taking into account all consumers of electricity that are powered by the designed transformer. Loads are accepted with a perspective of 10 years, the determination of the wire and cable section is made for 5 years from the moment of commissioning. If the project lay for three years and was not implemented, then the construction of electrical networks for it is not being carried out, the documentation data are being revised.
Indicators of reliability of electrical supply
Electrical receivers of non-agricultural consumers powered by agricultural networks are divided into categories depending on the requirements for the reliability of electrical supply. Reliability standards for each category are set out in departmental documentation and are determined by the type of consumer input device.
Designing a rural electrical network depends on the category of consumers of agricultural production, municipal and household supplies. Their division into 1 and 2 categories is given in the form of a list in the guidelines forproviding electricity to agricultural power consumers.
If consumers are not included in the list, then they are assigned to category 3. The power supply of the first two categories is provided by two interchangeable transformers, independent of each other. The interruption of their supply of electricity does not exceed the time of automatic restoration of power supply. To do this, the installation of automatic backup power is provided at the input to the consumer.
District power supply provides a second power source in the form of a substation with two transformers or two sections of busbars of the same substation. If the consumer is in remote access, then an autonomous backup power transformer is installed for him. For unforeseen backup power supply of receivers of the first two categories, which do not allow interruptions for more than 0.5 hours, the design of electrical networks provides for a backup source of autonomous supply, regardless of freelance power supply through the main lines.
General norms
The design of the structural part and the master plan is carried out taking into account the end point of the development of the substation, determined by the situational perspective at the time of design. The design of electrical networks is carried out in accordance with the norms of the Land Code. Such papers include decisions of local councils of the corresponding level on the seizure of land plots from owners for the construction of energy complexes.
Electrical network design uses the following information:
- consumer requirements for connecting the substation to the power grid;
- requirements for electrical receivers when connected to utilities;
- requirements of land owners in relation to the transformer and networks;
- norms of architectural and planning solution;
- loads and their distribution by stages of development of the substation, taking into account voltages and categories of users;
- technical data on the ultimate load of the transformer;
- estimated data on the total power of transformers and their number;
- requirements for building a wiring diagram;
- ways to adjust the voltage on the busbars of a transformer substation.
Sources of the above data
Power supply design uses the following documents to obtain the above requirements:
- schemes of energy development of electrical lines and technical characteristics of the external power supply of the facility;
- technical connection conditions of the power supply company;
- documentation on the alienation of a land plot for construction;
- technical parameters of the customer order.
If it is not possible to obtain data from primary sources or the information is outdated, then engineering workers make the necessary calculations and determine the missing information at the preliminary stage of construction.
Design of electrical networks and systems, thermalpower plants includes the following buildings and structures:
- production premises and workshops, main building, electrical buildings, water supply and heating systems, gas and oil installations;
- buildings and structures for auxiliary and industrial purposes, start-up boiler houses, storage buildings, administrative and amenity premises, workshops and oil stations;
- auxiliary facilities, railway tracks, stations, depots, garages;
- wastewater treatment plants, fences, highways, roads, landscaping, temporary buildings and bomb shelters.
Design work is carried out by highly technical specialists, the project provides for highly economical devices and equipment. Technical solutions are based on ensuring reliability, saving on investment and costs for further operation.
Technological equipment is located and assembled in such a way as to ensure convenient maintenance and repair, strive for full mechanization and reduce the proportion of manual work. The instruction for the design of electrical networks prescribes that rooms for service personnel and change houses be located in rooms separated by walls from working equipment. Pipes for technological purposes are not laid inside, with the exception of water supply, sewerage, heating and ventilation.
Control and automation
Modern power plants have control methodsusing an automated control system that allows you to systematize work from a remote point, regulate the operations of calculation, signaling, protection, urgent communication. The scope of control work is adopted in the project in accordance with the instructions of departmental guidance documents.
The volume of management operations is determined based on the direction of automation, the tasks of technological processes at startup, changes in load and shutdown of individual units or the entire system. Automatic control posts are installed of various types: controlling block power plants, high-voltage lines and cross-linked transformers.
Unit power plants are controlled from the central panel of compact distribution stands, control panels of auxiliary office premises, general fixed installations of the compressor substation.
Earth protection activities
Electric substations are located on the lands of private and municipal sites in accordance with the law on land legislation, the collection of acts on the protection of natural resources, building codes and regulations. The location of the future site is selected taking into account the link to the scheme of the existing layout and the general plan of the industrial enterprise.
The design of the district electrical network takes place taking into account the fact that for the location of substations and electrical networks use lands of non-agricultural use and lands with low productivity. During the construction process, the fertile layer of soil is cut off and preserved, which is subsequently restoredunproductive land.
The owners of the plots involved are provided with compensation for the agricultural land used. If land is allocated for temporary use, then in the future this soil is subject to secondary cultivation. Buildings on the sites allocated for the construction of power plants are located economically, the arrangement of auxiliary services in multi-storey buildings prevails. New buildings do not block existing industrial and residential facilities.
Design of electrical distribution networks takes place in strict accordance with building density standards given in SNiP. The areas provided for in the project for further expansion of electrical networks are determined in accordance with the design assignment and economic justification. The areas of ash and slag dumps are calculated taking into account the further use of materials for fertilizer in the national economy.
Entrances and roads to substation buildings are designed on the same land allotment strip, engineering communications, heating lines, water supply and sewerage channels are placed compactly, passing pipes do not violate the boundaries of agricultural land.
Protection of airspace
For this purpose, when drawing up the project, measures and special devices are envisaged to reduce the content of dust and harmful substances in the aboveground layer of the atmosphere to sanitary standards. This condition is provided in various performance indicators.transformer substation, including the highest power mode.
Measures for the protection of water spaces
Wastewater treatment facilities are being built to protect water bodies from pollution by sewage entering them. These facilities are built taking into account sanitary standards. The method of processing waste industrial water is selected depending on the specific operating conditions of the plant being designed. High-voltage lines are built at distances from water bodies provided for in the regulations.
The cleaning method is affected by the type of equipment used and its capacity. The mode of use, the type of fuel, the method of removing combustion products, the cooling system, climatic conditions and other technical indicators are taken into account. The project of discharged effluents is coordinated with the services of state sanitary supervision, protection of fish reservoirs and other bodies.
Transport movements
Transport of external and internal movement of goods for the operation of the substation is designed on the basis of a comparison of the technical and economic indicators of the options. Conveyor, rail, water, road or air transportation is used. The transportation of workers from their place of residence to the working area is carried out by the most efficient mode of transport, allowing to spend the least amount of time.
The transportation of goods and passengers to transformer substations located in industrial areas is tied to the general scheme of existing modes of transport and the project for the development of tracks for future periods. There is a mutually beneficial cooperation of transportation withneighboring operating and planned enterprises.
Reception, supply and storage of fuel oil, gas, oil
The daily requirement for fuel oil is calculated based on the operation of all boilers at their normal performance for 20 hours of operation. If the average temperature of the coldest month of the year is taken into account, then the calculation is carried out for 24 hours. Solid fuel power plants are designed taking into account the construction of a kindling unit. If hot water peak boilers are used, then their economy is combined with a kindling device.
Electrical networks of the enterprise are designed taking into account the supply of fuel oil to the starting boiler house from the main or secondary fuel oil unit. If the use of gas is envisaged as the main fuel, then a gas control point is designed as part of the boiler house. The distribution unit is located on the territory of the substation in a separate building or under a canopy.
Gas fuel consumption is determined based on the maximum consumption for all boilers. Gas supply is carried out separately for each distribution point, no backup connections are planned. The number of control devices in each distribution point is provided for one more, which is a reserve.
Power plants are equipped with a point for the economy of transformer and turbine oils. The facility includes storage tanks for fresh and used products, pumping devices, dryers, and recovery equipment. During pouring of transformers, mobiledegassing units protected by nitrogen or film material. Four tanks of turbine oil and transformer oil are installed in the substation complex, two tanks are provided separately for storing engine oil lubricant.
House Electricity Project
The project develops external electrical supply of residential and public buildings, internal wiring is not included in its composition. Typical projects are designed to connect electrical power to consumers with a standard layout. If the location of the courtyard buildings is far from the standard solution, then the project is revised taking into account these changes.
The apartment power supply project is mainly used in new buildings, in which the construction company is required to make a minimum number of connection points. There is a kind of project, which is called an individual project, which allows you to include external, internal and household power supply in the development. Household electricity supply allows communication and air conditioning systems to function.
Procedure for registering a project
The electricity supply project of the apartment basically contains technical specifications. They are developed by a representative of the electricity supplier, for this an application is submitted to the organization. The document indicates:
- name and legal address of the object;
- indicator of the design voltage value;
- calculated load indicators;
- type of connected voltage;
- indicates the direction of energy use, such as heating and hot water production.
In addition to the application, attach the general plan of the site, property documents, permits for work.
In conclusion, it should be noted that the implementation of the project requires professional knowledge and a license, therefore, the preparation of documents is carried out by the specialists of the energy company, the project is not done independently.
