Design of electrical network of industrial area

Contents

Content 1 Introduction... 3 2 Initial data... 5 3 Characteristics of electrified area  and electric consumers... 6 4 Preliminary considerations on selection of design and nominal voltage of network line7 5 Selection of quantity and power of power transformers at receiving substations... 11 6 Analysis and substantiation of electrical network diagrams 16 7 Feasibility comparison of options Selection and justification of optimal version of electric network 21 8 Electrical calculation of main operating modes of network 35 9 Selection of voltage control tools.....

The discipline of electrical systems and networks is one of the basic ones in which the foundation of special training of an energy engineer is laid. The purpose of the discipline study is to create knowledge in the field of calculation theory and analysis of modes of electrical systems and networks, ensuring their design and operation of economy, reliability, as well as quality of electricity.

The main tasks of the discipline are to teach the basics of designing electrical networks and systems and methods to increase their economy, reliability and quality of electricity, to familiarize with the physical nature of the phenomena accompanying the process of power production, distribution and consumption, to familiarize with the designs of elements of power transmission lines and equipment.

Modern electric power transmission systems are advanced electrical networks with numerous control, control and redundancy devices. Electric networks of even a separate power system number thousands of node points, dozens and hundreds of circuits of various rated voltages, include a variety of electrical equipment.

The power supply system should be built and operate in such a way that at a given useful supply of electricity to consumers the criteria of economic efficiency, reliability of electricity supply and quality of electricity supplied to consumers are met. As for the transmission part of the system, the structure, configurations and parameters of the electric networks of different rated voltages should have sufficient capacity to ensure stability. In addition, the electrical network should be designed and operated in such a way that its operability is ensured in all possible modes - normal, repair, and post-accident.

In order to ensure the operability, reliability of operation and quality of electricity, the network must meet the criteria of economic efficiency. Such criteria are a minimum of reduced costs, power losses, etc.

The task of designing electrical networks is to develop and feasibility studies of solutions that ensure optimal reliability of electric power supply to consumers in the required size and quality. 

The theme of the project under the course "Electrical networks is the preparation of a technical design at the stage of the design assignment of the electrified area, the power supply of which is carried out from a power source with a nominal voltage on 330/220/110/35 kV buses.

Characteristics of the electrified area and electric power consumers

We accept the conditions according to which the electrified area is located in an uninhabited area, without large crossings, in the second area in the wind (standard wind speed 29 m/s), in the second area in ice (standard ice wall thickness 15 mm), with an average annual duration of thunderstorms from 20 to 40 hours with a thunderstorm, which corresponds to the conditions of Moscow and the Moscow region or St. Petersburg.

ISP - power supply; A - machine tool plant; B - plant of lifting and transportation equipment; B - instrument-making plant; D - auto tractor plant; D - pulp and paper mill.

Preliminary Considerations for Design Selection and Rated Mains Voltage

Based on the initial data, we make a decision on the transfer of electricity using overhead power lines using reinforced concrete supports for their laying. Wires for VL will be used as standard, type IVS.

Since in accordance with the PUE, loads of category I should be provided with electricity from two independent power supplies and a break in their power supply is allowed only for the time of automatic switching on of the standby power supply, this should be taken into account when designing various versions of electrical networks. As a rule, a double-chain line made on one support does not meet the requirements of reliability of power supply to consumers of category I. For them, it is advisable to provide at least two separate single-chain lines. When meeting the requirements of reliability of power supply, consumers of category I should be provided with a hundred percent reserve, which should be turned on automatically. Due to the fact that consumers of category I prevail at the facilities under consideration, the design will proceed precisely from the conditions of reliability of the power supply.

Selection of number and power of power transformers at receiving substations

When designing a substation, it is necessary to take into account the requirements of redundancy, considering that consumers of category I should be powered by two independent power sources, while redundancy of the power supply and all other consumers can be provided. When supplying consumers of category I from one substation, in order to ensure the reliability of the power supply, it is necessary to have at least one transformer on each section of the buses, while the power of the transformers should be selected as follows. In case of failure of one of the transformers, the second, taking into account GOST 14209 - 97 [2], must provide power to all consumers of category I and withstand overload of 1.3 in fractions of rated power for 2 hours. In case of longer overload, alternation of consumers and other methods of maintaining power should be used.

The selection of transformers is made for each substation with two transformers at the rated power of each, calculated in the range from 60% to 70% of the maximum load and taking into account overload.