Reconstruction of substation 110/10

Contents

CONTENTS

Introduction

1. Characteristics of substation consumers

2. Data for reconstruction of substation electrical part

3. Substation electrical load schedules

3.1 Construction of 10 kV side load schedules

3.2 Construction of 110 kV side load schedules

4. Selection of power transformers at substation

4.1 Transformer Power Selection

5. Selection of main substation diagram

6. Calculation of short-circuit currents

6.1 Substation Replacement Diagram

6.2 System Resistance

6.3 Calculation of currents of three-phase short circuit at point K

6.4 Calculation of currents of three-phase short circuit at point K

6.5 Calculation of two-phase short circuit currents

6.6 Calculation of shock currents

7. Selection of electrical equipment

7.1 Selection of switching equipment

7.1.1 Selection of 110 kV switches

7.1.2 Select 110 kV disconnectors

7.1.3 Selection of 10 kV switches

7.2 Selection of bus bar

7.2.1 Selection of busbar on high voltage side

7.2.2 Selection of busbar on LV side

7.3 Selection of 10 kV support and bushing insulators

7.4 Overvoltage limiters

7.5 Selection of switchgear - 10 kV

7.6 Selection of current measuring transformers

7.6.1 Selection of 110 kV current transformers

7.6.2 Selection of current transformers on the 10 kV side

7.7 Selection of voltage transformers

7.7.1 TN selection on 110 kV side

7.7.2 TN selection on 10 kV side

7.8 Selection of operating current type

7.9 Substation Auxiliary System Design

7.9.1 Selection of TSN

7.9.2 Selection of MV board supply cables from TSN

7.9.3 Selection of cables of TSN power supply receivers

7.9.4 Calculation of short-circuit currents of MV system

7.9.5 Selection of fuses for TSN

7.9.6 Selection of automata on introductory panels

7.9.7 Selection of circuit breakers on MV outgoing electric receivers

8. Economic part

8.1 Calculation of Capital Costs for Reconstruction

8.2 Estimate of overhead costs

8.2.1 Depreciation deductions for renovation

8.2.2 Contributions to the repair fund

8.2.3 Equipment Maintenance Costs

8.2.4 Social Insurance Contribution

8.2.5 Transportation costs

8.2.6 Calculation of labor protection costs

8.3 Reconstruction Efficiency

8.3.1 Damage reduction

8.3.2 Cost Reduction

8.4 Reconstruction payback period

9. Relay protection

9.1 General information about emergency automation

9.2 General principles of ACF devices execution

9.3 Requirements for microprocessor devices

frequency unloading

9.3.1 Technical equipment requirements

9.3.2 Software Requirements

9.3.3 Requirements for operational elements of local control, control and signalling of ACR MP state

9.3.4 Emergency Event Recording Requirements

9.3.5 Reliability Requirements

10. Occupational safety

10.1 Protective grounding of 110 kV switchgear

10.2 Calculation of protective grounding

10.3 Lightning protection

10.4 Electrical protection substation configuration

means and devices

10.5 Safety Technical Measures

performance of works in electrical installations up to 1 kV

Conclusion

List of sources used

Introduction

The availability of energy for production is important in the development of any economy. Energy is equally important for the utility sector. However, the generation of energy directly at the point of its consumption is difficult and involves a number of difficulties. Centralized energy generation in large volumes is much more efficient - at the same time, the efficiency of the system will be maximum. But under these conditions, the problem of transporting energy arises. Most types of energy: thermal, mechanical, etc., it is problematic to transfer even over short distances. Under these conditions, electric energy occupies a special place - it is easy to transform it into any other types of energy, in addition, using high-voltage transmission, it is possible to transport it over long distances with minimal losses, without significantly increasing the cost of the system.

Today, of all sectors of human economic activity, energy has the greatest impact on our lives. Miscalculations in this area have serious consequences. Heat and light in homes, traffic flows and industrial work all require energy. The energy base of today is the fuel reserves of coal, oil and gas, which satisfy approximately ninety percent of the energy needs of mankind.

So, electricity is the most versatile form of energy, it is generated at power plants and distributed among consumers through electrical networks. But energy needs continue to grow. Any development requires, above all, energy costs. This means that today special attention needs to be paid to the modernization and reconstruction of both the power generation system and, to an equal extent, the system of delivery and distribution of electricity to consumers.

A properly chosen scheme for delivering electricity to consumers largely determines the reliability of supply, predetermines possible emergency situations and accidents. At the same time, when designing transformer substations, their configuration, transmission lines, etc., it is also necessary to proceed from economic feasibility. As a rule, several options are considered and, based on their comparison, the final one is chosen on the basis of the optimal relationship between technical need and economic feasibility. This allows you to achieve significant savings in materials and costs, facilitates the operation of equipment.

Recently, new types of electrical equipment have begun to be used more and more widely: vacuum and gas-insulated switches, instead of oil, microprocessor relay protection devices, instead of relay and lamp, etc. These devices at greater cost, however, provide greater reliability, flexibility and are generally more often preferred.

Selection of power transformers at substation

Three-phase and single-phase, two-winding and three-winding power transformers and autotransformers, as well as power single-phase and three-phase transformers with split low voltage winding are installed at power stations and substations.

Oil transformers, dry transformers filled with non-combustible liquid dielectric, and cast-insulated transformers are used.

When choosing the type and number of substation transformers, it is necessary to proceed both from the reliability of power supply to consumers and from the economic feasibility of this choice. It is also necessary to take into account the prospect of increasing loads in the future.

Calculation of short-circuit currents

To select the electrical equipment and equipment of the substation, it is necessary to determine the requirements for them for electrodynamic strength and thermal current action. This data can be obtained by calculating short circuit currents in the system. It is enough to calculate the current of the three-phase short circuit.

The following assumptions are accepted in the calculation:

load currents are not taken into account;

Capacity is not taken into account;

the three-phase network is received symmetrically, i.e. the phase resistances are taken exactly equal to each other;

no saturation of steel of electrical machines (generators, electric motors, transformers);

magnetization currents of transformers are not taken into account;

active resistances of generators, transformers and reactors are not taken into account;

phase shift of e.d.s. is not taken into account. various power supplies included in the design diagram.

Economic part

In the economic part of the diploma project, various economic parameters for reconstruction are calculated: capital costs for reconstruction, estimate of overhead costs, balance of working time, economic efficiency, payback period, etc.

General information about emergency automation

In the operation of the power system, accidents often occur due to various causes, as a result of which the system can lose part of its power sources (accidents at generators, power transformers), large consumers can also be emergency disconnected (accidents at transformer substations, power stations). Such accidents can cause undesirable consequences for the remaining part of the network. To prevent such consequences, various kinds of automation are used in the energy system: ACR, ATS, SAON, ALAR, AOSN, AOPN, etc.

Typically, in case of loss of one of the power supplies, there is a power deficit, which is manifested by a decrease in voltage and frequency. To limit these consequences, ATS devices are usually used, with the help of which additional sources are connected to the system; or the system is connected to a parallel operating system. However, in many cases, the power of the sources supplying the parallel system may not be sufficient to power its and the added load. In this case, SAON devices are used, operating mainly from ADV, which disconnect part of the least important consumers in case of lack of power.

Thanks to VSD devices, voltage reduction is most often managed to be leveled, while frequency reduction is a more dangerous consequence. A decrease in frequency by tenths of Hertz can lead to a deterioration in the economic performance of the system, but does not pose a serious danger. Reducing the frequency by 1-2 Hz or more can lead to serious consequences for the operation of the power system, as well as for its electric receivers.

This is due to the fact that when the operating frequency decreases, the rotation speed of the motors powered by the system decreases. Among them, in particular, are mechanisms of auxiliary needs of thermal power plants, which also power this system. As a result, the output power generated by thermal power plants is reduced and the frequency drops even faster. This process is called "frequency avalanche" and causes the system to fail.

Frequency reduction carries destructive actions for complex technological processes, can lead to a threat to human safety, entail serious man-made or environmental disasters. In particular, with the long operation of large steam turbines at a reduced frequency, destructive processes arise in them associated with the coincidence of the turbine speed with the resonant frequency of any of the groups of its blades.

In order to prevent frequency collapse in the system, it is customary to turn off some of the power receivers, thereby reducing the load on the system. Such a shutdown is called automatic frequency unloading (AHR).

According to PUE, all consumers of electric energy are divided into three categories: category I - consumers of this group include those whose failure to supply electricity can lead to danger to people's lives, significant material damage, danger to state security, violation of complex technological processes, etc. Category II - this group includes electric receivers, a break in the power supply of which can lead to mass underdelivery of products, downtime of workers, mechanisms, and industrial transport. Category III - all other consumers of electricity. Consumers of category I must have constant power supply, and from two independent sources. Interruption in power supply from one of the sources is allowed only for the duration of ALT operation. Consumers of category II allow operation from one source and the power supply break must not exceed the operation time of the redundancy automation. Consumers of category III allow a break in the power supply up to a day (time of accident elimination by an emergency exit team). Thus, the action of the ACR is aimed at disabling category III consumers as the least important.

When designing an ACR circuit of an electrical system, consumers should be distributed to substations and switchgears taking into account this division into categories. In addition, all possible types of accidents should be provided and the power of the disconnected electric receivers should be provided, which will be enough to return the system to normal after their disconnection. The AFR circuit itself is made multi-stage, where each stage differs from the other with a frequency setpoint. Thus, ACR is a classic feedback system. That is, if the frequency decreases below a certain value determined by the set point of the first stage, the first stage of the AFR will work and turn off part of the consumers. Then, if the frequency drop process does not stop, then when the frequency reaches the second set point, the next group of consumers will be turned off, which will further slow down the frequency drop process.

Conclusion

The diploma project is dedicated to the reconstruction of the existing 110/10 kV substation. The topic of the diploma project "Reconstruction of the 110 kV KSI substation."

In the diploma project, studies of the current operation of the substation are being carried out, on the basis of which a number of proposals for reconstruction have been developed. The following changes are proposed in the project:

replacement of power transformers;

replacement of existing 110 kV oil switches with more modern gas-insulated ones;

replacement of 10 kV switches with vacuum switches, including replacement of switchgear cells;

replacement of valve dischargers with non-linear voltage limiters (OPN);

It is also planned to replace measuring transformers, auxiliary transformers and other changes.

It should be noted that the funds of the CES branch are worn out by almost 50 percent, that is, they served half of the average normalized service life. Under these conditions, in order to prevent an increase in emergency situations due to equipment deterioration and an increase in the lack of electricity to the consumer, it is necessary to reconstruct fixed assets and replace the most worn out equipment. The proposed changes require financial injections of about 82 million rubles, however, as shown in the economic part of the diploma project, these investments will pay off in less than 10 years.