Technical transformation scheme of electrical primary system of hydropower station?

What is the specific content of the technical transformation scheme for the primary electrical system of hydropower station? The following Zhong Da Consultation will answer your questions.

1. Introduction

Converting water energy into electric energy is the main task of hydropower station. Water storage and drainage are the main functions of reservoirs. The water in the reservoir enters the water diversion system of the hydropower station, and after the continuous operation of the unit, it can be converted into electric energy to provide electricity for industry and civil use through the power grid.

2. Discussion on related concepts

2. 1 Electrical wiring of hydropower station

Electrical wiring can be divided into primary wiring and secondary wiring. The main wiring of a power plant refers to the interconnection of generators, circuit breakers, transformers, disconnectors, current transformers, buses and lines to ensure the smooth completion of power production, conversion and transmission. Primary wiring is the main part of power plant, which directly affects the economic and technical indicators of power plant. Its design principle is the function of the hydropower station electrical system, and comprehensively considers the characteristics of kinetic energy, hydrometeorology, construction scale, transportation conditions of geological terrain, design and wiring of access system and other factors.

2.2 Electrical primary wiring form

The primary electrical connection should be determined according to the specific conditions of hydropower station and power system. 10 ~ 1 10 kV connection forms mainly include busbar-free connection and busbar-free connection. The former includes polygon connection, transformer line unit connection and bridge connection. The latter includes single bus, intermediate bus section, additional bypass bus, double bus and bypass disconnector, etc.

2.3 Connection mode of main transformer and generator

Generally speaking, there are three reasonable connection modes between generator and main transformer: unit connection (one unit is connected to a main transformer), extended unit connection (two or more units are connected to a transformer) and combined unit connection (two groups of units are connected together). In order to ensure the safety of the generator connection line outlet, a circuit breaker is installed on the generator outlet connection. In order to prevent the generator from being burnt out by strong current, the generator is grounded through the transformer, and the generator and the transformer are connected through the off-phase bus.

3. Conditions for electrical transformation of hydropower stations

When the hydropower station is used for a period of time, the electrical equipment and its ancillary equipment are outdated, and the power generation benefit, safe power generation and power supply reliability cannot be guaranteed, it is necessary to carry out electrical transformation of the hydropower station. The necessity of electrical transformation of hydropower stations is mainly manifested in the following aspects:

First, some power stations are built by stages, and the main transformers put into operation are quite different in model, capacity and performance, which cannot meet the operation requirements.

Secondly, the oil circuit breaker is usually selected as the circuit breaker. With the increase of service life and short circuit, it has some problems such as aging, deformation and more oil leakage points. The matching operating mechanism is electromagnetic, which has some shortcomings, such as poor reliability, outdated accessories and difficult purchase.

Thirdly, when the bus is working, it is full load flow or overload flow, which has poor reliability and insufficient stability.

Fourth, the single bus configuration is usually used to connect the high and low voltage sides of the main transformer, and the low voltage incoming line of the main transformer is not equipped with a circuit breaker, which has low reliability, inflexible operation and large power loss.

Fifth, the model of distribution equipment is chaotic, and connecting cables are wasted, which brings inconvenience to operation and maintenance.

In a word, the purpose of electrical transformation of hydropower station is to change the status quo of aging and elimination of equipment, improve the reliability of power generation, increase the benefit of hydropower station and improve the regulation capacity of reservoir.

4. The principle of primary electrical transformation of hydropower station

The basis of electrical transformation of hydropower station is related rules and regulations, and the specific situation of hydropower station is fully considered, so as to shorten the construction period with the lowest engineering cost and obtain higher economic benefits.

4. 1 feasibility principle

The electrical transformation of hydropower stations is usually limited by unchangeable or inappropriate changes. The reconstruction should be reasonably designed according to the specific conditions of the original hydropower station, and the design scheme should conform to the relevant national standards and norms.

4.2 Scientific principles

On the basis of feasibility, new technologies, new equipment and new materials are adopted to make up for the shortcomings of the original hydropower station.

4.3 the principle of economy

For one-time investment equipment, such as circuit breakers and disconnectors, settings should be saved and the main wiring should be simple; The selection of main transformer should be economical and reasonable, and it is not recommended to increase the power loss, so as to ensure the reliability of the safe operation of the system, increase the annual power generation, improve the economic benefits and deal with special problems.

5. Advantages of electrical main wiring after transformation

After the electrical transformation of hydropower station, its operation safety and flexibility are greatly improved, which can be applied to various operation modes, with fast switching speed, strong applicability and good economy.

6. The content of primary electrical transformation of hydropower station

The primary electrical renovation design of hydropower station includes the following aspects: (1) Demonstration and modification of the original main wiring scheme; The adjustment of auxiliary power connection and wiring mode is based on the newly designed main wiring scheme; To calculate the short-circuit current, the technical transformation of small hydropower stations usually changes little; The selection of new substitute products should conform to the specific conditions of the original electrical equipment; The configuration wiring diagram of high-voltage switchgear is reformed and designed. Transform and design the layout of indoor and outdoor distribution equipment. At the same time, the corresponding electrical secondary, communication and related lighting, HVAC, civil engineering, water supply and drainage, lightning protection, grounding, etc. are reformed and designed, but it is not easy to do too many reforms except electrical secondary.

1). Select the main transformer.

The capacity and resistance percentage of several main transformers should be close to or the same, so as to ensure their parallel use. The main transformer with new material, new technology and new structure should be selected, which can effectively reduce no-load loss and short-circuit loss. If the capacity of the original transformer meets the requirements, it can be transformed into an energy-saving transformer through technical transformation.

2). Auxiliary power supply design

According to the specific situation of hydropower station, the auxiliary transformer is selected reasonably. Usually, the transformer in the factory is selected with protective shell, fan and temperature control device, which can meet the self-starting voltage drop and single unit capacity to meet the maximum operating load. Usually equipped with automatic input device and standby power supply to ensure the normal operation of equipment and improve the safety and reliability of operation.

3). Replace the high-voltage switchgear.

Eliminate fixed switchgear without "five-prevention" facilities, and choose new switchgear with higher reliability, smaller size and newer equipment, such as XGN- 10, but the price is higher. Vacuum circuit breaker is used to replace oil-free circuit breaker, new isolating switch is selected, and "five precautions" device is set at the same time. The scheme selection should be economical and reasonable, and at the same time reduce the workload of civil engineering.

4). Replace low-voltage AC and DC power supply equipment.

The selection of auxiliary switchboard, busbar connection circuit breaker and auxiliary outlet circuit breaker should be reasonable. At the same time, overhaul distribution boxes and power distribution boxes are set on all floors, such as main and auxiliary power houses, cable floors, tailrace gate rooms, installation rooms, high-level oil tank rooms and central control rooms, for the operation and power maintenance of related equipment. At the same time, appropriate circuit breakers should be selected as incoming lines and tap switches of the distribution box.

In the original hydropower station, lead-acid battery is usually used as DC power supply, which occupies a large area. In the electrical transformation, a suitable maintenance-free battery cabinet can be selected to meet the requirements of emergency lighting and control closing of hydropower station.

For the general electrical transformation of hydropower stations, the emphasis is mostly on equipment transformation and main wiring scheme transformation, and the general layout scheme of power stations, the channels of power distribution devices, the incoming and outgoing directions of voltages at all levels, the structure and the cable direction should remain basically unchanged. It is not appropriate to carry out too many transformations on the lighting, overvoltage protection and grounding in the station. The multi-purpose zinc oxide arrester with technical parameters meeting the operating conditions replaces the original valve arrester, which has the advantages of smaller volume, lower residual voltage, better protection performance, shorter discharge time and longer service life.

7. Conclusion:

The technical transformation of hydropower station with new technologies and materials can effectively improve equipment performance, greatly reduce equipment loss, reduce equipment failure probability, change and reduce unsafe factors in power generation operation, reduce maintenance costs, increase equipment maintenance cycle and improve economic benefits.

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