Gas turbine black-start method based on small gas turbine as black-start power supply

Abstract

The invention relates to a method for black start of a generator in a gas power plant, in particular to a gas turbine black-start method based on small gas turbine as a black-start power supply. The method is characterized by comprising the following steps that: a set of black-start small gas turbine is provided, and a pressure regulating unit of the black-start small gas turbine is connected with a pre-processing system in a natural gas system of the gas power plant; the energy supply output end of the black-start small gas turbine is connected with a high-voltage plant bus section of the gas power plant; a security diesel generator is started to charge a low-voltage plant bus section, and then the black-start small gas turbine is started to charge the high-voltage plant bus section; further, the high-voltage plant bus section supplies energy to the low-voltage plant bus section, and the security diesel generator is shut down; and a main gas turbine is started, and then black start is completed through grid connection. The method has the advantages that the operation reliability is improved, the operation and maintenance are convenient, and the workload is small; the income of the power plant is increased, the sinking cost is greatly reduced, and the efficiency and economy of the black-start small gas turbine are improved.

Description

technical field [0001] The invention relates to a method for black start of a generator in a gas-fired power plant, in particular to a method for starting a gas turbine based on a small gas turbine as a black start power source. Background technique [0002] In the prior art, according to the requirements of the power grid system, when the power grid system loses power, the power plant needs to use the power plant's own equipment to start automatically without relying on the power supply of the external power grid system, and further drive the generator without self-start capability ( Group) start, gradually expand the scope of power grid system restoration, and finally realize the restoration of power supply of the entire power grid system. For this reason, black-start diesel generators are usually required in large-capacity power plants, and gas-fired power plants are no exception. However, the use of diesel generators as black-start power sources has the following disadva...

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Problems solved by technology

[0003]1) The load capacity of the black start is large, especially when the natural gas pressure parameters do not meet the requirements of the main engine and a booster unit needs to be configured, the required installed power of the start power is often 10MW Above, however, diesel generators are limited by the manufacturing process, and the maximum power generally does not exceed 2000kW, so multiple diesel generators need to run in parallel to meet the start-up requirements

When multiple diesel generator sets form an isolated grid operation, there must be multiple grid connection processes, which increases the difficulty of successful grid connection, and because each generator may have deviations during manufacturing, during the restoration of power supply When switching on or off a large motor or a large load, it will interfere with the power supply system of the diesel generator, and in serious cases may cause the unit to be disconnected, resulting in black start failure of the gas turbine

[0004]2) The failure rate of diesel generator sets is high, which not only affects the reliability of operation, but also has a large maintenance workload

In a system with multiple machines running in parallel, the high failure rate of equipment is more likely to cause power interruption

In the actual operation and maintenance process, large-capacity diesel generators have poor emission indicators and more difficult noise control, so operation and maintenance are also inconvenient

[0005]3) Redundant fuel system configuration, inconvenient operation and maintenance

In gas-fired power plants, since the main fuel is natural gas, a natural gas supply system has been configured in the plant, and the diesel generators normally used for security loads are generally used in the mode of daily fuel tanks due to their small capacity, but for black start units Said that due to the large capacity, it is necessary to configure a special fuel supply system, which increases the system investment

[0006]4) Large-capacity black-start diesel generators can only be used in black-start process, and the sunk cost is high

Since the high-speed diesel generator cannot run continuously, it can only be shut down after the black start process, and cannot continue to be put into use to increase income. Therefore, the investment of the entire system is almost equivalent to the sunk cost, which cannot form a return on investment and causes a large burden on the investment of the power plant.

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