Electric energy converting-switching system and method and application thereof

Abstract

The invention discloses an electric energy converting-switching system and method applied to a thermal power plant. The frequency and / or voltage of at least one connection end can be adjusted through an electric energy transducer, and electric energy is controlled to flow among plant buses of different frequencies, or the electric energy can be controlled at different frequencies and can be controlled to flow among the plant buses of different frequencies, so that the throttling loss is reduced and even eliminated, the performance of a variable-frequency generating set is brought into full play, and the overall system efficiency is increased, thereby lowering the energy consumption and creating a greater economic benefit; meanwhile, a method of starting and switching through a motor of an auxiliary machine for a plant is improved, so that the flexibility of the overall running manner of the system is improved.

Description

technical field [0001] The present invention relates to a switching system and method for electrical energy conversion and plant auxiliary motors applied in thermal power plants, which can control the flow of electric energy between plant buses of different frequencies in thermal power plants, or both can Controlling electric energy at different frequencies can also control the flow of electric energy between plant buses of the same frequency, and can help start and / or switch electric motors of plant auxiliary machines in thermal power plants. Background technique [0002] Energy conservation and emission reduction are not only the external requirements put forward by the state and society for thermal power plants, but also the internal requirements for thermal power plants to reduce costs, increase profits, and fulfill social responsibilities. Therefore, thermal power plants are actively tapping internal potentials and carrying out energy-saving transformation , innovative ...

AI Technical Summary

Problems solved by technology

[0003] However, the existing centralized frequency conversion power supply technology also has certain shortcomings: on the one hand, throttling loss occurs

In order to match the power imbalance between the two, and to meet the power and frequency required by the electric motor of the plant auxiliary machine under the working condition of the main steam turbine generator set, it is necessary to rely on adjusting the opening of the steam inlet regulating valve of the small steam turbine. Help to adjust the operating pressure of the small steam turbine to achieve the purpose of adjusting the speed and output power of the small steam turbine, resulting in throttling loss

[0004] In the second case, due to the design margin of the extraction steam source of the small steam turbine itself, or the adjustment of the operation mode, throttling loss will also occur

In the above cases, throttling loss will occur

[0005] On the other hand, the existing centralized frequency conversion power supply technology will restrict the flexibility of the system's operation mode, and the start-up and switching of the motors of the plant's auxiliary machines will be restricted.

It is reflected in: Generally, the motor of the plant auxiliary machine is directly started under the power frequency condition. In this starting mode, the starting current is relatively large, generally up to 4-7 times the rated current, which will reduce the life of the motor and affect the Other devices on the same bus have a greater impact, and the requirements for system capacity are relatively high

The motor of the factory auxiliary machine cannot complete the switching under the condition of frequency conversion

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