Novel system and method for electric energy conversion and motor switching and application

Abstract

The invention relates to a novel system and a method for electric energy conversion and motor switching in a thermal power plant. The method has the advantages that the frequency and / or voltage of at least one connecting end can be adjusted by an electric energy converter, and the electric energy is controlled to flow between auxiliary buses of different frequency, or the electric energy is controlled to flow between the auxiliary buses of the same frequency and different frequency, so that the throttling loss is decreased and even eliminated, the property of a variable-frequency power generator is fully played, and the efficiency of whole system is improved, thereby decreasing the energy consumption, and creating larger economic benefit; the electric connecting relationship of the electric energy converter is increased, more motor starting and switching methods of the auxiliary units with more variety are improved and realized, and the flexibility in running type of the whole system is improved.

Description

Technical field [0001] The invention relates to a novel system and method for realizing electric energy conversion and motor switching, which can control electric energy to flow between service buses of different frequencies in a thermal power plant, or it can control electric energy at different frequencies as well as electric energy. It flows between the auxiliary buses of the same frequency, and can help the electric motors of auxiliary machines of thermal power plants to start and / or switch. Background technique [0002] Energy conservation and emission reduction are the external requirements of the state and society for thermal power plants, and also the internal requirements of thermal power plants to reduce costs, increase profits, and fulfill social responsibilities. Therefore, thermal power plants are actively tapping internal potential and carrying out energy-saving transformations. , Innovative design, or the use of new technologies and new equipment, do everything pos...

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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