Frequency conversion control system of boiler air pre-heater

Abstract

The invention relates to the technical field of air pre-heater control, in particular to a frequency conversion control system of a boiler air pre-heater. The system comprises a main motor power supply, an auxiliary motor power supply, a main motor control loop, an auxiliary motor control loop, a main motor frequency converter, an auxiliary motor frequency converter, a main motor and an auxiliary motor. Thefrequency converter is adopted to start directly, the soft starting requirements of the air pre-heater motor can be met, the output of a power frequency power supply can be directly provided for the motor on the basis of not changing a power supply loop, so that the loop switching of a double-contactor type is avoided; by changing a mode of directly dragging a frequency converter and optimizing a control loop, a power supply mode of a motor of the air pre-heater is simplified, a function of mutual standby of a main motor and an auxiliary motor is realized, the safe and stable operation capability of the air pre-heater of a thermal power plant is greatly improved, the risk of boiler shutdown is reduced, and the reliability of power supply is guaranteed; and meanwhile, the equipment maintenance difficulty of maintainers is reduced.

Description

technical field [0001] The invention relates to the technical field of air preheater control, and more specifically, relates to a frequency conversion control system for a boiler air preheater. Background technique [0002] The full name of air preheater is air preheater, which is an important boiler equipment in thermal power plants. [0003] The rotation of the air preheater is realized by the main motor or the auxiliary motor. At present, the starting method of the motor generally adopts the soft starter. After the start is completed, the soft starter is withdrawn through the switching circuit of the contactor, and the motor is directly powered by the power frequency power supply. . [0004] The general operation mode of the air preheater is driven by the main motor. When the auxiliary motor fails and the auxiliary motor fails, the air preheater loses power and stops. [0005] There are two main problems with this approach: [0006] 1. After the soft start of the air p...

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Problems solved by technology

[0006] 1. The motor of the air preheater cannot be switched to the power frequency power supply smoothly after soft start, resulting in the loss of power of the air preheater

The reason is that the switching process of the contactor is complicated and the reliability is poor, especially the contactor coil and contacts of the equipment that has been in operation for many years have aging phenomena, which exacerbates the possibility of switching failure failures.

[0007] 2. The main motor of the air preheater cannot be used as a backup motor for the auxiliary motor

The reason is that the control loop only considers the locking loop that the main and auxiliary motors cannot start at the same time, and lacks the control loop for the auxiliary motor to jointly start the main motor.

[0008] The above two problems reduce the reliability of the air preheater operation, and even have the risk of boiler shutdown, which seriously affects the stable operation and economic benefits of the thermal power plant. Therefore, in order to ensure the stable operation of the air preheater, it is necessary to use the inverter to start the motor. Combined with the control method that the main motor and the auxiliary motor serve as backup for each other

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