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Auxiliary power system with direct-current frequency converter and direct-current variable-frequency motor

A technology of DC frequency converter and factory power system, applied in the direction of DC motor speed/torque control, AC motor control, control system, etc., can solve the problems of low motor operation efficiency, high investment cost of frequency converter, low efficiency, etc.

Active Publication Date: 2015-11-11
CHINA POWER ENG CONSULTING GRP CORP EAST CHINA ELECTRIC POWER DESIGN INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the speed adjustment of the small steam turbine is realized by throttling the inlet steam valve, the throttling adjustment must have throttling loss, which reduces the overall efficiency
In addition, although this factory power system can simplify the electrical system, under the same load condition, all equipment motors share the same power supply frequency, which means that it is impossible for all motors to run at the highest efficiency, and there must be some The operating efficiency of the electric motor is low, which reduces the overall efficiency of the plant power system
Therefore, the existing factory power system has key technical problems such as energy loss, low efficiency, complex electrical system, and high investment cost of frequency converters.

Method used

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  • Auxiliary power system with direct-current frequency converter and direct-current variable-frequency motor
  • Auxiliary power system with direct-current frequency converter and direct-current variable-frequency motor
  • Auxiliary power system with direct-current frequency converter and direct-current variable-frequency motor

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Experimental program
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Effect test

Embodiment 1

[0114] The electricity generated by the AC generator set is transformed by the AC transformer and then sent to the AC power grid outside the factory and inside the factory. The AC power grid in the factory supplies power to the motors of various equipment in the factory. Among them, the AC power frequency motor with higher power can directly use the power frequency AC power provided by the AC power grid in the factory. The DC variable frequency motor needs the help of AC / DC converter or transformer and DC frequency converter. First, the AC / DC converter converts the plant's AC power to the plant's DC power. Secondly, the DC frequency converter converts the DC power in the factory into DC frequency conversion power, which is used to drive the DC frequency conversion motor.

[0115] In this system, both the AC / DC converter and the DC frequency converter are public equipment, and multiple DC variable frequency motors can be connected at the same time, without the need for one-to...

Embodiment 2

[0117] Figure 4 The proposed scheme and image 3 The basic principle of the scheme is the same, the difference is that for equipment motors operating under low-voltage conditions, an AC transformer is added as needed to provide low-voltage in-plant AC power frequency. Low-voltage in-factory AC power can supply power to AC power-frequency motors, and can also be converted into low-voltage in-factory DC power through AC / DC converters, and then supplied to DC variable-frequency motors after frequency conversion by DC converters. and image 3 similar, Figure 4 The converters and DC frequency converters on the medium, high and low voltage sides are common, and can drive multiple DC variable frequency motors at the same time.

[0118] and figure 2 compared to, Figure 4 The electrical system shown is obviously simplified, the system energy loss is also greatly reduced, and the power supply economy is obviously improved.

Embodiment 3

[0120] Figure 5 The schemes shown are image 3 The basic principles of the scheme are the same, the difference is that Figure 5 The AC frequency conversion motor is still retained in the factory, and this part of the motor still uses the AC frequency conversion system, that is, the AC frequency converter in the factory is still converted into AC frequency conversion power, and the AC frequency conversion power is used to drive the AC frequency conversion motor.

[0121] This plant power system scheme integrates the AC frequency conversion plant power system and the DC frequency conversion plant power system, which provides energy-saving space for the existing AC frequency conversion plant power system. For the built AC variable frequency plant power system, it is possible to retain part of the AC variable frequency motor to reduce the cost of transformation, and to improve the efficiency and economy of the plant power system to meet the requirements of energy saving.

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Abstract

The invention relates to an auxiliary power system with a direct-current (DC) frequency converter and a DC variable-frequency motor. Specifically, the system comprises an off-site alternating-current (AC) power grid, an on-site AC power grid, an on-site DC power grid, an AC generator or AC generator unit, an AC transformer, an AC / DC converter or transformer, a DC frequency converter, and a DC variable-frequency motor. By adopting the system, variable-speed running of power plant equipment can be effectively realized, the energy loss of the generator unit can be significantly reduced, the overall efficiency of the unit can be improved, and the unit can be simplified. Moreover, the system has the characteristic of controllable cost.

Description

technical field [0001] The invention relates to power plant equipment, in particular to a plant power system provided with a DC frequency converter and a DC frequency conversion motor. Background technique [0002] In a large-capacity power plant, according to the change of the operating conditions of the unit, the electric pumps, fans or compressors in the power plant generally need to be operated at variable speeds to achieve the purpose of saving energy and improving economy. The existing plant power system realizes the variable speed operation of the equipment through the combination of AC frequency converter and AC variable frequency motor. Among them, the working principle of the AC drive is to convert the power frequency AC into DC first, and then convert the DC into variable frequency AC. This conversion process leads to a large energy loss in the AC drive, and the frequency conversion efficiency is only about 90%, which greatly improves the efficiency of the AC driv...

Claims

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Application Information

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IPC IPC(8): H02J3/38H02P7/292H02P27/04
CPCY02P80/10
Inventor 申松林刘慧军鲍金花
Owner CHINA POWER ENG CONSULTING GRP CORP EAST CHINA ELECTRIC POWER DESIGN INST
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