Permanent magnet coal mill motor wiring system suitable for deep peak regulation

Abstract

The utility model discloses a permanent magnet coal mill motor wiring system suitable for deep peak regulation, which comprises a plurality of coal mill motor groups, a plurality of medium-voltage buses, a frequency conversion starting and speed regulating device and a frequency conversion device output bus, and is characterized in that the plurality of coal mill motor groups are respectively connected with the plurality of medium-voltage buses through a plurality of first circuit breaker groups; the input end of the frequency conversion starting and speed regulation device is connected with the medium-voltage buses through the input circuit breakers, the output end of the frequency conversion starting and speed regulation device is connected with the input end of the output bus of the frequency conversion device through the output circuit breaker, and the output bus outlet end of the frequency conversion device is connected with the coal mill motor sets through the second circuit breaker set. The coal mill motor set is started through the frequency conversion starting and speed adjusting device, the low-load operation rotating speed of the coal mill motor is adjusted, the risk of low-load operation vibration of the coal mill is eliminated, and the power consumption of the coal mill is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of installation and wiring, and in particular relates to a permanent magnet coal mill motor wiring system suitable for deep peak regulation. Background Art

[0002] With the development of new power systems, specific goals have been set for the flexibility and energy efficiency of coal-fired power units. In order to ensure stable combustion at low loads of deep peak-shaving boilers, in addition to optimizing the combustion system, it is necessary to optimize the operation mode of the boiler pulverizer.

[0003] The traditional pulverizing system of coal-fired power plants is driven by industrial frequency asynchronous motors. Compared with permanent magnet synchronous motors, industrial frequency asynchronous motors have poor energy-saving performance. In addition, under peak load conditions, traditional industrial frequency asynchronous motors can only be adjusted by the number of coal mill motors turned on to meet the stability of boiler combustion. At present, the power grid has put forward the requirement of deep peak load regulation for thermal power plants. When the coal mill load rate is further reduced, it is very necessary to use a frequency converter to adjust the speed during low load operation in order to eliminate the risk of coal mill vibration and reduce power consumption. Utility Model Content

[0004] The purpose of the utility model is to solve the shortcomings of the above-mentioned background technology and to provide a permanent magnet coal mill motor wiring system suitable for deep peak regulation, which is suitable for power supply wiring of various types of coal mill motors and can meet the deep peak regulation requirements of thermal power units.

[0005] The technical solution adopted by the utility model is: a permanent magnet coal mill motor wiring system suitable for deep peak regulation, including a plurality of coal mill motor sets, a plurality of medium voltage bus bars, a frequency conversion starting and speed regulating device, and a frequency conversion device output bus bar. The plurality of coal mill motor sets are respectively connected to the plurality of medium voltage bus bars through a plurality of first circuit breaker groups, the input end of the frequency conversion starting and speed regulating device is respectively connected to the plurality of medium voltage bus bars through a plurality of input circuit breakers, the output end of the frequency conversion starting and speed regulating device is connected to the input end of the frequency conversion device output bus bar through the output circuit breaker, and the output end of the frequency conversion device output bus bar is connected to the plurality of coal mill motor sets through the second circuit breaker group.

[0006] Furthermore, the number of the medium voltage busbars is one section or two sections.

[0007] Furthermore, the rated voltage of the medium voltage bus is 6 kV or 10 kV.

[0008] Furthermore, the coal mill motor in the coal mill motor unit is a permanent magnet synchronous motor.

[0009] Furthermore, the number of the coal mill motors in the coal mill motor group is 1-6.

[0010] Furthermore, an electrical locking circuit is provided between the plurality of input circuit breakers to prohibit simultaneous closing.

[0011] The beneficial effects of the utility model are:

[0012] The utility model proposes a wiring scheme for a permanent magnet coal mill motor, which not only meets the energy-saving operation requirements of a power plant, but also meets the deep peak regulation requirements of a power grid for a thermal power plant.

[0013] The utility model can eliminate the risk of low-load operation vibration of the coal mill and reduce the power consumption of the coal mill by adjusting the low-load operation speed of the coal mill motor through frequency conversion starting and speed regulation devices in cooperation with the power grid for deep peak regulation operation.

[0014] The utility model is provided with a "one-to-many" coal mill variable frequency starting and speed regulating device. Each unit is provided with a set of coal mill variable frequency starting and speed regulating devices, which can also be used for variable frequency starting of multiple permanent magnet coal mill motors, and can also have the function of variable frequency starting and speed regulating operation of one permanent magnet coal mill motor, thereby greatly improving the utilization rate of the frequency conversion device.

[0015] The utility model coal mill motor adopts a permanent magnet synchronous motor and has the advantage of good energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram showing an embodiment of the wiring system of the present utility model.

[0017] In the figure, 1- coal mill motor unit; 2- medium voltage bus; 3- frequency conversion starting and speed regulation device; 4- frequency conversion device output bus; 5- first circuit breaker group; 6- second circuit breaker group; 7- input circuit breaker; 8- output circuit breaker. DETAILED DESCRIPTION

[0018] The specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these implementation methods is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various implementation methods of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] The utility model provides a permanent magnet coal mill motor wiring system suitable for deep peak regulation, comprising a plurality of coal mill motor sets 1, a plurality of medium voltage busbars 2, a variable frequency starting and speed regulating device 3, and a variable frequency device output busbar 4. The variable frequency starting and speed regulating device 3 is a conventional variable frequency speed regulating device. The plurality of coal mill motor sets 1 are respectively connected to the plurality of medium voltage busbars 2 through a plurality of first circuit breaker sets 5, the input ends of the variable frequency starting and speed regulating device 3 are respectively connected to the plurality of medium voltage busbars 2 through a plurality of input circuit breakers 7, the output ends of the variable frequency starting and speed regulating device 3 are connected to the input ends of the variable frequency device output busbar 4 through the output circuit breaker 8, and the output ends of the variable frequency device output busbar 4 are connected to the plurality of coal mill motor sets 1 through the second circuit breaker set 6. The number of circuit breakers in the first circuit breaker set 5 and the second circuit breaker set 6 is the same as the number of coal mill motors in the coal mill motor set 1, that is, each coal mill motor is connected to the medium voltage busbar 2 through a circuit breaker and to the variable frequency device output busbar 4 through a circuit breaker. The utility model proposes a wiring scheme for a permanent magnet coal mill motor, which not only meets the energy-saving operation requirements of power plants, but also meets the deep peak regulation requirements of power grids for thermal power plants. In the deep peak regulation operation mode in cooperation with the power grid, the utility model starts the coal mill motor unit through a variable frequency start and speed regulating device, adjusts the low-load operation speed of the coal mill motor, eliminates the risk of low-load operation vibration of the coal mill and reduces the power consumption of the coal mill.

[0020] As a preferred solution, the number of the medium-voltage busbars 2 is one or two, and the number of the medium-voltage busbars 2 corresponds to the number of the coal mill motor units 1. When the number of the medium-voltage busbars is two, since the medium-voltage busbars are connected in a bridging manner to supply power to the variable frequency starting and speed regulating device 3, when any coal mill motor is started, any medium-voltage busbar can be controlled as needed to supply power to the variable frequency starting and speed regulating device.

[0021] As a preferred solution, the rated voltage of the medium voltage busbar 2 is 6 kV or 10 kV.

[0022] As a preferred solution, the coal mill motor in the coal mill motor unit 1 is a permanent magnet synchronous motor.

[0023] As a preferred solution, the number of coal mill motors in the coal mill motor unit 1 is set to 1-6 according to the unit capacity and process requirements.

[0024] As a preferred solution, an electrical interlocking circuit for prohibiting simultaneous closing is provided between the plurality of input circuit breakers 7 (2DL1, 2DL2), and the electrical interlocking circuit is a conventional interlocking circuit.

[0025] When several coal mill motor sets are started, the control operation is completed by the distributed control system (DCS). Before starting the coal mill motor, it is necessary to first confirm that all circuit breakers in the first circuit breaker group 5 and the second circuit breaker group 6 are in the open state, and at the same time detect that several medium-voltage busbars are energized. When the coal mill motor meets the starting conditions, by operating the first circuit breaker group, the second circuit breaker group, the input circuit breaker, and the output circuit breaker, multiple coal mill motors are switched to industrial frequency operation after variable frequency starting, or one variable frequency is started and then speed-controlled operation is achieved. The number of coal mills in operation is determined according to the different working conditions of the boiler, and the starting order of several coal mill motors can be specified as needed.

[0026] Example

[0027] like Figure 1 As shown in the figure, a 1000MW thermal power generating unit, the medium voltage distribution device unit includes bus section A and bus section B, its rated voltage adopts 10kV voltage level, and is equipped with 6 750kW permanent magnet synchronous coal mill motors A~F (that is, two coal mill motor groups, three coal mill motors in each group, and the coal mills are numbered in the order of tower furnace burners), and the capacity of the variable frequency starting and speed regulating device is selected as 1000kVA.

[0028] An electrical interlocking circuit is provided between the input circuit breakers 2DL1 and 2DL2 of the variable frequency starting and speed regulating device to prohibit simultaneous closing; the output circuit breaker 2DL3 is connected to the output busbar of the variable frequency device.

[0029] Under the peak load regulation demand of 20% of a single coal-fired power unit, the process requires two coal mill motors to operate. Taking coal mill motors A and E as examples, coal mill motor A operates at rated frequency and coal mill motor E operates at variable frequency.

[0030] The starting process of coal mill motor A and coal mill motor E is as follows:

[0031] Step 1: Confirm that the first circuit breaker group 1DL1~1DL6 and the second circuit breaker group 3DL1~3DL 6 are in the open state, and at the same time, it is detected that the 10kV A section bus of the medium voltage distribution device unit is energized.

[0032] Step 2: Confirm that the coal mill motor A meets the starting conditions. Through the operation of 2DL1, 2DL3, 3DL1, and 1DL1 circuit breakers, the coal mill motor A is first started by the frequency conversion and speed regulation device through the frequency conversion device output bus, and then switched to the unit 10kV A section bus for power supply and industrial frequency operation.

[0033] Step 3: Confirm that the coal mill motor E meets the starting conditions, and through the operation of the 3DL3 circuit breaker, realize the speed regulation operation of the coal mill motor E after it is started by the frequency conversion and speed regulation device through the frequency conversion device output bus.

[0034] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited to this. Any changes or substitutions that can be easily thought of by technicians familiar with the field within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field.

Claims

1. A permanent magnet coal mill motor wiring system suitable for deep peak regulation, characterized by: The invention comprises a plurality of coal mill motor sets (1), a plurality of medium voltage bus bars (2), a variable frequency starting and speed regulating device (3), and a variable frequency device output bus bar (4). The plurality of coal mill motor sets (1) are respectively connected to the plurality of medium voltage bus bars (2) via a plurality of first circuit breaker sets (5); the input end of the variable frequency starting and speed regulating device (3) is respectively connected to the plurality of medium voltage bus bars (2) via a plurality of input circuit breakers (7); the output end of the variable frequency starting and speed regulating device (3) is connected to the input end of the variable frequency device output bus bar (4) via an output circuit breaker (8); and the output end of the variable frequency device output bus bar (4) is connected to the plurality of coal mill motor sets (1) via a second circuit breaker set (6).

2. The permanent magnet coal mill motor wiring system suitable for deep peak load regulation according to claim 1 is characterized in that: The number of the medium voltage busbar (2) is one section or two sections.

3. The permanent magnet coal mill motor wiring system suitable for deep peak load regulation according to claim 1 is characterized in that: The rated voltage of the medium voltage busbar (2) is 6 kV or 10 kV.

4. The permanent magnet coal mill motor wiring system suitable for deep peak load regulation according to claim 1 is characterized in that: The coal mill motor in the coal mill motor unit (1) is a permanent magnet synchronous motor.

5. The permanent magnet coal mill motor wiring system suitable for deep peak load regulation according to claim 1 is characterized in that: The number of the coal mill motors in the coal mill motor group (1) is 1-6.

6. The permanent magnet coal mill motor wiring system suitable for deep peak load regulation according to claim 1 is characterized in that: An electrical interlocking circuit for prohibiting simultaneous closing is provided between a plurality of input circuit breakers (7).

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