Power plant coal feeder motor wiring framework

Abstract

The utility model belongs to the technical field of electrical equipment, and particularly discloses a power plant coal feeder motor wiring framework. Comprising a direct-current energy supply group, a low-voltage ride-through device, a plant alternating-current power supply, a frequency converter and a coal feeder motor, wherein the direct-current energy supply group is electrically connected with the input side of the low-voltage ride-through device, and the output side of the low-voltage ride-through device is electrically connected with the direct-current input side of the frequency converter; the auxiliary AC power supply is electrically connected with the AC input side of the frequency converter, the coal feeder motor is electrically connected with the AC output side of the frequency converter, the frequency converter can still drive the coal feeder motor to operate stably when the voltage of the auxiliary AC power supply is sag, and the device is simple and clear in wiring structure, low in extra energy consumption and convenient to maintain. The device is suitable for being popularized in a thermal power plant boiler fire coal supply process.

Description

Technical Field

[0001] This utility model belongs to the field of electrical equipment technology, and specifically discloses a wiring structure for a power plant coal feeder motor. Background Technology

[0002] The coal feeder is a key piece of equipment in a coal-fired power plant, responsible for continuously and evenly transporting loose coal particles to the boiler. Its stable operation directly affects combustion efficiency and unit safety. As the power source of the coal feeder, the rationality of the wiring structure design of the motor directly affects the performance of the coal feeder.

[0003] The power supply to the coal feeder may experience a momentary voltage drop due to the following possible reasons.

[0004] Phase-to-phase short circuit: When conductors of different phases in a power grid come into direct contact due to insulation damage or other reasons, the short-circuit current increases instantaneously. A large amount of electrical energy is consumed by the short-circuit path, causing the voltage of other parts of the power grid to drop instantaneously.

[0005] Grounding short circuit: When a conductor comes into contact with the earth or a grounding electrode, it can also cause a short circuit fault, causing current to flow to the earth, disrupting the normal current distribution of the power grid, and causing a voltage drop.

[0006] Start-up of large-capacity equipment: When large-capacity equipment such as large motors and large transformers are started, the grid voltage will drop momentarily.

[0007] Lightning strikes can induce high voltages on power lines. When these high voltages enter the power grid, they may trigger grid protection devices, causing some lines to trip and altering the grid's operation, resulting in a momentary voltage drop. Additionally, a direct lightning strike on grid equipment can damage the equipment, causing short circuits and other faults, also leading to a momentary voltage drop.

[0008] Sudden changes in grid load: When the load in the power grid suddenly increases or decreases, such as when a large number of users turn on or off electrical appliances at the same time, the power balance of the power grid is broken. The system needs to readjust parameters such as voltage and frequency to adapt to the new load conditions. In this process, there may be a momentary voltage drop.

[0009] Power system failures: Failures in key equipment within the power grid, such as generators, transformers, and transmission lines, can lead to interruptions or obstructions in power transmission, reducing the grid's supply capacity and causing voltage drops. Furthermore, power system stability issues, such as system oscillations, can also cause momentary voltage fluctuations and drops.

[0010] If a voltage drop causes the coal feeder to stop, it may lead to coal shortages, unstable combustion, or even boiler shutdown. Re-ignition is time-consuming and costly, causing unnecessary losses.

[0011] To address the aforementioned issues, a compensation circuit needs to be inserted into the power circuit of the coal feeder to maintain stable operation of the motor. However, the existing control circuit wiring method is complex and cumbersome. During motor installation and maintenance, technicians need to spend a significant amount of time clarifying the wiring connections, which not only reduces work efficiency but also increases the risk of operational errors. Wiring errors can prevent the motor from starting properly or even damage the motor and other related equipment, affecting production progress and incurring additional maintenance costs. Designing a convenient wiring architecture that clearly defines the power lines of each coal feeder motor and prevents interference, thereby accurately mitigating power distribution imbalances caused by voltage dips and ensuring the normal operation of the coal feeder, is a problem that power plant technicians need to solve. Utility Model Content

[0012] To address the technical problems listed in the background section, this utility model provides a wiring structure for a power plant coal feeder motor. The specific technical solution is as follows:

[0013] A wiring structure for a coal feeder motor in a power plant includes a DC power supply unit, a low-voltage ride-through device, a plant AC power supply, a frequency converter, and a coal feeder motor. The DC power supply unit is electrically connected to the input side of the low-voltage ride-through device, and the output side of the low-voltage ride-through device is electrically connected to the DC input side of the frequency converter. The plant AC power supply is electrically connected to the AC input side of the frequency converter, and the coal feeder motor is electrically connected to the AC output side of the frequency converter. The plant AC power supply provides 380V AC power, and the DC power supply unit provides 220V DC power.

[0014] Preferably, the DC power supply unit includes a plant DC power supply, a supercapacitor, and a dual power supply switching device; wherein, the output side of the dual power supply switching device is electrically connected to the input side of the low voltage ride-through device, the input side of the dual power supply switching device is normally connected to the plant DC power supply, and automatically switches to connect to the supercapacitor when the DC feeder loses power.

[0015] Preferably, each DC power supply unit is electrically connected to the input side of multiple low voltage ride-through devices.

[0016] Preferably, the plant's AC power supply is electrically connected to the AC input side of multiple frequency converters, and each frequency converter controls one coal feeder motor.

[0017] Compared with the prior art, this utility model has the following advantages:

[0018] By equipping each coal feeder motor with a frequency converter, continuous adjustment of motor speed is achieved, preventing combustion instability or efficiency reduction caused by coal quantity fluctuations. To address the issue of the frequency converter's DC bus voltage dropping rapidly when the AC input voltage dips, triggering undervoltage protection and causing shutdown, this invention incorporates a low-voltage ride-through device on the frequency converter's DC input side. The device is connected to a 220V DC power supply from the plant's DC system and a supercapacitor, automatically switching between them via a switching device, providing dual protection and ensuring stability and reliability. This ensures stable operation of the coal feeder motor even when the AC plant power voltage experiences a temporary drop. The wiring structure is simple and clear, consumes less additional energy, and is easy to maintain. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the wiring structure of the power plant coal feeder motor in an embodiment of this utility model. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0021] like Figure 1 As shown, the present invention provides an embodiment of a wiring structure for a power plant coal feeder motor, according to the appendix. Figure 1 The architecture is used for connection.

[0022] Taking a 600MW thermal power generating unit as an example, six 4kW coal feeder motors are configured according to the boiler capacity.

[0023] During normal operation, the power supply is provided to each coal feeder motor through the plant's 380V power supply and then through the frequency converter. The DC power supply group includes the plant's DC power supply (1 DC220V power supply), a super energy storage capacitor, and a dual power supply switching device; one set of DC power supply group is divided into 6 branches, which are connected one-to-one to the DC input side of the corresponding frequency converter that controls the speed of the coal feeder motor through 6 low voltage ride-through devices.

[0024] When the system voltage does not drop to 90%, the low-voltage ride-through device does not start and remains in hot standby mode. When the voltage drops to the range of 20%-90%, the low-voltage ride-through device starts instantaneously, with a switching time of <200µs, outputting DC 480-520V to the frequency converter to maintain the DC bus voltage of the frequency converter and ensure its normal operation. If the system voltage drops to 20% and remains there for 10 seconds, it will always ensure the supply of DC voltage to the frequency converter, achieving continuous and stable operation of the frequency converter during system faults. When the system voltage recovers, the frequency converter automatically switches to AC power supply.

[0025] The low voltage ride-through device is powered by a DC 220V power supply from the plant's DC system. When this power supply fails, it is quickly switched to supercapacitor power supply through a dual power supply switching device.

[0026] Finally, it should be noted that the above are merely preferred embodiments of this utility model and are not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A wiring structure for a power plant coal feeder motor, characterized in that, It includes a DC power supply unit, a low-voltage ride-through device, a plant AC power supply, a frequency converter, and a coal feeder motor; wherein, the DC power supply unit is electrically connected to the input side of the low-voltage ride-through device, and the output side of the low-voltage ride-through device is electrically connected to the DC input side of the frequency converter; the plant AC power supply is electrically connected to the AC input side of the frequency converter, and the coal feeder motor is electrically connected to the AC output side of the frequency converter; the plant AC power supply provides 380V AC power, and the DC power supply unit provides 220V DC power.

2. The wiring structure of a power plant coal feeder motor according to claim 1, characterized in that, The DC power supply unit includes a plant DC power supply, a supercapacitor, and a dual power supply switching device. The output side of the dual power supply switching device is electrically connected to the input side of the low voltage ride-through device. The input side of the dual power supply switching device is normally connected to the plant DC power supply, and automatically switches to the supercapacitor when the DC feeder loses power.

3. The wiring structure of a power plant coal feeder motor according to claim 2, characterized in that, Each DC power supply unit is electrically connected to the input side of multiple low-voltage ride-through devices.

4. The wiring structure of a power plant coal feeder motor according to claim 3, characterized in that, The plant's AC power supply is connected to the AC input side of multiple frequency converters, and each frequency converter controls one coal feeder motor.

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