Motor protection system

Abstract

The invention particularly relates to a motor protection system. Main modules comprise a power monitoring module, a power supply monitoring module, a control module and a self-adaptive debugging module, wherein the power monitoring module and the power supply monitoring module are used for monitoring motor state data; the control module automatically cuts off a motor power supply after the motor state data exceeds a trigger threshold value; the self-adaptive debugging module is used as a central node to communicate with the power monitoring module, the power supply monitoring module and the control module; and the self-adaptive debugging module automatically adjusts the trigger threshold value of the control module and sends the updated trigger threshold value to the control module. The system can adaptively adjust the monitored motor state data trigger threshold according to the actual working condition of the motor, and the applicability of equipment is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of motor protection, and in particular relates to a motor protection system. Background Art

[0002] Rotating machinery such as steam turbines, generators, fans, etc. are the most widely used type of mechanical equipment in the industrial sector. The operating environment and status of the motor require real-time monitoring and protection, such as detection of phase sequence errors, phase failure, three-phase imbalance, overheating, etc., monitoring the operating environment and status of the motor, timely determining the type of fault, and shutting down when necessary to prevent the motor from burning out. Status monitoring and fault diagnosis can not only detect equipment failures in advance and avoid serious accidents, but also avoid excessive maintenance and disrepair, and realize fault diagnosis and centralized control of production processes and large machinery. The vibration detection and analysis method in the prior art can realize the testing and protection of the motor, and can effectively detect faults caused by the design, manufacturing, operation, and assembly of the motor. However, it is impossible to effectively monitor the operating failures caused by power quality problems and make adaptive adjustments in time. Summary of the invention

[0003] In view of the above technical problems, the present invention proposes a motor protection system, including a monitoring module for monitoring power quality and motor status, a control module, and an adaptive debugging module;

[0004] The control module is configured with a motor protection program, which is activated after the motor status data reaches a trigger threshold;

[0005] The adaptive debugging module automatically adjusts the trigger threshold and sends the updated trigger threshold to the control module;

[0006] The adaptive debugging module adjusts the trigger threshold according to power quality and motor status data and based on an adaptive control method.

[0007] The system can adaptively adjust the trigger threshold of the monitored motor status data according to the motor's operating status and power quality, thereby improving the applicability of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 : Schematic diagram of the motor protection system;

[0009] Figure 2 : Flowchart of the adaptive control method. DETAILED DESCRIPTION

[0010] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention all fall within the scope of the present invention.

[0011] Some motor protection systems have the following principles: Figure 1 As shown, it includes a monitoring module for monitoring power quality and motor status, a control module, and an adaptive debugging module;

[0012] The control module is configured with a motor protection program, which is activated after the motor status data reaches a trigger threshold;

[0013] The adaptive debugging module automatically adjusts the trigger threshold and sends the updated trigger threshold to the control module;

[0014] The adaptive debugging module adjusts the trigger threshold according to power quality and motor status data and based on an adaptive control method.

[0015] The adaptive debugging module is implemented by DSP. The adaptive debugging modules of some specific solutions update the trigger threshold according to the working state data of the motor and based on the least mean square algorithm.

[0016] Motor status data includes phase current, phase voltage, phase angle, output power, and temperature parameters.

[0017] In some schemes, the monitoring module includes a three-phase mutual inductor current detection circuit and a phase sequence detection circuit. The three-phase mutual inductor current detection circuit inputs the sampling current into the measuring resistor and amplifier through its sampling coil to calculate the real-time value of the power flow; the output end of the three-phase mutual inductor current detection circuit is connected to the phase sequence detection circuit for determining the phase sequence of the power flow.

[0018] The phase sequence detection circuit is used to determine the phase sequence of the power flow, that is, the order of phase A, phase B and phase C. It is usually based on the measurement principle of phase difference. By comparing the phase difference of the power flow, the phase sequence detection circuit can determine the current phase sequence state, and can realize accurate detection and phase sequence judgment of the power flow to ensure the safe operation and protection of the motor.

[0019] In some embodiments, the steps of executing the motor protection program configured by the control module include:

[0020] The leakage current, three-phase voltage unbalance, and negative sequence current are read, and when the motor status data reaches the trigger threshold, the start breaker is executed to cut off the motor power supply.

[0021] Some motor protection systems also include a user interface, and the adaptive debugging module is provided with a data interface for communicating with the user interface. The triggering threshold of the control module can be modified directly through instructions issued by the user interface.

[0022] In some motor protection systems, the adaptive debugging module obtains the motor status data through the monitoring module. The motor status data includes phase current, phase voltage, phase angle, output power, and temperature parameters.

[0023] Some motor protection systems, whose adaptive debugging module adjusts the trigger threshold based on the adaptive control method, include Figure 2 The following steps are shown:

[0024] S1 obtains motor state data and extracts a motor state feature set from it;

[0025] S2 determines the estimator that best matches the actual motor state characteristics through the performance loss function, thereby diagnosing the actual fault mode;

[0026] S3 finds the fault mode corresponding to the estimator that best matches the actual fault, that is, the fault mode with the smallest performance loss function. Then the i-th fault mode is the fault mode diagnosed by the adaptive fault diagnosis strategy.

[0027] S4 obtains the triggering threshold of the protection motor to avoid the fault according to the parameter value corresponding to the i-th fault mode.

[0028] Some systems use the following MRAS adaptive control algorithm to estimate the motor parameters and make adjustments:

[0029] Step (1) Estimate the motor parameters according to formula I:

[0030]

[0031] in,

[0032] Estimated values ​​of motor parameters;

[0033] initial parameter estimates;

[0034] γ: adaptive gain;

[0035] y: actual output value;

[0036] y0: output value of the reference model;

[0037] Step (2) Adjust the motor parameters according to formula II:

[0038]

[0039] in,

[0040] Estimated values ​​of motor parameters;

[0041] θ: adjusted motor parameters;

[0042] Δθ: Motor parameter adjustment amount

[0043] Iterate steps (1-2) and estimate the motor parameter values ​​based on the actual output values ​​and the output values ​​of the reference model.

[0044] The reference models of some solutions use models based on the professional engineering analysis modules provided by LabVIEW to reduce the program development work.

[0045] Current sensors can sense changes in current and convert them into voltage or digital signals for real-time monitoring and measurement. Common current sensors include Hall effect sensors, current transformers, and resistive current sensors.

[0046] In some schemes, the adaptive debugging module, the monitoring module and the control module are star-linked via a CAN bus.

[0047] An electronic device of some solutions includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program / instructions are used by the processor to execute the steps of the above-mentioned solutions.

[0048] The embodiments and functional operations of the subject matter described in this specification may be implemented in: digital electronic circuits, tangibly implemented computer software or firmware, computer hardware, including the structures disclosed in this specification and their structural equivalents, or a combination of more than one of the above. The embodiments of the subject matter described in this specification may be implemented as one or more computer programs, that is, one or more modules of computer program instructions encoded on one or more tangible non-transitory program carriers, for execution by a data processing device or to control the operation of the data processing device. Alternatively or in addition, the program instructions may be encoded on an artificially generated propagating signal, such as a machine-generated electrical, optical or electromagnetic signal, which is generated as encoded information for transmission to an appropriate receiver device executed by a data processing device. The computer storage medium may be a machine-readable storage system, a machine-readable storage substrate, a random or serial access memory system, or a combination of one or more of the above systems.

[0049] Although the present invention has been described in detail above by general description, specific implementation methods and experiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A motor protection system, characterized in that: It includes a monitoring module, a control module, and an adaptive debugging module for monitoring power quality and motor status; The control module is configured with a motor protection program, which is activated after the motor status data reaches a trigger threshold; The adaptive debugging module automatically adjusts the trigger threshold and sends the updated trigger threshold to the control module; The adaptive debugging module adjusts the trigger threshold according to power quality and motor status data and based on an adaptive control method.

2. The motor protection system according to claim 1, characterized in that: The monitoring module is provided with a three-phase mutual inductor current detection circuit and a phase sequence detection circuit. The three-phase mutual inductor current detection circuit inputs the sampling current into the measuring resistor and the amplifier through its sampling coil to calculate the real-time value of the power flow; the output end of the three-phase mutual inductor current detection circuit is connected to the phase sequence detection circuit to determine the phase sequence of the power flow.

3. The motor protection system according to claim 1, characterized in that: The steps of executing the motor protection program configured by the control module include: Read leakage current, three-phase voltage imbalance, and negative sequence current; when the motor status data reaches the trigger threshold, execute the start breaker to cut off the motor power supply.

4. The motor protection system according to claim 1, characterized in that: The motor status data includes phase current, phase voltage, phase angle, output power, and temperature.

5. The motor protection system according to claim 1, characterized in that: The step of the adaptive debugging module adjusting the trigger threshold based on the adaptive control method includes: Acquire the motor state data, and extract a motor state feature set therefrom; The performance loss function is used to determine the estimator that best matches the actual motor state characteristics, thereby diagnosing the actual fault mode that occurred; Find the fault mode corresponding to the estimator that best matches the actual fault, that is, the fault mode with the smallest performance loss function. Then the i-th fault mode is the fault mode diagnosed by the adaptive fault diagnosis strategy. The triggering threshold that can prevent the motor from having this fault is obtained from the parameter value corresponding to the i-th fault mode.

6. The motor protection system according to claim 5, characterized in that: The following MRAS adaptive control algorithm is used to estimate motor parameters and make adjustments: Step (1) Estimate the motor parameters according to formula I: in, Estimated values ​​of motor parameters; initial parameter estimates; γ: adaptive gain; y: actual output value; y0: output value of the reference model; Step (2) Adjust the motor parameters: in, Estimated values ​​of motor parameters; θ: adjusted motor parameters; Δθ: adjustment amount of motor parameters; Iterate steps (1-2) and adjust the motor parameter values ​​according to the actual output value and the output value of the reference model.

7. The motor protection system according to claim 1, characterized in that: The adaptive debugging module is star-linked with the power monitoring module, the power supply monitoring module and the control module via a CAN bus.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the computer program / instructions are executed by a processor, the steps of the method of claims 1-7 are implemented.

9. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method of claims 1-7 are implemented.

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