KR102029723B1 - Control integrated system that can monitor power plant deterioration and optimize efficiency point control and fault diagnosis of motor - Google Patents

Abstract

The present invention is capable of sending a warning to an operator by electrically and accurately determining whether a motor malfunctions without using various sensors such as a temperature sensor, a vibration sensor, an ultrasonic sensor, an infrared sensor and the like. Accordingly, even in an environment in which attaching various sensors is practically hard, the malfunction of a motor can be accurately determined and a warning thereof can be sent to an operator. According to the present invention, a motor can be controlled at an optimal speed in accordance with a load characteristic. Therefore, the present invention is capable of preventing an unnecessary increase in the power consumption of a motor, which can be caused when the speed of the motor is determined only based on experience or knowledge of a driver on the site. According to the present invention, since a facility can be monitored and controlled based on information and communications technologies (ICT), an intuitive, stable and convenient facility management environment can be provided. Accordingly, an operator can easily identify the composition of a facility system and the deterioration and temperature of facilities, and also, can easily monitor and control the condition of a facility for efficient control of a motor. Moreover, a diagram and graph type alarm warning is provided to enable an operator to quickly identify and handle the condition of equipment.

Description

Control integrated system that can monitor power plant deterioration and optimize efficiency point control and fault diagnosis of motor

The present invention relates to a control integrated system capable of monitoring power equipment deterioration and optimum efficiency point control and fault diagnosis of a motor.

Power consumption from motors accounts for 70% of industrial power in the manufacturing field, which is a big part of the country's overall power consumption.

Considering that the average life of the motor is more than 15 years, the reduction of power consumption by the motor can only contribute greatly to the reduction of the national power consumption.

As a result, the demand for inverter drive motors that can reduce motor power consumption and improve efficiency continues to increase.

Inverter drive motors are widely used in pump motors for circulating water. These pump motors have a characteristic that torque is proportional to the power of two, and power consumption is proportional to the power of three.

Therefore, in order to reduce the inverter drive motor power consumption, it is important to control the motor at the optimum speed. In addition, there is also a need for a technique for determining whether the motor failure to control the motor at the optimum speed. In addition, there is a need for a technology that can easily monitor and confirm the failure of such a motor.

Korea Registered Patent (10-1703973)

The purpose of the present invention is to reduce the motor power consumption, to control the motor at the optimum speed, to determine the failure of the motor to control the motor at the optimum speed, can easily monitor and confirm the failure of such a motor, The present invention provides a control integrated system capable of monitoring deterioration of other power equipment components, controlling power equipment deterioration, controlling an optimum efficiency point of a motor, and diagnosing failure.

In order to achieve the above object, the integrated control system capable of monitoring the deterioration of the power equipment and controlling the optimum efficiency point of the motor and diagnosing the failure,

It consists of analog board, measurement MCU board, and main MCU board. After converting the output voltage / current of the inverter to dq by the following dq conversion method, By comparing the shapes of the q-axis current with each other, to determine whether the motor failure

In the stationary coordinate system, the d-axis current and the q-axis current have the same amplitude in the case of a motor in normal operation, but the d-axis current and the q-axis current have a different amplitude in the case of a non-normal motor.

In the rotational coordinate system, the d-axis current and the q-axis current have a linear form in the case of a motor in normal operation, but the d-axis current and the q-axis current have a wave form in the case of a non-normally operated motor. A failure determination unit for determining;

[dq conversion formula]

-Static coordinate system-

Rotation Coordinate System

The optimum control speed of the motor is determined by controlling the excitation current so that the input current of the inverter and the output current value according to the dq conversion of the motor are the same, or the reactive power ratio of the input to the output is minimized by changing the motor speed with the following equation. A speed control unit for deriving a point to be determined as the optimum control speed of the motor; And

[Equation]

According to the deterioration state of the motor, it displays the normal, caution, warning, severity colored letters and displays the deterioration monitoring unit for monitoring and diagnosing the deterioration and arc / corona discharge of the power equipment parts other than the motor with an infrared sensor or an ultrasonic sensor. It is characterized by.

The present invention, without using a variety of sensors, such as temperature sensors, vibration sensors, ultrasonic sensors, infrared sensors, it is possible to accurately determine whether the failure of the motor to send an alert to the operator. As a result, even in an environment in which it is difficult to attach various sensors, it is possible to accurately determine whether the motor is broken and to warn the operator.

The present invention can control the motor speed at the optimum speed according to the load characteristics. Therefore, by determining the motor speed vaguely based on the experience or knowledge of the driver in the field, it is possible to prevent unnecessary increase in the power consumption of the motor.

The present invention enables the status monitoring and control of facilities based on ICT (Information and Communications Technologies), thereby providing an intuitive, stable and convenient facility management environment. As a result, the operator can easily determine the configuration of the equipment system, the deterioration state and the temperature of the equipment, and also easily monitor and control the status of the equipment for the efficient control of the motor. It also provides alarm alarms in the form of diagrams and graphs, allowing operators to quickly identify and respond to equipment conditions.

1 is a view illustrating a control integrated system capable of monitoring power equipment degradation and controlling an optimum efficiency point of a motor and diagnosing a failure according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a failure determination unit illustrated in FIG. 1.
FIG. 3 is a diagram illustrating the analog monitor shown in FIG. 2.
4 is a diagram illustrating a zero crossing circuit.
FIG. 5 is a table listing data provided by the measurement MCU board illustrated in FIG. 2 by measuring voltage and current of input and output of the inverter.
FIG. 6 is a graph showing a result of stopping coordinate transformation of a three-phase current output from an inverter (input to a motor). FIG. 6 (a) is a graph showing a result of changing three-phase current stop coordinates of a motor in normal operation. 6 (b) is a graph showing the three-phase current stop coordinate change results of the motor in abnormal operation (fault).
FIG. 7 is a graph showing a result of rotational coordinate change of a three-phase current output from the inverter (input to a motor). FIG. 7 (a) is a graph showing a result of three-phase current rotational coordinate change of a motor in normal operation. FIG. 7B is a graph showing a result of changing three-phase current rotation coordinates of a motor in abnormal operation (failure).
8 is a flowchart illustrating Algorithm 1 in which the speed controller shown in FIG.
FIG. 9 is a flowchart illustrating Algorithm 2 in which the speed controller shown in FIG. 1 finds the optimum motor efficiency point control speed.
FIG. 10 is an enlarged view of a region A shown in FIG. 9.
FIG. 11 is an enlarged view of a region B shown in FIG. 9.
FIG. 12 is an enlarged view of a region C shown in FIG. 9.
FIG. 13 is a graph illustrating a result of controlling a pump motor at a motor optimum efficiency point control speed found in Algorithm 2. FIG.
14 is a diagram illustrating a state in which the degradation monitoring unit shown in FIG. 1 displays a deterioration state of a motor.
FIG. 15 is a view illustrating a state in which the degradation monitoring unit illustrated in FIG. 1 displays a pump installation state.

Hereinafter, a control integrated system capable of monitoring power equipment deterioration and optimal efficiency point control and failure diagnosis according to an embodiment of the present invention will be described in detail.

As shown in FIG. 1, the integrated control system 1 capable of monitoring power equipment deterioration and optimum efficiency point control and troubleshooting of a motor according to an embodiment of the present invention includes a failure determination unit 100 and a speed control unit ( 200, the deterioration monitoring unit 300.

Hereinafter, the failure determination unit 100 will be described in detail.

The failure determining unit 100 determines the failure of the motor by measuring the power of the inverter and the motor.

As shown in FIG. 2, the failure determining unit 100 includes an analog board 110, a measurement MCU board 120, and a main MCU board 130.

The analog board 110 converts the three-phase voltage and current into analog values, and transmits the converted data to the measurement MCU board 120. The analog board 110 monitors the external contact state of four channels and transmits contact state data to the main MCU board 130.

The measurement MCU board 120 measures three-phase voltage and current, and transmits measured data (unit, phase, magnitude) to the main MCU board 130. The measurement MCU board 120 includes an analog monitor 121.

The analog monitor 121 shown in FIG. 3 measures the input (system) voltage / current of the inverter and the output (motor) voltage / current of the inverter via the measurement board sigma-delta analog. The measured value is calculated in the microcontroller unit (MCU) of the measurement MCU board 120. By using such a measurement board sigma-delta analog, the accuracy of the voltage and current of the measured inverter and motor can be 1% accuracy.

The analog monitor 121 is provided with an electromagnetic filter 121a (EMI Filter) that filters noise generated from the input voltage / current of the inverter and the output voltage / current of the inverter. Due to the electromagnetic wave filter 121a, the input voltage / current of the inverter and the output voltage / current of the inverter can be accurately measured without noise.

The input of the inverter has a fixed frequency of 60Hz with three-phase voltage and current of the system. The inverter detects the digital value through sampling of 1920Hz (32 Sample) and processes the data through DFT and frequency calculation. The measured system three-phase voltage / current is processed into data on the effective, reactive, apparent, and cumulative amounts of power and the frequency, phase, and power factor of the system.

Because the output of the inverter has a variable frequency, an analog circuit for frequency measurement is needed. For this purpose, a zero crossing circuit, as shown in FIG. 4, is used.

The frequency output from the inverter can be changed by the speed of the motor, and can be converted by Equation 1.

[Equation 1]

Motor rotation speed N (rpm) = (120 X frequency (f)) / number of motor poles (P) = 30 X frequency (f) ※ Normal motor is 4 poles

The torque of the motor can be converted by Equation 2 through a constant constant (motor efficiency) value of the output power of the inverter.

[Equation 2]

Motor torque T (N.m) = (inverter output power / motor rotation speed) X motor efficiency

The measurement MCU board 120 measures voltages and currents of inputs and outputs of the inverter, and provides them with various data (power, voltage, current, power factor, vector, and speed) as shown in FIG. 5.

The main MCU board 130 receives power and contact data in real time from the measurement MCU board 120. The main MCU board 130 measures and calculates power through the channel combination of the measurement MCU board 120. The main MCU board 130 implements an Ethernet interface and Lora wireless communication for communication with a higher operating system. The main MCU board 130 implements a Human Machine Interface (HMI) function for user operation and power state monitoring.

In the fault determination unit 100 having the above-described configuration, the output (motor) voltage / current of the inverter is converted by dq to determine whether the motor has failed.

The d-axis is the axis in which the magnetic flux of the motor is generated and is selected in the direction of the magnetic flux generated in the stator U-phase winding. The q axis is an axis perpendicular to the d axis, and is selected as an axis of current generating torque.

[dq conversion formula]

-The static coordinate system is the coordinate system in which the coordinate axis is not rotated and is expressed as follows.

-The rotation coordinate system refers to a coordinate system that also rotates the d-q axis in the direction of the stationary coordinate vector sum. The coordinate system rotates at an angular velocity w, and the rotation coordinate system can be obtained from the stationary coordinate system. At this time, the angular velocity w can be obtained as the frequency value of the voltage.

Based on the result of dq conversion in the above formula, it is determined whether the motor has failed.

Referring to the stationary coordinate system shown in FIG. 6, in the case of a motor in normal operation, as shown in FIG. As shown in FIG. 6B, the d-axis current and the q-axis current have different amplitudes.

Looking at the rotational coordinate system shown in Figure 7, in the case of a motor in normal operation, as shown in Figure 7 (a), the d-axis current and the q-axis current has a date form, but in the case of a motor in non-normal operation (fault) As shown in FIG. 7B, it can be seen that the d-axis current and the q-axis current have a wave shape.

In each of the stationary coordinate system and the rotational coordinate system, by comparing the shapes of the d-axis current and the q-axis current when the motor is normal and when the motor is abnormal, the failure of the motor can be intuitively determined.

The failure determining unit 100 notifies the deterioration monitoring unit 300 when a motor failure occurs, and the deterioration monitoring unit 300 displays a warning so that an operator can know the failure of the motor. In addition, the failure determining unit 100 stops the inverter when a motor failure occurs. In addition, the failure determination unit 100 stores the data until the inverter is stopped for failure analysis when the motor failure, the operator can analyze the cause of the failure.

By using the failure determining unit 100, it is possible to accurately determine whether the failure of the motor, and to send a warning without using various sensors such as temperature sensor, vibration sensor, ultrasonic sensor, infrared sensor. In other words, even in an environment where it is difficult to attach various sensors, it is possible to accurately check whether the motor is broken and to send a warning.

For reference, the English abbreviations shown in FIGS. 2 and 3 mean the following.

GPIO: general-purpose input / output

SPI: serial peripheral interface bus

SCI: scalable coherent interface

PGA: programmable gain amplifier

MUX: multiplexer

Hereinafter, the speed control unit 200 will be described in detail.

The speed controller 200 controls the motor by finding the optimum efficiency point control speed of the motor.

[1] How to find the optimum speed control speed of the motor

After a long study, the applicant has found that the optimum excitation can be realized when the input current of the inverter and the output current value according to the dq conversion of the motor are the same.

Based on this finding, by controlling the excitation current such that the input current of the inverter and the output current value according to the dq conversion of the motor are equal, the optimum control speed of the motor can be determined.

Algorithm 1 for Method 1 is shown in FIG. 8.

The gist of Algorithm 1 is as follows.

1) Command the motor speed. Calculate the d-axis and q-axis currents of the motor.

2) Measure the current at the input (grid) of the inverter.

3) When the q-axis current of the motor / input (system) current of the inverter is equal to or greater than 1, the present value (qn) is stored. Stores the past value qn-1.

4) When the calculated value is between 0.8 ~ 1 in? = Present value-past value comparison, determine the motor speed at that time as the optimum control speed of the motor. Since the optimum control speed of the motor is continuously changed by the load variation, the above algorithm is executed repeatedly to find the optimum control speed of the motor.

[Method 2 to find the optimum speed control speed of the motor]

After a long study, the applicant found that the speed of the point where the reactive power ratio of the input to the output becomes the minimum becomes the optimum control speed of the motor through the change of the motor speed.

Based on this finding, the point where the reactive power ratio of the input to the output becomes minimum through the change of the motor speed can be derived through Equation 3.

[Equation 3]

Algorithm 2 for Method 2 is shown in FIGS. 9-12.

The gist of Algorithm 2 is as follows.

1) Drive the motor at the rated speed and initialize the parameters to measure the initial energy consumption of the initial motor.

2) It detects whether the present speed reaches the command speed at the same time as the start of drive.

3) Measure current input / output active power and reactive power when command speed is reached. That is, when the command speed and current speed are the same, the current input / output active power and reactive power are measured.

4) Store the current ratio of x (n).

5) The speed increase comparison statement changes the control syntax according to the speed change when controlling the maximum efficiency point, and the ratio calculation is reversed accordingly. In other words, if the speed does not increase at the initial rating of 100%, execute with No statement. If the speed is increased at the 100% initial rating, execute with Yes statement.

6) The value of x (n-1) represents the past value of the ratio of the input / output effective invalidity.

7) y (n) represents the value of x (n-1) -x (n). (That is, the difference between Xn's past and present)

8) y (n-1) represents the past value of y (n).

9) The count can be changed very largely due to external disturbance or noise of input / output, so it is optimal when the comparison statement of y (n-1)> y (n) comes in continuously. It executes as a routine to reduce or increase the current command speed by judging not by form.

[Experiment result]

As shown in FIG. 13, it takes about 33 minutes to drive a motor at a rated speed of 60 Hz at a target cumulative flow rate of 10000L, and the amount of input cumulative power was measured at 5.78 kWh. On the other hand, when the motor is driven at the optimum efficiency control point of the motor found by Algorithm 2, it takes about 34 minutes and 19 seconds to reach the target cumulative flow rate 10000L, and thus the input cumulative power amount is measured as 2.8 kWh. That is, it can be seen that 51.557% of power improvement is achieved.

Hereinafter, the degradation monitoring unit 300 will be described in detail.

The degradation monitoring unit 300 determines and warns whether or not the motor is deteriorated. For example, the module ID 345 shown in FIG. 14 is designated as a motor, and according to the deterioration state of the motor, it indicates normal, caution, warning, and severity, and the letters are colored so that an operator can easily check the state of the motor. Make it

On the other hand, the degradation monitoring unit 300 monitors and diagnoses deterioration and arc / corona discharge of power equipment parts other than the motor with an infrared sensor or an ultrasonic sensor.

For example, an infrared sensor measures the temperature change according to whether the component is deteriorated and diagnoses the deterioration state, and an ultrasonic sensor detects the ultrasonic wave generated by the arc discharge or the corona discharge to determine whether the arc discharge or the corona discharge is generated. do. This allows the operator to quickly detect and respond to hazards on non-motor components.

In addition, the deterioration monitoring unit 300 enables the status monitoring and control of the facility based on ICT (Information and Communications Technologies), thereby providing an intuitive, stable and convenient facility management environment. For example, the degradation monitoring unit 300 may display a pump facility state, as shown in FIG. 15. Of course, the equipment object to be monitored for degradation, and the manner of displaying the degradation of the equipment object may vary.

Claims (3)

It consists of analog board, measurement MCU board, and main MCU board, and converts dq of inverter output voltage / current by dq conversion formula, and then the d-axis current at normal and abnormal motor and By comparing the shapes of the q-axis current with each other, to determine whether the motor failure
In the stationary coordinate system, the d-axis current and the q-axis current have the same amplitude in the case of a motor in normal operation, but the d-axis current and the q-axis current have a different amplitude in the case of a non-normal motor.
In the rotational coordinate system, the d-axis current and the q-axis current have a linear form in the case of a motor in normal operation, but the d-axis current and the q-axis current have a wave form in the case of a non-normally operated motor. A failure determination unit for determining;
[dq conversion formula]
-Static coordinate system-

Rotation Coordinate System

A speed control unit for deriving a point at which the reactive power ratio of the input to the output is minimized by changing the motor speed by the following equation and determining the speed of the point as an optimum control speed of the motor; And
[Equation]

According to the deterioration state of the motor, it displays the normal, caution, warning, severity colored letters and displays the deterioration monitoring unit for monitoring and diagnosing the deterioration and arc / corona discharge of the power equipment parts other than the motor with an infrared sensor or an ultrasonic sensor. Control integrated system capable of monitoring power equipment deterioration and optimum efficiency point control and troubleshooting of the motor. delete delete

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