RU1781628C - Active power meter - Google Patents

Abstract

The invention can be used as a discrete medium power meter in electrode production, as well as in other industries where electric furnaces are used in technological processes. SUMMARY OF THE INVENTION: the device improves the accuracy of measuring average power and the reliability of information, thereby increasing product quality and reducing energy consumption. The device for measuring active power includes a sensor 1. a transducer 2, a measuring unit 8, a nickel meter 5, a switch 7, a software timer 4, a control unit 3, a circuit And 6, and a rotary encoder 10 to rotate 360 °. 1 C.p. f-ls, 1 ill.

Description

The invention relates to a control and measuring technique and is intended for use as a discrete meter of average power, namely in electrode production during the process in graphite furnaces for the production of graphite electrode products.

At present, the graphitization process in domestic plants is carried out in special electric furnaces. The graphitization process is carried out according to a predetermined schedule of power increase by discrete changes in the voltage supplied to the furnace, and the end of the graphitization process is determined by the amount of consumed electricity depending on the tonnage of the loaded product.

The power introduced into the furnace is determined using ferrodynamic wattmeters, and the power consumption is determined by electromechanical meters.

These devices, having different accuracy classes and the principle of action, react differently to changes in electrical parameters (to the appearance of higher harmonics, to changes in the active power factor (cos (fty.

If the error of the electromechanical counter depends on the distortion of the sine wave (the appearance of higher harmonics), then the change in the active power factor sharply affects the error of the wattmeter.

Due to the characteristics of graphitization furnaces, and most importantly, due to changes in the properties of carbon materials during the graphitization process, the power factor during the graphitization process decreases all the time and decreases to 0.6-0.5 at the end of the graphitization process. As a result of this, the error of the wattmeter departs from the given one and can reach large values. An increase in the error of the device affects the accuracy of the measurement of the power input into the furnace, and, therefore, the control accuracy

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graphitization process; which reduces the quality of graphite products. In addition, the graphitization furnace is an inertial object, therefore, after changing the power (increase, decrease), it is necessary to measure the latter after a certain time equal to the transient time in the furnace, and when measuring the power with a wattmeter measuring instantaneous power, it is difficult to determine the time when you can again act on the furnace.

Measurement of the power introduced into the graphitization furnace by a device whose measurement results are independent of the change in the power factor and taking into account the inertia time of the object (transient time) will increase the accuracy of power measurement and the accuracy of control of the graphitization process, which will increase the yield and reduce power consumption.

A digital power meter is known that includes a strain gauge, including strain gauges, one of which is connected to the input of the driver and the information input of one of the key circuits, and the second through the second key circuit is connected to the second input of the former. The control outputs of the key circuits are connected respectively to the single and zero outputs of the control trigger, whose installation inputs are connected to the first and second command outputs of the control circuit. The outputs of the formers are connected to the inputs of the phase discriminator, the sign output of which is connected to the sign input of the logic circuit, and its information output is connected to the measuring input of the logic circuit. The measuring input of the second logic circuit is connected to the output of one of the pulse shapers. The clock inputs of the logic circuits are connected to the output of the master oscillator. The first and second outputs of the first logic circuit are connected respectively to the summing and subtracting inputs of the counter. The output of the second logic circuit is connected to the input of the second counter. The counter outputs through the zero analyzers are connected to the first and second command inputs of the control circuit.

The operation of the digital power meter consists in the fact that in each cycle of measuring the power, the measured phase shift between the signals from the outputs of the strain gauges (characterizing the magnitude of the torque) is automatically corrected by

corresponding to the phase difference (error) between the formers by connecting, using key schemes, a signal from one of the deformation sensors to the inputs of both pulse formers.

This power measuring device can only be used for objects in which, when the input power changes, the shaft deformation changes, i.e. torque value.

A digital power meter is also known, which consists of a sum-difference block, the outputs of which are connected to the adders. Two thermal converters are connected to the outputs of the operational amplifier. The heaters are connected in parallel to the operational amplifiers. The output voltage reference is connected to the input of the operational amplifier, the output of which is connected via a converter to a matching element. The output of the matching element is connected to the input of the digital register.

This device provides high accuracy of measuring the power of thermo-converters due to the isothermal mode of the latter in wide ranges of input voltage variations, and also has a wide frequency range, high speed, simplicity of circuit design and digital representation of the measurement results.

The disadvantage of this device is the nonlinearity of the reference scale, as well as the inadmissibility of even short-term overloads and distortion of the sinusoidal current, which causes additional errors. .

Closest to the proposed one is a telemechanical device for measuring active power, containing an induction energy meter, the disk of which has rectangular cutouts above which the illuminator and lens are located, under the hole there is a photodiode connected to an asymmetric trigger. The transistor switch is connected to the output of the trigger and the generator with self-excitation. The generator generates pulses; the number of which depends on the speed of rotation of the disk, as well as on the width of the working part of the cut. Pulses are generated in a burst and transmitted via a communication line to a converter, where the pulses are converted to a DC voltage and are measured by a measuring unit. The voltage at the output of the measuring unit has an amplitude proportional to the active power.

The power measurement results of the known device are independent of the change in the power factor (cos jp) and with it the power input to the graphitization furnace can be measured.

However, the measurement accuracy of the known device is affected by external interference caused by the switching on or off of powerful units and fluctuation changes inside the object (graphitization furnace), which can occur at any time and cannot be foreseen in advance.

These interferences can cause an asymmetric trigger to fail when a signal from the photodiode appears at its input, or vice versa, its false operation, and therefore, pulses are not transmitted along the communication line from the generator to the converter or transmission takes place. This adversely affects the accuracy of power measurements.

In addition, the known device does not take into account the time of the transition process, which negatively affects the quality of control of the graphitization process (i.e., the graphitization furnace and graphitized carbonaceous material have not yet responded to the input power, the transient has not ended, and the measurement has already ended and the operator indicators of the measuring device makes an unlawful conclusion about the magnitude of the next control action).

The purpose of the invention is to increase the accuracy of measuring average power, as well as to increase the reliability of information.

This is achieved by the fact that the device for measuring active power, comprising a sensor, which is an induction energy meter with a disk above which a light bulb is located, and a photodiode, a converter and a measuring unit connected to the sensor, is equipped with a storage meter, a switch, a program timer. a control unit and an AND circuit connected to one of the outputs of the software time relay, the other outputs of which are connected to the switch, one output of which is connected to the counter-drive, and two others They are connected to the measuring unit, the second input of the counter-drive through the circuit And is connected to the output of the converter and to one of the inputs of the control unit, the sensor is equipped with a 360 ° disk rotation sensor, the output of which is connected to the second input of the control unit, the output of which is connected to the third input counter-drive and to the input of the software timer, the second

the input of which is connected to the converter, and the outputs of the drive counter with the inputs of the measuring unit.

The 360 ° disk rotation sensor is made in the form of a dark strip located on the disk having one bright area, and the boundaries of which are two concentric circles, the center of which is the center of the disk, and a photodiode.

0 perceiving light reflected from a white area.

The proposed device differs from the prototype by the presence of a 360 ° disk rotation sensor, a counter-drive, a control unit, a switch, a software timer and circuit I.

The presence of a disk rotation sensor 360 ° and a control unit connected in series, as well as a drive counter0, one of the inputs of which is connected to the output of the control unit, the second through the AND circuit with the converter output, and the outputs with the measuring unit, as well as communication control unit with software relay

5 times, it allows information about the average power to be received in the measuring unit only if, as a result of the appearance of interference, not a single pulse carrying information about the power value is lost and not a single excess is present, i.e. improves the accuracy of power measurements.

In the case of an inaccurate measurement result, information about the average power in a given time interval does not appear at all.

Since in the process of graphitization, the graph of the temperature change of graphitized products must be maintained exactly, then

0 it is better to skip one or two time intervals, having the previous information, than to receive false information, based on which the amount of power introduced into the furnace can be changed, so

5 in such a way that the technological mode will be violated (overheating or underheating of the product), and ultimately the quality of the finished product will decrease.

The presence of a software time switch,

0 one of the inputs of which is connected to the converter, one of the outputs with the circuit And, and the remaining outputs through the switch with a measuring unit, allows you to measure the average power for

5 is a time equal to the transient time in the furnace, i.e. during which time the properties of the graphitized carbon materials and the graphitization furnace change after the input voltage is changed and a certain value of the power consumed by the graphitization furnace is established, therefore, the reliability of the information increases.

The drawing shows a functional diagram of a device for measuring active power.

The device for measuring active power contains a sensor 1, two outputs of which are connected to the inputs of the converter 2, and a third with a second input of the control unit 3, the first input of which is connected to one of the outputs of the converter 2, the second output of which is connected to the second input of the program timer 4 , the first input of which is connected to the output of the control unit 3, with which the third input of the counter-accumulator 5 is also connected, and the first output of the program timer 4 with one of the inputs of the circuit And b, the second input of which is connected to the first output m converter 2, connected to the first input of the control unit 3. The output of circuit I 6 is connected to one of the inputs of the counter-accumulator 5, and the remaining (second, third and fourth) outputs of the program timer 4 are connected via switch 7 to measuring unit 8 , which are connected and the outputs of the counter-drive 5. The outputs of the measuring unit 8 are connected to the indicator 9. The third output of the switch 7 is connected to the first input of the counter-drive 5.

As the sensor 1, an electro-mechanical counter type СО-И446 was used with a built-in disk 10 on which two code tracks 11, 12 are applied. Black and white areas located in a checkerboard pattern are applied on code tracks 11 and 12. In addition, on the disk 10 there is also a control track 13, made in the form of a dark strip, the boundaries of which are two concentric circles, the center of which is the center of the disk 10. Track 13 has one bright (white) area, equal in area to the white area code tracks 11 ,. A lamp 14 is located above the paths 11,12,13. Photodiodes 15,16 are used to pick up the light reflected from the light areas of the code tracks 11,12, and a photodiode 17 is used to pick up the light reflected from the light area of the wander 13. with track -13 it forms a sensor for the rotation of the disk 10 through 360 °. The outputs of the photodiodes 15, 16 are the outputs of the pulse sensor 1. connected to the transducer 2, and the output of the photodiode 17 is the output of the 360 ° disk rotation sensor. connected to input 2 of control unit 3.

A device for measuring active power operates as follows. When power is supplied to the graphitization furnace, the disk 10 of the sensor 1 (electromechanical counter) starts to rotate and the light areas deposited on the code tracks 11, 12 alternately fall under a beam of light coming from the bulb 14, which is reflected from them. Periodically gets

0 under the beam of light coming from the bulb 14, and the track 13 is light.

When light areas fall under a ray of light emanating from bulb 14, the latter is reflected from them and perceives 5 with photodiodes 15.16. The signals from the photodiodes 15 and 16 are fed to the corresponding inputs of the converter 2, namely, to the inputs of the trigger 18. Since the light areas on the code tracks 11,12 are arranged in a checkerboard pattern, the signals at the inputs of the trigger 18 appear alternately, setting trigger 18 is now in the working position, then in the original.

In the initial state of the trigger 18

5, the potential pulse element 19 is prepared for operation, and when the trigger 18 is transferred from the initial state to the operational state, i.e. when you turn the disc at an angle corresponding to the sum of the lengths of dark and light

0 pads of code tracks 11,12, the potential-pulse element 19 generates a pulse,

The ray of light from the bulb 14, reflected from the light area of the track 13, is sensed by the photodiode 17, while the signal from the output of the photodiode 17 is fed to the input of the trigger 20 of the control unit 3.

Trigger 20 operates in counting mode: from the first pulse it is set to

0 working position, and from the second to the starting position, etc. Since there is one bright area on track 13, the trigger 20 is in working position after one revolution of the disk 10, i.e. at one turn of a disk 10

5, trigger 20 is in the operating position, the next in the initial position, etc. In the operating position, the trigger 20 prepares for operation the element And 21 and the pulses from the Converter 2 (with a potential pulse

0 of element 19) are supplied through element And 21 to the input of counter 22 of control unit 3, and through circuit I b, prepared for operation by a software time relay 4 (by a signal from element NOT 23), to the input of counter 24 of counter 5 of accumulator B. Counters 22 and 24 operate synchronously. After a complete revolution of the disk 10, the number counted by the counter 22 through the decoder / is compared using the comparison circuit 25 with the number specified by the master 26. The number specified by the master 26,

corresponds to the number of bright areas of the code track of the disk 10 of the pulse sensor 1. In our case there are 24 of them, this means that for one revolution of the disk 10, 24 pulses should arrive at the counters 22 and 24.

If for a full revolution of the disk 10, each of the counters 22 and 24 received a number of pulses equal to the number set by the setpoint 26, then the sensor is working correctly. After a full turn of the light disk 10, the track 13 is located under the light source 14, after it leaves the light, the trigger 20 is set to its initial state, the And 21 element is closed and no signals are sent to the counter 22, and the counter 24 continues to summarize the ones coming from the code lanes 11,12 sensor 1 impulses.

At the end of the cycle (the cycle is the transient time in the graphitization furnace, in our case, the cycle is 36 s) - 35, 57 seconds after the voltage supplied to the furnace has changed, in the program timer 4, the counter 27 is operating from the generator 28, sets through output 1 trigger 29 in the working position. From the output of the trigger 29, the signal is supplied to the first input of the element And 30.

When the logic 0 signal appears at the output of the trigger 18, the HE 31 element allows the And 30 element, which passes the signal from the trigger 29, to work, setting the trigger 32 in working condition. The signal from the output of the trigger 32 prepares the elements And 33, And 34, And 35 of the switch 7 for operation and prohibits (through the element NOT 23) the operation of the circuit And 6. After 35, 58 s after changing the voltage supplied to the furnace from the output 2 of the counter 27, the signal enters through the And 34 element of the switch 7 to the input Reset register 36 of the measuring unit 8 and sets it to its original state, and after 35.59 s after changing the voltage supplied to the furnace, the signal from the third output of the counter 27 through the And 33 element of the switch 7 sets the elements And 37, ..., And 56 of the measuring unit 8 in the working position and thereby, it rewrites the number counted by the counter 24 through the elements AND 37, ... 56 to the register 36, and from the register 36 through the decoder 57 the number goes to the indicator 9. 36 seconds after changing the voltage supplied to the furnace from the fourth output of the counter 27, the signal through the AND element 35 of the switch 7 and the OR element 58 of the drive 5, the counter 24 is reset, setting it to the initial state, and through the delay element 59 and the And 60 element, prepared for operation by the signal from the output of the trigger 32, sets the counter 27 and the trigger 29 and 32 to the initial state.

In this case, the signal from the output of the trigger 32 prohibits the operation of the elements And 33, 34, And 35, and through the elements NOT 23 allows the operation of the circuit And 6, from the output of which the signals begin to flow to the input of the counter 24. The cycle repeats.

If during one revolution of the disk 10 (i.e., at the moment when the light area of the control track 13 is under the light source 14), the counters 22 and 24 received a smaller number of pulses. Than the number specified by the setter 26 (in our case, the number is less 24), when the light area of the control track 13 exits from under the light source 14, the trigger 20 switches from the working position to the initial position, the element 21 closes, the trigger 61 is transferred to the operating position, in which a signal is sent from the trigger 61 to one of the inputs And element 63. To the second input of the And element 63, a signal is received from the second output of the trigger 20, and since the counter 22 has not counted the number set by the setter 26, the signal to the third input of the And 63 element also comes from the comparison element 25 through the HE 62 element. Since all three inputs of the And 63 element have signals , the signal also appears at its output, which sets the counter 24 to its initial state through the elements OR 64 and OR 58, and the counter 27 through the elements OR 64 and OR 65. After that, the pulse counting starts again.

Thus, if during one revolution of the disk 10 not all the information has reached the counter 24 (22) (one or several pulses have disappeared), then this incorrect information is reset and the measurement starts again.

If the disk 10 has made an incomplete turn, and the counter 22 has already counted the number of pulses set by the setter 26, the matching circuit 25 is activated and gives a signal to one of the inputs of the And 66 element. And since at that time the light of the control track 13 is not under the light source 14 , then the trigger 20 is in this position, and the logic 1 signal from its first output goes to the second input of the And 66 element. Since both the inputs of the And 66 element receive the logic 1 signals, the output of And 66 also appears the signal is logical 1, which, through the elements of OR 64 and OR 58, sets the counter 24 to its original state, and through the elements of OR 64, OR 65, the counter 27. The disk 10 continues to rotate, and when the light area of the track 13 leaves the light beam (after falling it under a beam of light, the trigger 20 is set to its initial position) the Reset signal coming through the elements OR 64, OR 58 to the counter 24 and through the elements OR 64, OR 65 to the counter 27 disappears (because the logical 1 signal from the second input of AND element 66) disappears, and the logical O signal that appeared on the first output of trigger 5 20 sets the counter 22 to its initial position. The count of pulses from the sensor 1 to the counters 22, 24 starts from the beginning, the clock cycle (after resetting the counter 27) is counted -10 again.

Thus, if the disk 10 has not yet completed a full revolution, and the number of pulses arriving at the counter 22 (24) is already equal to the number of pulses per full disk revolution 15 10, i.e. if false information arrives (false pulses appear), then this incorrect information is reset and the measurement starts again.

Information from the counter 24 is input into the 20 measuring unit 8 only in the absence of distortion due to interference, which increases the accuracy of the measurement. And the input of information from the counter 24 into the measuring unit 8 after measuring the power for 25 a period of time equal to the transient time in the furnace increases the reliability of the information.

A schematic diagram of the proposed device for measuring the active power of 30 is performed on K511 series microcircuits, photodiodes of the type F 23 K are used.

Compared with the prototype, the use of the claimed technical solution 35 will increase the accuracy and reliability of measuring the average power due to the fact that the average power is measured over a period of time equal to the transient time in the furnace, and 40 false information, distorted by interference, is not received measuring unit. Thanks to the latter, the operator (or control device) will not be able to develop an unlawful control action, 45 guided by false (or inaccurate) information.

Since the graphitization furnace is an inertial object, it is better to skip one or two measurement cycles, having the previous information, than to receive inaccurate (false) information, which, the operator (or control device) can enter into the furnace excess electricity or dramatically reduce the input of electricity into the furnace, which

children to a violation of the technological regime (overheating or underheating of the product) and, ultimately, reduce the quality of the product.

Using the proposed device for measuring active power will increase the yield by 3% and reduce energy consumption.

In addition, a significant economic effect is possible from the use in the ferrous and non-ferrous metallurgy of high-quality graphite electrodes with a given value of electrical conductivity, which ensures a reduction in the loss of electricity supplied to the technological zone of the units.

7 devices for measuring active power were manufactured and implemented at the Dnieper electrode plant.

Claims (2)

1. A device for measuring active power, comprising a sensor, which is an induction energy meter with a disk, an illuminator and a photodiode, as well as a converter and a measuring unit connected to the sensor, characterized in that, in order to increase the accuracy of measurement and the reliability of the information, it is equipped a drive counter, a switch, a program timer, a control unit and an AND circuit connected by one input to one of the outputs of the program timer, the other outputs of which are connected to the switch ru, one output of which is connected to the counter-drive, and the other two are connected to the measuring unit, while the second input of the counter-drive through the circuit And is connected to the output of the converter and to one of the inputs of the control unit, the sensor is also equipped with a 360-degree disk rotation sensor, the output of which is connected to the second input of the control unit, the output of which is connected to the third input of the counter-accumulator and the input of the program timer, the second input of which is connected to the output of the converter, and the outputs of the counter-accumulator - with the inputs will measure spruce block 2. The device according to claim 1, with the fact that the 360P disk rotation sensor is made in the form of a dark strip located on the disk having one bright area, and the borders of which are two concentric circles whose centers coincide with the center of the disk.