CN110824226A - Direct current measuring method, device and system - Google Patents
Direct current measuring method, device and system Download PDFInfo
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- CN110824226A CN110824226A CN201910987854.6A CN201910987854A CN110824226A CN 110824226 A CN110824226 A CN 110824226A CN 201910987854 A CN201910987854 A CN 201910987854A CN 110824226 A CN110824226 A CN 110824226A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
Abstract
The invention relates to a direct current measuring method, a direct current measuring device and a direct current measuring system. According to the direct current measuring method, one end of the grounding flat steel between the neutral point of the power transformer and the ground wire is selected as the flat steel to be measured. And (3) introducing a constant current to the flat steel to be detected, comparing the voltage change of the flat steel to be detected before and after the constant current is introduced to obtain the resistance value of the flat steel to be detected, and then obtaining the real-time current of the flat steel to be detected according to the resistance value and the real-time voltage of the flat steel to be detected. The direct current measuring method can effectively measure the direct current data of the neutral point of the power transformer, thereby effectively monitoring the direct current data of the neutral point of the power transformer.
Description
Technical Field
The invention relates to the field of electrical characteristic measurement of power equipment, in particular to a direct current measurement method, a direct current measurement device and a direct current measurement system.
Background
With the development of power grids, high-voltage direct-current power transmission is increasingly applied to domestic power grid construction due to the characteristics of long transmission distance, large transmission capacity, small loss, asynchronous networking and the like.
Conventionally, a high voltage direct current transmission system usually performs voltage conversion through a power transformer. When the power transformer is used for voltage conversion, direct current may flow into the power transformer through a neutral point of the power transformer, so that direct current magnetic bias of the power transformer is caused, and safe operation of the power transformer is damaged.
The inventor finds out in the process of realizing the conventional technology that: the conventional art lacks a scheme for effectively monitoring dc current data of a neutral point of a power transformer.
Disclosure of Invention
Based on this, it is necessary to provide a dc measurement method, apparatus and system for detecting a real-time current of a neutral point of a power transformer, aiming at the problem that a dc current in the conventional technology may flow into the transformer through the neutral point of the power transformer, resulting in dc magnetic bias of the power transformer.
A direct current measurement method for detecting a real-time current of a neutral point of a power transformer, the neutral point being connected to a ground line through a ground flat, comprising:
selecting a section of the grounding flat steel as a flat steel to be detected;
introducing a constant current into the flat steel to be detected, and acquiring the line end voltage of the flat steel to be detected to obtain a first voltage value;
stopping introducing the constant current, and obtaining the line end voltage of the flat steel to be detected to obtain a second voltage value;
calculating the resistance value of the flat steel to be detected according to the first voltage value, the second voltage value and the constant current;
acquiring the real-time voltage of the flat steel to be detected to obtain a third voltage value;
and calculating the real-time current according to the third voltage value and the resistance value.
In one embodiment, the obtaining the line end voltage of the flat steel to be measured to obtain a first voltage value includes:
and acquiring the voltage of the circuit end of the flat steel to be detected through a voltage collector to obtain a first voltage value.
In one embodiment, before stopping supplying the constant current, the method further includes:
acquiring the current value of the constant current;
the step of calculating the resistance value of the flat steel to be tested according to the first voltage value, the second voltage value and the constant current comprises the following steps:
and calculating the resistance value of the flat steel to be detected according to the first voltage value, the second voltage value and the current value.
In one embodiment, the calculating the resistance value of the flat steel to be tested according to the first voltage value, the second voltage value and the current value includes:
acquiring a voltage difference value of the first voltage value and the second voltage value;
and calculating the ratio of the voltage difference value to the current value according to the voltage difference value, namely the resistance value of the flat steel to be detected.
In one embodiment, said calculating said real-time current according to said third voltage value and said resistance value comprises:
and calculating the ratio of the third voltage value to the resistance value according to the third voltage value and the resistance value, namely the real-time current.
In one embodiment, after calculating the real-time current according to the third voltage value and the resistance value, the method further includes:
acquiring the time corresponding to the third voltage value, and acquiring the position of the power transformer corresponding to the flat steel to be tested;
and sending the real-time current, the time corresponding to the third voltage value and the position of the power transformer.
According to the direct current measuring method, one end of the grounding flat steel between the neutral point of the power transformer and the ground wire is selected as the flat steel to be measured. And (3) introducing a constant current to the flat steel to be detected, comparing the voltage change of the flat steel to be detected before and after the constant current is introduced to obtain the resistance value of the flat steel to be detected, and then obtaining the real-time current of the flat steel to be detected according to the resistance value and the real-time voltage of the flat steel to be detected. The direct current measuring method can effectively measure the direct current data of the neutral point of the power transformer, thereby effectively monitoring the direct current data of the neutral point of the power transformer.
A direct current measuring apparatus based on the direct current measuring method in any one of the above embodiments, comprising:
the voltage collector is provided with a first clamp and a second clamp, the first clamp and the second clamp are used for being connected with two ends of the flat steel to be detected so as to obtain the end-of-line voltage of the flat steel to be detected, and the end-of-line voltage comprises a first voltage value, a second voltage value and a third voltage value;
the constant current power supply is used for being connected with two ends of the flat steel to be detected so as to feed constant current into the flat steel to be detected;
the controller is connected with the voltage collector to obtain the voltage of the circuit end, and the resistance value of the flat steel to be detected is calculated according to the first voltage value, the second voltage value and the constant current; calculating the real-time current of the flat steel to be detected according to the third voltage value and the resistance value;
and the working power supply is connected with the voltage collector and the controller to supply power to the voltage collector and the controller.
In one embodiment, the dc current measuring device further includes:
the current acquisition assembly is connected between the constant current power supply and the flat steel to be detected so as to detect the current value of the constant current; the current collecting assembly comprises a shunt and a current collector, the shunt is used for being connected between the constant current power supply and the flat steel to be detected, and the current collector is connected with the shunt in parallel so as to detect the current value of the constant current;
the current collector is connected with the controller to transmit the current value of the constant current to the controller; the current collector is also connected with the working power supply so that the working power supply supplies power to the current collector.
In one embodiment, the dc current measuring device further includes:
the clock is used for recording the time corresponding to the third voltage value, and is connected with the controller so as to transmit the time corresponding to the third voltage value to the controller;
the positioner is used for acquiring the position of the power transformer corresponding to the flat steel to be detected, and the positioner is connected with the controller so as to transmit the position of the power transformer corresponding to the flat steel to be detected to the controller;
and the first communicator is connected with the controller so as to acquire and transmit the real-time current transmitted by the controller, the time corresponding to the third voltage value and the position of the power transformer.
The direct current measuring device comprises a voltage collector, a constant current power supply, a controller and a working power supply. The constant current power supply can supply constant current to the flat steel to be tested. The voltage collector is used for collecting the voltage change of the flat steel to be detected before and after the constant current is introduced. The controller can obtain the resistance value of the flat steel to be detected according to the voltage change of the flat steel to be detected before and after the constant current is introduced, and then obtain the real-time current of the flat steel to be detected according to the resistance value and the real-time voltage of the flat steel to be detected. The direct current measuring device can effectively measure the direct current data of the neutral point of the power transformer, thereby effectively monitoring the direct current data of the neutral point of the power transformer.
A direct current measuring system comprising the direct current measuring device of any of the above embodiments.
The direct current measuring system can monitor the direct current data of the neutral point of the power transformer remotely through the upper computer, so that the direct current data of the neutral point of the power transformer can be effectively monitored.
Drawings
Fig. 1 is a schematic flow chart of a dc current measurement method according to an embodiment of the present application.
Fig. 2 is a schematic structural diagram of a dc current measuring device according to an embodiment of the present application.
Fig. 3 is a schematic structural diagram of a dc current measuring device according to another embodiment of the present application.
Fig. 4 is a schematic structural diagram of a dc current measuring device according to another embodiment of the present application.
Wherein, the meanings represented by the reference numerals of the figures are respectively as follows:
10. a direct current measuring device;
110. a voltage collector;
112. a first clamp;
114. a second clamp;
120. a constant current power supply;
130. a controller;
140. a working power supply;
150. a current collection assembly;
152. a flow divider;
154. a current collector;
162. a clock;
164. a positioner;
166. a first communicator;
20. and (5) testing the flat steel to be tested.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
The high-voltage direct-current transmission system has the advantages of long transmission distance, large transmission capacity, small loss, asynchronous networking and the like. After power transmission using a hvdc transmission system, a power transformer is usually required to convert high voltage dc power to rated voltage dc power or ac power. When the power transformer works, the neutral point is a grounding point and is generally connected with a ground wire through a grounding flat steel. When a power transformer is used for voltage conversion, a direct current may flow into the power transformer through a neutral point of the power transformer due to a large potential difference near the power transformer, thereby causing direct current magnetic biasing of the power transformer. When the power transformer is subjected to direct current magnetic biasing, noise and loss of the power transformer are increased, and therefore safe operation of the power transformer is endangered. However, there is a lack of a scheme for effectively monitoring dc data of a neutral point of a power transformer in the conventional art.
Based on this, the application provides a direct current measuring method, device and system. A direct current measurement method for detecting a real-time current of a neutral point of a power transformer, as shown in fig. 1, comprising the steps of:
and S100, selecting a section of the grounding flat steel as the flat steel to be detected.
As is known from the above description, the neutral point of the power transformer is the grounding point, which is connected to the ground wire via the grounding flat bar. Therefore, in the present embodiment, the real-time current of the neutral point of the power transformer can be detected by detecting the real-time current of the ground flat bar. When detecting the real-time current of the grounded flat steel, one section of the grounded flat steel can be selected as the flat steel to be detected.
When the flat steel to be tested is selected, the middle section of the grounding flat steel can be selected as the flat steel to be tested.
S200, constant current is introduced into the flat steel to be detected, and the voltage of the circuit end of the flat steel to be detected is obtained, so that a first voltage value is obtained.
And introducing constant current into the flat steel to be detected. Generally, the power supply includes both a constant voltage power supply and a constant current power supply. The constant voltage power supply is a power supply with constant output voltage, and in a circuit where the constant voltage power supply is located, as the resistance in the circuit increases, the voltage at the line end of the circuit does not change, and the current at the line end decreases. The constant current power supply is a power supply with constant output current, and in a circuit where the constant current power supply is located, as the resistance in the circuit increases, the current at a circuit end is constant, and the voltage at the circuit end increases.
In this embodiment, a constant current can be applied to the flat steel to be tested by the constant current power supply. The constant current point currentThe current value of (c) may be preset and stored. At the moment, the line end voltage of the flat steel to be measured is measured, and a first voltage value U can be obtainedX。
And S300, stopping introducing the constant current, obtaining the line end voltage of the flat steel to be detected, and obtaining a second voltage value.
Obtain a first voltage value UXThen, the constant current can be stopped. At the moment, the line end voltage of the flat steel to be measured is measured again, and a second voltage value U 'can be obtained'X. Second voltage value U'XAnd a first voltage value UXThe difference value is the voltage variation value brought by the constant current.
S400, calculating the resistance value of the flat steel to be measured according to the first voltage value, the second voltage value and the constant current.
Obtain a first voltage value UXAnd a second voltage value U'XThen, according to the first voltage value UXAnd a second voltage value U'XAnd calculating the current value of the constant current to obtain the resistance value of the flat steel to be measured.
S500, acquiring the real-time voltage of the flat steel to be detected, and acquiring a third voltage value.
And S600, calculating real-time current according to the third voltage value and the resistance value.
And after the resistance value of the flat steel to be detected is obtained through calculation, calculating to obtain the real-time current of the flat steel to be detected according to the real-time voltage U of the flat steel to be detected.
According to the direct current measuring method, one end of the grounding flat steel between the neutral point of the power transformer and the ground wire is selected as the flat steel to be measured. And (3) introducing a constant current to the flat steel to be detected, comparing the voltage change of the flat steel to be detected before and after the constant current is introduced to obtain the resistance value of the flat steel to be detected, and then obtaining the real-time current of the flat steel to be detected according to the resistance value and the real-time voltage of the flat steel to be detected. The direct current measuring method can effectively measure the direct current data of the neutral point of the power transformer, thereby effectively monitoring the direct current data of the neutral point of the power transformer.
In an embodiment, in the direct current measurement method, the step S100 of obtaining the line end voltage of the flat steel to be measured to obtain the first voltage value may specifically be: and acquiring the voltage of the line end of the flat steel to be detected through a voltage collector to obtain a first voltage value. The voltage collector here may be a voltmeter.
Meanwhile, in step S300 and step S500, a second voltage value and a third voltage value may also be acquired by the voltage collector.
In one embodiment, the current value of the constant current may be detected when the above steps are performed. At this time, before step S300, the method may further include:
and S700, acquiring the current value of the constant current.
The current value I of the constant current led into the flat steel to be detected is obtained by detecting the constant current led into the flat steel to be detected0。
At this time, step S400 includes:
and calculating the resistance value of the flat steel to be detected according to the first voltage value, the second voltage value and the current value.
Specifically, the process of calculating the resistance value of the flat steel to be measured according to the first voltage value, the second voltage value, and the current value may be:
obtaining a first voltage value UXAnd a second voltage value U'XVoltage difference value UX-U′X。
After obtaining the voltage difference value of the first voltage value and the second voltage value, calculating the voltage difference value UX-U′XAnd current value I0The ratio of (A) to (B) is the resistance value R of the flat steel to be measuredX。
From this, the resistance value of the flat steel to be measured is RX＝(UX-U′X)/I0。
Further, step S600 includes:
and calculating the ratio of the third voltage value to the resistance value according to the third voltage value and the resistance value, namely the real-time current.
Specifically, the third voltage value U is a real-time voltage of the line end voltage of the flat steel to be measured. At this time, according to the formula
The real-time current I of the flat steel to be measured can be obtained.
It should be noted that, in the above steps, the resistance value R of the flat steel to be testedXThe measuring method comprises the following steps: according to the first voltage value UXAnd a second voltage value U'XObtain a voltage difference value UX-U′XAnd according to the voltage difference UX-U′XAnd current value I0The specific value of the resistance value R of the flat steel to be measured is obtainedX＝(UX-U′X)/I0. In this step, the resistance value of the flat steel to be measured may have an error, and therefore, the resistance value of the flat steel to be measured may be measured for a plurality of times, for example, for more than ten times, and the resistance value of the flat steel to be measured may be obtained by taking the arithmetic average value of the maximum value and the minimum value after the maximum value and the minimum value are removed.
In an embodiment, after the step S600, the method may further include:
and S810, acquiring the time corresponding to the third voltage value, and acquiring the position of the power transformer corresponding to the flat steel to be measured.
The time of day can be obtained by setting a clock. The time corresponding to the third voltage value is the time point corresponding to the dc current measurement method, which is obtained while step S500 is executed. The position of the power transformer corresponding to the flat steel to be measured can be obtained by arranging a positioner such as a Global Positioning System (GPS).
And S820, sending the real-time current, the time corresponding to the third voltage value and the position of the power transformer.
And calculating to obtain the real-time current according to the step S600, and after obtaining the time corresponding to the third voltage value and the position of the power transformer according to the step S810, sending the real-time current, the time corresponding to the third voltage value and the position of the power transformer to an upper computer, and monitoring and recording by the upper computer.
The present application also provides a dc current measuring device 10, which is based on the dc current measuring method in any of the above embodiments. As shown in fig. 2, the dc current measuring apparatus 10 includes: a voltage collector 110, a constant current source 120, a controller 130 and an operating power source 140.
Specifically, the voltage collector 110 may be a voltmeter. The voltage harvester 110 has a first clamp 112 and a second clamp 114. The first clamp 112 and the second clamp 114 are used for connecting with two ends of the flat steel 20 to be measured, so as to obtain the line end voltage of the two ends of the flat steel 20 to be measured. Based on the direct current measurement method in the foregoing embodiment, it can be known that the line end voltage of the flat steel 20 to be measured includes the first voltage value, the second voltage value, and the third voltage value. Wherein, the first voltage is the circuit end voltage when the constant current is introduced into the flat steel 20 to be detected; the second voltage value is the line end voltage when the constant current is not introduced into the flat steel 20 to be tested; the third voltage value is the line end voltage at any time except the measuring time of the first voltage value and the second voltage value.
The constant current source 120 is a power source whose output current is constant, and in a circuit in which the constant current source 120 is located, the line end current is constant and the line end voltage is increased as the resistance in the circuit increases. When the constant current power supply 120 works, the constant current power supply is connected with two ends of the flat steel 20 to be tested and is used for introducing a constant current into the flat steel 20 to be tested.
The controller 130 is connected to the voltage collector 110 for obtaining the line end voltage. In other words, the voltage collector 110 collects the end-of-line voltage and transmits the end-of-line voltage to the controller 130. After the controller 130 obtains the line end voltage including the first voltage value, the second voltage value, and the third voltage value, the resistance value of the flat steel 20 to be measured may be calculated according to the first voltage value, the second voltage value, and the constant current. The current value of the constant current may be stored in the controller 130 in advance. After the controller 130 calculates the resistance value of the flat steel 20 to be measured, the real-time current of the flat steel 20 to be measured can be calculated according to the third voltage value and the resistance value.
The operation power source 140 is connected to the voltage collector 110 and the controller 130, and is used for supplying power to the voltage collector 110 and the controller 130, so that the voltage collector 110 and the controller 130 can be electrically operated. Generally, the output voltage of the operating power supply 140 should be the rated voltage of the voltage harvester 110 and the controller 130. The output current of the operating power supply 140 may be the rated current of the voltage harvester 110 and the controller 130.
More specifically, when the dc current measuring device 10 is in operation, the operating power supply 140 supplies power to the voltage collector 110 and the controller 130. The constant current power supply 120 supplies power to the flat steel 20 to be measured. When the constant current power supply 120 supplies power to the flat steel 20 to be tested, the voltage collector 110 collects the line end voltage at the two ends of the flat steel 20 to be tested to obtain a first voltage value UX(ii) a Subsequently, the constant current power supply 120 stops supplying power to the flat steel 20 to be measured. The voltage collector 110 collects the line end voltages at the two ends of the flat steel 20 to be tested to obtain a second voltage value U'X. The controller 130 stores a constant current value I0At this time, the controller 130 can calculate that the resistance value of the flat steel 20 to be measured is RX＝(UX-U′X)/I0. Then according toThe controller 130 can obtain the real-time current of the flat steel 20 to be measured.
The dc current measuring device 10 includes a voltage collector 110, a constant current source 120, a controller 130, and a working power source 140. The constant current source 120 may supply a constant current to the flat steel 20 to be tested. The voltage collector 110 is used for collecting the voltage change of the flat steel 20 to be measured before and after the constant current is introduced. The controller 130 may obtain the resistance value of the flat steel 20 to be measured according to the voltage change of the flat steel 20 to be measured before and after the constant current is applied, and obtain the real-time current of the flat steel 20 to be measured according to the resistance value and the real-time voltage of the flat steel 20 to be measured. The dc current measuring device 10 can effectively measure the dc current data of the neutral point of the power transformer, thereby effectively monitoring the dc current data of the neutral point of the power transformer.
In one embodiment, the current value of the constant current may be preset in the controller 130, or may be detected when the dc current measuring device is operated. When the current value of the constant current is detected when the direct current measuring device is in operation, as shown in fig. 3, the direct current measuring device 10 further includes a current collecting assembly 150.
Specifically, the current collecting assembly 150 is operatively connected between the constant current source 120 and the flat steel 20 to be detected, and is configured to detect a current value of the constant current. The current collection assembly 150 may include a shunt 152 and a current collector 154. The shunt 152 is connected between the constant current power supply 120 and the flat steel 20 to be tested during operation, and is used for shunting. The shunt 152 may be a 100 milliohm shunt 152. The current collector 154 is connected in parallel to the shunt 152, and detects a current value of the constant current. The current collector 154 may be an ammeter.
The current collector 154 is connected to the controller 130 so that the current value of the constant current can be transmitted to the controller 130 after the current value of the constant current is obtained. The current collector 154 is also connected to the operating power supply 140 so that the operating power supply 140 can supply power to the current collector 154.
In one embodiment, as shown in fig. 4, the dc current measuring device may further include a clock 162, a locator 164, and a first communicator 166 respectively connected to the controller 130.
Specifically, the clock 162 is used for recording the time, especially for recording the time corresponding to the third voltage value. The time corresponding to the third voltage value is the time when the voltage collector 110 of the direct current measuring device collects the third voltage value. The clock 162 may be connected to the controller 130 to transmit the time corresponding to the third voltage value to the controller 130.
The positioner 164 is used to obtain the position of the power transformer corresponding to the flat steel 20 to be tested. The positioner 164 is connected to the controller 130 to transmit the position of the power transformer corresponding to the flat bar 20 to be tested to the controller 130. The locator 164 may be a GPS.
The first communicator 166 is connected to the controller 130 for transmitting signals. After the controller 130 obtains the time and the position of the power transformer corresponding to the real-time current and the third voltage value, the time and the position of the power transformer corresponding to the real-time current and the third voltage value can be transmitted to the first communicator 166. At this time, the first communicator 166 is responsible for information transmission, and transmits the real-time current, the time corresponding to the third voltage value, and the position of the power transformer.
As the clock 162, the locator 164 and the first communicator 166 need to be powered on, they can also be connected to the working power supply 140 so that the working power supply 140 can supply power to the clock 162, the locator 164 and the first communicator 166.
In one embodiment, the ac input voltage of the working power supply 140 is 85V to 246V, and a short-circuit protection circuit, an overload protection circuit, and an overvoltage protection circuit are disposed therein. The output channels of the working power supply 140 may include three channels of 5V/4A, 12V/2A and-12V/0.5A to supply power to other devices.
In an embodiment, the voltage collector 110 may convert the electrical signal of the collected line end voltage into a digital signal, so as to eliminate power frequency and higher harmonics in the measurement signal, and perform program-controlled amplification on a weak dc signal, thereby improving the detection accuracy and stability of the dc current measurement apparatus.
In one embodiment, the splitter 152 may be a 0.05 stage splitter 152. Meanwhile, the current collector 154 may also perform analog-to-digital conversion, thereby improving the detection accuracy and stability of the dc current measuring device.
The dc current measuring device 10 of the present application further has the following advantages: the structure is simple, and no external power supply is needed during working; the detachability is strong, and the power transformer can be flexibly disassembled and assembled without power failure and changing the operation mode; the measurement precision is high; the stability is strong, and the interference of external strong electric field and strong magnetic field is avoided; a channel for an oscilloscope or other acquisition device to quickly acquire and analyze data can be provided.
The application also provides a direct current measuring system. The dc current measuring system may comprise the dc current measuring device 10 of any of the above embodiments.
Specifically, the dc current measuring device 10 includes a voltage collector 110, a constant current source 120, a controller 130, and an operating power supply 140. The voltage collector 110 has a first clamp 112 and a second clamp 114, and the first clamp 112 and the second clamp 114 are used for being connected to two ends of the flat steel 20 to be measured to obtain the end-of-line voltage of the flat steel 20 to be measured. The line end voltage comprises a first voltage value, a second voltage value and a third voltage value. The constant current power supply 120 is used for connecting with two ends of the flat steel 20 to be tested so as to supply a constant current into the flat steel 20 to be tested. The controller 130 is connected with the voltage collector 110 and is configured to obtain a line end voltage, and calculate a resistance value of the flat steel 20 to be measured according to the first voltage value, the second voltage value, and the constant current; and calculating the real-time current of the flat steel 20 to be measured according to the third voltage value and the resistance value. The operating power supply 140 is connected to the voltage collector 110 and the controller 130 to supply power to the voltage collector 110 and the controller 130.
Further, the direct current measuring system can also comprise an upper computer.
Specifically, the upper computer may have a second communicator, and the second communicator is configured to be in communication with the first communicator 166, so as to obtain the time corresponding to the real-time current and the third voltage value and the position of the power transformer.
The direct current measuring system can monitor direct current data of the neutral point of the power transformer remotely through the upper computer, so that the direct current data of the neutral point of the power transformer can be effectively monitored.
The operation of the dc current measuring system of the present application will be described with reference to fig. 1 and 4, from a specific embodiment. The direct current measuring system comprises a direct current measuring device and an upper computer shown in fig. 4. The direct current measuring device includes a voltage collector 110, a constant current source 120, a controller 130, a working power source 140, a current collecting component 150, a clock 162, a locator 164, and a first communicator 166. The host computer (not shown) may have a second communicator and a processor, display.
When the dc current measuring system operates, the constant current power supply 120 operates to output a constant current. The constant current flows into the flat steel 20 to be measured through the shunt 152 of the current collection assembly 150, and then flows back to the constant current power supply 120. At this time, the voltage collector 110 collects the line end voltage of the flat steel 20 to be measured to obtain a first voltage value UXAnd transmitted to the controller 130; meanwhile, the current collector 154 may collect the current value I of the constant current through the shunt 1520And transmitted to the controller 130. Obtain a first voltage value UXSum current value I0Then, stopping the constant current and obtaining the path of the flat steel 20 to be measuredTerminal voltage to obtain a second voltage value U'XAnd transmitted to the controller 130. At this time, the controller 130 calculates the resistance value R of the flat steel 20 to be measuredX＝(UX-U′X)/I0. Here, the controller 130 may repeat the above steps 15 times to obtain the resistance values of the flat bars 20 to be measured, and after the highest and lowest resistance values of 15 flat bars 20 to be measured are removed, the arithmetic mean value of the remaining 13 resistance values is determined as the resistance value of the flat bar 20 to be measured. After the resistance value of the flat steel 20 to be measured is obtained, the voltage collector 110 collects the line end voltage at the two ends of the flat steel 20 to be measured to obtain a third voltage value U, and the third voltage value U is related to time and is the real-time line end voltage of the flat steel 20 to be measured; at the same time, the controller 130 acquires the time of day through the clock 162. At this time, the controller 130 can be according to the formula
And obtaining the real-time current I of the flat steel 20 to be measured.
The controller 130 calculates the real-time current I of the flat bar 20 to be measured, and after acquiring the time corresponding to the third voltage value U through the clock 162, acquires the position of the power transformer corresponding to the flat bar 20 to be measured through the positioner 164, and transmits the time corresponding to the real-time current I and the third voltage value U and the position of the power transformer to the first communicator 166.
The first communicator 166 and the second communicator may be ethernet interfaces, which are communicatively coupled. At this time, the first communicator 166 may transmit the time corresponding to the real-time current I and the third voltage value U and the position of the power transformer to the second communicator, and receive the time and the position from the upper computer. The processor of the upper computer processes the data and then displays the data through the display.
Further, the first communicator 166 and the second communicator may be ethernet interfaces. The ethernet interface may convert serial data output from the controller 130 into TCP/IP packets; meanwhile, the network command sent by the upper computer can be received, analyzed and sent to the controller 130. The Ethernet interface is configured to be a TCP (Transmission control protocol) client working mode, and can normally and rapidly operate in a high-load network environment, so that zero packet loss of TCP Transmission data is realized, and the reliability of the direct current measurement system is improved.
In one embodiment, the first voltage value U of the dc current measuring system is set when the dc current measuring system is in operationXAnd a second voltage value U'XThe detection time can be from two points in the morning to five points in the morning, and the actual resistance of the grounding flat steel is less influenced by the outside in the time period. Measuring a first voltage value UXIn time, the constant current can be applied for 10 seconds before measurement.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A direct current measurement method for detecting a real-time current of a neutral point of a power transformer, the neutral point being connected to a ground line through a ground flat, comprising:
selecting a section of the grounding flat steel as a flat steel to be detected;
introducing a constant current into the flat steel to be detected, and acquiring the line end voltage of the flat steel to be detected to obtain a first voltage value;
stopping introducing the constant current, and obtaining the line end voltage of the flat steel to be detected to obtain a second voltage value;
calculating the resistance value of the flat steel to be detected according to the first voltage value, the second voltage value and the constant current;
acquiring the real-time voltage of the flat steel to be detected to obtain a third voltage value;
and calculating the real-time current according to the third voltage value and the resistance value.
2. The direct current measurement method according to claim 1, wherein the obtaining of the line end voltage of the flat steel to be measured to obtain a first voltage value comprises:
and acquiring the voltage of the circuit end of the flat steel to be detected through a voltage collector to obtain a first voltage value.
3. The method of measuring direct current according to claim 1, further comprising, before stopping the flowing of the constant current:
acquiring the current value of the constant current;
the step of calculating the resistance value of the flat steel to be tested according to the first voltage value, the second voltage value and the constant current comprises the following steps:
and calculating the resistance value of the flat steel to be detected according to the first voltage value, the second voltage value and the current value.
4. The direct current measurement method according to claim 3, wherein the calculating of the resistance value of the flat steel to be measured from the first voltage value, the second voltage value and the current value comprises:
acquiring a voltage difference value of the first voltage value and the second voltage value;
and calculating the ratio of the voltage difference value to the current value according to the voltage difference value, namely the resistance value of the flat steel to be detected.
5. The method of measuring direct current according to claim 1, wherein calculating the real-time current from the third voltage value and the resistance value comprises:
and calculating the ratio of the third voltage value to the resistance value according to the third voltage value and the resistance value, namely the real-time current.
6. The method of measuring direct current according to claim 1, wherein after calculating the real-time current according to the third voltage value and the resistance value, further comprising:
acquiring the time corresponding to the third voltage value, and acquiring the position of the power transformer corresponding to the flat steel to be tested;
and sending the real-time current, the time corresponding to the third voltage value and the position of the power transformer.
7. A direct current measuring apparatus according to any one of claims 1 to 6, comprising:
the voltage collector (110) is provided with a first clamp (112) and a second clamp (114), the first clamp (112) and the second clamp (114) are used for being connected with two ends of the flat steel (20) to be detected so as to obtain the end-of-circuit voltage of the flat steel (20) to be detected, and the end-of-circuit voltage comprises a first voltage value, a second voltage value and a third voltage value;
the constant current power supply (120) is used for being connected with two ends of the flat steel (20) to be tested so as to supply constant current into the flat steel (20) to be tested;
the controller (130) is connected with the voltage collector (110) to obtain the end-of-line voltage, and calculates the resistance value of the flat steel (20) to be tested according to the first voltage value, the second voltage value and the constant current; calculating the real-time current of the flat steel (20) to be detected according to the third voltage value and the resistance value;
and the working power supply (140) is connected with the voltage collector (110) and the controller (130) to supply power to the voltage collector (110) and the controller (130).
8. The direct current measurement device according to claim 7, further comprising:
the current acquisition assembly (150) is connected between the constant current power supply (120) and the flat steel (20) to be detected so as to detect the current value of the constant current; the current collecting assembly (150) comprises a current divider (152) and a current collector (154), the current divider (152) is used for being connected between the constant current power supply (120) and the flat steel (20) to be detected, and the current collector (154) is connected with the current divider (152) in parallel so as to detect the current value of the constant current;
the current collector (154) is connected with the controller (130) to transmit the current value of the constant current to the controller (130); the current collector (154) is also connected with the working power supply (140) so that the working power supply (140) supplies power to the current collector (154).
9. The direct current measurement device according to claim 7, further comprising:
the clock (162) is used for recording the time corresponding to the third voltage value, and the clock (162) is connected with the controller (130) so as to transmit the time corresponding to the third voltage value to the controller (130);
the positioner (164) is used for acquiring the position of the power transformer corresponding to the flat steel (20) to be tested, and the positioner (164) is connected with the controller (130) so as to transmit the position of the power transformer corresponding to the flat steel (20) to be tested to the controller (130);
and the first communicator (166) is connected with the controller (130) to acquire and transmit the real-time current transmitted by the controller (130), the time corresponding to the third voltage value and the position of the power transformer.
10. A direct current measuring system comprising a direct current measuring device (10) according to any of claims 7 to 9.
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| CN201910987854.6A CN110824226A (en) | 2019-10-17 | 2019-10-17 | Direct current measuring method, device and system |
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| CN201910987854.6A CN110824226A (en) | 2019-10-17 | 2019-10-17 | Direct current measuring method, device and system |
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Application publication date: 20200221 |