CN110632452A - Flexible direct-current power grid ground insulation fault detection method and computer equipment - Google Patents
Flexible direct-current power grid ground insulation fault detection method and computer equipment Download PDFInfo
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- CN110632452A CN110632452A CN201910818969.2A CN201910818969A CN110632452A CN 110632452 A CN110632452 A CN 110632452A CN 201910818969 A CN201910818969 A CN 201910818969A CN 110632452 A CN110632452 A CN 110632452A
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- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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Abstract
The application provides a method for detecting insulation faults of a flexible direct current power grid to the ground and computer equipment. According to the detection method, the difference value between the common-mode voltage direct-current component amplitude of the bus at the first moment and the common-mode voltage direct-current component amplitude of the bus at the second moment is obtained and used as the voltage reference. And obtaining a difference value between the third harmonic common-mode current vector amplitude of the power supply branch circuit at the first moment and the third harmonic common-mode current vector amplitude of the power supply branch circuit at the second moment, and using the difference value as a first current reference quantity. And judging whether the voltage reference quantity is larger than or equal to an overvoltage threshold value or not. And judging whether the first current reference quantity is smaller than an overcurrent threshold value or not, and further judging whether the power supply branch circuit has an insulation fault to the ground or not. According to the method and the device, the grounding fault branch is diagnosed by utilizing the direct-current voltage bias and the third harmonic common-mode current of each branch, so that the short-time power failure of other branches caused by the fact that each branch is disconnected one by one to search for the fault branch is avoided, and the reliability of a direct-current power grid is improved.
Description
Technical Field
The application relates to the field of power systems, in particular to a method for detecting insulation faults of a flexible direct-current power grid to the ground and computer equipment.
Background
If the AC side of the flexible DC power distribution system adopts high-resistance grounding, the DC side does not need other grounding measures, and if a point of grounding fault occurs on the DC side, DC voltage bias can occur on the DC side, but short-circuit current is very small. The flexible direct current power distribution system may cause great potential safety hazards due to insulation damage, and electrical safety accidents such as electric shock and fire are caused, so an insulation monitoring method is often adopted for prevention.
In order to improve the reliability and accuracy of insulation detection of a direct-current power distribution and utilization system, the traditional method generally adopts the way-by-way disconnection of each branch circuit to search for a grounding branch circuit, and the searching method can cause short-time power failure of the branch circuit trying to be pulled and reduce the reliability of the operation of a direct-current power grid.
Disclosure of Invention
On the basis, it is necessary to provide a flexible dc power grid ground insulation fault detection method and computer equipment for solving the problems of low reliability of dc power grid operation, such as the conventional method of disconnecting each branch circuit one by one to search for a ground branch circuit.
A method for detecting insulation fault of a flexible direct current power grid to the ground, wherein the flexible direct current power grid comprises a bus and a power supply branch circuit electrically connected with the bus, and the detection method comprises the following steps:
s100, acquiring a difference value between a common-mode voltage direct-current component amplitude value at a first moment and a common-mode voltage direct-current component amplitude value at a second moment of the bus as a voltage reference, and acquiring a difference value between a third harmonic common-mode current vector amplitude value at the first moment of the power supply branch circuit and a third harmonic common-mode current vector amplitude value at the second moment of the power supply branch circuit as a first current reference;
s200, judging whether the voltage reference quantity is larger than or equal to an overvoltage threshold value or not;
s300, when the voltage reference is larger than or equal to the overvoltage threshold, judging whether the first current reference is smaller than an overcurrent threshold;
and S400, when the first current reference is smaller than the overcurrent threshold, the power supply branch circuit has an insulation fault to the ground.
In one embodiment, the flexible dc power grid further includes a plurality of load branches electrically connected to the bus bars, respectively, and the detection method further includes:
when the first current reference is larger than or equal to the overcurrent threshold, the insulation fault to the ground occurs in the plurality of load branches.
In one embodiment, the step of generating an insulation to ground fault for the plurality of load branches when the first current reference is greater than or equal to the overcurrent threshold comprises:
obtaining a difference value between the third harmonic common-mode current vector amplitude of each load branch circuit at the first moment and the third harmonic common-mode current vector amplitude of each load branch circuit at the second moment, and taking the difference value as a second current reference quantity;
comparing and obtaining the maximum value of the second current reference quantity of each load branch;
and the load branch corresponding to the maximum value has insulation fault to the ground.
In one embodiment, the detection method further includes:
and when the power supply branch circuit has an insulation fault to the ground or the load branch circuit corresponding to the maximum value has an insulation fault to the ground, sending a circuit breaking signal to the fault branch circuit to break the fault branch circuit.
In one embodiment, the step of obtaining the common mode voltage dc component amplitude of the bus bar includes:
respectively acquiring the voltage of a bus anode and the voltage of a bus cathode in real time;
obtaining a bus common-mode voltage instantaneous data set according to the bus positive voltage and the bus negative voltage which are obtained in real time;
and decomposing the bus common-mode voltage instantaneous data set by utilizing Fourier transform to obtain the common-mode voltage direct-current component amplitude at any moment.
In one embodiment, the step of obtaining the third harmonic common mode current vector magnitude of the power branch includes:
respectively acquiring the positive current and the negative current of a power supply branch in real time;
obtaining a power branch common-mode current instantaneous data set according to the power branch positive current and the power branch negative current which are obtained in real time;
and decomposing the power supply branch common-mode current instantaneous data set by utilizing Fourier transform to obtain the third harmonic common-mode current vector amplitude at any moment.
In one embodiment, when the magnitude of the common mode voltage direct current component is smaller than the overvoltage threshold value, the flexible direct current power grid has no insulation fault to the ground.
In one embodiment, the overvoltage threshold is a product of a voltage reliability factor and a voltage between electrodes.
In one embodiment, the voltage reliability factor ranges from 0 to 0.5.
In one embodiment, the overcurrent threshold is 1% of the rated current of the power branch.
A computer device, comprising:
a processor;
a memory for storing the processor-executable instructions;
the processor is configured to:
obtaining a difference value between a common-mode voltage direct-current component amplitude value at a first moment of the bus and a common-mode voltage direct-current component amplitude value at a second moment of the bus as a voltage reference, and obtaining a difference value between a third harmonic common-mode current vector amplitude value at the first moment of the power supply branch and a third harmonic common-mode current vector amplitude value at the second moment of the power supply branch as a first current reference;
judging whether the voltage reference quantity is larger than or equal to an overvoltage threshold value;
when the voltage reference is greater than or equal to the overvoltage threshold, judging whether the first current reference is smaller than an overcurrent threshold;
when the first current reference quantity is smaller than the overcurrent threshold value, the power supply branch circuit has insulation fault to the ground.
According to the method for detecting the ground insulation fault of the flexible direct current power grid, the difference value between the common mode voltage direct current component amplitude of the bus at the first moment and the common mode voltage direct current component amplitude of the bus at the second moment is obtained and used as the voltage reference. And obtaining a difference value between the third harmonic common-mode current vector amplitude of the power supply branch circuit at the first moment and the third harmonic common-mode current vector amplitude of the power supply branch circuit at the second moment, and using the difference value as a first current reference quantity. And judging whether the voltage reference quantity is larger than or equal to an overvoltage threshold value or not. When the voltage reference is greater than or equal to the overvoltage threshold, determining whether the first current reference is less than an overcurrent threshold. When the first current reference quantity is smaller than the overcurrent threshold value, the power supply branch circuit has insulation fault to the ground. According to the method and the device, the grounding fault branch is diagnosed by utilizing the direct-current voltage bias and the third harmonic common-mode current of each branch, so that the short-time power failure of other branches caused by the fact that each branch is disconnected one by one to search for the fault branch is avoided, and the reliability of a direct-current power grid is improved.
Drawings
Fig. 1 is a structural diagram of a ground insulation fault detection device of a flexible direct current power grid according to an embodiment of the present application;
fig. 2 is a structural diagram of a ground insulation fault detection device of a flexible direct current power grid according to an embodiment of the present application;
fig. 3 is a structural diagram of a ground insulation fault detection device of a flexible direct current power grid according to an embodiment of the present application;
fig. 4 is a structural diagram of a ground insulation fault detection device of a flexible direct current power grid according to an embodiment of the present application;
fig. 5 is a flowchart of a method for detecting insulation fault to ground of a flexible dc power grid according to an embodiment of the present application;
fig. 6 is an installation schematic diagram of a detection device in a method for detecting an insulation fault to ground of a flexible direct current power grid according to an embodiment of the present application;
fig. 7 is a logic block diagram for performing fault protection in a method for detecting an insulation fault to ground of a flexible dc power grid according to an embodiment of the present application;
fig. 8 is a schematic structural diagram of a computer device according to an embodiment of the present application.
Reference numerals for the main figure elements
Flexible direct current power grid ground insulation fault detection device 10
Parameter detecting element 100
First current detecting unit 120
Second current detecting unit 130
Relay protection element 200
Analog quantity acquisition unit 210
First processing module 221
Second processing module 222
Third processing module 223
Computer device 20
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clearly apparent, a dc power distribution system and a ground insulation fault detection method thereof according to the present application are further described in detail by embodiments and with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Referring to fig. 1, in one embodiment of the present application, a flexible dc power grid ground insulation fault detection apparatus 10 is provided, where the flexible dc power grid includes a bus bar and a plurality of branches electrically connected to the bus bar. The detection device 10 includes a parameter detection element 100 and a relay protection element 200.
The parameter detecting element 100 is electrically connected to the positive bus, the negative bus, the positive branch and the negative branch respectively. The parameter detecting element 100 is used for detecting the bus positive voltage, the bus negative voltage, the branch positive current and the branch negative current. Alternatively, the parameter sensing element 100 may be a voltage sensor and a current sensor. The voltage sensor and the current sensor are arranged in each branch in the flexible direct current power grid.
The relay protection device 200 is electrically connected to the parameter detection device 100. The relay protection element 200 is configured to obtain the bus positive voltage, the bus negative voltage, the branch positive current, and the branch negative current. The relay protection element 200 is further configured to obtain a common-mode voltage dc component amplitude of the bus according to the bus positive voltage, the bus negative voltage, the branch positive current, and the branch negative current, and obtain a third harmonic common-mode current vector amplitude of each branch, thereby determining whether any one of the branches has an insulation fault to ground. For example, at a certain time, the bus positive voltage obtained by the relay protection element 200 is upThe negative voltage of the bus is unThen the bus common mode voltage at this time is (u)p+un)/2. Common mode voltage direct current component U of bus can be obtained through continuous sampling and Fourier algorithmcom0The absolute value is obtained to obtain the amplitude value | U of the common-mode voltage DC componentcom0L. The positive current i of each direct current branch acquired by the relay protection element 200ipNegative electrode current iinThen the common mode current of the branch circuit at this time is iip+iin. The third harmonic of each branch can be obtained by continuous sampling and Fourier algorithmCommon mode current vector
The absolute value of the common mode current vector is obtained to obtain the third harmonic common mode current vector amplitude value | U of each branch circuitcom0|。
In this embodiment, the apparatus detects dc voltage bias by using the parameter detection element 100, detects triple harmonic common mode current of each branch, and diagnoses the ground fault branch by using the relay protection element 200, thereby avoiding short-term power failure of other branches caused by disconnecting each branch one by one to search for a faulty branch, and improving reliability of the dc power grid.
Referring to fig. 2, in one embodiment, the flexible dc power grid includes a plurality of branches. The branch circuit comprises a power supply branch circuit and a plurality of load branch circuits. The parameter sensing element 100 includes a voltage sensing unit 110 and two first current sensing units 120 and a plurality of second current sensing units 130.
The primary side of the voltage detection unit 110 is electrically connected to the positive bus and the negative bus respectively, and is configured to obtain a positive bus voltage and a negative bus voltage. The primary side of one of the first current detecting units 120 is electrically connected to the positive electrode of the power branch for obtaining the current of the positive electrode of the power branch. The primary side of the other first current detecting unit 120 is electrically connected to the negative electrode of the power supply branch for obtaining the negative current of the power supply branch. The primary side of each second current detection unit 130 is electrically connected to the positive electrode or the negative electrode of the load branch, and is configured to obtain the positive current or the negative current of the load branch in real time.
The voltage detection unit 110 may be a voltage sensor. The first current detecting unit 120 may be a current sensor. The number of the first current detection units 120 is not limited to two. The number of the first current detecting units 120 may be determined according to the number of the power branches, as long as the first current detecting units 120 can detect the positive and negative currents of the power branches. One end of the primary side of the voltage detection unit 110 is further connected to the ground terminal. The secondary side of the voltage detection unit 110 and the secondary side of the first current detection unit 120 are electrically connected to the relay protection element 200, and are configured to send voltage and current information to the relay protection element 200.
Referring to fig. 3, in one embodiment, the relay protection element 200 includes an analog quantity acquisition unit 210, a processing unit 220, and a threshold storage unit 240.
The analog quantity acquisition unit 210 is electrically connected to the secondary sides of the voltage detection units 110, the two primary current detection units 120, and the multiple secondary current detection units 130, respectively. The analog quantity acquisition unit 210 is used for acquiring the bus positive voltage, the bus negative voltage, the power branch positive current, the power branch negative current, each load branch positive current and each load branch negative current. The analog quantity collecting unit 210 may adopt an RS485 communication network to transmit analog quantities of scattered field data points to the processing unit 220 through AD conversion. The analog acquisition unit 210 may have a unique dual watchdog security design. The analog quantity acquisition unit 210 may be a DATA-7215 analog quantity acquisition module. The DATA-7215 analog quantity acquisition module has multiple functions of measurement DATA acquisition, equipment on-off state acquisition, external logic control and the like, is mainly used as DATA acquisition, control and display equipment of various measurement and control terminals, and is suitable for automation and informatization systems of various industries. The analog quantity acquisition unit 210 can acquire the voltage and current information acquired by the parameter detection element in real time, and transmit the voltage and current information to the processing unit 220 through AD conversion.
The processing unit 220 is electrically connected to the analog quantity acquisition unit 210. The processing unit 220 is configured to obtain a common-mode voltage dc component amplitude of the bus according to the bus positive-pole voltage, the bus negative-pole voltage, the power branch positive-pole current, the power branch negative-pole current, each load branch positive-pole current, and each load branch negative-pole current, and obtain a third harmonic common-mode current vector amplitude of the power branch and each load branch, and further determine whether any one of the branches has an earth insulation fault. The processing unit 220 may be a single chip, a microprocessor, or the like.
The threshold storage unit 240 is used to store an overvoltage threshold and an overcurrent threshold. The overvoltage threshold is the product of a voltage reliability coefficient and an inter-electrode voltage. The value range of the voltage reliability coefficient is 0 to 0.5. The overcurrent threshold is 1% of the rated current of the power supply branch.
In an alternative embodiment, the processing unit 220 includes a first processing module 221, a second processing module 222, and a third processing module 223.
The first processing module 221 is electrically connected to the analog quantity acquisition unit 210. The first processing module 221 is configured to obtain a bus common-mode voltage instantaneous data set according to the bus positive voltage and the bus negative voltage obtained in real time, and decompose the bus common-mode voltage instantaneous data set by using fourier transform to obtain a common-mode voltage direct-current component amplitude at any time. The first processing module 221 may further be configured to determine whether the magnitude of the common mode voltage dc component is greater than or equal to an overvoltage threshold. The overvoltage threshold is the product of a voltage reliability coefficient and an inter-electrode voltage. The value range of the voltage reliability coefficient is 0 to 0.5. And when the amplitude of the common-mode voltage direct-current component is larger than or equal to an overvoltage threshold value, considering that the ground insulation fault occurs in the flexible direct-current power grid. The first processing module 221 sends an operation instruction to the second processing module 222.
The second processing module 222 is electrically connected to the analog quantity acquisition unit 210. After the second processing module 222 receives the operation instruction, the second processing module 222 is configured to obtain a power branch common-mode current instantaneous data set according to the power branch positive current and the power branch negative current obtained in real time, and decompose the power branch common-mode current instantaneous data set by using fourier transform to obtain a third harmonic common-mode current vector amplitude at any time. The second processing module 222 is further configured to determine whether the third harmonic common mode current vector magnitude of the power branch is smaller than an overcurrent threshold, so as to determine whether a ground insulation fault occurs in the power branch. The overcurrent threshold is 1% of the rated current of the power supply branch. And when the third harmonic common mode current vector magnitude of the power supply branch is smaller than an overcurrent threshold, considering that the ground insulation fault occurs in the power supply branch. The second processing module 222 will send a trip command. When the third harmonic common mode current vector magnitude of the power branch is greater than or equal to the overcurrent threshold, the second processing module 222 sends an operation instruction to the third processing module 223.
The third processing module 223 is electrically connected to the analog quantity acquisition unit 210. After the third processing module 223 receives the operation instruction, the third processing module 223 is configured to obtain a load branch common-mode current instantaneous data set according to the load branch positive current and the load branch negative current obtained in real time, and decompose the load branch common-mode current instantaneous data set by using fourier transform to obtain a third harmonic common-mode current vector amplitude at any moment. The third processing module 223 is further configured to compare and obtain a maximum value of the third harmonic common mode current vector magnitude of each of the load branches. And the load branch corresponding to the maximum value has insulation fault to the ground. After that, the third processing module 223 will send a disconnection command. The processing unit 220 can detect ground insulation faults by matching with other elements, and timely opens a fault branch to ensure safe and reliable operation of the flexible direct-current power grid.
Referring to fig. 4, in another alternative embodiment, the processing unit 220 includes a fourth processing module 224, a fifth processing module 225 and a sixth processing module 226.
The fourth processing module 224 is electrically connected to the analog quantity acquisition unit 210. The fourth processing module 224 is configured to obtain a bus common mode voltage instantaneous data set according to the bus positive voltage and the bus negative voltage obtained in real time, and decompose the bus common mode voltage instantaneous data set by using fourier transform to obtain a common mode voltage direct-current component amplitude at any time. The fourth processing module 224 is further configured to determine whether a difference between the common mode voltage dc component amplitude at the first time and the common mode voltage dc component amplitude at the second time is greater than or equal to an overvoltage threshold. The overvoltage threshold is the product of a voltage reliability coefficient and an inter-electrode voltage. The value range of the voltage reliability coefficient is 0 to 0.5. And when the difference value between the common-mode voltage direct-current component amplitude at the first moment and the common-mode voltage direct-current component amplitude at the second moment is larger than or equal to an overvoltage threshold value, considering that the ground insulation fault occurs in the flexible direct-current power grid. The fourth processing module 224 sends an operation instruction to the fifth processing module 225.
The fifth processing module 225 is electrically connected to the analog quantity acquisition unit 210. The fifth processing module 225 is configured to obtain a power branch common-mode current instantaneous data set according to the power branch positive current and the power branch negative current obtained in real time, and decompose the power branch common-mode current instantaneous data set by using fourier transform to obtain a third harmonic common-mode current vector amplitude at any time. The fifth processing module 225 is further configured to determine whether a difference between a third harmonic common mode current vector magnitude at the first time of the power supply branch and a third harmonic common mode current vector magnitude at the second time of the power supply branch is smaller than an overcurrent threshold, so as to determine whether a ground insulation fault occurs in the power supply branch. The overcurrent threshold is 1% of the rated current of the power supply branch. And when the difference value between the third harmonic common-mode current vector amplitude at the first moment and the third harmonic common-mode current vector amplitude at the second moment of the power supply branch circuit is smaller than an overcurrent threshold, considering that an insulation fault to the ground occurs in the power supply branch circuit. The fifth processing module 225 will send a trip instruction. When the difference between the third harmonic common mode current vector magnitude at the first time and the third harmonic common mode current vector magnitude at the second time of the power supply branch is greater than or equal to the overcurrent threshold, the fifth processing module 225 sends an operation instruction to the sixth processing module 226.
The sixth processing module 226 is electrically connected to the analog quantity acquisition unit 210. After the sixth processing module 226 receives the operation instruction, the sixth processing module 226 is configured to obtain a load branch common-mode current instantaneous data set according to the load branch positive current and the load branch negative current obtained in real time, and decompose the load branch common-mode current instantaneous data set by using fourier transform to obtain a third harmonic common-mode current vector amplitude at any time. The sixth processing module 226 is further configured to compare and obtain a maximum value of a difference between the third harmonic common mode current vector magnitude of each load branch at the first time and the third harmonic common mode current vector magnitude of each load branch at the second time. And the load branch corresponding to the maximum value has insulation fault to the ground. After that, the sixth processing module 226 will send a disconnection instruction. The processing unit 220 can realize the detection of ground insulation fault by matching with other elements, and can open the fault branch in time to ensure the safe and reliable operation of the flexible direct current power grid
In one embodiment, the relay protection device 200 further includes an execution unit 230.
The execution unit 230 is electrically connected to the processing unit 220. After the execution unit 230 receives the disconnection instruction, the execution unit 230 sends a disconnection signal to the branch with the ground insulation fault, and disconnects the branch with the ground insulation fault. The execution unit 230 may be a circuit breaker provided to each branch circuit. The execution unit 230 can timely cut off the connection between the fault line and the power grid to ensure the safe and reliable operation of the flexible direct current power grid.
The application provides a system for detecting insulation faults of a flexible direct current power grid to the ground in one embodiment. The flexible direct current grid ground insulation fault detection system comprises a plurality of flexible direct current grid ground insulation fault detection devices 10 in any one of the above embodiments, and each flexible direct current grid ground insulation fault detection device 10 is used for detecting a ground insulation fault of one flexible direct current grid.
Referring to fig. 5, in an embodiment of the present application, a method for detecting an insulation fault to ground of a flexible direct current power grid is provided, where the flexible direct current power grid includes a bus and a power branch electrically connected to the bus. The detection method comprises the following steps:
and S100, acquiring a difference value between a common-mode voltage direct-current component amplitude value at a first moment of the bus and a common-mode voltage direct-current component amplitude value at a second moment of the bus as a voltage reference, and acquiring a difference value between a third harmonic common-mode current vector amplitude value at the first moment of the power supply branch and a third harmonic common-mode current vector amplitude value at the second moment of the power supply branch as a first current reference. The method for obtaining the common-mode voltage direct-current component amplitude of the bus can be used for respectively obtaining the bus positive voltage and the bus negative voltage in real time. And obtaining a bus common-mode voltage instantaneous data set according to the bus positive voltage and the bus negative voltage which are obtained in real time. And decomposing the bus common-mode voltage instantaneous data set by utilizing Fourier transform to obtain the common-mode voltage direct-current component amplitude at any moment. The method for obtaining the third harmonic common mode current vector amplitude of the power supply branch circuit can be used for respectively obtaining the positive current and the negative current of the power supply branch circuit in real time. And obtaining a power branch common-mode current instantaneous data set according to the power branch positive current and the power branch negative current which are obtained in real time. And decomposing the power supply branch common-mode current instantaneous data set by utilizing Fourier transform to obtain the third harmonic common-mode current vector amplitude at any moment. The two amplitudes may be obtained by the processing unit 220.
And S200, judging whether the voltage reference quantity is greater than or equal to an overvoltage threshold value. The overvoltage threshold may be a product of a voltage reliability factor and an inter-electrode voltage. The value range of the voltage reliability coefficient is 0 to 0.5. The determination may be made by the processing unit 220. When all direct current branches connected with the bus of the flexible direct current power grid do not have ground faults, common mode direct current bias voltage and third harmonic common mode current do not appear, and bus direct current common mode voltage variation | U obtained through relay protection calculationcom0(t1+m·Δt)-Ucom0(t1) Third harmonic common mode current variation I of I and DC branchicom3(t1+m·Δt)-Iicom3(t1) And both the error values are not larger than the maximum error of measurement, and misjudgment is avoided.
And S300, when the voltage reference is greater than or equal to the overvoltage threshold, judging whether the first current reference is smaller than an overcurrent threshold. The over-current threshold may be 1% of the rated current of the power branch. And when the amplitude of the common-mode voltage direct-current component is smaller than the overvoltage threshold, the flexible direct-current power grid has no insulation fault to the ground.
And S400, when the first current reference is smaller than the overcurrent threshold, the power supply branch circuit has an insulation fault to the ground. When the first current reference is greater than or equal to the overcurrent threshold, the ground insulation fault is considered to occur in the load branch. When a certain direct current branch circuit has a ground fault, a common-mode direct current power supply is connected equivalently to a fault point, direct current common-mode voltage bias occurs on a direct current line, namely the voltage reference is larger than or equal to the overvoltage threshold, third harmonic voltage generated by the AC/DC converter forms a channel, the third harmonic voltage is transmitted to a direct current side, and third harmonic common-mode current occurs on the direct current line. If the fault point occurs in the power supply inlet line branch circuit, each direct current branch circuit cannot detect third harmonic common mode current, the common mode current amplitude obtained by relay protection calculation cannot be larger than the maximum measurement error, namely the first current reference quantity is smaller than the overcurrent threshold value, and at this moment, it can be determined that the power supply inlet line branch circuit has a ground fault.
In this embodiment, a difference between a common mode voltage dc component amplitude at a first time and a common mode voltage dc component amplitude at a second time of the bus is obtained as a voltage reference. And obtaining a difference value between the third harmonic common-mode current vector amplitude of the power supply branch circuit at the first moment and the third harmonic common-mode current vector amplitude of the power supply branch circuit at the second moment, and using the difference value as a first current reference quantity. And judging whether the voltage reference quantity is larger than or equal to an overvoltage threshold value or not. When the voltage reference is greater than or equal to the overvoltage threshold, determining whether the first current reference is less than an overcurrent threshold. When the first current reference quantity is smaller than the overcurrent threshold value, the power supply branch circuit has insulation fault to the ground. According to the method and the device, the grounding fault branch is diagnosed by utilizing the direct-current voltage bias and the third harmonic common-mode current of each branch, so that the short-time power failure of other branches caused by the fact that each branch is disconnected one by one to search for the fault branch is avoided, and the reliability of a direct-current power grid is improved.
In one embodiment, the flexible dc power grid further includes a plurality of load branches electrically connected to the bus bars, respectively. Fig. 6 shows a schematic installation diagram of the detection device in the method for detecting the insulation fault to ground of the flexible direct current power grid. A logic block diagram for fault protection is shown in fig. 7. The detection method further comprises the following steps:
when the first current reference is larger than or equal to the overcurrent threshold, the insulation fault to the ground occurs in the plurality of load branches. In order to detect the load branches with the ground insulation fault, the difference value between the third harmonic common-mode current vector magnitude of each load branch at the first moment and the third harmonic common-mode current vector magnitude of each load branch at the second moment can be obtained and used as the second current reference. And comparing and obtaining the maximum value of the second current reference quantity of each load branch. And the load branch corresponding to the maximum value has insulation fault to the ground. For example, if a fault occurs in another load branch, the load branch and the power branch form a path, and both the load branch and the power branch detect a large third harmonic common mode current. Without loss of generality, a power supply branch is set as a first branch, a jth load branch is grounded, j is more than or equal to 2 and less than or equal to n, and I1com3(t1+m·Δt)-I1com3(t1) I is equal to or more than epsilon, the amplitude of the third harmonic common mode current is approximate to 0 because other branches are not grounded, and therefore the variation of the amplitude of the third harmonic common mode current in the load branch of the j branch is detected to be maximum, namelyTherefore, the grounding fault of the jth load branch can be judged.
And when the power supply branch circuit has an insulation fault to the ground or the load branch circuit corresponding to the maximum value has an insulation fault to the ground, sending a circuit breaking signal to the fault branch circuit to break the fault branch circuit. So as to ensure the safe and reliable operation of the flexible direct current power grid.
Referring to fig. 8, an embodiment of the present application further provides a computer device 20, which includes a memory 21, a processor 22, and a computer program 23 stored on the memory 21 and executable on the processor, where the processor 22 implements the method for detecting insulation fault to ground of the flexible dc power grid when executing the computer program 23.
There is also provided in an embodiment of the present application a computer readable storage medium, on which a computer program is stored, which when executed by a processor, implements the steps of the flexible dc power grid ground insulation fault detection method.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
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 application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A method for detecting insulation fault of a flexible direct current power grid to the ground is characterized in that the flexible direct current power grid comprises a bus and a power supply branch circuit electrically connected with the bus, and the detection method comprises the following steps:
s100, acquiring a difference value between a common-mode voltage direct-current component amplitude value at a first moment and a common-mode voltage direct-current component amplitude value at a second moment of the bus as a voltage reference, and acquiring a difference value between a third harmonic common-mode current vector amplitude value at the first moment of the power supply branch circuit and a third harmonic common-mode current vector amplitude value at the second moment of the power supply branch circuit as a first current reference;
s200, judging whether the voltage reference quantity is larger than or equal to an overvoltage threshold value or not;
s300, when the voltage reference is larger than or equal to the overvoltage threshold, judging whether the first current reference is smaller than an overcurrent threshold;
and S400, when the first current reference is smaller than the overcurrent threshold, the power supply branch circuit has an insulation fault to the ground.
2. The method for detecting the insulation fault to ground of the flexible direct current power grid according to claim 1, wherein the flexible direct current power grid further comprises a plurality of load branches electrically connected with the bus bars respectively, and the method further comprises:
when the first current reference is larger than or equal to the overcurrent threshold, the insulation fault to the ground occurs in the plurality of load branches.
3. The flexible direct current power grid ground insulation fault detection method according to claim 2, wherein when the first current reference is greater than or equal to the overcurrent threshold, then the step of the plurality of load branches generating ground insulation fault is followed by the steps of:
obtaining a difference value between the third harmonic common-mode current vector amplitude of each load branch circuit at the first moment and the third harmonic common-mode current vector amplitude of each load branch circuit at the second moment, and taking the difference value as a second current reference quantity;
comparing and obtaining the maximum value of the second current reference quantity of each load branch;
and the load branch corresponding to the maximum value has insulation fault to the ground.
4. The detection method according to claim 3, characterized in that the detection method further comprises:
and when the power supply branch circuit has an insulation fault to the ground or the load branch circuit corresponding to the maximum value has an insulation fault to the ground, sending a circuit breaking signal to the fault branch circuit to break the fault branch circuit.
5. The method for detecting the insulation fault to ground of the flexible direct current power grid according to claim 1, wherein the step of obtaining the amplitude of the common mode voltage direct current component of the bus comprises:
respectively acquiring the voltage of a bus anode and the voltage of a bus cathode in real time;
obtaining a bus common-mode voltage instantaneous data set according to the bus positive voltage and the bus negative voltage which are obtained in real time;
and decomposing the bus common-mode voltage instantaneous data set by utilizing Fourier transform to obtain the common-mode voltage direct-current component amplitude at any moment.
6. The flexible direct current power grid ground insulation fault detection method according to claim 1, wherein the step of obtaining the third harmonic common mode current vector magnitude of the power branch circuit comprises:
respectively acquiring the positive current and the negative current of a power supply branch in real time;
obtaining a power branch common-mode current instantaneous data set according to the power branch positive current and the power branch negative current which are obtained in real time;
and decomposing the power supply branch common-mode current instantaneous data set by utilizing Fourier transform to obtain the third harmonic common-mode current vector amplitude at any moment.
7. The method for detecting the insulation fault to ground of the flexible direct current power grid according to claim 1, wherein when the amplitude of the common mode voltage direct current component is smaller than the overvoltage threshold value, no insulation fault to ground of the flexible direct current power grid occurs.
8. The method for detecting the insulation fault to ground of the flexible direct current power grid according to claim 1, wherein the overvoltage threshold value is a product of a voltage reliability coefficient and an inter-electrode voltage.
9. The detection method according to claim 8, wherein the voltage reliability factor has a value in a range of 0 to 0.5.
10. The flexible direct current power grid ground insulation fault detection method according to claim 1, wherein the overcurrent threshold is 1% of a rated current of a power branch.
11. A computer device, comprising:
a processor (22);
a memory (21) for storing instructions executable by the processor (22);
the processor (22) is configured to:
obtaining a difference value between a common-mode voltage direct-current component amplitude value at a first moment of the bus and a common-mode voltage direct-current component amplitude value at a second moment of the bus as a voltage reference, and obtaining a difference value between a third harmonic common-mode current vector amplitude value at the first moment of the power supply branch and a third harmonic common-mode current vector amplitude value at the second moment of the power supply branch as a first current reference;
judging whether the voltage reference quantity is larger than or equal to an overvoltage threshold value;
when the voltage reference is greater than or equal to the overvoltage threshold, judging whether the first current reference is smaller than an overcurrent threshold;
when the first current reference quantity is smaller than the overcurrent threshold value, the power supply branch circuit has insulation fault to the ground.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006001566A1 (en) * | 2004-06-26 | 2006-01-05 | Korea Railroad Research Institute | Ground overcurrent protection relay system for ungrounded dc power feed system and method of controlling the same |
| CN201302604Y (en) * | 2008-11-21 | 2009-09-02 | 山东惠工仪器有限公司 | Distributed direct current earthing failure testing device |
| CN203241494U (en) * | 2013-02-01 | 2013-10-16 | 广州优维电子科技有限公司 | Direct current system AC series current fault and insulation fault monitoring line-selection apparatus |
| CN104578127A (en) * | 2014-12-10 | 2015-04-29 | 华南理工大学 | Insulative matching method for intelligent power distribution system based on flexible direct current |
| CN104678264A (en) * | 2013-11-30 | 2015-06-03 | 中国科学院沈阳自动化研究所 | Online insulation detection and fault processing device and method of AUV (Autonomous Underwater Vehicle) direct-current power supply system |
-
2019
- 2019-08-30 CN CN201910818969.2A patent/CN110632452B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006001566A1 (en) * | 2004-06-26 | 2006-01-05 | Korea Railroad Research Institute | Ground overcurrent protection relay system for ungrounded dc power feed system and method of controlling the same |
| CN201302604Y (en) * | 2008-11-21 | 2009-09-02 | 山东惠工仪器有限公司 | Distributed direct current earthing failure testing device |
| CN203241494U (en) * | 2013-02-01 | 2013-10-16 | 广州优维电子科技有限公司 | Direct current system AC series current fault and insulation fault monitoring line-selection apparatus |
| CN104678264A (en) * | 2013-11-30 | 2015-06-03 | 中国科学院沈阳自动化研究所 | Online insulation detection and fault processing device and method of AUV (Autonomous Underwater Vehicle) direct-current power supply system |
| CN104578127A (en) * | 2014-12-10 | 2015-04-29 | 华南理工大学 | Insulative matching method for intelligent power distribution system based on flexible direct current |
Non-Patent Citations (5)
| Title |
|---|
| JIAJIE ZANG: "Grounding Design and Fault Analysis of MMC Based Flexible Interconnection Device in Future Distribution Networks", 《2018 IEEE INTERNATIONAL POWER ELECTRONICS AND APPLICATION CONFERENCE AND EXPOSITION (PEAC)》 * |
| JIE YANG: "Characteristics and Recovery Performance of VSC-HVDC DC Transmission Line Fault", 《2010 ASIA-PACIFIC POWER AND ENERGY ENGINEERING CONFERENCE》 * |
| YIRUN JI: "Fault location method for multi-terminal MMC-based MVDC distribution system under DC pole-to-ground fault", 《THE 11TH IET INTERNATIONAL CONFERENCE ON ADVANCES IN POWER SYSTEM CONTROL, OPERATION AND MANAGEMENT (APSCOM 2018)》 * |
| 何秋萍: "_10kV柔性直流配电系统接地方案研究", 《广东电力》 * |
| 陈亚娟: "一种新型直流系统在线监测装置的研制", 《电力系统及其自动化学报》 * |
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