CN218099426U - Circuit monitoring system of neutral point non-grounding system - Google Patents
Circuit monitoring system of neutral point non-grounding system Download PDFInfo
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- CN218099426U CN218099426U CN202122034102.3U CN202122034102U CN218099426U CN 218099426 U CN218099426 U CN 218099426U CN 202122034102 U CN202122034102 U CN 202122034102U CN 218099426 U CN218099426 U CN 218099426U
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Abstract
The application discloses circuit monitoring system of neutral point non-ground system includes: the system comprises zero-sequence current detection equipment, zero-sequence voltage detection equipment, phase voltage detection equipment and fault monitoring equipment, wherein the zero-sequence current detection equipment, the zero-sequence voltage detection equipment and the phase voltage detection equipment are respectively connected with the fault monitoring equipment, and the zero-sequence current detection equipment is arranged on a line to be monitored and used for detecting the zero-sequence current of the line to be monitored, generating a corresponding zero-sequence current detection signal and transmitting the zero-sequence current detection signal to the fault monitoring equipment; the zero sequence voltage detection equipment is arranged on a line to be monitored; the phase voltage detection equipment is arranged on a line to be monitored; and the fault monitoring equipment is used for receiving the detection signals transmitted by the zero sequence current detection equipment, the zero sequence voltage detection equipment and the phase voltage detection equipment and monitoring and processing the line to be monitored.
Description
Technical Field
The present application relates to the field of electrical technologies, and in particular, to a circuit monitoring system for a neutral point non-grounded system.
Background
In a neutral point non-grounded system, generally, the insulation state of a distribution line is monitored, and when insulation deterioration occurs, measures are taken in advance to prevent an accident from occurring. When a grounding accident occurs, the position and degree of insulation deterioration are detected quickly, and protection operation is performed to prevent the expansion of power failure. Checking the insulation resistance of a line is one of the more cost effective methods of monitoring the state of insulation. Conventionally, the insulation state of a line is generally investigated by a method of measuring the insulation resistance of the line periodically using a megohmmeter, but when measuring the insulation resistance using a megohmmeter, it is necessary to perform the measurement in a state of short-time power failure, and online monitoring cannot be performed.
In recent years, a method capable of performing insulation detection in an on-line state has been desired, and various proposals have been made. Such as a partial discharge method, a direct current superposition method, an alternating current superposition method, and the like. The partial discharge method needs to be provided with a high-frequency sampling device; the superimposed signal method (direct current superimposed method or alternating current superimposed method) requires a dedicated superimposed signal transmitter, a coupling device for superimposing the signal, a device for taking out the superimposed signal, and the like, and the cost for performing insulation detection is too high, which is disadvantageous to the insulation detection in an on-line state.
Aiming at the technical problem that the insulation state of the line cannot be monitored on line in the prior art, an effective solution is not provided at present.
SUMMERY OF THE UTILITY MODEL
The disclosure provides a circuit monitoring system of a neutral point non-grounded system, which at least solves the technical problem that the insulation state of a circuit cannot be monitored on line in the prior art.
According to an aspect of the present application, there is provided a circuit monitoring system of a neutral point ungrounded system, comprising: the system comprises zero-sequence current detection equipment, zero-sequence voltage detection equipment, phase voltage detection equipment and fault monitoring equipment, wherein the zero-sequence current detection equipment, the zero-sequence voltage detection equipment and the phase voltage detection equipment are respectively connected with the fault monitoring equipment, and the zero-sequence current detection equipment is arranged on a line to be monitored and used for detecting the zero-sequence current of the line to be monitored, generating a corresponding zero-sequence current detection signal and transmitting the zero-sequence current detection signal to the fault monitoring equipment; the zero-sequence voltage detection equipment is arranged on the monitoring line and used for detecting the zero-sequence voltage of the line to be monitored, generating a corresponding zero-sequence voltage detection signal and transmitting the zero-sequence voltage detection signal to the fault monitoring equipment; the phase voltage detection equipment is arranged on the line to be monitored and used for detecting the phase voltage of each phase line of the line to be monitored, generating a corresponding phase voltage detection signal and transmitting the phase voltage detection signal to the fault monitoring equipment; and the fault monitoring equipment is used for receiving the detection signals transmitted by the zero sequence current detection equipment, the zero sequence voltage detection equipment and the phase voltage detection equipment and monitoring and processing the line to be monitored.
Optionally, the fault monitoring device comprises: the monitoring device comprises a processing unit, a display, an alarm and a protector, wherein the display is connected with the processing unit and used for displaying monitoring information received from the processing unit; the alarm is connected with the processing unit and used for alarming according to the alarm instruction received from the processing unit; the protector is connected with the processing unit and used for protecting the line to be monitored according to the circuit protection instruction received from the processing unit; and the processing unit is used for monitoring and processing the detection signals transmitted from the zero-sequence current detection equipment, the zero-sequence voltage detection equipment and the phase voltage detection equipment, transmitting monitoring information to the display, transmitting an alarm instruction to the alarm and transmitting a circuit protection instruction to the protector according to the monitoring and processing result.
Optionally, the fault monitoring device further comprises: the first filter, the first amplifier and the first waveform shaping circuit are connected with the zero sequence current detection device and used for removing noise in the signal; the first amplifier is connected with the first filter and used for amplifying signals; and the first waveform shaping circuit is connected with the first amplifier and is used for carrying out waveform shaping on the signal.
Optionally, the fault monitoring device comprises: the second filter, the second amplifier and the second waveform shaping circuit, wherein the second filter is connected with the zero sequence voltage detection equipment and is used for removing noise in the signal; the second amplifier is connected with the second filter and used for amplifying the signal; and the second waveform shaping circuit is connected with the second amplifier and the processing unit and is used for carrying out waveform shaping on the signal.
Optionally, the fault monitoring device comprises: the third filter, the fourth filter and the fifth filter are respectively connected with phase voltage detection equipment and used for removing noise in signals; the third amplifier is connected with the third filter, the fourth amplifier is connected with the fourth filter, and the fifth amplifier is connected with the fifth filter; and
the third waveform shaping circuit is connected to the third amplifier and the processing unit, the fourth waveform shaping circuit is connected to the fourth amplifier and the processing unit, and the fifth waveform shaping circuit is connected to the fifth amplifier and the processing unit.
Optionally, the fault monitoring device further comprises: and the input end of the A/D converter is respectively connected with the first amplifier, the second amplifier, the third amplifier, the fourth amplifier and the fifth amplifier, and the output end of the A/D converter is connected with the processing unit.
Optionally, the processing unit is configured to perform the following operations: determining a zero-sequence current value of the zero-sequence current detection signal; determining a zero sequence voltage value of the zero sequence voltage detection signal; determining a phase voltage value of the phase voltage detection signal; and determining a single-phase earth fault point of the line to be monitored according to the zero sequence current value, the zero sequence voltage value and the phase voltage value.
Optionally, determining an operation of the single-phase ground fault of the line to be monitored according to the zero-sequence current value, the zero-sequence voltage value, and the phase voltage value includes: and determining the current value between the ground phase and the ground according to the zero sequence current value, the zero sequence voltage value and the phase voltage value.
Optionally, determining an operation of the single-phase ground fault of the line to be monitored according to the zero-sequence current value, the zero-sequence voltage value, and the phase voltage value, further includes: and determining the insulation degradation resistance value of the single-phase ground fault point according to the zero sequence current value, the zero sequence voltage value and the phase voltage value, wherein the insulation degradation resistance value is used for indicating the resistance value between the ground phase and the ground in the line to be monitored.
Therefore, through the technical scheme of the embodiment, the circuit monitoring system is added in the line to be monitored, and the circuit monitoring system is provided with zero sequence current detection equipment, zero sequence voltage detection equipment, phase voltage detection equipment and fault monitoring equipment. And transmitting the zero-sequence current detection signal measured by the zero-sequence current detection equipment, the zero-sequence voltage detection signal measured by the zero-sequence voltage detection equipment and the phase voltage detection signal measured by the phase voltage detection equipment to fault monitoring equipment. And the fault monitoring equipment receives the zero-sequence current detection signal, the zero-sequence voltage detection signal and the phase voltage detection signal and then calculates the resistance value of the insulation degradation resistor and the current flowing through the insulation degradation resistor. And displaying, alarming and protecting the line to be monitored according to the obtained result. Thereby reached through above-mentioned operation can the on-line monitoring wait to monitor the circuit and according to the technical effect that the result of detection carried out the warning. And then the technical problem that the insulation state of the circuit can not be monitored on line in the prior art is solved.
The above and other objects, advantages and features of the present application will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.
Drawings
Some specific embodiments of the present application will be described in detail hereinafter by way of illustration and not limitation with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:
FIG. 1 is an overall schematic mechanical diagram of an insulation monitoring system according to one embodiment of the present application;
FIG. 2 is an internal block diagram of the fault monitoring device in the insulation monitoring system shown in FIG. 1;
FIG. 3 is a schematic diagram of a distribution line with single phase grounding;
FIG. 4 is an equivalent circuit diagram showing a distribution line with single-phase grounding;
fig. 5 is a vector diagram showing voltages and currents when insulation deterioration of a distribution line occurs; and
fig. 6 is an enlarged view of a vector diagram of each voltage and current when insulation degradation occurs in the distribution line shown in fig. 5.
Detailed Description
It should be noted that, in the present disclosure, the embodiments and the features of the embodiments may be combined with each other without conflict. The present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
In order to make the technical solutions of the present disclosure better understood by those skilled in the art, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are only some embodiments of the present disclosure, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.
It should be noted that the terms "first," "second," and the like in the description and claims of the present disclosure and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances for describing the embodiments of the disclosure herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Fig. 1 is a schematic diagram of the overall structure of an insulation monitoring system according to one embodiment of the present application. Referring to fig. 1, a circuit monitoring system of a neutral-point ungrounded system includes: zero sequence current detection device 10, zero sequence voltage detection device 20, phase voltage detection device 30 and fault monitoring device 40. Wherein the zero sequence current detection device 10, the zero sequence voltage detection device 20 and the phase voltage detection device 30 are respectively connected with the fault monitoring device 40. The zero sequence current detection device 10 is disposed on the line 50 to be monitored, and is configured to detect a zero sequence current of the line 50 to be monitored, generate a corresponding zero sequence current detection signal, and transmit the zero sequence current detection signal to the fault monitoring device 40; the zero sequence voltage detection device 20 is disposed on the line 50 to be monitored, and is configured to detect a zero sequence voltage of the line 50 to be monitored, generate a corresponding zero sequence voltage detection signal, and transmit the zero sequence voltage detection signal to the fault monitoring device 40; the phase voltage detection device 30 is arranged on the line 50 to be monitored, and is used for detecting phase voltages of phase lines of the line 50 to be monitored, generating corresponding zero sequence voltage detection signals and transmitting the phase voltage detection signals to the fault monitoring device 40; and the fault monitoring device 40 is configured to receive the detection signals transmitted by the zero sequence current detection device 10, the zero sequence voltage detection device 20, and the phase voltage detection device 30, and perform monitoring processing on the line 50 to be monitored.
As described in the background art, in a neutral point ungrounded system, generally, by monitoring the insulation state of a distribution line, a countermeasure is taken in advance to prevent occurrence of an accident when insulation deterioration occurs. When a grounding accident occurs, the position and degree of insulation deterioration are detected quickly, and protection operation is performed to prevent the expansion of power failure. Checking the insulation resistance of a line is one of the more cost effective methods of monitoring the state of insulation. Conventionally, the insulation state of a line has been generally investigated by a method of measuring the insulation resistance of the line by a megohmmeter periodically, but when the insulation resistance is measured by a megohmmeter, the insulation resistance must be measured in a state of short-time power failure, and online monitoring cannot be performed.
In recent years, a method capable of detecting insulation in an on-line state has been desired, and various proposals have been made. Such as a partial discharge method, a direct current superposition method, an alternating current superposition method, and the like. The partial discharge method needs to be provided with a high-frequency sampling device; the superimposed signal method (direct current superimposed method or alternating current superimposed method) requires a dedicated superimposed signal transmitter, a coupling device for superimposing the signal, a device for taking out the superimposed signal, and the like, and the cost for performing insulation detection is too high, which is disadvantageous to the insulation detection in an on-line state.
In view of this technical problem, referring to fig. 1, the present embodiment provides a circuit monitoring system of a neutral point non-grounded system, which includes a zero sequence current detection device 10, a zero sequence voltage detection device 20, and a phase voltage detection device 30 disposed on a line 50 to be monitored. And the zero sequence current detection device 10, the zero sequence voltage detection device 20, and the phase voltage detection device 30 are all connected to the fault monitoring device 40. The zero sequence current detection device 10 is configured to detect a zero sequence current detection signal on a line 50 to be monitored and transmit the detected zero sequence current detection signal to the fault monitoring device 40. The zero-sequence voltage detection device 20 detects a zero-sequence voltage detection signal on the line 50 to be monitored and transmits the detected zero-sequence voltage detection signal to the fault monitoring device 40. The phase voltage detection device 30 detects phase voltage detection signals of the respective phases of the line 50 to be monitored and transmits the detected phase voltage detection signals to the fault monitoring device 40. The fault monitoring device 40 receives the detection signals transmitted by the zero sequence current detection device 10, the zero sequence voltage detection device 20, and the phase voltage detection device 30 and performs monitoring processing on the line 50 to be monitored.
When a transmission line of a neutral point non-grounded system (i.e., the line to be monitored 50) has a fault such as single-phase grounding, zero-sequence currents and zero-sequence voltages are generated, and variations in phase voltages of the respective phase lines are caused. The fault monitoring device 40 thus receives the zero-sequence current detection signal transmitted by the zero-sequence current detection device 10, the zero-sequence voltage detection signal transmitted by the zero-sequence voltage detection device 20 and the phase voltage detection signal transmitted by the phase voltage detection device 30 and processes the received detection signals for the purpose of monitoring the line 50 to be monitored. Therefore, the technical effects of monitoring the line to be monitored on line and warning according to the detection result are achieved through the operation of the embodiment. And then the technical problem that the insulation state of the circuit can not be monitored on line in the prior art is solved.
Alternatively, as shown with reference to fig. 2, the fault monitoring apparatus 40 includes: the monitoring system comprises a processing unit 401, a display 402, an alarm 403 and a protector 404, wherein the display 402 is connected with the processing unit 401 and is used for displaying monitoring information received from the processing unit 401; the alarm 403 is connected to the processing unit 401, and configured to perform alarm warning according to the alarm instruction received from the processing unit 401; the protector 404 is connected to the processing unit 401, and is configured to protect the line to be monitored 50 according to the circuit protection instruction received from the processing unit 401; and the processing unit 401 is configured to perform monitoring processing on the detection signals transmitted from the zero-sequence current detection device 10, the zero-sequence voltage detection device 20, and the phase voltage detection device 30, and transmit monitoring information to the display 402, transmit an alarm instruction to the alarm 403, and transmit a circuit protection instruction to the protector 404 according to a result of the monitoring processing.
Thus, the processing unit 401 performs a monitoring process on the detection signals transmitted from the zero-sequence current detection device 10, the zero-sequence voltage detection device 20, and the phase voltage detection device 30.
After the processing unit 401 completes calculation processing of the zero-sequence current detection signal, the zero-sequence voltage detection signal, and the phase voltage detection signal, the processing unit 401 transmits the obtained result to the display 402 as monitoring, or transmits an alarm instruction to the alarm 403 according to the result of the calculation processing, or transmits a circuit protection instruction to the protector 404.
Preferably, a detection threshold is preset in the processing unit 401, the processing unit 401 compares the calculated result with the detection threshold, and if the calculated result exceeds the threshold, the calculated result is transmitted to the display 402, or an alarm instruction is transmitted to the alarm 403, or a circuit protection instruction is transmitted to the protector 404.
Thus, the present embodiment displays monitoring information using the display 402, and when a fault is detected, alarms through the alarm 403 and protects the line to be monitored 50 through the protector 404. Therefore, the technical scheme of the embodiment can achieve the technical effects of obtaining the detected result of the line 50 to be monitored in real time and warning and protecting the line 50 to be monitored in real time.
Optionally, referring to fig. 2, the fault monitoring apparatus 40 further includes: a first filter 405a, a first amplifier 406a and a first waveform shaping circuit 407a, wherein the first filter 405a is connected to the zero sequence current detection device 10; the first amplifier 406a is connected to the first filter 405 a; and a first waveform shaping circuit 407a is connected to the first amplifier 406a and the processing unit 401.
Thus, after the zero-sequence current detection device 10 transmits the detected zero-sequence current detection signal to the fault monitoring device 40, the first filter 405a filters out unwanted noise, and transmits the noise-removed zero-sequence current to the first amplifier 406a. The first amplifier 406a amplifies the obtained zero-sequence current detection signal and transmits the amplified zero-sequence current detection signal to the first waveform shaping circuit 407a. The first waveform shaping circuit 407a performs waveform shaping on the received zero sequence detection signal current and transmits the waveform-shaped zero sequence current detection signal to the processing unit 401.
Thus, the technical effect of filtering, amplifying and waveform shaping the zero sequence current detection signal transmitted by the zero sequence current detection device 10 can be achieved by the operation of providing the first filter 405a, the first amplifier 406a and the first waveform shaping circuit 407a in the fault monitoring device 40.
Alternatively, as shown with reference to fig. 2, the fault monitoring apparatus 40 includes: a second filter 405b, a second amplifier 406b, a second waveform shaping circuit 407b, wherein the second filter 405b is connected to the zero sequence voltage detecting device 20; the second amplifier 406b is connected to the second filter 405 b; and a second waveform shaping circuit 407b is connected to the second amplifier 406b and the processing unit 401.
Thus, after the zero-sequence voltage detection device 20 transmits the detected zero-sequence voltage detection signal to the fault monitoring device 40, the second filter 405b filters out unwanted noise, and transmits the zero-sequence voltage detection signal with the noise removed to the second amplifier 406b. The second amplifier 406b amplifies the obtained zero sequence voltage detection signal and transmits the amplified zero sequence voltage detection signal to the second waveform shaping circuit 407b. The second waveform shaping circuit 407b performs waveform shaping on the received zero sequence voltage detection signal, and transmits the waveform-shaped zero sequence voltage detection signal to the processing unit 401.
Thus, the technical effect of filtering, amplifying and waveform shaping the zero sequence voltage detection signal transmitted by the zero sequence voltage detection device 20 can be achieved by the operation of providing the second filter 405b, the second amplifier 406b and the second waveform shaping circuit 407b in the fault monitoring device 40.
Alternatively, as shown with reference to fig. 2, the fault monitoring apparatus 40 includes: a third filter 405c, a fourth filter 405d, a fifth filter 405e, a third amplifier 406c, a fourth amplifier 406d, a fifth amplifier 406e, a third waveform shaping circuit 407c, a fourth waveform shaping circuit 407d, and a fifth waveform shaping circuit 407e. Wherein the third amplifier 406c is connected to the third filter 405c, the fourth amplifier 406d is connected to the fourth filter 405d, and the fifth amplifier 406e is connected to the fifth filter 405 e; and the third waveform shaping circuit 407c is connected to the third amplifier 406c and the processing unit 401, the fourth waveform shaping circuit 407d is connected to the fourth amplifier 406d and the processing unit 401, and the fifth waveform shaping circuit 407e is connected to the fifth amplifier 406e and the processing unit 401.
Thus, after the phase voltage detection device 30 transmits the detected phase voltage detection signal of each phase line to the fault monitoring device 40, unnecessary noise is filtered out by the third filter 405c, the fourth filter 405d, and the fifth filter 405e, and the phase voltage detection signal from which the noise is removed is transmitted to the third amplifier 406c, the fourth amplifier 406d, and the fifth amplifier 406e. The obtained phase voltage detection signals are amplified by the third amplifier 406c, the fourth amplifier 406d, and the fifth amplifier 406e, and then transmitted to the third waveform shaping circuit 407c, the fourth waveform shaping circuit 407d, and the fifth waveform shaping circuit 407e, respectively. The third waveform shaping circuit 407c, the fourth waveform shaping circuit 407d, and the fifth waveform shaping circuit 407e perform waveform shaping on the received phase voltage detection signal, and then transmit the phase voltage detection signal obtained through the waveform shaping to the processing unit 401.
Therefore, by providing the third filter 405c, the fourth filter 405d, the fifth filter 405e, the third amplifier 406c, the fourth amplifier 406d, the fifth amplifier 406e, the third waveform shaping circuit 407c, the fourth waveform shaping circuit 407d, and the fifth waveform shaping circuit 407e in the failure monitoring device 40, it is possible to achieve the technical effect of filtering, amplifying, and waveform shaping the phase voltage detection signal transmitted by the phase voltage detection device 30.
Optionally, referring to fig. 2, the fault monitoring apparatus 40 further includes: an a/D converter 408, wherein inputs of the a/D converter 408 are connected to the first amplifier 406a, the second amplifier 406b, the third amplifier 406c, the fourth amplifier 406D and the fifth amplifier 406e, respectively, and an output of the a/D converter 408 is connected to the processing unit 401.
After the amplified zero-sequence current detection signal, zero-sequence voltage detection signal, and phase voltage detection signal are transmitted to the a/D converter 408, the a/D converter 408 performs analog-digital conversion on the obtained signals, and then transmits the converted digital signals to the processing unit 401. Thus, the signal can be analog-to-digital converted by providing the a/D converter 408 in the fault monitoring device 40 to facilitate digital signal processing by the processing unit 401.
Optionally, the processing unit 401 is configured to perform the following operations: determining a zero sequence current value of the zero sequence current detection signal; determining a zero sequence voltage value of the zero sequence voltage detection signal; determining a phase voltage value of the phase voltage detection signal; and determining a single-phase earth fault point of the line 50 to be monitored according to the zero sequence current value, the zero sequence voltage value and the phase voltage value.
Specifically, fig. 3 shows a schematic diagram of a distribution line with single-phase grounding. Fig. 4 shows an equivalent circuit diagram of a distribution line with single-phase grounding. Fig. 5 shows a vector diagram of each voltage and current when insulation deterioration occurs in the distribution line. Fig. 6 is an enlarged view of a vector diagram of each voltage and current when insulation deterioration occurs in the distribution line shown in fig. 5. Referring to fig. 3, when a ground fault occurs at a point G in a line, a certain resistance value is generated between the line 50 to be detected and the point G of the ground point due to the fault, and such a resistance generated due to the fault between the line 50 to be detected and the point G of the ground point is referred to as insulation degradation resistance. Therefore, a zero-sequence current, a zero-sequence voltage, and a phase voltage are generated in a circuit having a single-phase ground fault, and when the circuit is energized, a ground phase voltage and a current flowing through the insulation deterioration resistance are generated at both ends of the insulation deterioration resistance.
That is, when the main purpose is to monitor the insulation state in the neutral point non-grounded system line and determine the insulation deterioration resistance and the current flowing through the insulation deterioration resistance, it is necessary to determine the resistance value of the insulation deterioration resistance and the magnitude of the current flowing through the insulation deterioration resistance using the relationship among the zero-sequence current value, the zero-sequence voltage value, and the phase voltage value.
Wherein, C L Represents the electrostatic capacitance of the load side to ground; IC (integrated circuit) L A current representing a load-side electrostatic capacitance to ground; I.C. A 0 Representing the zero sequence current flowing through the zero sequence current detection equipment; e represents the system phase voltage; cs represents a power supply side to ground electrostatic capacitance; ICs represent the current of the power supply side to the ground electrostatic capacitance; vg represents the ground phase voltage; rg represents insulation degradation resistance; ig represents a current flowing through the insulation deterioration resistance; IR 0 Representing the current flowing through the ground line; v 0 Representing the zero sequence voltage generated upon insulation degradation.
Referring to fig. 3 and 4, first, if insulation degradation occurs at the G point in the drawing, a current IR flowing through the ground-to-ground line 0 Namely, through the neutral point resistor R 0 I.e. the current IR 0 With zero sequence voltage V 0 In phase. But observes the zero sequence voltage detection signal V from the zero sequence current detection device 10 0 Is in reverse phase when the current IR is 0 With respect to zero sequence voltage V 0 Becomes 180 deg. phase. Power supply side to ground electrostatic capacitance C S Flowing current I CS Is zero sequence voltage V 0 The generated electrostatic capacitance current, and thus with respect to the zero sequence voltage V 0 Leading by 90 deg., but in anti-phase from the zero sequence current detection device 10, lagging by 90 deg.. Wherein the relationship between the parameters can be represented by formula
And (4) expressing. And the vector relationship between the respective voltages and currents is shown with reference to fig. 5 or 6. If the current I flowing through the insulation deterioration point G is to be determined g Then the current I needs to be understood g Is passed through the earth to neutral point current IR 0 And a current flowing through the power supply side to the ground electrostatic capacitor C S Current Ics and electrostatic capacitance C flowing through the load side to ground L Current Ic of L The vector sum of (2). Ground phase voltage V during insulation degradation g (ground phase-ground voltage) is insulation deterioration resistance R g And flows through R g Current of (I) g Is thus the ground phase voltage V g Phase and current of g In phase.
Zero sequence voltage V due to insulation degradation 0 Voltage V to ground g Is θ. When neutral point resistance Ro is infinite, current IR flowing into the grounded-to-neutral point 0 Zero, θ is 90 °; when the power supply side electrostatic capacitance Cs to ground is zero, the current flows into the electrostatic capacitance C S The current Ics of (a) is 0, then theta is 180 degrees; neutral resistance R if grounded 0 Not infinite, then 90 °<θ≤180°。
Then, the zero-sequence current detection signal I detected in the zero-sequence current detection device 10 0 Current IR flowing from ground to neutral 0 And the sum of the current Ics flowing through the power supply side to ground electrostatic capacitance Cs. Referring to fig. 5 or fig. 6, there is a zero sequence current I 0 Current IR flowing through the ground line 0 And flowing through the insulation deterioration resistance R g Current of (I) g The phase between.
Finally, the resistance R at the neutral point is determined according to the above-mentioned relationship 0 Zero sequence voltage detection signal V measured by the zero sequence voltage detection device 20 under a condition that it is not infinite 0 The absolute value and phase of the zero-sequence current detection signal I measured by the zero-sequence current detection device 10 0 Absolute value and phase of (a), phase voltage detection signal V of a ground short-circuit phase measured by phase voltage detection device 30 g Absolute value and phase. And by the formula
I R0 ＝I 0 ×cos(180°-φ) (5)
I g ＝I R0 ÷cos(180-θ) (6)
Determining the current I flowing through the insulation deterioration resistance g . Wherein phi is zero sequence voltage V 0 With zero sequence current I 0 Theta is zero sequence voltage V 0 Voltage V to ground g The phase difference of (1).
Thus, the determination of which phase the grounding phase is, the phase voltage of each phase relative to the zero sequence voltage V when a single-phase ground fault occurs through the line 50 to be monitored 0 Whether the delay range is in the range of 90-180 degrees is judged. If a certain phase is in the range of 90 ° to 180 °, the phase in this range is an insulation deterioration phase.
Therefore, according to the principle and relationship described above, when a single-phase ground fault occurs in the line 50 to be monitored, the processing unit 401 may be provided in the line 50 to be monitored. The processing unit 401 may detect the signal I according to the zero sequence current transmitted by the zero sequence current detection device 10 and the zero sequence voltage detection device 20, respectively 0 And zero sequence voltage detection signal V 0 Determines whether the insulation deterioration is on the power supply side or the load side. If the zero sequence current detects the signal I 0 Detecting signal V relative to zero sequence voltage 0 When the delay range of (2) is from 45 DEG to 225 DEG, it means that a fault occurs or insulation deterioration occurs on the load side. Then, the processing unit 401 receives the phase and zero sequence voltage detection signals V of the phase voltage detection signals E of the respective phases transmitted by the phase voltage detection device 30 again 0 The phase of (c). If the phase voltage detection signal E of a certain phase is relative to the zero sequence voltage detection signal V 0 Is in the range of 90 to 180, the phase is a ground short phase or an insulation deterioration phase.
Optionally, determining the operation of the single-phase ground fault of the line 50 to be monitored according to the zero-sequence current value, the zero-sequence voltage value and the phase voltage value includes: and determining the current value between the ground phase and the ground according to the zero sequence current value, the zero sequence voltage value and the phase voltage value.
Specifically, referring to fig. 3 and 4, if insulation degradation occurs at a G point in the drawing, a zero-sequence current, a zero-sequence voltage, and a phase voltage are generated in the line 50 to be monitored. The current IR flowing through the ground to earth line 0 Namely, through the neutral point resistor R 0 I.e. the current IR 0 And zero sequence voltage V 0 In phase. But observes the zero sequence voltage detection signal V from the zero sequence current detection device 10 0 Is in reverse phase when the current IR is 0 With respect to zero sequence voltage V 0 Becomes 180 deg. phase. Power supply side to ground electrostatic capacitance C S Flowing current I CS Is zero sequence voltage V 0 The generated electrostatic capacitance current, and thus with respect to the zero sequence voltage V 0 Leading by 90 deg., but being in anti-phase from the zero sequence current detection device 10, lagging by 90 deg.. Wherein the relationship between the parameters can be represented by formula
And (4) expressing. And the relationship between the respective parameters is shown with reference to fig. 3. If the current I flowing through the insulation deterioration point G is to be determined g Then the current I needs to be understood g Is passed through the earth to neutral point current IR 0 A current flows through the power supply side to the ground electrostatic capacitor C S Current Ics and electrostatic capacitance C flowing through the load side to ground L Current Ic of L The vector sum of (1). Ground phase voltage V during insulation degradation g (ground phase-ground voltage) is insulation-deteriorated electricityResistance R g And flows through R g Current of (I) g Is thus the ground phase voltage V g Phase and current of g In phase.
Then, referring to fig. 3, zero sequence voltage V generated due to insulation deterioration 0 Voltage V to ground g Is θ. When neutral point resistance Ro is infinite, current IR flowing into the grounded neutral point 0 Zero, θ is 90 °; when the power supply side electrostatic capacitance Cs to ground is zero, the current flows into the electrostatic capacitance C S The current Ics of (a) is 0, then theta is 180 degrees; neutral resistance R if grounded 0 Not infinite, then 90 °<θ≤180°。
Then, the zero-sequence current detection signal I detected in the zero-sequence current detection device 10 0 Is the current IR flowing through the earth to neutral point 0 And the sum of the currents Ics flowing through the power supply side to ground electrostatic capacitance Cs. Referring to FIG. 3, there is a zero sequence current I 0 Current IR flowing through the ground line 0 And flowing through the insulation deterioration resistance R g Current of (I) g The phase between.
Finally, according to the known relationship, the resistance R is measured at the neutral point 0 Zero sequence voltage detection signal V measured by the zero sequence voltage detection device 20 under a condition that it is not infinite 0 Zero sequence current detection signal I measured by the absolute value and phase, zero sequence current detection device 10 0 Absolute value and phase of (a), phase voltage detection signal V of a ground short-circuit phase measured by phase voltage detection device 30 g Absolute value and phase. And by the formula
I R0 ＝I 0 ×cos(180°-φ) (5)
I g ＝I R0 ÷cos(180-θ) (6)
Determining the current I flowing through the insulation deterioration resistance g . Wherein phi is zero sequence voltage V 0 With zero sequence current I 0 Theta is zero sequence voltage V 0 Voltage V to ground g The phase difference of (1).
Thereby, a zero-sequence current detection signal detected by the zero-sequence current detection device 10, a zero-sequence voltage detection are measuredThe zero sequence voltage detection signal measured by the device 20 and the phase voltage detection signal measured by the phase voltage detection device 30 and determine a zero sequence current value, a zero sequence voltage value and a phase voltage value. And the insulation deterioration resistance R can be obtained according to the zero sequence current value, the zero sequence voltage value and the phase relation and formula g Current of (I) g 。
Optionally, determining the operation of the single-phase ground fault of the line 50 to be monitored according to the zero-sequence current value, the zero-sequence voltage value and the phase voltage value further includes: and determining the insulation degradation resistance value of the single-phase ground fault point according to the zero sequence current value, the zero sequence voltage value and the phase voltage value, wherein the insulation degradation resistance value is used for indicating the resistance value between the ground phase and the ground in the line 50 to be monitored.
Specifically, as shown with reference to fig. 3 and 4, if insulation degradation occurs at the G point in the drawing, a zero-sequence current, a zero-sequence voltage, and a phase voltage are generated among the lines 50 to be monitored. If the resistance value of the insulation deterioration resistor is required, the current I flowing through the insulation deterioration resistor needs to be obtained according to the steps g Then according to formula R g ＝V g /I g The resistance R of the insulation deterioration resistor can be obtained g 。
Therefore, first, a zero sequence current value, a zero sequence voltage value and a phase voltage value are determined respectively by a zero sequence current detection signal detected by the zero sequence current detection device 10, a zero sequence voltage detection signal detected by the zero sequence voltage detection device 20 and a phase voltage detection signal detected by the phase voltage detection device 30. Then, according to the zero sequence current value, zero sequence voltage value and phase voltage value and the above-mentioned phase relation and formula the resistance value R flowing through the insulation deterioration resistor can be worked out g 。
The technical effect that this embodiment can reach:
1. the insulation state of the line 50 to be monitored can be monitored on-line without powering off the circuit;
2. the zero-sequence current detection device 10 and the zero-sequence voltage detection device 20 may be the same as the zero-sequence current converter or the zero-sequence voltage detection apparatus used by the primary and secondary fusion switch;
3. the phase voltage detection can be realized by adding a phase voltage detection component without a special device;
4. determining an insulation deterioration part by installing a plurality of branches;
5. by detecting the zero sequence current flowing in the ground wire, it is possible to monitor whether the insulation degradation of the line 50 to be monitored occurs and the degree of insulation degradation of the line 50 to be monitored;
6. the monitoring result does not change according to the change of the electrostatic capacitance on the load side, and accurate insulation monitoring can be always performed.
The relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
For ease of description, spatially relative terms such as "over … …", "over … …", "over … …", "over", etc. may be used herein to describe the spatial positional relationship of one device or feature to another device or feature as shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In the description of the present disclosure, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are presented only for the convenience of describing and simplifying the disclosure, and in the absence of a contrary indication, these directional terms are not intended to indicate and imply that the device or element being referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore, should not be taken as limiting the scope of the disclosure; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.
The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (6)
1. A circuit monitoring system for a neutral ungrounded system, comprising: a zero sequence current detection device (10), a zero sequence voltage detection device (20), a phase voltage detection device (30) and a fault monitoring device (40), wherein the zero sequence current detection device (10), the zero sequence voltage detection device (20) and the phase voltage detection device (30) are each connected with the fault monitoring device (40), and wherein
The zero sequence current detection device (10) is arranged on a line (50) to be monitored, and is used for detecting the zero sequence current of the line (50) to be monitored, generating a corresponding zero sequence current detection signal and transmitting the zero sequence current detection signal to the fault monitoring device (40);
the zero sequence voltage detection equipment (20) is arranged on the line (50) to be monitored and used for detecting the zero sequence voltage of the line (50) to be monitored, generating a corresponding zero sequence voltage detection signal and transmitting the zero sequence voltage detection signal to the fault monitoring equipment (40);
the phase voltage detection equipment (30) is arranged on the line (50) to be monitored and used for detecting the phase voltage of each phase line of the line (50) to be monitored, generating a corresponding phase voltage detection signal and transmitting the phase voltage detection signal to the fault monitoring equipment (40); and
the fault monitoring device (40) is used for receiving detection signals transmitted by the zero sequence current detection device (10), the zero sequence voltage detection device (20) and the phase voltage detection device (30) and monitoring the line (50) to be monitored.
2. The circuit monitoring system of a neutral point ungrounded system according to claim 1, characterized in that the fault monitoring device (40) comprises: a processing unit (401), a display (402), an alarm (403) and a protector (404), wherein
The display (402) is connected with the processing unit (401) and is used for displaying the monitoring information received from the processing unit (401);
the alarm (403) is connected with the processing unit (401) and is used for alarming according to an alarm instruction received from the processing unit (401); and
the protector (404) is connected with the processing unit (401) and used for protecting the line (50) to be monitored according to a circuit protection instruction received from the processing unit (401); and
the processing unit (401) is configured to perform monitoring processing on detection signals transmitted from the zero sequence current detection device (10), the zero sequence voltage detection device (20) and the phase voltage detection device (30), and transmit monitoring information to the display (402), transmit the alarm instruction to the alarm (403) and transmit the circuit protection instruction to the protector (404) according to a result of the monitoring processing.
3. The circuit monitoring system of a neutral point ungrounded system according to claim 2, characterized in that said fault monitoring device (40) further comprises: a first filter (405 a), a first amplifier (406 a) and a first waveform shaping circuit (407 a), wherein
The first filter (405 a) is connected with the zero sequence current detection device (10);
the first amplifier (406 a) is connected to the first filter (405 a); and
the first waveform shaping circuit (407 a) is connected to the first amplifier (406 a) and to the processing unit (401).
4. A circuit monitoring system of a neutral point ungrounded system according to claim 3, characterised in that the fault monitoring device (40) comprises: a second filter (405 b), a second amplifier (406 b), a second waveform shaping circuit (407 b), wherein
The second filter (405 b) is connected with the zero sequence voltage detection device (20);
the second amplifier (406 b) is connected to the second filter (405 b); and
the second waveform shaping circuit (407 b) is connected to the second amplifier (406 b) and the processing unit (401) for waveform shaping a signal.
5. Circuit monitoring system of a neutral point ungrounded system according to claim 4, characterised in that the fault monitoring device (40) comprises: a third filter (405 c), a fourth filter (405 d), a fifth filter (405 e), a third amplifier (406 c), a fourth amplifier (406 d), a fifth amplifier (406 e), a third waveform shaping circuit (407 c), a fourth waveform shaping circuit (407 d), and a fifth waveform shaping circuit (407 e), wherein
The third filter (405 c), the fourth filter (405 d) and the fifth filter (405 e) are respectively connected with the phase voltage detection device (30);
-the third amplifier (406 c) is connected to the third filter (405 c), a fourth amplifier (406 d) is connected to the fourth filter (405 d), and the fifth amplifier (406 e) is connected to the fifth filter (405 e); and
the third waveform shaping circuit (407 c) is connected to the third amplifier (406 c) and the processing unit (401), the fourth waveform shaping circuit (407 d) is connected to the fourth amplifier (406 d) and the processing unit (401), and the fifth waveform shaping circuit (407 e) is connected to the fifth amplifier (406 e) and the processing unit (401).
6. The circuit monitoring system of a neutral point ungrounded system according to claim 5, wherein the fault monitoring device (40) further comprises: an A/D converter (408), wherein
The input terminals of the A/D converter (408) are connected to a first amplifier (406 a), a second amplifier (406 b), the third amplifier (406 c), the fourth amplifier (406D) and the fifth amplifier (406 e), respectively, and the output terminal of the A/D converter (408) is connected to a processing unit (401).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122034102.3U CN218099426U (en) | 2021-08-27 | 2021-08-27 | Circuit monitoring system of neutral point non-grounding system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122034102.3U CN218099426U (en) | 2021-08-27 | 2021-08-27 | Circuit monitoring system of neutral point non-grounding system |
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| CN218099426U true CN218099426U (en) | 2022-12-20 |
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| CN202122034102.3U Active CN218099426U (en) | 2021-08-27 | 2021-08-27 | Circuit monitoring system of neutral point non-grounding system |
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| CN (1) | CN218099426U (en) |
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