CN204142841U - A kind of three-phase current unbalance monitoring system - Google Patents
A kind of three-phase current unbalance monitoring system Download PDFInfo
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- CN204142841U CN204142841U CN201420096221.9U CN201420096221U CN204142841U CN 204142841 U CN204142841 U CN 204142841U CN 201420096221 U CN201420096221 U CN 201420096221U CN 204142841 U CN204142841 U CN 204142841U
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 14
- 238000012806 monitoring device Methods 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 description 9
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- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 1
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Abstract
The utility model discloses a kind of three-phase current unbalance monitoring system.This system comprises: current measuring device, for measuring amplitude and the phase place of three-phase current; And balance monitoring device, for determining whether three-phase current balances according to the negative sequence component parameter of the amplitude of three-phase current and the positive-sequence component parameter of phase calculation three-phase current and three-phase current; Wherein said current measuring device is connected with described balance monitoring device.The utility model can be monitored three-phase current unbalance, thus can timely and effective discovery electrical fault, improves the quality of power supply, ensures that electrical equipment normally runs.
Description
Technical field
The utility model relates to automation field, particularly, relates to a kind of three-phase current unbalance monitoring system.
Background technology
High-voltage motor is generally threephase asynchronous, if the imbalance of three-phase voltage of input, overload, stator rotor winding break down and Operation and Maintenance is improper etc. all can cause three-phase current unbalance, and motor may be caused to damage and line loss increase, and harm may be produced to the transformer in network system or other electrical equipments.In prior art, the safeguard measure adopted mainly lays particular emphasis on the protection of overcurrent, quick-break and zero-sequence current, and lacks the safeguard measure of monitoring three-phase current unbalance, and this is unfavorable for the protection to electrical equipment in electric power system.
Utility model content
The purpose of this utility model is to provide a kind of three-phase current unbalance monitoring system, to monitor three-phase current unbalance degree, prevents from causing damage to electrical equipment.
To achieve these goals, the utility model provides a kind of three-phase current unbalance monitoring system, and this system comprises: current measuring device, for measuring amplitude and the phase place of three-phase current; And balance monitoring device, for determining whether three-phase current balances according to the negative sequence component parameter of the amplitude of three-phase current and the positive-sequence component parameter of phase calculation three-phase current and three-phase current; Wherein said current measuring device is connected with described balance monitoring device.
Preferably, the positive-sequence component of described three-phase current and the negative sequence component of described three-phase current are calculated according to symmetrical component method by balance monitoring device:
Wherein
for measuring the vector representation drawing three-phase current,
for the vector representation of A phase current positive-sequence component, negative sequence component, zero-sequence component, a=e
j120 °.
Preferably, the positive-sequence component parameter of described three-phase current is the positive-sequence component root mean square of A phase current, and the negative sequence component parameter of described three-phase current is the negative sequence component root mean square of A phase current, and described three-phase current unbalance degree is the negative phase-sequence degree of unbalancedness of three-phase current; Described balance monitoring device calculates three-phase current unbalance degree ε according to following formula
i2:
wherein, I
1for the positive-sequence component root mean square of three-phase current, I
2for the negative sequence component root mean square of three-phase current.
Preferably, described current measuring device is current transformer.
Preferably, described balance monitoring device is used for calculated three-phase current unbalance degree to compare with the three-phase current unbalance degree scope preset to determine whether three-phase current balances.
Preferably, balance monitoring device is used for when calculated three-phase current unbalance degree is positioned at the first three-phase current unbalance degree scope, determine that three-phase current is the first estate current imbalance, when calculated three-phase current unbalance degree is positioned at the second three-phase current unbalance degree scope, determine that three-phase current is that the second grading current is uneven, when calculated three-phase current unbalance degree is positioned at the 3rd three-phase current unbalance degree scope, determine three-phase balance;
Wherein said first three-phase current unbalance degree scope is 10%≤ε
i2< 20%, described second three-phase current unbalance degree scope is ε
i2>=20%, described 3rd three-phase current unbalance degree scope is ε
i2< 10%.
Preferably, balance monitoring device is used for sending off-limit alarm signal when determining that three-phase current unbalance degree is the first estate current imbalance to remote equipment, sends sub-gate signal when determining that three-phase current unbalance degree is the second grading current imbalance to breaker of switch cabinet.
The utility model provides a kind of three-phase current unbalance monitoring method, and the method comprises: amplitude and the phase place of measuring three-phase current; And determine whether three-phase current balances according to the negative sequence component parameter of the amplitude of three-phase current and the positive-sequence component parameter of phase calculation three-phase current and three-phase current.
Preferably, the positive-sequence component of described three-phase current and the negative sequence component of described three-phase current calculate according to symmetrical component method:
Wherein
for measuring the vector representation drawing three-phase current,
for the vector representation of A phase current positive-sequence component, negative sequence component, zero-sequence component, a=e
j120 °.
Preferably, the positive-sequence component parameter of described three-phase current is the positive-sequence component root mean square of three-phase current, and the negative sequence component parameter of described three-phase current is the negative sequence component root mean square of three-phase current; Three-phase current unbalance degree ε is calculated according to following formula
i2:
wherein, I
1for the positive-sequence component root mean square of three-phase current, I
2for the negative sequence component root mean square of three-phase current.
Preferably, amplitude and the phase place of three-phase current is measured by current transformer.
Preferably, describedly determine whether three-phase current balances and comprise: calculated three-phase current unbalance degree is compared with the three-phase current unbalance degree scope preset and determines whether three-phase current balances.
Preferably, described being compared with the three-phase current unbalance degree scope preset by calculated three-phase current unbalance degree is determined whether three-phase current balances and is comprised: when calculated three-phase current unbalance degree is positioned at the first three-phase current unbalance degree scope, determine that three-phase current is the first estate current imbalance, when calculated three-phase current unbalance degree is positioned at the second three-phase current unbalance degree scope, determine that three-phase current is that the second grading current is uneven, when calculated three-phase current unbalance degree is positioned at the 3rd three-phase current unbalance degree scope, determine three-phase balance, wherein said first three-phase current unbalance degree scope is 10%≤ε
i2< 20%, described second three-phase current unbalance degree scope is ε
i2>=20%, described 3rd three-phase current unbalance degree scope is ε
i2< 10%.
Preferably, the method also comprises: send off-limit alarm signal when determining that three-phase current unbalance degree is the first estate current imbalance to remote equipment, send sub-gate signal when determining that three-phase current unbalance degree is the second grading current imbalance to breaker of switch cabinet, and send separating brake warning to remote equipment.
The utility model can be monitored three-phase current unbalance, thus can timely and effective discovery electrical fault, improves the quality of power supply, ensures that electrical equipment normally runs.
Other feature and advantage of the present utility model are described in detail in embodiment part subsequently.
Accompanying drawing explanation
Accompanying drawing is used to provide further understanding of the present utility model, and forms a part for instructions, is used from explanation the utility model, but does not form restriction of the present utility model with embodiment one below.In the accompanying drawings:
Fig. 1 is the three-phase current unbalance monitoring system schematic diagram that the utility model provides;
Fig. 2 is the three-phase current unbalance monitoring process flow diagram that the utility model provides.
Description of reference numerals
100 current measuring device 200 balance monitoring devices
300 breaker of switch cabinet 400 remote equipments
Embodiment
Below in conjunction with accompanying drawing, embodiment of the present utility model is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the utility model, is not limited to the utility model.
In order to whether Real-Time Monitoring three-phase current balances the safety protecting electrical equipment, the utility model provides three-phase current unbalance monitoring system as shown in Figure 1, and this system comprises: current measuring device 100, for measuring amplitude and the phase place of three-phase current; And balance monitoring device 200, determine whether three-phase current balances for the positive-sequence component parameter of three-phase current according to the amplitude of three-phase current and phase calculation and the negative sequence component parameter of described three-phase current; Wherein said current measuring device is connected with described balance monitoring device.By current measuring device 100 and the process balancing monitoring device 200, three-phase current can be determined and whether balance.For the ease of following description, breaker of switch cabinet 300 and remote equipment 400 have been shown in Fig. 1, the signal separating brake that switch disconnector 300 can send according to balance monitoring device 200, the signal alarm that remote equipment 400 can send according to balance monitoring device 200.
Specifically, current measuring device 100 can be current transformer.It should be noted that, current transformer is only with explaining but not limiting.Preferably, the positive-sequence component parameter of described three-phase current is the positive-sequence component root mean square of three-phase current, and the negative sequence component parameter of described three-phase current is the negative sequence component root mean square of three-phase current.Balance monitoring device 200 calculates three-phase current positive sequence, negative sequence component according to following formula:
Wherein
for measuring the vector representation drawing three-phase current,
for the vector representation of A phase current positive sequence, negative phase-sequence, zero-sequence component, a=e
j120 °.It should be noted that, carry out calculating only making example with the positive sequence of A phase current, negative sequence component herein, also can realize the utility model with B phase current or C phase current.Meanwhile, balance monitoring device 200 utilizes the positive-sequence component root mean square of three-phase current and the negative sequence component root mean square of three-phase current and calculates three-phase current unbalance degree ε according to following formula
i2:
wherein, I
1for the positive-sequence component root mean square of three-phase current, I
2for the negative sequence component root mean square of three-phase current.This quality of balance computing formula is only with for referencial use but not to restriction of the present utility model, the utility model also can utilize other formula to calculate three-phase current unbalance degree.
In order to determine whether three-phase current balances, the utility model passes through calculated three-phase current unbalance degree and default degree of unbalancedness scope compares, and then determines whether three-phase current balances.In order to ensure each electrical equipment safety and ensure the operation of electrical network, three-phase current unbalance is divided into two grades by the utility model.Certainly, those skilled in the art also can carry out other division, and control operation corresponding to each different grade.Preferably, when calculated three-phase current unbalance degree is positioned at the first three-phase current unbalance degree scope, balance monitoring device 200 determines that three-phase current is the first estate current imbalance, when calculated three-phase current unbalance degree is positioned at the second three-phase current unbalance degree scope, balance monitoring device 200 determines that three-phase current is that the second grading current is uneven, when calculated three-phase current unbalance degree is positioned at the 3rd three-phase current unbalance degree scope, balance monitoring device 200 determines three-phase balance; Wherein said first three-phase current unbalance degree scope is 10%≤ε
i2< 20%, described second three-phase current unbalance degree scope is ε
i2>=20%, described 3rd three-phase current unbalance degree scope is ε
i2< 10%.For the setting of frontier point, shown here 10%, 20% also only makes example but not to restriction of the present utility model, and more excellent frontier point can be found by several times test in this area.
In addition, in order to carry out reporting to the police and carry out failture evacuation, balance monitoring device 200 sends off-limit alarm signal when determining that three-phase current unbalance degree is the first estate current imbalance to remote equipment 400, sends sub-gate signal when determining that three-phase current unbalance degree is the second grading current imbalance to breaker of switch cabinet 300.Send to remote equipment the three-phase current unbalance that more line alerting signal can remind managerial personnel current, and breaker of switch cabinet 300 sends sub-gate signal and can excise fault.Correspondingly, when breaker of switch cabinet 300 receives sub-gate signal to excise fault, remote equipment 400 also can send corresponding alerting signal.Remote equipment 400 can telemetry equipment, remote signalling equipment and remote control equipment.
Correspondingly, the utility model provides three-phase current unbalance monitoring method flow process, as shown in Figure 2.In Fig. 2, first measure three-phase current (step 201), this can be realized by current transformer, calculates three-phase current positive sequence, negative sequence component after measuring the amplitude of three-phase current and phase place according to following formula:
Wherein
for measuring the vector representation drawing three-phase current,
for the vector representation of A phase current positive sequence, negative phase-sequence, zero-sequence component, a=e
j120 °; It should be noted that, carry out calculating only making example with the positive sequence of A phase current, negative sequence component herein, also can realize the utility model with B phase current or C phase current.The negative sequence component parameter of three-phase current positive-sequence component parameter and three-phase current is obtained afterwards according to the positive sequence negative sequence component calculated, the positive-sequence component parameter of three-phase current can be the positive-sequence component root mean square of three-phase current, and the negative sequence component parameter of three-phase current can be the negative sequence component root mean square of three-phase current; Then three-phase current unbalance degree ε can be calculated
i2(step 203),
wherein, I
1for the positive-sequence component root mean square of three-phase current, I
2for the negative sequence component root mean square of three-phase current; Then ε is judged
i2whether be less than or equal to 10%(step 205), if be less than or equal to 10%, then think that three-phase balance continues to perform step 201, otherwise continue to judge ε
i2whether be more than or equal to 20%(step 207), if ε
i2be more than or equal to 20%, then send sub-gate signal (step 213), thus breaker open operation and remote equipment carries out separating brake alarm (step 215), finally continue to perform step 201; If ε
i2be less than 20%, then send off-limit alarm signal (step 209), thus remote equipment carries out Threshold Crossing Alert, finally perform step 201.
By above-mentioned flow process, the protection that the utility model can realize electrical equipment and electrical network by the three-phase current unbalance degree that calculates and default mode of operation.
Below preferred implementation of the present utility model is described by reference to the accompanying drawings in detail; but; the utility model is not limited to the detail in above-mentioned embodiment; within the scope of technical conceive of the present utility model; can carry out multiple simple variant to the technical solution of the utility model, these simple variant all belong to protection domain of the present utility model.
It should be noted that in addition, each the concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode.In order to avoid unnecessary repetition, the utility model illustrates no longer separately to various possible array mode.
In addition, also can carry out combination in any between various different embodiment of the present utility model, as long as it is without prejudice to thought of the present utility model, it should be considered as content disclosed in the utility model equally.
Claims (2)
1. a three-phase current unbalance monitoring system, is characterized in that, this system comprises:
Current measuring device, for measuring amplitude and the phase place of three-phase current; And
Balance monitoring device, for determining whether three-phase current balances according to the negative sequence component parameter of the amplitude of three-phase current and the positive-sequence component parameter of phase calculation three-phase current and three-phase current;
Wherein said current measuring device is connected with described balance monitoring device.
2. system according to claim 1, is characterized in that, described current measuring device is current transformer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420096221.9U CN204142841U (en) | 2014-03-04 | 2014-03-04 | A kind of three-phase current unbalance monitoring system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420096221.9U CN204142841U (en) | 2014-03-04 | 2014-03-04 | A kind of three-phase current unbalance monitoring system |
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| Publication Number | Publication Date |
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| CN204142841U true CN204142841U (en) | 2015-02-04 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103823126A (en) * | 2014-03-04 | 2014-05-28 | 中国神华能源股份有限公司 | Method and system for monitoring three-phase current unbalance |
| CN109001548A (en) * | 2017-06-07 | 2018-12-14 | 广东电网有限责任公司佛山供电局 | A kind of distribution transforming current imbalance judgment method based on metering centralized meter reading terminal data |
| CN110850200A (en) * | 2019-10-28 | 2020-02-28 | 深圳供电局有限公司 | Method, estimation device and system for acquiring load current unbalance degree |
-
2014
- 2014-03-04 CN CN201420096221.9U patent/CN204142841U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103823126A (en) * | 2014-03-04 | 2014-05-28 | 中国神华能源股份有限公司 | Method and system for monitoring three-phase current unbalance |
| CN109001548A (en) * | 2017-06-07 | 2018-12-14 | 广东电网有限责任公司佛山供电局 | A kind of distribution transforming current imbalance judgment method based on metering centralized meter reading terminal data |
| CN110850200A (en) * | 2019-10-28 | 2020-02-28 | 深圳供电局有限公司 | Method, estimation device and system for acquiring load current unbalance degree |
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Granted publication date: 20150204 |
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