CN105633913A - Self-balancing differential protection structure for motor - Google Patents
Self-balancing differential protection structure for motor Download PDFInfo
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- CN105633913A CN105633913A CN201410602605.8A CN201410602605A CN105633913A CN 105633913 A CN105633913 A CN 105633913A CN 201410602605 A CN201410602605 A CN 201410602605A CN 105633913 A CN105633913 A CN 105633913A
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Abstract
The invention discloses a self-balancing differential protection structure for a motor, and the structure comprises the motor and a high-voltage switch cabinet connected with the motor. The head and tail leads of each phase of a three-phase winding of the motor pass through one self-balancing current transformer at the same time according to the polarity. The structure can greatly reduce the misoperation possibility of a protection device. Compared with other protection structures, the structure greatly improves the protection sensitivity, so the structure can create conditions for the long-time stable operation of a unit and the shortening of the maintenance cycle, can increase the power generation amount, and creates more benefits for a power plant.
Description
Technical field
The technology of the present invention is applied to thermal power plant high pressure 2000kW and above motor, if desired, it is also possible in the motor less than 2000kW.
Background technology
At present, power plant 2000kW and the differential protection with upper motor are generally adopted by switch cubicle to install one group of current transformer, and motor neutral point is installed one group of current transformer and constituted the differential protection of motor. This Main Basis China existing technical regulation of power industry, Specification Design.
As described in Figure 1, it is existing conventional electric motor differential protection structure. It comprises motor 1 and the high-tension switch cabinet 2 being connected with motor 1; motor is arranged in motor main junction box 11; motor neutral point connects the differential protection that three the first current transformers 31 are constituted; differential protection also includes three measuring second current transformers 32 and three differential protections and the 3rd current transformer 33 of other protections, and this second current transformer and the 3rd current transformer are placed in switch cubicle.
The shortcoming of this mode is:
1., due to different for the first current transformer of differential protection and the actual secondary burden of the second current transformer, therefore, the electric current difference respective exported (such as during motor starting) when larger current is bigger, it is easy to cause Miss-operation of Motor Differential Protection. Common solution is to improve the working value of protection, or increases the criterion of through current. The former typically results in the sensitivity decrease of protection, and the latter then causes that the logic of protection complicates, and makes extend the movement time of protection.
2. the different shaped of two kinds of current transformers. This electric current difference also leading to send into protection increases, and solution is only improved the working value of protection.
Summary of the invention
In view of this; technical problem solved by the invention is in that to provide a kind of motor self-balancing differential protection structure; can greatly reduce the probability of protection error action of device; the sensitivity of protection and can be greatly improved compared with existing protection structure; for ensureing that the operation steady in a long-term of unit, shortening time between overhauls(TBO) create conditions; thus increasing generated energy, create benefit.
Patent of the present invention adopts the following technical scheme that motor self-balancing differential protection structure; it comprises motor and the high-tension switch cabinet being connected with motor, and in motor three-phase windings, every head of phase, 2 lead-out wires of tail press polarity also cross 1 self-balancing current transformer.
The technology of the present invention adopts the advantage of technique scheme to be in that: can greatly reduce the possibility of protection error action of device; the sensitivity of protection can be greatly enhanced compared with other protection; therefore can create conditions for the operation steady in a long-term of unit, shortening time between overhauls(TBO); generated energy can also be increased simultaneously, create more benefit for power plant.
Accompanying drawing explanation
Fig. 1 is existing conventional electric motor differential protection structural representation.
Fig. 2 is the structural representation of the present invention.
Detailed description of the invention
As shown in Figure 2; motor self-balancing differential protection structure of the present invention; it comprises motor 1 and the high-tension switch cabinet 2 being connected with motor 1; motor is arranged in motor main junction box 11; its emphasis in: every head of phase in motor 1 three-phase windings 11,2 lead-out wires of tail are also magnetic balance current transformer by polarity also cross 1 self-balancing current transformer 3(), the secondary side of self-balancing current transformer succeeds electrical protective device. Additionally; same installation three-phase type motor protecting device in switch cubicle 2; it is a kind of simplest current quick; and do not need time delay; it is a set of common motor protection conventionally configured; it can include measuring second current transformer 32, and other except differential protection are protected with the 3rd current transformer 33.
This programme has the advantage that
1. being designed as power frequency operation, when changing converting operation into, the protection structure of the present invention is without change. This is because when properly functioning, the electric current of inflow motor has the characteristic of " equal in magnitude, in opposite direction " all the time with the electric current flowing out motor, regardless of whether the electric current of inflow motor is power frequency or frequency conversion.
2. the self-balancing differential protection of motor of the present invention both can be adjusted according to minimum fault current (sensitivity now protecting device is the highest), it is possible to adjusts according to coordinating with the fast tripping protection at power supply place, to ensure not having dead band when big short circuit current.
Constantly increase for China's unit capacity in recent years, make full use of the construction features of motor self-balancing differential protection, improve the sensitivity of protection; reduce the dead band of protection; improving protection act speed, thus shortening the repair time, creating service condition better, more for country and enterprise.
Being below case history: power plant's 600MW Turbo-generator Set of design, its primary air fan is by 4300kW motor-driven, the motor self-balancing differential protection structure of this case of employing. When starting 2A primary air fan, 2A primary air fan switch trip, protection device display zero-sequencedirectional protection action, and self-balancing differential protection action. Self-balancing differential protection setting valve is 0.1A, and time delay 0s action is in tripping operation. After protection act; carry out high tension cable and motor winding respectively surveying insulation; cable insulation is good, and motor winding three-phase resistance over the ground is respectively as follows: A:1G ��, B:1G ��; C:0.2M ��; open the end cap inspection of motor both sides, find trouble point 3 place at shaft coupling side stator end, be stator core notch front rod scaling loss; confirm as motor fault, protect correct operation and quickly excised fault. Owing to protecting the quick acting of device, reduce the difficulty of reparation, reduce loss.
Claims (1)
1. motor self-balancing differential protection structure, it comprises motor and the high-tension switch cabinet being connected with motor, it is characterised in that: in motor three-phase windings, every head of phase, 2 lead-out wires of tail press polarity also cross 1 self-balancing current transformer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410602605.8A CN105633913A (en) | 2014-10-31 | 2014-10-31 | Self-balancing differential protection structure for motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410602605.8A CN105633913A (en) | 2014-10-31 | 2014-10-31 | Self-balancing differential protection structure for motor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN105633913A true CN105633913A (en) | 2016-06-01 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410602605.8A Pending CN105633913A (en) | 2014-10-31 | 2014-10-31 | Self-balancing differential protection structure for motor |
Country Status (1)
| Country | Link |
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| CN (1) | CN105633913A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1665093A (en) * | 2005-03-18 | 2005-09-07 | 清华大学 | Large-scale steamer generator neutral point lead-out mode and arrangement protecting method |
| CN101882778A (en) * | 2010-06-30 | 2010-11-10 | 中国电力工程顾问集团华北电力设计院工程有限公司 | Incomplete differential protection technology for turbonator |
| CN103812086A (en) * | 2014-02-28 | 2014-05-21 | 中国能源建设集团广东省电力设计研究院 | High voltage electromotor protection system |
-
2014
- 2014-10-31 CN CN201410602605.8A patent/CN105633913A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1665093A (en) * | 2005-03-18 | 2005-09-07 | 清华大学 | Large-scale steamer generator neutral point lead-out mode and arrangement protecting method |
| CN101882778A (en) * | 2010-06-30 | 2010-11-10 | 中国电力工程顾问集团华北电力设计院工程有限公司 | Incomplete differential protection technology for turbonator |
| CN103812086A (en) * | 2014-02-28 | 2014-05-21 | 中国能源建设集团广东省电力设计研究院 | High voltage electromotor protection system |
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| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20160601 |