CN105006803B - Alternating current filter differential protecting method based on high voltage side current virtual value - Google Patents
Alternating current filter differential protecting method based on high voltage side current virtual value Download PDFInfo
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- CN105006803B CN105006803B CN201510450086.2A CN201510450086A CN105006803B CN 105006803 B CN105006803 B CN 105006803B CN 201510450086 A CN201510450086 A CN 201510450086A CN 105006803 B CN105006803 B CN 105006803B
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Abstract
The invention provides a kind of alternating current filter differential protecting method based on high voltage side current virtual value, it comprises the following steps：Step 1, alternating current filter high voltage side current and low-pressure side electric current are sampled；Step 2, the high voltage side current of sampling and low-pressure side electric current filtered by 50HZ, high and low pressure side difference between current stream is calculated using 50HZ components, and manservant of an official's stream definite value is compared；Step 3, calculating high voltage side current virtual value, and be compared with virtual value definite value；Step 4, it is more than difference stream definite value when high and low pressure side difference between current stream, and when high voltage side current virtual value is more than virtual value definite value simultaneously, the no-delay action outlet of differential protection, tripping high side switch, other situation differential protections are failure to actuate.The present invention makes a distinction because employing high voltage side current completely different feature when alternating current filter is exited with failure, it is ensured that protection energy action message when earth fault occurs for body, is reliably failure to actuate during alternating current filter is exited.
Description
Technical field
The invention belongs to alternating current filter technical field, and in particular to a kind of exchange filter based on high voltage side current virtual value
Ripple device differential protecting method.
Background technology
Power engineering alternating current filter structure and differential protection 87ACF schematic diagrames are as shown in figure 1, existing alternating current filter is poor
Dynamic Protection criteria is ABS (IT1-IT3) ﹥ △, and wherein IT1 is high voltage side current, and IT3 is low-pressure side electric current, and ABS represents to take absolutely
To value, △ is difference stream definite value.After differential Protection criteria ABS (IT1-IT3) ﹥ △ are met, protection act outlet, tripping high pressure
Side is switched.
Differential protection answers action message when earth fault occurs for alternating current filter body, should be reliable motionless under other situations
Make.But live repeatedly to occur during alternating current filter exits, the event of differential protection misoperation.
During alternating current filter is exited, A, B, C threephase switch disconnect successively, under normal circumstances, high and low pressure side A, B, C tri-
Phase current is cut off in zero crossing successively, and high and low pressure side electric current will not form poor stream, and differential protection will not be acted.
But the live recording of a protection misoperation event can be seen that during alternating current filter exits therefrom, high
Do not removed after pressure side A phase current zero passages, the afterflow of about 2/3 power frequency period is occurred in that, as shown in Fig. 2 high and low pressure side A phase currents
In the presence of the difference stream in 2/3 cycle, cause protection act.
It is can be seen that from the live recording of another protection misoperation event during alternating current filter exits, high-pressure side B
Do not removed after phase current zero passage, occur in that the afterflow of about 1/3 power frequency period, as shown in figure 3, high and low pressure side B phase currents are present
The difference stream in 1/3 cycle, causes protection act.
The content of the invention
Afterflow causes the problem of differential protection is acted during being exited for alternating current filter, and the present invention provides a kind of use
High voltage side current virtual value is as the alternating current filter differential protecting method of assistant criteria, and when earth fault occurs for body, energy can
By action, reliably it is failure to actuate during alternating current filter is exited.
To achieve these goals, the present invention is realized by following technical proposal:
A kind of alternating current filter differential protecting method based on high voltage side current virtual value, it comprises the following steps：
Step 1, alternating current filter high voltage side current IT1 and low-pressure side electric current IT3 are sampled；
Step 2, the high voltage side current IT1 of sampling and low-pressure side electric current IT3 filtered by 50HZ, using 50HZ components
High and low pressure side difference between current stream DIF is calculated, and manservant of an official's stream definite value is compared, and is used as the main criterion of alternating current filter differential protection；
Wherein, difference stream DIF computational methods are：
DIF (p)=| | IT1_50HZ (p) |-| IT3_50HZ (p) | | (1)
Wherein, DIF (p) is p interrupt cycle poor flow valuve, and IT1_50HZ (p) is p interrupt cycle high voltage side current value
50HZ component values；IT3_50HZ (p) be interrupt cycle p low-pressure side current value 50HZ component values；
Step 3, calculating high voltage side current IT1 virtual values, and be compared with virtual value definite value, it is poor as alternating current filter
The assistant criteria of dynamic protection, the computational methods of high voltage side current IT1 virtual values are as follows：
Wherein, IT1_rms (p) is p interrupt cycle high voltage side current IT1 virtual values, | IT1 (n) | for n's interrupt cycle
High voltage side current value, (p-N+1)≤n≤p, N is the interruption sampling number in a primitive period, and K is setting coefficient, its size
For sine wave virtual value and the ratio of average value；
Step 4, when interrupt period p high and low pressure side difference between current stream DIF (p) be more than difference stream definite value, and simultaneously high-pressure side electricity
When flowing virtual value IT1_rms (p) more than virtual value definite value, the no-delay action outlet of differential protection, tripping high side switch, other
Situation differential protection is failure to actuate.
The half of through current 50HZ component peak values when the difference stream definite value takes the alternating current filter normally to run.
Virtual value definite value is 0.8 times of through current virtual value when alternating current filter is normally run.
The present invention is by calculating high and low pressure side difference between current stream, and manservant of an official's stream definite value is compared, poor as alternating current filter
The main criterion of dynamic protection；High voltage side current IT1 virtual values are calculated, and are compared with virtual value definite value, alternating current filter is used as
The assistant criteria of differential protection；It is more than virtual value when high and low pressure side difference between current stream is more than difference stream definite value, high voltage side current virtual value
Definite value is met simultaneously when, that is, main criterion, the assistant criteria protected are while when meeting, protect no-delay action outlet, other situations
Protection is failure to actuate.
To form the time cooperation relation that the main criterion of alternating current filter differential protection, assistant criteria are certain, and reduce poor stream
The fluctuation of result of calculation, 50HZ filtering has been carried out to high and low pressure side electric current, and high and low pressure side difference between current stream is calculated using 50HZ components.
The present invention compared with prior art, has the following advantages that：Because employing high voltage side current when alternating current filter is exited
High voltage side current is basically unchanged this completely different feature and made a distinction when being reduced to 0 and alternating current filter failure, in exchange
The correct operation of protection is not influenceed during wave filter failure, protects and is reliably failure to actuate in the case of alternating current filter is exited.
Brief description of the drawings
Fig. 1 is existing alternating current filter structure and differential protection schematic diagram (by taking double tunning as an example)；
Fig. 2 is the live recording one of differential protection misoperation when alternating current filter is exited in Fig. 1；
Fig. 3 is the live recording two of differential protection misoperation when alternating current filter is exited in Fig. 1；
Fig. 4 is the logic chart of the alternating current filter differential protecting method of the invention based on high voltage side current virtual value；
Embodiment
Present disclosure is described in further details with reference to the accompanying drawings and detailed description.
Alternating current filter differential protecting method based on high voltage side current virtual value, it comprises the following steps：
(1) high voltage side current IT1 and low-pressure side electric current IT3 is carried out after 50HZ filtering, following dashed box is described in Fig. 4
It is a kind of calculate high and low pressure side difference between current stream programmed logic, respectively to high and low pressure side current draw 50HZ components, take absolute value, so
After subtract each other, then the result subtracted each other is taken absolute value, acquired results are poor stream, shown in formula (1).
(2) dashed box above Fig. 4 describes a kind of programmed logic for calculating high voltage side current IT1 virtual values, to high-pressure side
Electric current takes absolute value, and then calculates absolute value the average value of a cycle (power frequency period 20ms), and average value is multiplied by one and is
Number acquired results are virtual value, shown in formula (2).
(3) criterion：When the high and low pressure side difference between current stream of certain interrupt cycle is more than difference stream definite value, and high voltage side current virtual value
When being met more than virtual value definite value simultaneously, explanation is alternating current filter failure, the no-delay action outlet of differential protection, tripping high pressure
Side is switched, and other situation differential protections are failure to actuate.Wherein, preferably, difference stream definite value can use alternating current filter and normally transport
The half of through current 50HZ component peak values during row；It is effective that virtual value definite value can use through current when alternating current filter is normally run
0.8 times (certainly, can also be carried out suitably adjusting according to concrete engineering different parameters) of value.
Above-described embodiment is simply to illustrate that the technical concepts and features of the present invention, the purpose is to be to allow in the art
Those of ordinary skill can understand present disclosure and implement according to this, and it is not intended to limit the scope of the present invention.It is all
It is the equivalent change or modification made according to the essence of present invention, should all covers within the scope of the present invention.
Claims (4)
1. a kind of alternating current filter differential protecting method based on high voltage side current virtual value, it is characterised in that it includes following
Step：
Step 1, alternating current filter high voltage side current IT1 and low-pressure side electric current IT3 are sampled；
Step 2, the high voltage side current IT1 of sampling and low-pressure side electric current IT3 filtered by 50HZ, calculated using 50HZ components
High and low pressure side difference between current stream DIF, and the manservant of an official stream definite value be compared, be used as the main criterion of alternating current filter differential protection；Its
In, difference stream DIF computational methods are：
DIF (p)=| | IT1_50HZ (p) |-| IT3_50HZ (p) | | (1)
Wherein, DIF (p) be interrupt cycle p poor flow valuve, IT1_50HZ (p) be interrupt cycle p high voltage side current value 50HZ
Component value；IT3_50HZ (p) be interrupt cycle p low-pressure side current value 50HZ component values；
Step 3, calculating high voltage side current IT1 virtual values, and be compared with virtual value definite value, it is used as alternating current filter is differential to protect
The assistant criteria of shield, the computational methods of high voltage side current IT1 virtual values are as follows：
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Wherein, IT1_rms (p) is p interrupt cycle high voltage side current IT1 virtual values, | IT1 (n) | for n interrupt cycle high pressure
Side current value, (p-N+1)≤n≤p, N is the interruption sampling number in a primitive period, and K is setting coefficient, and its size is just
The ratio of string ripple virtual value and average value；
Step 4, when the high and low pressure side difference between current stream DIF (p) for interrupting period p is more than difference stream definite value, and high voltage side current has simultaneously
When valid value IT1_rms (p) is more than virtual value definite value, the no-delay action outlet of differential protection, tripping high side switch, other situations
Differential protection is failure to actuate.
2. the alternating current filter differential protecting method according to claim 1 based on high voltage side current virtual value, its feature
It is, the half of through current 50HZ component peak values when the difference stream definite value takes the alternating current filter normally to run.
3. the alternating current filter differential protecting method according to claim 1 based on high voltage side current virtual value, its feature
It is, virtual value definite value is 0.8 times of through current virtual value when alternating current filter is normally run.
4. the alternating current filter differential protecting method according to claim 1 based on high voltage side current virtual value, its feature
It is, the primitive period is 20ms.
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| CN106300290B (en) * | 2016-08-26 | 2018-07-06 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | A kind of DC transmission engineering alternating current filter group differential protection setting method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3984734A (en) * | 1974-10-29 | 1976-10-05 | Siemens Aktiengesellschaft | Protective circuit arrangement for a high-voltage capacitor bank |
| CN101127439A (en) * | 2007-07-20 | 2008-02-20 | 南方电网技术研究中心 | 50Hz and 100Hz protection and setting method for high voltage DC power input system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7660088B2 (en) * | 2005-09-07 | 2010-02-09 | Schweitzer Engineering Laboratories, Inc. | System, apparatus and method for compensating the sensitivity of a sequence element in a line current differential relay in a power system |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3984734A (en) * | 1974-10-29 | 1976-10-05 | Siemens Aktiengesellschaft | Protective circuit arrangement for a high-voltage capacitor bank |
| CN101127439A (en) * | 2007-07-20 | 2008-02-20 | 南方电网技术研究中心 | 50Hz and 100Hz protection and setting method for high voltage DC power input system |
Non-Patent Citations (2)
| Title |
|---|
| 《云广直流系统交流滤波器保护误动作分析及改进措施》;罗宇航 等;《电力系统保护与控制》;20110201;第39卷(第3期);第137-140页 * |
| 《交流滤波器速断类保护的误动及防治》;任峰 等;《山西电力》;20120630(第3期);第30-32页 * |
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