CN105006803A - AC filter differential protection method based on high-voltage side current effective value - Google Patents
AC filter differential protection method based on high-voltage side current effective value Download PDFInfo
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- CN105006803A CN105006803A CN201510450086.2A CN201510450086A CN105006803A CN 105006803 A CN105006803 A CN 105006803A CN 201510450086 A CN201510450086 A CN 201510450086A CN 105006803 A CN105006803 A CN 105006803A
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Abstract
The invention provides an AC filter differential protection method based on a high-voltage side current effective value. The method comprises the following steps that step one, high-voltage side current and low-voltage side current of an AC filter are sampled; step two, 50HZ filtering is performed on the sampled high-voltage side current and low-voltage side current, differential current of high-voltage side and low-voltage side current is calculated by adopting a 50HZ component and is compared with a differential current fixed value; step three, a high-voltage side current effective value is calculated and compared with an effective value fixed value; and step four, when differential current of high-voltage side and low-voltage side current is greater than the differential current fixed value and the high-voltage side current effective value is greater than the effective value fixed value, actuation of differential protection is outputted without time delay, a high-voltage side switch is tripped off, and differential protection does not actuate under other conditions. Distinguishing is performed by adopting different characteristics of high-voltage side current when the AC filter withdraws and fails to work so that reliable actuation protection in a local grounding fault can be guaranteed and no actuation in the withdrawing process of the AC filter can be reliably guaranteed.
Description
Technical field
The invention belongs to alternating current filter technical field, be specifically related to a kind of alternating current filter differential protecting method based on high voltage side current effective value.
Background technology
Power engineering alternating current filter structure and differential protection 87ACF schematic diagram are as shown in Figure 1; existing alternating current filter differential protection criterion is ABS (IT1-IT3) ﹥ △, and wherein IT1 is high voltage side current, and IT3 is low-pressure side electric current; ABS represents and takes absolute value, and △ is difference stream definite value.After differential Protection criteria ABS (IT1-IT3) ﹥ △ meets, protection act exports, tripping high side switch.
Differential protection answers action message when alternating current filter body generation earth fault, should reliably be failure to actuate under other situations.But scene repeatedly occurs that alternating current filter exits in process, the event of differential protection misoperation.
Alternating current filter exits in process, and A, B, C threephase switch disconnects successively, and under normal circumstances, high and low pressure side A, B, C three-phase current is successively in zero crossing excision, and high and low pressure side electric current can not form difference stream, and differential protection can not action.
But as can be seen from the scene record ripple of a wherein protection misoperation event, alternating current filter exits in process, does not remove after the A phase current zero passage of high-pressure side; there is the afterflow of about 2/3 power frequency period; as shown in Figure 2, there is the difference stream in 2/3 cycle in high and low pressure side A phase current, causes protection act.
As can be seen from the scene record ripple of another protection misoperation event, alternating current filter exits in process, does not remove after the B phase current zero passage of high-pressure side; there is the afterflow of about 1/3 power frequency period; as shown in Figure 3, there is the difference stream in 1/3 cycle in high and low pressure side B phase current, causes protection act.
Summary of the invention
The problem that afterflow in process causes differential protection action is exited for alternating current filter; the invention provides a kind of high voltage side current effective value that adopts as the alternating current filter differential protecting method of assistant criteria; when body generation earth fault, energy action message, exits in process at alternating current filter and is reliably failure to actuate.
To achieve these goals, the present invention is realized by following technical proposal:
Based on an alternating current filter differential protecting method for high voltage side current effective value, it comprises the following steps:
Step 1, alternating current filter high voltage side current IT1 and low-pressure side electric current I T3 to be sampled;
Step 2, by the high voltage side current IT1 of sampling and low-pressure side electric current I T3 all by 50HZ filtering, adopt 50HZ component calculating high and low pressure side difference between current stream DIF, and the manservant of an official flows definite value compares, as the main criterion of alternating current filter differential protection; Wherein, the computational methods of difference stream DIF are:
DIF(p)＝||IT1_50HZ(p)|-|IT3_50HZ(p)|| (1)
Wherein, DIF (p) is the poor flow valuve of p interrupt cycle, and IT1_50HZ (p) is the 50HZ component value of high voltage side current value of p interrupt cycle; IT3_50HZ (p) is the 50HZ component value of low-pressure side current value of p interrupt cycle;
Step 3, calculating high voltage side current IT1 effective value, and compare with effective value definite value, as the assistant criteria of alternating current filter differential protection, the computational methods of high voltage side current IT1 effective value are as follows:
Wherein, IT1_rms (p) is the high voltage side current IT1 effective value of p interrupt cycle, | IT1 (n) | be the high voltage side current value of n interrupt cycle, (p-N+1)≤n≤p, N is the interruption sampling number in the primitive period, K is setting coefficient, and its size is the ratio of sinusoidal wave effective value and mean value;
Step 4, be greater than difference stream definite value when interrupting high and low pressure side difference between current stream DIF (p) of period p; and when high voltage side current effective value IT1_rms (p) is greater than effective value definite value simultaneously; differential protection exports without deferred action; tripping high side switch, other situation differential protections are failure to actuate.
Described difference stream definite value gets the half of through current 50HZ component peak value when alternating current filter normally runs.
Effective value definite value is alternating current filter 0.8 times of through current effective value when normally running.
The present invention is by calculating high and low pressure side difference between current stream, and the manservant of an official flows definite value compares, as the main criterion of alternating current filter differential protection; Calculate high voltage side current IT1 effective value, and compare, as the assistant criteria of alternating current filter differential protection with effective value definite value; When high and low pressure side difference between current stream be greater than difference stream definite value, high voltage side current effective value be greater than effective value definite value meet simultaneously time, when the main criterion namely protected, assistant criteria meet simultaneously, protection is without deferred action outlet, and the protection of other situations is failure to actuate.
For forming alternating current filter differential protection main criterion, time cooperation relation that assistant criteria is certain, and reducing the fluctuation of differential current computing result, 50HZ filtering having been carried out to high and low pressure side electric current, has adopted 50HZ component to calculate high and low pressure side difference between current stream.
The present invention compared with prior art; tool has the following advantages: distinguish because have employed high voltage side current this distinct feature substantially constant when high voltage side current when alternating current filter exits is reduced to 0 and alternating current filter fault; do not affect the correct operation of protection when alternating current filter fault, protect under alternating current filter exits situation and be reliably failure to actuate.
Accompanying drawing explanation
Fig. 1 is existing alternating current filter structure and differential protection schematic diagram (for double tunning);
Fig. 2 is the scene record ripple one of differential protection misoperation when alternating current filter exits in Fig. 1;
Fig. 3 is the scene record ripple two of differential protection misoperation when alternating current filter exits in Fig. 1;
Fig. 4 is the logic diagram of the alternating current filter differential protecting method that the present invention is based on high voltage side current effective value;
Embodiment
Below in conjunction with the drawings and specific embodiments, content of the present invention is described in further details.
Based on the alternating current filter differential protecting method of high voltage side current effective value, it comprises the following steps:
(1) after 50HZ filtering being carried out to high voltage side current IT1 and low-pressure side electric current I T3, empty frame below in Fig. 4 describes a kind of programmed logic calculating high and low pressure side difference between current stream, respectively to high and low pressure side current draw 50HZ component, take absolute value, then subtract each other, again the result of subtracting each other is taken absolute value, acquired results is difference stream, shown in formula (1).
(2) the empty frame above Fig. 4 describes a kind of programmed logic calculating high voltage side current IT1 effective value, high voltage side current is taken absolute value, then absolute value is calculated to the mean value of a cycle (power frequency period 20ms), mean value is multiplied by a coefficient acquired results and is effective value, shown in formula (2).
(3) criterion: the high and low pressure side difference between current stream when certain interrupt cycle is greater than difference stream definite value; and high voltage side current effective value is greater than effective value definite value when meeting simultaneously; explanation is alternating current filter fault; differential protection exports without deferred action; tripping high side switch, other situation differential protection is failure to actuate.Wherein, preferably, the half of through current 50HZ component peak value when the desirable alternating current filter of difference stream definite value normally runs; 0.8 times (certainly, also suitably can adjust according to concrete engineering different parameters) of through current effective value when the desirable alternating current filter of effective value definite value normally runs.
Above-described embodiment, just in order to technical conceive of the present invention and feature are described, its objective is and is one of ordinary skilled in the art can be understood content of the present invention and implement according to this, can not limit the scope of the invention with this.The change of every equivalence made according to the essence of content of the present invention or modification, all should be encompassed in protection scope of the present invention.
Claims (4)
1., based on an alternating current filter differential protecting method for high voltage side current effective value, it is characterized in that, it comprises the following steps:
Step 1, alternating current filter high voltage side current IT1 and low-pressure side electric current I T3 to be sampled;
Step 2, by the high voltage side current IT1 of sampling and low-pressure side electric current I T3 all by 50HZ filtering, adopt 50HZ component calculating high and low pressure side difference between current stream DIF, and the manservant of an official flows definite value compares, as the main criterion of alternating current filter differential protection; Wherein, the computational methods of difference stream DIF are:
DIF(p)＝||IT1_50HZ(p)|-|IT3_50HZ(p)|| (1)
Wherein, DIF (p) is the poor flow valuve of p interrupt cycle, and IT1_50HZ (p) is the 50HZ component value of high voltage side current value of p interrupt cycle; IT3_50HZ (p) is the 50HZ component value of low-pressure side current value of p interrupt cycle;
Step 3, calculating high voltage side current IT1 effective value, and compare with effective value definite value, as the assistant criteria of alternating current filter differential protection, the computational methods of high voltage side current IT1 effective value are as follows:
Wherein, IT1_rms (p) is the high voltage side current IT1 effective value of p interrupt cycle, | IT1 (n) | be the high voltage side current value of n interrupt cycle, (p-N+1)≤n≤p, N is the interruption sampling number in the primitive period, K is setting coefficient, and its size is the ratio of sinusoidal wave effective value and mean value;
Step 4, be greater than difference stream definite value when interrupting high and low pressure side difference between current stream DIF (p) of period p; and when high voltage side current effective value IT1_rms (p) is greater than effective value definite value simultaneously; differential protection exports without deferred action; tripping high side switch, other situation differential protections are failure to actuate.
2. the alternating current filter differential protecting method based on high voltage side current effective value according to claim 1, is characterized in that, described difference stream definite value gets the half of through current 50HZ component peak value when alternating current filter normally runs.
3. the alternating current filter differential protecting method based on high voltage side current effective value according to claim 1, is characterized in that, effective value definite value is alternating current filter 0.8 times of through current effective value when normally running.
4. the alternating current filter differential protecting method based on high voltage side current effective value according to claim 1, is characterized in that, the described primitive period is 20ms.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106300290A (en) * | 2016-08-26 | 2017-01-04 | 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 (3)
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|---|---|---|---|---|
| US3984734A (en) * | 1974-10-29 | 1976-10-05 | Siemens Aktiengesellschaft | Protective circuit arrangement for a high-voltage capacitor bank |
| US20070070565A1 (en) * | 2005-09-07 | 2007-03-29 | 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 |
| 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 |
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Patent Citations (3)
| 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 |
| US20070070565A1 (en) * | 2005-09-07 | 2007-03-29 | 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 |
| 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)
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| 任峰 等: "《交流滤波器速断类保护的误动及防治》", 《山西电力》 * |
| 罗宇航 等: "《云广直流系统交流滤波器保护误动作分析及改进措施》", 《电力系统保护与控制》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106300290A (en) * | 2016-08-26 | 2017-01-04 | 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 |
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