阅读说明：本技术 一种应用于过流保护的延时计算方法 (Delay calculation method applied to overcurrent protection ) 是由 丁晓兵 王风光 徐鹏 张弛 彭业 吕航 李力 杨贵 于 2020-05-21 设计创作，主要内容包括：本发明公开了一种应用于过流保护的延时计算方法,采集数字化电流,得到电流幅值<Image he="74" wi="88" file="DDA0002502287470000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>和电流幅值<Image he="78" wi="111" file="DDA0002502287470000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>判断该两个电流幅值是否相等,如果不相等且该两个电流幅值均小于电流定值门槛时,时间计数器清零,如果幅值不相等,且任一幅值大于电流定值门槛,或者幅值相等但是<Image he="71" wi="90" file="DDA0002502287470000013.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>数据品质异常,则认为该采样点为异常采样点,并根据上一个采样点计算当前时间计数器的值t,当时间计数器t大于预设的时间阈值时,过流保护动作。本发明所述的方法,解决了数据品质间断异常时过流保护慢动或者拒动的问题,避免了事故范围扩大化。(The invention discloses a time delay calculation method applied to overcurrent protection, which is used for acquiring digital current to obtain current amplitude Sum current amplitude Judging whether the two current amplitudes are equal, if not, resetting the time counter when the two current amplitudes are both smaller than the current fixed value threshold, if not, resetting the time counter when any one of the two current amplitudes is larger than the current fixed value threshold, or else, the two current amplitudes are equal but smaller than the current fixed value threshold If the data quality is abnormal, the sampling point is considered as an abnormal sampling point, and the current time counter is calculated according to the previous sampling pointAnd the value t is used for performing overcurrent protection when the time counter t is greater than a preset time threshold value. The method solves the problem of slow movement or refusal movement of the overcurrent protection when the data quality is discontinuous and abnormal, and avoids the expansion of the accident range.)

1. A delay calculation method applied to overcurrent protection is applied to an overcurrent protection module of relay protection, and is characterized by comprising the following steps:

step 1: when the current sampling point passes, the digital current in the overcurrent protection module is collected to obtain SV data, so that the current amplitude value is obtained

Step 2: when in useLess than a predetermined abnormal current thresholdTurning to step 3; otherwise, turning to the step 5;

and step 3: judging the current amplitudeWhether the current is greater than a preset current fixed value threshold valueIf yes, turning to step 4; otherwise, resetting the time counter, and continuing to collect the next sampling point in the step 1;

and 4, step 4: judging the current amplitude

and 5: judgment of

step 6: judging whether the value t of the current time counter is greater than a preset time threshold value, if so, starting overcurrent protection; otherwise, turning to the step 1, and continuing to collect the next sampling point.

2. The delay calculation method applied to overcurrent protection according to claim 1, wherein in steps 4 and 5: the specific method for calculating the value t of the current time counter according to the last sampling point comprises the following steps: judging whether the last sampling point is an abnormal sampling point, if so, judging that the current sampling point is the nth abnormal sampling point in the continuous abnormal sampling points, and when t is_-1When-nk < 0, t is 0, when t is_-1When-nk is more than or equal to 0, t is t_-1-nk, where k is a coefficient and k > 1, t_-1The value of the time counter corresponding to the last sampling point; otherwise, when t_-1When k < 0, t is 0, when t is_-1When-k is greater than or equal to 0, t is t_-1-k。

3. The delay calculation method applied to overcurrent protection according to claim 1, wherein when the current rating IN of the current transformer is 1A,

4. The delay calculating method applied to overcurrent protection according to claim 1, wherein when the overcurrent protection of the relay protection is phase overcurrent protection, the time counter is a split-phase counter, and each phase counter is independent of each other.

Technical Field

The invention belongs to the field of relay protection of power systems.

Background

For the overcurrent protection, when the amplitude of the input current is greater than the current fixed value threshold and the time counter is greater than the time fixed value threshold, the overcurrent protection is performed. If the quality of the input current is abnormal, the current method is to lock the overcurrent protection function and clear the time counter.

When system faults occur and data quality is discontinuous and abnormal, the existing method can cause that overcurrent protection is refused to operate and the previous stage of protection action needing overcurrent protection trips, so that the accident range is expanded.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the problem that the prior art has the risk of refusing the action of overcurrent protection, the invention provides a delay calculation method applied to overcurrent protection.

The technical scheme is as follows: the invention provides a delay calculation method applied to overcurrent protection, which is applied to an overcurrent protection module of relay protection and specifically comprises the following steps:

step 1: when the current sampling point passes, the digital current in the overcurrent protection module is collected to obtain SV data, so that the current amplitude value is obtained

Sum current amplitude

Step 2: when in use

Less than a predetermined abnormal current threshold

Turning to step 3; otherwise, turning to the step 5;

and step 3: judging the current amplitudeWhether the current is greater than a preset current fixed value threshold valueIf yes, turning to step 4; otherwise, resetting the time counter, and continuing to collect the next sampling point in the step 1;

and 4, step 4: judging the current amplitude

If not, the value t of the current time counter is t +1, and go to step 6; otherwise, the current sampling point is regarded as an abnormal sampling point, and the value t of the current time counter is calculated according to the last sampling point, and the step 6 is carried out;

and 5: judgment ofOrWhether or not greater thanIf yes, the current sampling point is also determined as an abnormal sampling point, and meanwhile, the sampling point is determined as the previous sampling pointCalculating the value t of the current time counter by the sampling point, and turning to step 6; otherwise, resetting the time counter, and continuing to collect the next sampling point in the step 1;

step 6: judging whether the value t of the current time counter is greater than a preset time threshold value, if so, starting overcurrent protection; otherwise, turning to the step 1, and continuing to collect the next sampling point.

Further, the specific method for calculating the value of the current time counter according to the previous sampling point in the steps 4 and 5 is as follows: judging whether the last sampling point is an abnormal sampling point, if so, judging that the current sampling point is the nth abnormal sampling point in the continuous abnormal sampling points, and when t is_-1-nk<When t is 0, t is 0_-1When-nk is more than or equal to 0, t is t_-1-nk, where k is a coefficient and k > 1, t_-1The value of the time counter corresponding to the last sampling point; otherwise, when t_-1-k<When t is 0, t is 0_-1When-k is greater than or equal to 0, t is t_-1-k。

Further, when the current value IN of the current transformer is 1A,

the value range of (A) is 0.04-0.06A; when the current rating value IN of the current transformer is 5A,

the value range of (A) is 0.2-0.3A.

Further, when the overcurrent protection of the relay protection is phase overcurrent protection, the time counter adopts a split-phase counter, and each phase counter is independent.

Has the advantages that: compared with the prior art, the method can reduce the risk of slow movement or refusal movement of overcurrent protection when system failure occurs and data quality is in discontinuous abnormity, thereby keeping the protection function as much as possible and preventing the accident scope from being expanded.

Drawings

FIG. 1 is a flow chart of the present invention.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention.

As shown in fig. 1, the present embodiment provides a delay calculation method applied to overcurrent protection, which specifically includes the following steps:

step 1: when the current sampling point passes, the first and second acquisition modules simultaneously acquire the digital current in the overcurrent protection module to obtain SV data (sampling data), and the current amplitude value is calculated according to the digital current acquired by the first acquisition module in the SV data

Calculating to obtain a current amplitude value according to the digital current acquired by the second acquisition module in the SV data

In this embodiment, a Link sampling Valid bit (Valid), a Link communication normal bit (Link), and a Link communication Enable bit (Enable) in SV data quality are processed respectively.

Step 2: when in useLess than a predetermined abnormal current thresholdTurning to step 4; otherwise, turning to the step 3.

And step 3: judgment ofOr

Whether the current is greater than a preset current fixed value threshold valueIf yes, the current sampling point is determined as an abnormal sampling point,and 6, calculating the value t of the current time counter according to the last sampling point, and turning to the step 6. If it is

Andare all less than the preset current constant value thresholdAnd if the time counter t is equal to 0, continuing to acquire the digital current of the next sampling point, and turning to the step 1.

And 4, step 4: judging the current amplitudeWhether or not greater thanAnd (5) if so, continuing to collect the digital current of the next sampling point, and turning to the step 1, otherwise, keeping the time counter t equal to 0.

And 5: judgment of

If the data quality is normal, the value t of the current time counter is t +1, and go to step 6; otherwise, the current sampling point is determined as an abnormal sampling point, and the value t of the current time counter is calculated according to the last sampling point.

Step 6: judging whether t is greater than a preset time threshold value, if yes, performing overcurrent protection action; and otherwise, continuously acquiring the digital current of the next sampling point, and turning to the step 1.

In this embodiment, when the Enable bit in the SV data quality is 1, if the Valid bit is 0 or the Link bit is 0, the data quality is considered to be abnormal; when the Enable bit in the SV data quality is 1, if the Valid bit is 1 and the Link bit is 1, the data quality is considered to be normal; when the Enable bit in the SV data quality is 0, the overcurrent protection function is exited.

Preferably, when currently minedWhen the sampling point is an abnormal sampling point, the specific method for calculating the value t of the current time counter is as follows: judging whether the last sampling point is an abnormal sampling point, if so, judging that the current sampling point is the nth abnormal sampling point in the continuous abnormal sampling points, and when t is_-1-nk<When t is 0, t is 0_-1When-nk is more than or equal to 0, t is t_-1-nk, where k is a coefficient and k > 1, t_-1The value of the time counter corresponding to the last sampling point; otherwise, when t_-1-k<When t is 0, t is 0_-1When-k is greater than or equal to 0, t is t_-1-k。

Preferably, when the current rating value IN of the current transformer is 1A,

the value range of (A) is 0.04-0.06A; when the current rating value IN of the current transformer is 5A,

the value range of (A) is 0.2-0.3A.

Preferably, in this embodiment, when the overcurrent protection is phase overcurrent protection, the time counter is a split-phase counter, and when the data quality of a certain phase current SV is abnormal, only the time counter corresponding to the phase current protection is affected, and the other two phase time counters are not affected.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.