Intelligent contactor overcurrent protection delay determination method and intelligent contactor overcurrent protection delay protection method

Abstract

The invention belongs to the technical field of intelligent contactor over-current protection design, and particularly relates to an intelligent contactor over-current protection delay determination method and a delay protection method thereof, and the intelligent contactor over-current protection delay determination method comprises the following steps: t = L / s * c; s = S (It), Itlt; i < 1.7 >; s = a1 * It + b1, and I1.7 is less than or equal to Itlt; i2; s = a2 * It + b2, and I2 is less than or equal to Itlt; i3; s = a3 * It + b3, and I3 is less than or equal to Itlt; i4; s = a4 * It + b4, and I4 is less than or equal to Itlt; i5; s (It) = a1 * It + b1, t is the protection delay, L is the total delay step length, s is the step length, and c is the operation period; it is real-time monitoring effective current, and I1.7, I2, I3, I4 and I5 are 1.7, 2, 3, 4 and 5 times of rated current; s (It) is a dynamic delay recovery step length; a1, a2, a3 and a4 are used for calculating the straight slope for the protection delay step length corresponding to the corresponding effective current, and b1, b2, b3 and b4 are used for calculating the straight intercept for the protection delay step length corresponding to the corresponding effective current.

Description

Technical Field

[0001] The present application belongs to the technical field of intelligent contactor overcurrent protection design, and specifically relates to an intelligent contactor overcurrent protection delay determination method and a delay protection method thereof. Background Art

[0002] The intelligent contactor control module is a key component of the platform power distribution system. It usually works together with the intelligent contactor control software to complete the control, fault protection, self-detection, fault isolation, communication and data recording of the platform power distribution system.

[0003] Fault protection is an indispensable function of intelligent contactor control. It can ensure that the intelligent contactor control takes necessary measures to ensure the safety of electrical equipment in an overcurrent state. Usually, the fault protection function of intelligent contactor control is realized by the intelligent contactor control software. The intelligent contactor control software compares the sampling value and the threshold value, determines that a fault has occurred and delays when it is judged that the fault condition is met, and disconnects the contactor for protection after the delay time. The delay process is the process of confirming the fault. Reasonable delay can detect overcurrent faults in time to prevent damage to electrical equipment, and can avoid malfunctions caused by interference signals or transients. Therefore, the accuracy of protection delay is particularly important.

[0004] From the perspective of the harm caused by large current of electrical equipment to itself and the line, overcurrent protection has an anti-delay characteristic, that is, the higher the current, the shorter the delay time and the faster the action. At present, a step-by-step algorithm is used to set the corresponding delay in different current ranges. By judging the current value, different step sizes are set in different ranges to obtain different delays. The delay step consists of two parts. The first part is the dynamic integration step, that is, the step size set in different current ranges. The second part is the overcurrent protection recovery step, which is a fixed value.

[0005] When the intelligent contactor control software runs with a cycle of 10ms, when the current value is greater than the overcurrent protection threshold value, the delay value of each cycle increases according to the step size. When the delay time reaches the set value, the protection is performed. Otherwise, the overcurrent protection delay decreases according to the overcurrent protection recovery step size. Under the current protection delay, within the protection area, that is, when the current value is greater than the overcurrent protection threshold value, the overcurrent protection delay is determined by calculating the dynamic integral step length using the method of determining a straight line with two points. The step-type overcurrent protection delay curve designed by this method meets the overcurrent protection anti-delay requirements and has no time jump within the protection area. However, within the protection recovery area, that is, when the current value is lower than the overcurrent protection threshold value, the fixed overcurrent protection recovery step length is not adaptable enough to current fluctuations. First, when the fixed overcurrent protection recovery step length is too large, the current value protection at some points will be too slow. When it is too small, the current value protection at some points will be too fast, causing false protection. Secondly, the fixed overcurrent protection recovery step length cannot achieve the ideal requirements of fast overcurrent protection delay recovery when the real-time current value is large and slow overcurrent protection delay recovery when the real-time current value is small. It cannot adaptively adjust the duration of the overcurrent protection delay recovery according to the current size.

[0006] This application is proposed in view of the above-mentioned technical defects. Summary of the invention

[0007] The purpose of the present application is to provide a method for determining the delay of overcurrent protection of an intelligent contactor and a delayed protection method thereof, so as to overcome or alleviate at least one aspect of the known technical defects.

[0008] The technical solution of this application is:

[0009] On the one hand, a method for determining an overcurrent protection delay of an intelligent contactor is provided, comprising:

[0010] t = L / s × c;

[0011]

[0012] S(I t )=a1×I t +b1;

[0013] in,

[0014] t is the protection delay, L is the total delay step, s is the step length, and c is the operation cycle;

[0015] I t To monitor the effective current in real time, I 1.7 , I2, I3, I4, I5 are 1.7, 2, 3, 4, 5 times the rated current;

[0016] S(I t ) is the dynamic delay recovery step length;

[0017] a1, a2, a3, and a4 are the slopes of the straight lines for calculating the protection delay step lengths corresponding to the corresponding effective currents, and b1, b2, b3, and b4 are the intercepts of the straight lines for calculating the protection delay step lengths corresponding to the corresponding effective currents.

[0018] According to at least one embodiment of the present application, in the above-mentioned method for determining the overcurrent protection delay of the intelligent contactor, c is 10 ms.

[0019] According to at least one embodiment of the present application, in the above-mentioned method for determining the overcurrent protection delay of the intelligent contactor,

[0020] in,

[0021] t 1.7 , t2 is 1.7 and 2 times of the rated current, corresponding to the overcurrent protection inverse delay requirements.

[0022] According to at least one embodiment of the present application, in the above-mentioned method for determining the overcurrent protection delay of the intelligent contactor,

[0023] in,

[0024] t3 is 3 times the rated current, corresponding to the overcurrent protection inverse delay requirement.

[0025] According to at least one embodiment of the present application, in the above-mentioned method for determining the overcurrent protection delay of the intelligent contactor,

[0026] in,

[0027] t4 is 4 times the rated current, corresponding to the overcurrent protection inverse delay requirement.

[0028] According to at least one embodiment of the present application, in the above-mentioned method for determining the overcurrent protection delay of the intelligent contactor,

[0029] in,

[0030] t5 is 5 times the rated current, corresponding to the overcurrent protection inverse delay requirement.

[0031] On the other hand, a method for determining the overcurrent protection delay of an intelligent contactor is provided. Based on the above method for determining the overcurrent protection delay of an intelligent contactor, the protection delay t of each section of the effective current is monitored in real time, including:

[0032] Calculate real-time monitoring effective current I t ;

[0033] Real-time monitoring of effective current I t When the current is greater than 5 times the rated current I5, the overcurrent fault flag is set to fault, the short circuit delay is 10 cycles, and the short circuit fault protection flag is set to fault;

[0034] Real-time monitoring of effective current I t When it is less than 5 times the rated current I5 and greater than 4 times the rated current I4, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 4-5 times rated current section I4-I5;

[0035] Real-time monitoring of effective current I t When it is less than 4 times the rated current I4 and greater than 3 times the rated current I3, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 3-4 times rated current section I3-I4;

[0036] Real-time monitoring of effective current I t When it is less than 3 times the rated current I3 and greater than 2 times the rated current I2, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 2-3 times rated current section I2-I3;

[0037] Real-time monitoring of effective current I t Less than 2 times the rated current I2 and greater than 1.7 times the rated current I 1.7 When the overcurrent fault flag is set to fault, the heat accumulation value is 1.7-2 times the rated current section I 1.7 -I2 protection delay function accumulation;

[0038] Real-time monitoring of effective current I t Less than 1.7 times the rated current I 1.7 When the overcurrent fault flag is set to normal, the short-circuit delay count is reset, and the thermal accumulation value is judged to be greater than 0. If the thermal accumulation value is greater than 0, it is judged whether the thermal accumulation value is greater than 1.7 times the rated current I 1.7 The square of the real-time monitoring effective current I t If the square of the heat accumulation value is equal to the dynamic delay recovery step length S(I t ), if not, set the heat accumulation value to 0;

[0039] Determine whether the heat accumulation value is greater than the overcurrent heat accumulation protection threshold. If so, set the overcurrent protection fault flag to fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the intelligent contactor overcurrent delay protection method provided in an embodiment of the present application.

[0041] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. In addition, the drawings are only used for illustrative purposes and should not be construed as limitations on the present application. DETAILED DESCRIPTION

[0042] In order to make the technical solution and advantages of the present application clearer, the technical solution of the present application will be described in further detail in detail and in detail with reference to the accompanying drawings. It can be understood that the specific embodiments described here are only partial embodiments of the present application, which are only used to explain the present application, not to limit the present application. It should be noted that, for the convenience of description, only the parts related to the present application are shown in the accompanying drawings, and other related parts can refer to the general design.

[0043] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall have the usual meanings understood by those of ordinary skill in the art to which this application belongs. The words used in the description of this application to indicate orientation are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application indicates that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0044] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0045] The current method for determining the overcurrent protection delay of the intelligent contactor is as follows:

[0046] t = L / s × c;

[0047]

[0048] in,

[0049] t is the protection delay, L is the total delay step, s is the step length, and c is the operation cycle, which can be 10ms;

[0050] I t To monitor the effective current in real time, I 1.7 , I2, I3, I4, I5 are 1.7, 2, 3, 4, 5 times the rated current;

[0051] b0 is the fixed delay recovery step length;

[0052] a1, a2, a3, and a4 are the slopes of the straight lines for calculating the protection delay step lengths corresponding to the corresponding effective currents, and b1, b2, b3, and b4 are the intercepts of the straight lines for calculating the protection delay step lengths corresponding to the corresponding effective currents.

[0053] The present application provides a method for determining the overcurrent protection delay of an intelligent contactor. Based on the original step calculation, the fixed overcurrent protection recovery step is changed to an overcurrent protection recovery step adapted to the current value, so that when the current value is less than the overcurrent protection threshold value, the smaller the current value, the larger the overcurrent protection recovery step, and the faster the overcurrent protection delay recovery.

[0054] The step s is calculated as follows:

[0055]

[0056] S(I t ) = a1 × I t + b1 It < I0;

[0057] Wherein,

[0058] S(I t ) is the dynamic delay recovery step, and I0 is the current value at S(I t ).

[0059] The dynamic delay recovery step S(It), when the step calculated at I t < I0 is negative. At this time, the dynamic delay recovery step S(It) calculated according to the current is added to the total step L to implement the overcurrent protection exit mechanism.

[0060] a1, a2, a3, a4, b1, b2, b3, b4 are calculated as follows:

[0061]

[0062]

[0063]

[0064]

[0065] Wherein,

[0066] t 1.7 , t2, t3, t4, t5 are 1.7, 2, 3, 4, 5 times the rated current, corresponding to the inverse time delay requirements of overcurrent protection.

[0067] In a specific example, the operating point current of the overcurrent protection is 1.7 times the rated current. When it is sensitive that the highest phase current exceeds the operating point current, the intelligent contactor module performs protection according to the following inverse time delay characteristics table. <![CDATA[Real-time monitoring of the effective current I t (A)]]> Overcurrent protection delay requirement (S) <![CDATA[I2>I t ≥I 1.7 ]]> No more than 105 <![CDATA[I3>I t ≥I2]]> Not more than 13.125 <![CDATA[I4>I t ≥I3]]> Not more than 3.153153 <![CDATA[I5>I t ≥I4]]> Not more than 1.693548 <![CDATA[I t ≥I5]]> No more than 0.5

[0068] For "I i > current ≥ I j , the overcurrent protection inverse time delay is not greater than t" can be simplified to "the current is Ij When the delay time is not greater than t", the anti-delay requirements for overcurrent protection in the above table can be obtained, as shown in the following table: <![CDATA[Real-time monitor of the effective current I t (A)]]> <![CDATA[I 1.7 ]]> <![CDATA[I2]]> <![CDATA[I3]]> <![CDATA[I4]]> <![CDATA[I5]]> Overcurrent protection delay requirement (S) 105 13.125 3.153153 1.693548 0.4995

[0069] Protection delay t and real-time monitoring of effective current I t The relationship is:

[0070] t = L / s × c;

[0071] Among them, L is the total delay step, c is the operation cycle, and s is the step size.

[0072] For the current range (I i ,I j ), I i ,I j The corresponding protection delays are t1 and t2 respectively. The corresponding protection delay step can be calculated by the equation group to calculate the slope a of the straight line. i , intercept b i :

[0073]

[0074] Let L×c=105, calculate the slope and intercept of the protection delay step calculation line corresponding to the corresponding effective current, a1, a2, a3, a4, b1, b2, b3, b4 as follows:

[0075]

[0076]

[0077]

[0078]

[0079] For the inverse delay step:

[0080] when When it is equal to 0, I t =I 1.677 , that is, when the monitoring current It is less than 1.677 times the rated current I, the dynamic delay recovery step length S (I t )for

[0081] The method for determining the overcurrent protection delay of an intelligent contactor disclosed in the above-mentioned embodiment improves the existing method for determining the overcurrent protection delay of an intelligent contactor, so that it is close to the inverse delay protection requirement within the protection area, can automatically adapt to the current sampling fluctuation at the protection critical point, and can adjust the duration of the overcurrent protection delay recovery according to the current size within the protection recovery area, and has high practicality.

[0082] Based on the method for determining the overcurrent protection delay of the intelligent contactor disclosed in the above embodiment, the protection delay t of each section of the effective current is determined by real-time monitoring. The overcurrent delay protection method of the intelligent contactor is implemented as follows: Figure 1 shown.

[0083] Calculate real-time monitoring effective current I t ;

[0084] Real-time monitoring of effective current I t When the current is greater than 5 times the rated current I5, the overcurrent fault flag is set to fault, the short circuit delay is 10 cycles, and the short circuit fault protection flag is set to fault;

[0085] Real-time monitoring of effective current I t When it is less than 5 times the rated current I5 and greater than 4 times the rated current I4, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 4-5 times rated current section I4-I5;

[0086] Real-time monitoring of effective current I t When it is less than 4 times the rated current I4 and greater than 3 times the rated current I3, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 3-4 times rated current section I3-I4;

[0087] Real-time monitoring of effective current I t When it is less than 3 times the rated current I3 and greater than 2 times the rated current I2, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 2-3 times rated current section I2-I3;

[0088] Real-time monitoring of effective current I t Less than 2 times the rated current I2 and greater than 1.7 times the rated current I 1.7 When the overcurrent fault flag is set to fault, the heat accumulation value is 1.7-2 times the rated current section I 1.7 -I2 protection delay function accumulation;

[0089] Real-time monitoring of effective current I t Less than 1.7 times the rated current I 1.7 When the overcurrent fault flag is set to normal, the short-circuit delay count is reset, and the thermal accumulation value is judged to be greater than 0. If the thermal accumulation value is greater than 0, it is judged whether the thermal accumulation value is greater than 1.7 times the rated current I1.7 The square of the real-time monitoring effective current I t If the square of the heat accumulation value is equal to the dynamic delay recovery step length S(I t ), if not, set the heat accumulation value to 0;

[0090] Determine whether the heat accumulation value is greater than the overcurrent heat accumulation protection threshold. If so, set the overcurrent protection fault flag to fault.

[0091] For the intelligent contactor overcurrent protection delay determination method disclosed in the above embodiment, the intelligent contactor overcurrent protection delay determination method disclosed in the above embodiment is implemented, and the description is relatively simple. For specific related matters, please refer to the relevant description of the intelligent contactor overcurrent protection delay determination method part. Its technical effect can also refer to the technical effect of the relevant part of the intelligent contactor overcurrent protection delay determination method, which will not be repeated here.

[0092] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for determining the delay of overcurrent protection of an intelligent contactor, characterized in that: include: t = L / s × c; S(I t )=a1×I t +b1; in, t is the protection delay, L is the total delay step, s is the step length, and c is the operation cycle; I t To monitor the effective current in real time, I 1.7 , I2, I3, I4, I5 are 1.7, 2, 3, 4, 5 times the rated current; S(I t ) is the dynamic delay recovery step length; a1, a2, a3, and a4 are the slopes of the straight lines for calculating the protection delay step lengths corresponding to the corresponding effective currents, and b1, b2, b3, and b4 are the intercepts of the straight lines for calculating the protection delay step lengths corresponding to the corresponding effective currents.

2. The method for determining the delay of overcurrent protection of an intelligent contactor according to claim 1, characterized in that: c is 10ms.

3. The method for determining the delay of overcurrent protection of an intelligent contactor according to claim 2, characterized in that: in, t 1.7 , t2 is 1.7 and 2 times of the rated current, corresponding to the overcurrent protection inverse delay requirements.

4. The method for determining the delay of overcurrent protection of an intelligent contactor according to claim 3, characterized in that: in, t3 is 3 times the rated current, corresponding to the overcurrent protection inverse delay requirement.

5. The method for determining the delay of overcurrent protection of an intelligent contactor according to claim 4, characterized in that: in, t4 is 4 times the rated current, corresponding to the overcurrent protection inverse delay requirement.

6. The method for determining the delay of overcurrent protection of an intelligent contactor according to claim 5, characterized in that: in, t5 is 5 times the rated current, corresponding to the overcurrent protection inverse delay requirement.

7. A method for determining the overcurrent protection delay of an intelligent contactor, based on the method for determining the overcurrent protection delay of an intelligent contactor according to claim 1, determines the protection delay t of each section of the effective current monitored in real time, characterized in that: include: Calculate real-time monitoring effective current I t ; Real-time monitoring of effective current I t When the current is greater than 5 times the rated current I5, the overcurrent fault flag is set to fault, the short circuit delay is 10 cycles, and the short circuit fault protection flag is set to fault; Real-time monitoring of effective current I t When it is less than 5 times the rated current I5 and greater than 4 times the rated current I4, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 4-5 times rated current section I4-I5; Real-time monitoring of effective current I t When it is less than 4 times the rated current I4 and greater than 3 times the rated current I3, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 3-4 times rated current section I3-I4; Real-time monitoring of effective current I t When it is less than 3 times the rated current I3 and greater than 2 times the rated current I2, the overcurrent fault flag is set as a fault, and the heat accumulation value is accumulated according to the protection delay function of the 2-3 times rated current section I2-I3; Real-time monitoring of effective current I t Less than 2 times the rated current I2 and greater than 1.7 times the rated current I 1.7 When the overcurrent fault flag is set to fault, the heat accumulation value is 1.7-2 times the rated current section I 1.7 -I2 protection delay function accumulation; Real-time monitoring of effective current I t Less than 1.7 times the rated current I 1.7 When the overcurrent fault flag is set to normal, the short-circuit delay count is reset, and the thermal accumulation value is judged to be greater than 0. If the thermal accumulation value is greater than 0, it is judged whether the thermal accumulation value is greater than 1.7 times the rated current I 1.7 The square of the real-time monitoring effective current I t If the square of the heat accumulation value is equal to the dynamic delay recovery step length S(I t ), if not, set the heat accumulation value to 0; Determine whether the heat accumulation value is greater than the overcurrent heat accumulation protection threshold. If so, set the overcurrent protection fault flag to fault.

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