A method for calculating the switching sequence of on-load tap changer

Abstract

The present invention discloses a method for calculating the switching timing of an on-load tap changer. The method comprises the steps of: obtaining a switching timing diagram of the on-load tap changer, and obtaining a switching timing division list of the on-load tap changer according to the switching timing diagram; simultaneously measuring a transition waveform diagram and a vibration waveform diagram of the switching process of the on-load tap changer to obtain a synchronous measurement waveform diagram; determining a first switch switching timing point at a time corresponding to the first vibration amplitude extreme point of the vibration waveform in the synchronous measurement waveform diagram; matching the characteristic position of the transition waveform in the synchronous measurement waveform diagram with the switching timing of the middle switch in the switching timing diagram to obtain a second switch switching timing point at the characteristic position; and determining a third switch switching timing point on the vibration waveform in the synchronous measurement waveform diagram according to the switching timing diagram and the second switch switching timing point. The technical solution of the present invention increases the number of measurements of the switching timing of the on-load tap changer.

Description

Technical Field

[0001] The invention relates to the technical field of on-load tap changer switching sequence, and in particular to a method for calculating the switching sequence of an on-load tap changer. Background Art

[0002] The on-load tap changer is a device that changes the turns ratio of the high and low voltage windings by switching the transformer winding taps when the transformer is excited or loaded, thereby adjusting the output voltage. It plays an important role in the voltage regulation of the power system. The switching process of the on-load tap changer involves the disconnection and connection of the load current and the circulating current. The contacts have the function of arc extinguishing. At the same time, as a mechanical device, long-term and frequent operation may cause the failure of internal components, which will eventually affect the contact of the contacts, making it impossible to effectively extinguish the arc and cause a short circuit fault. Actual operation shows that most of the faults of the on-load tap changer occur during the switching process, especially the action switching of the main current-carrying contacts and arc extinguishing contacts.

[0003] However, the main field test items of on-load tap changers (DC resistance test and transition waveform test or action characteristic test) cannot fully reflect the action contact conditions of each contact during the switching process. Among them, the DC resistance test can only reflect the static contact part, that is, the static contact conditions of the moving and static contacts of each gear of the selector switch, the moving and static contacts of the polarity switch, and the main current-carrying contacts of the transfer switch; while the transition waveform test can only reflect the bridging (the time when the transition resistor is connected and removed) timing and the resistance value of the transition resistor (the connection condition of the transition resistor) during the switching process.

[0004] At the same time, the vibration waveform detection method is also used in practice to determine the switching status of the on-load switch. However, because the vibration sensor is installed on the wall of the transformer oil tank, the vibration signal of the on-load switch switching needs to pass through the switching core oil chamber, the oil chamber wall, the transformer oil tank and the tank wall. The waveform detected by the vibration method cannot accurately reflect the status of each contact during the on-load switch switching process. Therefore, the measured timing of the on-load tap changer is also less. Summary of the invention

[0005] The present invention provides a method for calculating the switching timing of an on-load tap changer. The method calculates the timing of the switching process of the on-load tap changer by synchronously measuring a transition waveform and a vibration waveform of the on-load tap changer, thereby improving the calculation completeness of the switching timing of the on-load tap changer, that is, increasing the number of measurements of the switching timing of the on-load tap changer.

[0006] An embodiment of the present invention provides a method for calculating the switching timing of an on-load tap changer, comprising the following steps:

[0007] Acquire a switching timing diagram of the on-load tap changer, and obtain a switching timing division list of the on-load tap changer according to the switching timing diagram, wherein the on-load tap changer includes a main current-carrying contact, a main on-off contact, and a transition contact;

[0008] Simultaneously measuring a transition waveform and a vibration waveform of the on-load tap changer switching process, and merging the measured transition waveform and vibration waveform to obtain a synchronous measurement waveform;

[0009] Determine the first switch switching timing point according to the time corresponding to the first vibration amplitude extreme value point appearing in the vibration waveform in the synchronous measurement waveform graph;

[0010] Matching the characteristic position of the transition waveform in the synchronous measurement waveform diagram with the switching timing of the intermediate switch in the switching timing diagram to obtain a second switch switching timing point at the characteristic position, wherein the intermediate switch refers to a non-main current-carrying contact in the on-load tap changer;

[0011] According to the switching timing diagram and the second switch switching timing point, a third switch switching timing point on the vibration waveform in the synchronous measurement waveform diagram is determined.

[0012] Further, the first switch switching timing point is determined by the time corresponding to the first vibration amplitude extreme point of the vibration waveform in the synchronous measurement waveform diagram, specifically:

[0013] For the vibration waveform, starting from the initial moment, the vibration amplitude y corresponding to the minimum sampling moment is continuously read backward i , y i Compared with the average value of the vibration amplitude at all previous time points, when y i-1 <y i <y i+1 , and 130%*Σy i-2 / (i-2)<y i-1 When y i The corresponding moment is the first switch switching timing point, and the first switch switching timing point is specifically the starting moment when the first main current-carrying contact opens and the next contact closes; i is a natural number.

[0014] Further, the on-load tap changer comprises two main current-carrying contacts KA and KB, two main on-off contacts K1 and K4, and two transition contacts K2 and K3;

[0015] According to the switching timing diagram, the switching timing division list of the on-load tap changer is as follows:

[0016] Initial time t 0 ;

[0017] The starting time t when contact KA opens and contact K2 closes 1 ;

[0018] The time t when contact KA opens and contact K2 closes 2 ;

[0019] The starting time t when contact K1 opens 3 ;

[0020] The completion time t of contact K1 opening 4 ;

[0021] The starting time t of contact K3 closing 5 ;

[0022] The closing time of contact K3 is t 6 ;

[0023] The starting time t when contact K2 opens 7 ;

[0024] The completion time t of contact K2 opening 8 ;

[0025] The starting time t of contact K4 closing 9 ;

[0026] The closing time of contact K4 is t 10 ;

[0027] The starting time t when contact KB closes and contact K3 opens 11 ;

[0028] The time t when contact KB closes and contact K3 opens 12 .

[0029] Furthermore, the characteristic position of the transition waveform in the synchronous measurement waveform diagram is matched with the switching timing of the middle switch in the switching timing diagram to obtain a second switch switching timing point at the characteristic position, wherein the second switch switching timing point includes t 3 ,t 6 ,t 7 and t 10 ;.

[0030] Further, according to the switching timing diagram and the second switch switching timing point, a third switch switching timing point on the vibration waveform in the synchronous measurement waveform diagram is determined, specifically:

[0031] The vibration waveform is 3 ,t 7 and t 10 The time corresponding to the first vibration amplitude extreme point after the moment is determined as t 4 ,t8 and t 11 ;

[0032] The vibration waveform is 11 The time corresponding to the first vibration amplitude extreme point that appears after time is determined as t 12 .

[0033] Furthermore, the vibration waveform is 3 ,t 7 and t 10 The time corresponding to the first vibration amplitude extreme point after the moment is determined as t 4 ,t 8 and t 11 , specifically:

[0034] From 3 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , y i With t 3 The vibration amplitude f corresponding to the moment 3 Compare, when y i-1 <y i <y i+1 , and y i Greater than 1.3 times f 3 When y i The corresponding time is t 4 ;

[0035] From 7 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , y i With t 7 The vibration amplitude f corresponding to the moment 7 Compare, when y i-1 <y i <y i+1 , and y i Greater than 1.3 times f 7 When y i The corresponding time is t 8

[0036] From 10 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , y i With t 10 The vibration amplitude f corresponding to the moment 10 Compare, when y i-1 <y i <y i+1 , and y i Greater than 1.3 times f10 When y i The corresponding time is t 11 .

[0037] Further, the vibration waveform at t 11 The time corresponding to the first vibration amplitude extreme point that appears after time is determined as t 12 , specifically:

[0038] From 11 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , when the comparison shows that y i When it is the maximum value of the entire vibration waveform amplitude, record y i The corresponding time is t 12 .

[0039] The embodiments of the present invention have the following beneficial effects:

[0040] The present invention provides a method for calculating the switching timing of an on-load tap changer. The method simultaneously measures a transition waveform and a vibration waveform of the switching process of the on-load tap changer, and merges the measured transition waveform and vibration waveform to obtain a synchronous measurement waveform, so that the timing information of both the transition waveform and the vibration waveform can be combined to calculate more timing information. At the same time, the characteristic position of the transition waveform in the synchronous measurement waveform is matched with the switching timing of the middle switch in the switching timing diagram to obtain the second switch switching timing point at the characteristic position, and then the third switch switching timing point on the vibration waveform in the synchronous measurement waveform is determined according to the switching timing diagram and the second switch switching timing point. It can be seen that the present invention increases the number of measurements of the switching timing of the on-load tap changer by using the second switch switching timing point obtained in the transition waveform to determine the third switch switching timing point on the vibration waveform. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of a method for calculating the switching timing of an on-load tap changer provided by an embodiment of the present invention;

[0042] Figure 2 It is a schematic diagram of the switching timing of an on-load tap changer according to a method for calculating the switching timing of an on-load tap changer provided by an embodiment of the present invention;

[0043] Figure 3 It is a schematic diagram of synchronous measurement waveforms of a method for calculating the switching timing of an on-load tap changer provided by an embodiment of the present invention;

[0044] Figure 4 The present invention is a schematic diagram of the principle of measuring the transition waveform of an on-load tap changer in a method for calculating the switching timing of an on-load tap changer provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] like Figure 1 As shown, an embodiment of the present invention provides a method for calculating the switching timing of an on-load tap changer, comprising the following steps:

[0047] Step S101: Figure 2 As shown, a switching timing diagram of the on-load tap changer is obtained, and a switching timing division list of the on-load tap changer is obtained according to the switching timing diagram. The on-load tap changer includes a main current-carrying contact, a main on-off contact and a transition contact. Figure 2 The switching timing diagram of the on-load tap changer in the embodiment of the present invention includes two rows of contact opening and closing diagrams (a total of 7 contact opening and closing diagrams), and the 3 contact opening and closing diagrams in the upper row represent from left to right: the left main current-carrying contact is closed, the left main current-carrying contact is opened, and the left main on-off contact is opened. The 4 contact opening and closing diagrams in the lower row represent from left to right: the right transition contact is closed, the left transition contact is opened, the right main on-off contact is closed, and the right main current-carrying contact is closed. The on-load tap changer of the embodiment of the present invention includes two main current-carrying contacts KA and KB, two main on-off contacts K1 and K4, and two transition contacts K2 and K3.

[0048] As one embodiment, the switching timing division list of the on-load tap changer is obtained as follows:

[0049] Corresponding actions Representative symbol Initial moment <![CDATA[t 0 ]]> The starting time when contact KA opens and contact K2 closes <![CDATA[t 1 ]]> The moment when contact KA opens and contact K2 closes <![CDATA[t 2 ]]> The starting time of opening of contact K1 <![CDATA[t 3 ]]> The moment when contact K1 opens <![CDATA[t 4 ]]> The starting time of contact K3 closing <![CDATA[t 5 ]]> The moment when contact K3 closes <![CDATA[t 6 ]]> The starting time of opening of contact K2 <![CDATA[t 7 ]]> The moment when contact K2 opens <![CDATA[t 8 ]]> The starting time of contact K4 closing <![CDATA[t 9 ]]> The moment when contact K4 closes <![CDATA[t 10 ]]> The starting time when contact KB closes and contact K3 opens <![CDATA[t 11 ]]> The moment when contact KB closes and contact K3 opens <![CDATA[t 12 ]]>

[0050] Step S102: Simultaneously measure the transition waveform and vibration waveform of the on-load tap changer switching process, and merge the measured transition waveform and vibration waveform to obtain a synchronous measurement waveform. Specifically, the transition waveform of the on-load tap changer is measured using a voltage source method or a current source method to obtain the transition waveform.

[0051] Figure 4 The principle of measuring the transient waveform of the on-load tap changer using the current source method is shown. Figure 4The transition resistance branch of the switching switch circuit in the switch is of Ω level, and the resistances of other main current-carrying and main on-off branches are of mΩ and uΩ level respectively. Therefore, when the current source method is used to measure the transition waveform of the on-load tap changer, the output voltage (or current) changes of the measuring device in the processes of the left transition resistor connected, the transition resistors on both sides connected in parallel, the right transition resistor connected (that is, the left transition resistor is disconnected), and the right transition resistor is disconnected in the timing sequence of the on-load tap changer can be obviously detected by the acquisition device, that is, the transition resistor bridging process (corresponding to the left main on-off contact open, the right transition contact closed, and the left transition contact open in the contact opening and closing diagram), while the other timing changes have little effect on the output voltage (or current) of the measuring device and are difficult to detect. Therefore, the present invention obtains the waveforms during the other timing changes by simultaneously measuring the vibration waveform of the on-load tap changer. The present invention adopts conventional technical means in the field to measure the vibration waveform of the on-load tap changer, so it will not be repeated in the description of the present invention. ,

[0052] The synchronous measurement waveform is as follows Figure 3 As shown. Among them, Figure 3 T 0 , T s KA , T f KA , T s K1开 , T f K1开 , T K3闭 , T s K2开 , T f K2开 , T K4闭 , T s KB and T f KB Corresponding to t in the switching timing division list respectively 0 ,t 1 ,t 2 ,t 3 ,t 4 ,t 6 ,t 7 ,t 8 ,t 10 ,t 11 and t 12 .

[0053] Step S103: Determine the first switch switching timing point by the time corresponding to the first vibration amplitude extreme point of the vibration waveform in the synchronous measurement waveform diagram. Specifically, for the vibration waveform, from the initial time t 0 Start by reading the vibration amplitude y corresponding to the minimum sampling time continuously. i(i=1, 2, 3, i is a natural number), y i Compared with the average value of the vibration amplitude at all previous time points, when y i-1 <y i <y i+1 , and 130%*Σy i-2 / (i-2)<y i-1 When y i The first switch switching timing point corresponding to the moment is specifically the start time when the first main current-carrying contact opens and the next contact closes, specifically t 1 .

[0054] Step S104: Match the characteristic position of the transition waveform in the synchronous measurement waveform diagram with the switching timing of the intermediate switch in the switching timing diagram to obtain the second switch switching timing point at the characteristic position, wherein the intermediate switch refers to the non-main current-carrying contact in the on-load tap changer. The second switch switching timing point includes t 3 ,t 6 ,t 7 and t 10 , the intermediate switches are specifically contacts K1, K2, K3 and K4. In this step, those skilled in the art can observe the characteristic positions of the measured transition waveforms, and directly correspond the characteristic positions to the switching timings of the intermediate switches according to the characteristics of the transition waveforms and the switching sequence of the intermediate switches, and obtain t 3 ,t 6 ,t 7 and t 10 The specific time.

[0055] Step S105: Determine a third switch switching timing point on the vibration waveform in the synchronous measurement waveform diagram according to the switch timing diagram and the second switch switching timing point. Specifically comprising:

[0056] The vibration waveform is 3 ,t 7 and t 10 The time corresponding to the first vibration amplitude extreme point after the moment is determined as t 4 ,t 8 and t 11 ;

[0057] The vibration waveform is 11 The time corresponding to the first vibration amplitude extreme point that appears after time is determined as t 12 .

[0058] As one embodiment, the vibration waveform is 3 ,t 7and t 10 The time corresponding to the first vibration amplitude extreme point after the moment is determined as t 4 ,t 8 and t 11 , specifically:

[0059] From 3 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , y i With t 3 The vibration amplitude f corresponding to the moment 3 Compare, when y i-1 <y i <y i+1 , and y i Greater than 1.3 times f 3 When y i The corresponding time is t 4 ;

[0060] From 7 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , y i With t 7 The vibration amplitude f corresponding to the moment 7 Compare, when y i-1 <y i <y i+1 , and y i Greater than 1.3 times f 7 When y i The corresponding time is t 8

[0061] From 10 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , y i With t 10 The vibration amplitude f corresponding to the moment 10 Compare, when y i-1 <y i <y i+1 , and y i Greater than 1.3 times f 10 When y i The corresponding time is t 11 .

[0062] As one embodiment, the vibration waveform at t 11 The time corresponding to the first vibration amplitude extreme point that appears after time is determined as t 12 , specifically:

[0063] From11 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , when the comparison shows that y i When it is the maximum value of the entire vibration waveform amplitude, record y i The corresponding time is t 12 .

[0064] The present invention synchronously measures the transition resistance waveform (i.e., transition waveform) and vibration waveform of the on-load tap changer and performs comparative analysis under the same time base. At the same time, the transition resistance bridging moment that can be accurately obtained is used as a reference. In combination with the inherent characteristic range of the switching of each contact of the on-load switch switching core, other contact switching timings that cannot be obtained using the transition resistance waveform are obtained from the amplitude characteristics of the vibration signal. 3 ,t 6 ,t 7 and t 10 ), within a certain interval after that moment (the interval is related to the inherent characteristics of the specific on-load tap changer, and can refer to the factory test data of the switch), the moment corresponding to the point of maximum vibration amplitude is the moment corresponding to the next time sequence (that is, according to t 3 ,t 6 ,t 7 and t 10 Get 4 ,t 8 and t 11 At the same time, taking the calculated time corresponding to a certain time sequence as a reference, within a certain interval after that time (the interval is related to the specific inherent characteristics of the on-load tap changer, and can refer to the factory test data of the switch), the time corresponding to the maximum amplitude point of vibration is the time corresponding to the next time sequence (that is, according to t 11 Get 12 ).

[0065] The present invention synchronously measures the transition resistance waveform and vibration waveform of the on-load tap changer and performs comparative analysis under the same time base, realizing the reproduction of the full time sequence information of the on-load tap changer switching. The present invention can detect the action of the main current-carrying contacts and arc-extinguishing contacts in the switching part of the on-load tap changer, which is both the top priority of the on-load tap changer switching and the detection blind spot of other single test detection methods of the on-load tap changer.

[0066] Those of ordinary skill in the art can understand and implement it without creative work. The above is a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. Those of ordinary skill in the art can understand that all or part of the processes in the above embodiments can be implemented by instructing related hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the above embodiments. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

Claims

1. A method for calculating the switching sequence of an on-load tap changer, characterized in that: The following steps are involved: Acquire a switching timing diagram of the on-load tap changer, and obtain a switching timing division list of the on-load tap changer according to the switching timing diagram, wherein the on-load tap changer includes a main current-carrying contact, a main on-off contact, and a transition contact; Simultaneously measuring a transition waveform and a vibration waveform of the on-load tap changer switching process, and merging the measured transition waveform and vibration waveform to obtain a synchronous measurement waveform, wherein the transition waveform is a voltage waveform corresponding to the transition resistance of the on-load tap changer; Determine the first switch switching timing point according to the time corresponding to the first vibration amplitude extreme value point appearing in the vibration waveform in the synchronous measurement waveform graph; Matching the characteristic position of the transition waveform in the synchronous measurement waveform diagram with the switching timing of the intermediate switch in the switching timing diagram to obtain a second switch switching timing point at the characteristic position, wherein the intermediate switch refers to a non-main current-carrying contact in the on-load tap changer; According to the switching timing diagram and the second switch switching timing point, a third switch switching timing point on the vibration waveform in the synchronous measurement waveform diagram is determined, wherein the third switch switching timing point is a moment selected according to a vibration amplitude extreme value point that appears after a moment corresponding to the second switch switching timing point; The first switch switching timing point is determined by the time corresponding to the first vibration amplitude extreme point of the vibration waveform in the synchronous measurement waveform diagram, specifically: For the vibration waveform, starting from the initial moment, the vibration amplitude y corresponding to the minimum sampling moment is continuously read backward i , when y i-1 <y i <y i+1 , and 130%*Σy i-2 / (i-2)<y i-1 When y i The corresponding moment is the first switch switching timing point, which is specifically the starting moment when the first main current-carrying contact opens and the next contact closes; i is a natural number.

2. The method for calculating the switching sequence of the on-load tap changer according to claim 1, characterized in that: The on-load tap changer comprises two main current-carrying contacts KA and KB, two main on-off contacts K1 and K4, and two transition contacts K2 and K3; According to the switching timing diagram, the switching timing division list of the on-load tap changer is as follows: Initial time t0; The starting time t1 when contact KA opens and contact K2 closes; The moment t2 when contact KA opens and contact K2 closes; The starting time t3 when the contact K1 opens; The completion time t4 of the opening of the contact K1; The starting time t5 of the closing of contact K3; The closing time of contact K3 is completed at t6; The starting time t7 when the contact K2 opens; The completion time t8 of the opening of the contact K2; The starting time t9 of the closing of contact K4; The closing time of contact K4 is t 10 ; The starting time t when contact KB closes and contact K3 opens 11 ; The time t when contact KB closes and contact K3 opens 12 .

3. The method for calculating the switching sequence of the on-load tap changer according to claim 2, characterized in that: The characteristic position of the transition waveform in the synchronous measurement waveform diagram is matched with the switching timing of the middle switch in the switching timing diagram, and the second switch switching timing point at the characteristic position is obtained. The second switch switching timing point includes t3, t6, t7 and t 10 .

4. The method for calculating the switching sequence of the on-load tap changer according to claim 3, characterized in that: According to the switching timing diagram and the second switch switching timing point, a third switch switching timing point on the vibration waveform in the synchronous measurement waveform diagram is determined, specifically: The vibration waveform is set at t3, t7 and t 10 The time corresponding to the first vibration amplitude extreme point after the moment is determined as t4, t8 and t 11 ; The vibration waveform is 11 The time corresponding to the first vibration amplitude extreme point that appears after time is determined as t 12 .

5. The method for calculating the switching timing of the on-load tap changer according to claim 4, characterized in that: The vibration waveform is set at t3, t7 and t 10 The time corresponding to the first vibration amplitude extreme point after the moment is determined as t4, t8 and t 11 , specifically: Starting from time t3, the vibration amplitude y corresponding to the minimum sampling time is read continuously backward i , y i Compared with the vibration amplitude f3 corresponding to time t3, when y i-1 <y i <y i+1 , and y i When it is greater than 1.3 times f3, record y i The corresponding time is t4; Starting from time t7, the vibration amplitude y corresponding to the minimum sampling time is read continuously backward i , y i Compared with the vibration amplitude f7 corresponding to time t7, when y i-1 <y i <y i+1 , and y i When it is greater than 1.3 times f7, record y i The corresponding time is t8 From 10 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , y i With t 10 The vibration amplitude f corresponding to the moment 10 Compare, when y i-1 <y i <y i+1 , and y i Greater than 1.3 times f 10 When y i The corresponding time is t 11 .

6. The method for calculating the switching sequence of the on-load tap changer according to claim 5, characterized in that: The vibration waveform is 11 The time corresponding to the first vibration amplitude extreme point that appears after time is determined as t 12 , specifically: From 11 Starting from the moment, the vibration amplitude y corresponding to the minimum sampling moment is read continuously backward i , when the comparison shows that y i When it is the maximum value of the entire vibration waveform amplitude, record y i The corresponding time is t 12 .

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