Knife switch position confirmation method and system in bus switching operation process

Abstract

The invention relates to the field of power system operation and control, and discloses a disconnecting link position confirmation method and system in the bus switching operation process, and the method comprises the steps: executing the operation of closing a to-be-closed bus disconnecting link, and forming a double-span state; whether a disconnecting link to be closed is closed or not is judged according to the bus coupler current measured value, the section switch current measured value and the bus unbalanced current measured value in the double-span state, if yes, the next step is executed, and if not, closing abnormity is prompted, and operation is stopped; executing the operation of opening the to-be-opened disconnecting link; and whether the to-be-opened disconnecting link is opened is judged according to the bus coupler current measured value, the section switch current measured value and the bus unbalanced current measured value after the to-be-opened disconnecting link is opened, if yes, operation is ended, switching succeeds, and if not, opening abnormity is prompted, and operation is stopped. By means of the method, the accuracy and reliability of knife switch position judgment can be improved.

Description

Technical Field

[0001] The present invention relates to the field of power system operation and control, and in particular to a method and system for confirming a switch position during a busbar switching operation. Background Art

[0002] The double busbar wiring method is a commonly used electrical wiring method in power systems. The double busbar wiring method allows operators to switch the lines between different busbars, thereby improving the flexibility of system operation.

[0003] The bus switching operation is referred to as "bus switching", which refers to the operation of switching some or all switches on one bus to another bus for operation or hot standby in a substation with double bus connection. Under normal circumstances, the bus switching operation is carried out under the energized state, using the principle of equipotential operation. Under the condition of parallel operation of the busbars, one set of bus disconnectors is closed first, and then the other set of bus disconnectors is pulled to ensure that the bus switching is achieved without power outage. Figure 3 Take the double busbar connection shown in the figure as an example. The station has three outgoing line intervals: Outgoing Line 1, Outgoing Line 2, Outgoing Line 3. Each interval has two busbar switches Q1 and Q2, which are connected to busbar I and busbar II respectively. The outgoing line circuit breaker DL is outside the busbar switch. During normal operation, one outgoing line runs on one of the two busbars, that is, only one of the two switches Q1 and Q2 is in the closed position. In the example, outgoing line 1 runs on busbar I, and outgoing lines 2 and 3 run on busbar II.

[0004] If it is necessary to switch the outgoing line 3 from II bus to I bus, it involves the equipotential pulling and closing operation of the bus switches Q1 and Q2. The steps are as follows:

[0005] 1. Close the Q1 switch at equal potential;

[0006] 2. Confirm that Q1 switch is closed;

[0007] 3. Open the Q2 switch at equal potential;

[0008] 4. Confirm that Q2 knife switch can be opened reliably;

[0009] 5. The operation is completed.

[0010] It is very important to confirm that the Q1 knife switch is in place and that the Q2 knife switch is reliably separated. If the Q2 knife switch is opened when the Q1 knife switch is not in place, it will cause a malicious misoperation accident of pulling the knife switch with load. If the knife switch is not opened in place, it may cause misjudgment in operation and maintenance, resulting in consequences such as protection misoperation. Therefore, the substation safety regulations have clear provisions: when checking the position of the equipment after the operation is completed, the actual position of the equipment shall be used as the basis. When the position status of the equipment cannot be directly observed, at least two non-homologous or non-same principle position status indications should be set. The commonly used indication methods indicate the knife switch position through the position of the transmission mechanism crank arm connecting rod or through the knife switch position auxiliary node, both of which may cause misjudgment due to mechanical or electrical failures. Summary of the invention

[0011] The present invention provides a method and system for confirming the position of a knife switch during a bus switching operation, which comprehensively utilizes multi-dimensional current information to determine whether the knife switch is fully closed during the bus switching operation, so as to improve the accuracy and reliability of the knife switch position judgment.

[0012] The present invention is achieved through the following technical solutions:

[0013] A method for confirming a switch position during a busbar switching operation, comprising:

[0014] The busbar reversing operation starts, and the busbar knife switch to be closed is closed to form a double-span state, and the busbar current, the section switch current, and the busbar unbalanced current in the double-span state are respectively the first measured value of the busbar current, the first measured value of the section switch current, and the first measured value of the busbar unbalanced current;

[0015] According to the first measured value of the busbar current, the first measured value of the sectionalized switch current and the first measured value of the busbar unbalanced current, respectively, it is judged whether the switch to be closed has been closed; if so, it is jumped to the next step; otherwise, it is prompted that the closing is abnormal and the operation is terminated;

[0016] Execute the operation of pulling open the knife switch to be opened, and make the bus tie current, the sectionalizing switch current, and the bus unbalanced current after the operation of pulling open the knife switch to be opened be the second measured value of the bus tie current, the second measured value of the sectionalizing switch current, and the second measured value of the bus unbalanced current respectively;

[0017] According to the second measured value of the bus current, the second measured value of the section switch current and the second measured value of the bus unbalanced current, it is judged whether the switch to be opened has been opened. If so, the operation is terminated and the switching is successful. Otherwise, it is prompted that the opening is abnormal and the operation is terminated.

[0018] As an optimization, the specific process of judging whether the switch to be closed is closed according to the first measured value of the busbar current, the first measured value of the segment switch current and the first measured value of the busbar unbalanced current is as follows:

[0019] Collect the first measured value of the bus tie current and the first measured value of the sectional switch current, and compare the first measured value of the bus tie current and the first measured value of the sectional switch current with the theoretical value of the bus tie current and the theoretical value of the sectional switch current in the double-span state to obtain a first comparison result. If the first comparison result is in line with expectations, proceed to the next step; otherwise, prompt a closing abnormality;

[0020] Collect the first measured value of the bus unbalanced current, and compare the first measured value of the bus unbalanced current with the theoretical value of the bus unbalanced current in the double-span state to obtain a second comparison result. If the second comparison result is as expected, proceed to the next step; otherwise, prompt that the closing is abnormal and terminate the operation.

[0021] As an optimization, the theoretical value of the busbar current in the double-span state is obtained by power flow calculation and should satisfy the expression:

[0022] I′ ML =I ML -I′ h -∑I′ t +∑I′ t ;

[0023] Among them, I′ h is the current flowing through the switch to be closed in the double span state, I′ t I is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed and not where the switch to be closed is located in the double-span state. t I′ is the outgoing current of the branch that is connected to the same busbar as the switch to be closed before switching and is not where the switch to be closed is located. ML is the current flowing through the bus tie switch in the double span state, I ML It is the current flowing through the bus tie switch before switching. The reference positive direction of the current here is defined as: the current of the branch switch and the knife switch is positive when it flows out of the bus, and the reference positive direction of the bus tie current is positive when it flows from the new bus to which the switching branch will switch to the original bus.

[0024] As an optimization, the specific expression of the theoretical value of busbar unbalanced current in the double-span state is:

[0025] I′ dt =∑I′ t +I′ ML = -I′ h ;

[0026] I′ df =∑I′ f -I′ ML =I′ h ;

[0027] Among them, I′ dtI′ is the unbalanced current on the busbar connected to the switch in the double-span state. df is the unbalanced current on the busbar connected to the other switch in the same branch of the switch to be closed in the double span state. Let the other switch in the same branch of the switch to be closed be the switch to be opened, I′ t I′ is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed and not where the switch to be closed is located in the double-span state. f I′ is the branch current flowing through the outgoing line connected to the same busbar as the switch to be disconnected in the double span state. h is the current flowing through the switch to be closed in the double span state, I′ ML It is the current flowing through the bus tie switch in the double span state. The reference positive direction of the current here is defined as: the branch switch and knife switch current are positive when they flow out of the bus, and the reference positive direction of the bus tie current is positive when it flows from the new bus to which the switching branch will be switched to the original bus.

[0028] As an optimization, the specific process of judging whether the switch to be disconnected has been opened according to the second measured value of the busbar current, the second measured value of the segment switch current and the second measured value of the busbar unbalanced current is as follows:

[0029] Collect the second measured value of the busbar unbalanced current, and determine whether the second measured value of the busbar unbalanced current is zero. If so, proceed to the next step; otherwise, prompt a trip abnormality.

[0030] Collect the second measured value of the main bus current and the second measured value of the segmented switch current, and compare the second measured value of the main bus current and the second measured value of the segmented switch current with the theoretical value of the main bus current and the theoretical value of the segmented switch current after disconnection to obtain a third comparison result. If the third comparison result is as expected, the operation is completed and the switching is successful. Otherwise, it is prompted that the closing is abnormal and the operation is terminated.

[0031] As an optimization, the expressions of the theoretical value of the busbar current and the theoretical value of the sectionalized switch current after the switch is opened are:

[0032] I″ ML =-∑I″ t =∑I″ f ;

[0033] Among them, I″ ML The theoretical value of the busbar current after the switch is opened, I″ t I″′ is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed after the opening operation is performed. Let the other switch on the same branch as the switch to be closed be the switch to be opened, f It is the outgoing current that flows through the branch connected to the same bus as the switch to be opened and not the branch where the switch to be opened is located after the opening operation is performed.

[0034] As an optimization, before starting the busbar reversing operation, first confirm whether the status of all switches in the station is normal. If normal, perform the busbar reversing operation. Otherwise, the operation can be performed only after the defects are eliminated.

[0035] As an optimization, if there are multiple bus couplers and / or sectionalizers, the theoretical values ​​of the bus coupler current corresponding to each bus coupler and / or the sectionalizer current corresponding to each sectionalizer are calculated.

[0036] As an optimization, the bus unbalanced current, bus coupling current, section switch current and branch current on the bus are all three-phase currents.

[0037] The present invention also discloses a system for confirming the position of a switch during a bus switching operation, which is used to implement the aforementioned method for confirming the position of a switch during a bus switching operation, and comprises:

[0038] An acquisition module, used for acquiring a first measured value of a bus-tie current, a first measured value of a sectional switch current, a first measured value of a bus unbalanced current, a second measured value of a bus-tie current, a second measured value of a sectional switch current, and a second measured value of a bus unbalanced current;

[0039] A first judgment module is used to judge whether the to-be-closed knife switch has been closed according to the first measured value of the bus current, the first measured value of the segment switch current and the first measured value of the bus unbalanced current;

[0040] A second judgment module is used to judge whether the switch to be disconnected has been opened according to the second measured value of the bus tie current, the second measured value of the sectionalized switch current and the second measured value of the bus unbalanced current;

[0041] The alarm module is used to issue an early warning prompt when the knife switch to be closed fails to close or the knife switch to be opened fails to open.

[0042] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0043] The present invention utilizes multi-dimensional current information to determine the position of the knife switch by the current change before and after the knife switch is opened and closed. Since this method identifies the connection relationship change of the primary circuit electrically, compared with the existing indirect judgment methods such as travel switches, position sensors or video images, the present invention has higher accuracy and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0045] Figure 1A general flow chart of a method for confirming the position of a switch during a bus switching operation according to the present invention;

[0046] Figure 2 A detailed flow chart of a method for confirming the position of a switch during a bus switching operation according to the present invention;

[0047] Figure 3 Schematic diagram of the circuit structure before the knife switch is closed in the embodiment;

[0048] Figure 4 Schematic diagram of the circuit structure after the knife switch to be closed in the embodiment;

[0049] Figure 5 A schematic diagram of the structure of another circuit in the embodiment;

[0050] Figure 6 Based on Figure 5 A flow chart of one of the cases when the circuit in implements the method of the present invention;

[0051] Figure 7 Based on Figure 5 The circuit in FIG. 1 is a flow chart of another case in which the method of the present invention is implemented. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0053] Before introducing the specific process of the present invention, the principle of the present invention is first introduced.

[0054] (1) Determine the switch position based on the busbar unbalanced current

[0055] The busbar unbalanced current defined in the present invention refers to the vector sum of the currents of each branch of the busbar:

[0056] I d =∑I n (1)

[0057] The positive direction of each branch current is defined as the current flowing out of the busbar. All interval currents when the busbar switches are in the closed position are included in the unbalanced current calculation branch. For the "double span" state, the state before the "double span" is used as the standard. Assume that the state of a substation with double busbar connection before the switching operation is as follows: Figure 1 As shown, the bus unbalanced current I d1 ,I d2 They are:

[0058]

[0059] Under normal circumstances, according to the node current balance relationship, when the bus is fault-free, the unbalanced current is 0, that is, I d1 =I d2 = 0. Outgoing line 3 performs busbar reversing operation, and the status after closing Q1 is as follows Figure 4 As shown. At this time, the outgoing line 3 is connected to both the I mother and the II mother, forming a "double span" state. At this time, the current I3 of the outgoing line 3 is split on the two switches Q1 and Q2, and the currents on the two branches are recorded as I 31 ,I 32 According to the definition of busbar unbalanced current in this patent, the unbalanced current is calculated based on the state before the formation of "double span". Figure 4 In the double span state shown, the unbalanced currents of the two buses are:

[0060]

[0061] It is not difficult to see that the unbalanced current of the two busbars is equal to the current I flowing through the rear closing switch 31 ′. Therefore, the change of unbalanced current can be used to determine whether Q1 switch has been closed. When unbalanced current is generated and its amplitude is equal to I 31 ', it can be determined that the knife switch Q1 has been fully closed, otherwise it can be determined that Q1 has not been fully closed.

[0062] (2) Determine the switch position based on the change of busbar current

[0063] In addition to the unbalanced current changes of the two busbars, the busbar current also changes after the outgoing line 3 switch Q1 is closed. According to the node current balance relationship, before the outgoing line 3 switch Q1 is closed, for I bus:

[0064] I1+I ML =0(4)

[0065] After the outgoing line 3 knife switch Q1 is closed, there are:

[0066] I1′+I ML ′+I 31 ′=0(5)

[0067] From (4) and (5), we can get:

[0068] I ML -I ML ′=I 31 ′+I1′-I1(6)

[0069] From formula (6), we can see that when the incoming line current I1 remains unchanged, that is, I1′-I1=0, the current change of the bus tie switch before and after the knife switch Q1 is closed is exactly equal to the current I flowing through the outgoing line 3 knife switch Q1 after closing. 31'. If the incoming current changes at this time, I1'-I1 must also be taken into account. Therefore, whether the bus tie switch changes and whether the value after the change is consistent with the expected value can be used as the criterion for closing the knife switch Q1. For wiring methods with multiple bus ties and section switches (such as double busbars and double sections, etc.), the current information of multiple bus ties and section switches can be used for judgment at the same time to further improve the reliability of judgment.

[0070] Similarly, for the operation of separating the switch to be separated after the double span is formed, the above principle can also be used to judge whether the separation operation is successful by the disappearance of the unbalanced current of the busbar and the changes in the unbalanced current of the related busbar and section switches.

[0071] Based on the above principle, the present invention proposes a method for determining the position of a switch based on multi-dimensional current information of a substation for the busbar reversal operation of a double busbar connection. The current information used includes: the outgoing line current of each interval in the entire station and the current of each busbar and section switch.

[0072] This embodiment provides a method for confirming the position of a switch during a bus switching operation. Figure 1 As shown, including:

[0073] Step 1: Before starting the bus reversal operation, first confirm whether the status of all switches in the station is normal. If normal, then perform the bus reversal operation. Otherwise, the operation can be performed only after the defects are eliminated. Start the bus reversal (bus reversal) operation, triggering the switch position discrimination function based on multi-dimensional current information to start.

[0074] Step 2: Close the bus switch to be closed to form a double-span state. That is, execute the operation of closing the bus switch to be closed to form a double-span state, and make the bus tie current, section switch current, and bus unbalanced current in the double-span state the first measured value of the bus tie current, the first measured value of the section switch current, and the first measured value of the bus unbalanced current, respectively. Then, judge whether the bus switch to be closed has been closed based on the first measured value of the bus tie current, the first measured value of the section switch current, and the first measured value of the bus unbalanced current. If so, jump to the next step. Otherwise, prompt that the closing is abnormal and terminate the operation. That is:

[0075] (1) Measure the bus tie current and the sectionalized switch current (obtain the first measured value of the bus tie current and the first measured value of the sectionalized switch current), and compare the calculated results with the theoretical values ​​of the bus tie current and the sectionalized switch current (i.e. the theoretical value of the bus tie current and the theoretical value of the sectionalized switch current in the double span state) to determine whether they meet expectations. If they do not meet expectations, a "closing abnormality" prompt is displayed and the operation is terminated.

[0076] (2) Measure the busbar unbalanced current in the double-span state and compare it with the calculated result of the theoretical value of the busbar unbalanced current to determine whether the newly generated unbalanced current meets expectations. If it does not meet expectations, an "abnormal" prompt will be displayed and the operation will be terminated.

[0077] The more specific process is:

[0078] Collect the first measured value of the bus tie current and the first measured value of the sectional switch current, and compare the first measured value of the bus tie current and the first measured value of the sectional switch current with the theoretical value of the bus tie current and the theoretical value of the sectional switch current in the double-span state to obtain a first comparison result. If the first comparison result is in line with expectations, proceed to the next step; otherwise, prompt a closing abnormality;

[0079] The control and protection system of the substation collects the above current in real time for monitoring and protection functions, and can be used when needed.

[0080] In some embodiments, the specific expression of the theoretical value of the busbar current in the double-span state is:

[0081] I′ ML =I ML -I′ h -∑I′ t +∑I t ;

[0082] Among them, I′ h is the current flowing through the switch to be closed in the double span state, I′ t I is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed and not where the switch to be closed is located in the double-span state. t I′ is the outgoing current of the branch that is connected to the same busbar as the switch to be closed before switching and is not where the switch to be closed is located. ML is the current flowing through the bus tie switch in the double span state, I ML It is the current flowing through the bus tie switch before switching. The reference positive direction of the current here is defined as: the current of the branch switch and the knife switch is positive when it flows out of the bus, and the reference positive direction of the bus tie current is positive when it flows from the new bus to which the switching branch will switch to the original bus.

[0083] Combination Figure 3 , 4 The circuit in the embodiment is used to explain the parameters in the present invention. Q1 of the outgoing line (branch) 3 is a knife switch to be closed, Q2 of the outgoing line 3 is a knife switch to be opened, the bus connected to Q1 is bus I, and the bus connected to Q2 is bus II.

[0084] I ML That is Figure 3 The current flowing through the bus tie switch DL, I′ ML That is Figure 4The current flowing through the bus tie switch DL, I′ h That is Figure 4 middle I' 31 , I′ t That is Figure 4 I′1 and I′2 in I t That is Figure 3 I1 and I2 in.

[0085] Collect the first measured value of the bus unbalanced current, and compare the first measured value of the bus unbalanced current with the theoretical value of the bus unbalanced current in the double-span state to obtain a second comparison result. If the second comparison result is as expected, proceed to the next step; otherwise, prompt that the closing is abnormal and terminate the operation.

[0086] In some embodiments, the specific calculation formula of the theoretical value of bus unbalanced current in the double-span state is:

[0087] I′ dt =∑I′ t +I′ ML = -I′ h ;

[0088] I′ df =∑I′ f -I′ ML =I′ h ;

[0089] Among them, I′ dt I′ is the unbalanced current on the busbar connected to the switch in the double-span state. df is the unbalanced current on the busbar connected to the other switch in the same branch of the switch to be closed in the double span state. Let the other switch in the same branch of the switch to be closed be the switch to be opened, I′ t I′ is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed and not where the switch to be closed is located in the double-span state. f I′ is the branch current flowing through the outgoing line connected to the same busbar as the switch to be disconnected in the double span state. h is the current flowing through the switch to be closed in the double span state, I′ ML It is the current flowing through the bus tie switch in the double span state. The reference positive direction of the current here is defined as: the branch switch and knife switch current are positive when they flow out of the bus, and the reference positive direction of the bus tie current is positive when it flows from the new bus to which the switching branch will be switched to the original bus.

[0090] Combination Figure 3 , 4 The circuit in the embodiment is used to explain the parameters in the present invention. Q1 of the outgoing line (branch) 3 is a knife switch to be closed, Q2 of the outgoing line 3 is a knife switch to be opened, the bus connected to Q1 is bus I, and the bus connected to Q2 is bus II.

[0091] Therefore, I′ dt for Figure 4 The unbalanced current on bus I in the double span state is I′ d1 , I′ df for Figure 4 The unbalanced current on the bus in the double span state II is I′ d2 , I′ h for Figure 4 I′ 31 , I′ t for Figure 4 I′1, I′ f for Figure 4 I′2 and I′3 in .

[0092] Here, meeting expectations means that the measured value is equal to the corresponding theoretical value.

[0093] Step 3: After determining that the knife switch to be closed is indeed closed, execute the next step: open the knife switch to be opened. That is, execute the operation of opening the knife switch to be opened, and make the bus tie current, section switch current, and bus unbalanced current after the operation of opening the knife switch to be opened be the second measured value of the bus tie current, the second measured value of the section switch current, and the second measured value of the bus unbalanced current, respectively. Then, determine whether the knife switch to be opened has been opened based on the second measured value of the bus tie current, the second measured value of the section switch current, and the second measured value of the bus unbalanced current. If so, end the operation and the switching is successful. Otherwise, prompt that the opening is abnormal and terminate the operation. That is:

[0094] (1) Measure the bus unbalanced current and compare it with the calculated value of the bus unbalanced current to determine whether the unbalanced current has returned to zero. If the unbalanced current has not returned to zero, an "abnormal" message will be displayed and the operation will be terminated.

[0095] (2) Measure the busbar and section switch currents after the disconnection switch is opened, and compare them with the theoretical calculation results of the busbar and section switch currents to determine whether they meet expectations. If they do not meet expectations, an "abnormal" prompt will be displayed and the operation will be terminated.

[0096] The more specific process is:

[0097] Collect the second measured value of the busbar unbalanced current, and determine whether the second measured value of the busbar unbalanced current is zero. If so, proceed to the next step; otherwise, prompt a trip abnormality.

[0098] Collect the second measured value of the main bus current and the second measured value of the sectional switch current after the operation of pulling open the knife switch to be opened, and compare the second measured value of the main bus current and the second measured value of the sectional switch current after the operation of pulling open the knife switch to be opened with the theoretical value of the main bus current and the theoretical value of the sectional switch current after opening to obtain a third comparison result. If the third comparison result is as expected, the operation is completed and the switching is successful. Otherwise, it is prompted that the closing is abnormal and the operation is terminated.

[0099] For more specific implementation steps, see Figure 2 .

[0100] In some embodiments, the specific expressions of the theoretical value of the busbar current and the theoretical value of the segmented switch current after the switch is opened are:

[0101] I″ ML =-∑I″ t =∑I″ f ;

[0102] Among them, I″ ML The theoretical value of the busbar current after the switch is opened, I″ t I″ is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed after the opening operation is performed. Let the other switch on the same branch as the switch to be closed be the switch to be opened, f It is the outgoing current that flows through the branch connected to the same bus as the switch to be opened and not the branch where the switch to be opened is located after the opening operation is performed.

[0103] Or Figure 3 , 4 Take as an example to illustrate the parameters of the above formula.

[0104] I″ ML is the current flowing through the bus tie breaker DL after opening, I″ t That is, the current appearing in line 1 and line 3, that is, I″1 and I″3, I″2 is the current of line 2, and the currents with two superscripts are in the corresponding positions of the same variables in the figure.

[0105] In some embodiments, if there are multiple bus couplers and / or segment switches, the theoretical value of the bus coupler current corresponding to each bus coupler and / or the segment switch current corresponding to each segment switch is calculated. The bus unbalanced current, bus coupler current, segment switch current, and branch current on the bus are all three-phase currents.

[0106] In some embodiments, a system for confirming the position of a switch during a bus switching operation is further disclosed, which is used to implement the aforementioned method for confirming the position of a switch during a bus switching operation, including:

[0107] The acquisition module is used to collect the measured value of the bus coupling current (the first measured value of the bus coupling current), the measured value of the sectional switch current (the first measured value of the sectional switch current), and the measured value of the bus unbalanced current (the first measured value of the bus unbalanced current) in the double-span state, as well as the measured value of the bus coupling current (the second measured value of the bus coupling current), the measured value of the sectional switch current (the second measured value of the sectional switch current), and the measured value of the bus unbalanced current (the second measured value of the bus unbalanced current) after the operation of pulling open the knife switch to be disconnected is performed;

[0108] A first judgment module is used to judge whether the to-be-closed knife switch has been closed according to the first measured value of the bus current, the first measured value of the segment switch current and the first measured value of the bus unbalanced current;

[0109] A second judgment module is used to judge whether the switch to be disconnected has been opened according to the second measured value of the bus tie current, the second measured value of the sectionalized switch current and the second measured value of the bus unbalanced current;

[0110] The alarm module is used to issue an early warning prompt when the knife switch to be closed fails to close or the knife switch to be opened fails to open.

[0111] Implementation and effect verification:

[0112] The present invention is specifically demonstrated through examples below. It is necessary to point out that the examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the contents of the present invention.

[0113] Example:

[0114] This implementation example Figure 5 The 220kV substation shown in the figure adopts a double-bus single-section main wiring mode. The station has a total of 6 outgoing lines, of which outgoing lines 2, 3, and 6 run on bus I, outgoing line 1 runs on bus II, and outgoing lines 4 and 5 run on bus III. The main wiring and initial operating status of the station are as follows Figure 5 shown.

[0115] (1) Example of successful knife switch operation

[0116] First, consider that all the switch devices in the station are in normal state. It is necessary to switch the outgoing line 3 from I mother to II mother for operation. According to the method proposed by the present invention, the process is as follows: Figure 6 shown.

[0117] First, the system records the current operating status. Then, the "Close 2032 knife switch" operation is executed. After the operation is completed, the system calculates the expected state changes of the current of the busbars and section switches such as 212DL, 213DL, and 223DL. Among them, the three phases of the 212DL switch current should change from 287A to 98A, the 213DL current should drop from 344A to 228A, and the 223DL current should change from 98A to 42A. The system reads the actual measured values ​​of the three switch currents of 212DL, 213DL, and 223DL, which are consistent with expectations. Further compare whether the unbalanced currents of the three busbars after the 2032 knife switch is closed are in line with expectations. The system calculates that the three phases of the unbalanced current of #1M are 309A, the three phases of the unbalanced current of #2M are 196A, and the unbalanced current of #3M is 0A. The measured results are consistent with the theoretical values, so it is determined that the 2032 switch has been reliably closed. Continue to the next step "Close 2031 knife switch operation". After the operation is executed, first determine that the unbalanced current of #1M and #2M is zero. At the same time, the current changes of the monitoring busbar and section switches are in line with expectations. The operation is completed and the switch is switched successfully. The detailed process is as follows: Figure 6 As shown in the flow chart.

[0118] (2) The closing of the circuit breaker fails due to the failure of the contact to close properly

[0119] Still considering such an operation, it is assumed that at this time, the 2032 knife switch cannot actually close the contact due to an abnormality in the operating mechanism, which is manifested as the electrical and mechanical indicators showing that the closing is successful after the closing operation, but the contacts are not actually in contact. The process of confirming the knife switch operation position according to the method proposed by the present invention is as follows: Figure 7 shown.

[0120] First, the "close 2032 knife switch" operation is still performed. After the operation is completed, the system calculates the expected state changes of the current of the busbars and section switches such as 212DL, 213DL, and 223DL. Among them, the three phases of the 212DL switch current should change from 287A to 98A, the 213DL current should drop from 344A to 228A, and the 223DL current should change from 98A to 42A. The system reads the measured current values ​​of the three switches 212DL, 213DL, and 223DL. The currents of the A and B phases of the three switches are consistent with expectations, but the currents of the C phase do not match, indicating that the closing of the C phase of the 2032 knife switch is abnormal. Further comparison is made to see whether the unbalanced currents of the three busbars after the 2032 knife switch is closed are in line with expectations. The system calculates that the three phases of the unbalanced current of #1M are 309A, the three phases of the unbalanced current of #2M are 196A, and the unbalanced current of #3M is 0A. The measured results show that the unbalanced currents of the #1M and #2MC phases are inconsistent with expectations. It indicates that the closing of phase C of 2023 knife switch is abnormal. At the same time, the operation is terminated.

[0121] The above embodiments show that the present invention can effectively identify whether the knife switch is fully closed during the hot bus-reversing operation of double bus connection when mechanical and electrical indications fail.

[0122] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for confirming the position of a switch during a busbar switching operation, characterized in that: include: The busbar reversing operation starts, and the busbar knife switch to be closed is closed to form a double-span state, and the busbar current, the section switch current, and the busbar unbalanced current in the double-span state are respectively the first measured value of the busbar current, the first measured value of the section switch current, and the first measured value of the busbar unbalanced current; According to the first measured value of the busbar current, the first measured value of the sectionalized switch current and the first measured value of the busbar unbalanced current, respectively, it is judged whether the switch to be closed has been closed; if so, it is jumped to the next step; otherwise, it is prompted that the closing is abnormal and the operation is terminated; Execute the operation of pulling open the knife switch to be opened, and make the bus tie current, the sectionalizing switch current, and the bus unbalanced current after the operation of pulling open the knife switch to be opened be the second measured value of the bus tie current, the second measured value of the sectionalizing switch current, and the second measured value of the bus unbalanced current respectively; According to the second measured value of the bus current, the second measured value of the section switch current and the second measured value of the bus unbalanced current, it is judged whether the switch to be opened has been opened. If so, the operation is terminated and the switching is successful. Otherwise, it is prompted that the opening is abnormal and the operation is terminated.

2. A method for confirming the position of a switch during a bus switching operation according to claim 1, characterized in that: The specific process of judging whether the switch to be closed is closed according to the first measured value of the bus coupling current, the first measured value of the sectionalized switch current and the first measured value of the bus unbalanced current is as follows: Collect the first measured value of the bus tie current and the first measured value of the sectional switch current, and compare the first measured value of the bus tie current and the first measured value of the sectional switch current with the theoretical value of the bus tie current and the theoretical value of the sectional switch current in the double-span state to obtain a first comparison result. If the first comparison result is in line with expectations, proceed to the next step; otherwise, prompt a closing abnormality; Collect the first measured value of the bus unbalanced current, and compare the first measured value of the bus unbalanced current with the theoretical value of the bus unbalanced current in the double-span state to obtain a second comparison result. If the second comparison result is as expected, proceed to the next step; otherwise, prompt that the closing is abnormal and terminate the operation.

3. A method for confirming the position of a switch during a bus switching operation according to claim 2, characterized in that: The theoretical value of the busbar current in the double-span state is obtained by power flow calculation and should satisfy the expression: I′ ML =I ML -I′ h -∑I′ t +∑I t ; Among them, I′ h is the current flowing through the switch to be closed in the double span state, I′ t I is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed and not where the switch to be closed is located in the double-span state. t I′ is the outgoing current of the branch that is connected to the same busbar as the switch to be closed before switching and is not where the switch to be closed is located. ML is the current flowing through the bus tie switch in the double span state, I ML It is the current flowing through the bus tie switch before switching. The reference positive direction of the current here is defined as: the current of the branch switch and the knife switch is positive when it flows out of the bus. The reference positive direction of the bus tie current is from the new bus to which the switching branch is to be switched to to the original bus.

4. A method for confirming the position of a switch during a bus switching operation according to claim 2, characterized in that: The specific expression of the theoretical value of busbar unbalanced current in the double-span state is: I′ dt =∑I′ t +I′ ML =-I′ h ; I′ df =∑I′ f -I′ ML =I′ h ; Among them, I′ dt I′ is the unbalanced current on the busbar connected to the switch in the double-span state. df is the unbalanced current on the busbar connected to the other switch in the same branch of the switch to be closed in the double span state. Let the other switch in the same branch of the switch to be closed be the switch to be opened, I′ t I′ is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed and not where the switch to be closed is located in the double-span state. f I′ is the branch current flowing through the outgoing line connected to the same busbar as the switch to be disconnected in the double span state. h is the current flowing through the switch to be closed in the double span state, I′ ML It is the current flowing through the bus tie switch in the double-span state. The reference positive direction of the current here is defined as: the current of the branch switch and the knife switch is positive when it flows out of the bus. The reference positive direction of the bus tie current is from the new bus to which the switching branch is to be switched to the original bus.

5. The method for confirming the position of a switch during a bus switching operation according to claim 1, characterized in that: The specific process of judging whether the switch to be disconnected has been opened according to the second measured value of the busbar current, the second measured value of the sectionalized switch current and the second measured value of the busbar unbalanced current is as follows: Collect the second measured value of the busbar unbalanced current, and determine whether the second measured value of the busbar unbalanced current is zero. If so, proceed to the next step; otherwise, prompt a trip abnormality. Collect the second measured value of the main bus current and the second measured value of the segmented switch current, and compare the second measured value of the main bus current and the second measured value of the segmented switch current with the theoretical value of the main bus current and the theoretical value of the segmented switch current after disconnection to obtain a third comparison result. If the third comparison result is as expected, the operation is completed and the switching is successful. Otherwise, it is prompted that the closing is abnormal and the operation is terminated.

6. A method for confirming the position of a switch during a bus switching operation according to claim 5, characterized in that: The specific expression of the theoretical value of the busbar current after opening is: I″ ML =-∑I″ t =∑I″ f ; Among them, I″ ML The theoretical value of the busbar current after the switch is opened, I″ t I″ is the outgoing current flowing through the branch connected to the same busbar as the switch to be closed after the opening operation is performed. Let the other switch on the same branch as the switch to be closed be the switch to be opened, f It is the outgoing current that flows through the branch connected to the same bus as the switch to be opened and not the branch where the switch to be opened is located after the opening operation is performed.

7. A method for confirming the position of a switch during a bus switching operation according to claim 1, characterized in that: Before starting the busbar reversing operation, first confirm whether the status of all switches in the station is normal. If normal, perform the busbar reversing operation. Otherwise, the operation can be performed only after the defects are eliminated.

8. A method for confirming the position of a switch during a bus switching operation according to claim 1, characterized in that: If there are multiple bus couplers and / or sectional switches, the theoretical values ​​of the bus coupler current corresponding to each bus coupler and / or the sectional switch current corresponding to each sectional switch are calculated.

9. A method for confirming the position of a switch during a bus switching operation according to claim 1, characterized in that: The bus unbalanced current, bus coupling current, section switch current and branch current on the bus are all three-phase currents.

10. A system for confirming the position of a switch during a bus switching operation, used to implement a method for confirming the position of a switch during a bus switching operation according to any one of claims 1 to 9, characterized in that: include: An acquisition module, used for acquiring a first measured value of a bus-tie current, a first measured value of a sectional switch current, a first measured value of a bus unbalanced current, a second measured value of a bus-tie current, a second measured value of a sectional switch current, and a second measured value of a bus unbalanced current; A first judgment module is used to judge whether the to-be-closed knife switch has been closed according to the first measured value of the bus current, the first measured value of the segment switch current and the first measured value of the bus unbalanced current; A second judgment module is used to judge whether the switch to be disconnected has been opened according to the second measured value of the bus tie current, the second measured value of the sectionalized switch current and the second measured value of the bus unbalanced current; The alarm module is used to issue an early warning prompt when the knife switch to be closed fails to close or the knife switch to be opened fails to open.

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