CN109802364B - Bus protection method and system for self-adaptive switching of transformer substation - Google Patents
Bus protection method and system for self-adaptive switching of transformer substation Download PDFInfo
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Abstract
The invention provides a bus protection method for self-adaptive switching of a transformer substation, which comprises the following steps: receiving a current sampling value of a first bus, a current sampling value of a second bus, a current sampling value of each branch circuit and a position signal of a disconnecting link through a bus protection device; the bus protection device calculates the virtual differential flow of the bus system, the virtual differential flow of the first bus and the virtual differential flow of the second bus according to the collected current sampling value and the position signal of the disconnecting link; if the virtual differential flow of the bus system is balanced, and when the virtual differential flow of at least one bus of the first bus and the second bus is unbalanced, determining the position of the knife switch with the abnormality and the position signal of the knife switch before the abnormality according to the position signal of each knife switch at the current moment, the position signal of each knife switch at the last moment and the current sampling value of each branch. The invention can judge the fault of the disconnecting link in time and take measures to remove the fault, thereby avoiding the expansion of the accident and the power failure of the whole station.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to a bus protection method and system for self-adaptive switching of a transformer substation.
Background
The switching operation is one of the most important daily works of substation operators on duty, and is also misoperation causing the most serious accidents, and meanwhile, the operation mode during switching is also the weakest link of the operation of a power grid. In order to reduce the influence of the switching operation on the power grid, the power grid organization sets a strict switching operation principle, the switching operation is required to avoid a sensitive time period (7: 00-23:00 per day and a special power supply guarantee period), and meanwhile, a single fault is required in the switching operation process to avoid voltage loss of the whole station. The management measures reduce the risk of the power grid to a certain extent, but increase a large amount of night operations, cause unstable mental states of operators and increase the risk of misoperation.
Meanwhile, with the popularization and application of the intelligent substation, the programmed operation of the substation is already applied to multiple test points, however, the inter-bay interval programmed operation in the substation has no effective solution, and particularly, the problems of bus coupler idle opening, switching-on and switching-off of a protection pressing plate, position identification of a disconnecting link in double-bay and the like are very difficult during double-bus switching operation. Therefore, the research on the self-adaptive switching operation of the transformer substation is significant.
1) Loss of selectivity in busbar protection: during the whole switching operation period, due to the long-term input of the bus interconnection pressing plate of the busbar differential protection, the busbar differential protection loses selectivity for a long time, so that faults occur during the switching operation period, and the accident range is enlarged.
2) Uncertainty of manual operation: the switching on and off of the bus interconnection pressing plate and the bus coupler circuit breaker control power supply are completely completed manually by operators, the switching-off operation time is prolonged to a certain extent, and the risk that the transformer substation breaks down in an abnormal operation mode is increased. In addition, the switching operation is often performed at night, and the unstable mental state of the operator increases the risk of misoperation.
Disclosure of Invention
In order to solve the technical problems, the invention provides a bus protection method and a bus protection system for self-adaptive switching of a transformer substation, which can judge the fault of a disconnecting link according to the calculation result of virtual differential current, adopt measures to remove related faults and avoid the serious consequences of accident enlargement and power failure of the whole substation.
The invention provides a bus protection method for self-adaptive switching of a transformer substation, which is applied to a bus system of the transformer substation and a plurality of branches, wherein the bus system comprises a first bus and a second bus, each branch is respectively connected into the first bus and the second bus through two disconnecting links,
the bus protection method for the self-adaptive switching of the transformer substation comprises the following steps:
s1, receiving the current sampling value of the first bus and the current sampling value of the second bus which are acquired in real time, the current sampling value of each branch circuit which is acquired in real time and the position signal of the disconnecting link on each branch circuit through a bus protection device, wherein the position signal of the disconnecting link comprises a closing contact signal and a separating contact signal of the disconnecting link;
s2, the bus protection device calculates the virtual differential current of the bus system, the virtual differential current of the first bus and the virtual differential current of the second bus according to the collected current sampling value and the position signal of the disconnecting link on each branch circuit;
s3, the bus protection device judges whether the virtual differential flow of the bus system is balanced, and if the virtual differential flow of the bus system is balanced, the bus protection device further judges whether the virtual differential flow of the first bus and the virtual differential flow of the second bus are balanced;
s4, when the virtual differential current of at least one of the first bus and the second bus is unbalanced, determining the position of the abnormal disconnecting link and the position signal of the disconnecting link before the abnormality according to the position signal of each disconnecting link on each branch at the current moment, the position signal of each disconnecting link on each branch at the previous moment and the current sampling value of each branch, and recording the position signal of the disconnecting link before the abnormality so as to cut off the fault branch according to the position signal of the disconnecting link before the abnormality.
Preferably, step S4 specifically includes the following steps:
when the virtual differential current of only one of the first bus and the second bus is unbalanced, judging whether a branch with a current sampling value of zero exists according to the current sampling value of each branch, if so, judging whether a position signal of a disconnecting link on the branch with the current sampling value of zero at the current moment is abnormal and a position signal at the previous moment is normal, and if the position signal of the disconnecting link at the current moment is abnormal and the position signal at the previous moment is normal, taking the position signal of the disconnecting link at the previous moment as the position signal before the disconnecting link is abnormal.
Preferably, step S4 specifically includes the following steps:
when the virtual differential flow of the first bus is unbalanced and the virtual differential flow of the second bus is unbalanced, judging whether a position signal of a knife switch on a branch circuit at the current moment is abnormal or not and whether a position signal at the previous moment is normal or not, if the position signal of the knife switch at the current moment is abnormal and the position signal at the previous moment is normal, calculating a virtual differential flow of a first bus and a virtual differential flow of a second bus corresponding to the time of closing the knife switch, judging that a position signal before the knife switch is abnormal corresponds to a closing state when only one of the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch is zero and the other is not zero, and judging that the position signal before the knife switch is abnormal corresponds to the closing state and a position before other knife switches of the branch circuit where the knife switch is abnormal when the knife switch is closed is not zero The set signal also corresponds to a closed state.
Preferably, the method further comprises the following steps:
when the bus protection device does not receive the position signal of the disconnecting link and the duration time reaches the set maximum time of the disconnecting link operation, judging that the position of the disconnecting link is abnormal, automatically identifying the position of the disconnecting link according to the tide, and controlling all disconnecting links on a branch where the disconnecting link is located to be switched on after identifying the position of the disconnecting link so as to enable the branch to be converted into double-bus operation.
Preferably, the method further comprises the following steps:
when the bus protection device receives closing contact signals and opening contact signals of two disconnecting switches on the same branch at the same time, the position of the disconnecting switch is judged to be abnormal, and one disconnecting switch on the branch is controlled to be closed and the other disconnecting switch on the branch is controlled to be opened, so that the branch is converted into single bus operation.
The invention also provides a bus protection system for the self-adaptive switching of the transformer substation, which comprises the following components: the bus protection device comprises a bus system, a plurality of branches, a current transformer and a bus protection device, wherein the bus system comprises a first bus and a second bus, and each branch is respectively connected to the first bus and the second bus through two disconnecting links;
the current transformer is used for acquiring a current sampling value of the first bus, a current sampling value of the second bus and a current sampling value of each branch circuit in real time, and uploading the acquired current sampling values to the bus protection device;
the bus bar protection device includes:
the signal acquisition module is used for receiving the current sampling value of the first bus and the current sampling value of the second bus which are acquired in real time, and the current sampling value of each branch and the position signal of the disconnecting link on each branch which are acquired in real time, wherein the position signal of the disconnecting link comprises a closing contact signal and a separating contact signal of the disconnecting link;
the differential current calculation module is used for calculating the virtual differential current of the bus system, the virtual differential current of the first bus and the virtual differential current of the second bus according to the collected current sampling value and the position signal of the disconnecting link on each branch circuit;
the balance judging module is used for judging whether the virtual differential flow of the bus system is balanced or not, and further judging whether the virtual differential flow of the first bus is balanced or not and the virtual differential flow of the second bus is balanced if the virtual differential flow of the bus system is balanced;
and the position signal recording module is used for determining the position of the abnormal disconnecting link and the position signal of the disconnecting link before the abnormity occurs according to the position signal of each disconnecting link on each branch at the current moment, the position signal of each disconnecting link on each branch at the last moment and the current sampling value of each branch when the virtual differential current of at least one of the first bus and the second bus is unbalanced, and recording the position signal of the disconnecting link before the abnormity occurs so as to cut off the fault branch according to the position signal of the disconnecting link before the abnormity occurs.
Preferably, the position signal recording module is further configured to:
when the virtual differential current of only one of the first bus and the second bus is unbalanced, judging whether a branch with a current sampling value of zero exists according to the current sampling value of each branch, if so, judging whether a position signal of a disconnecting link on the branch with the current sampling value of zero at the current moment is abnormal and a position signal at the previous moment is normal, and if the position signal of the disconnecting link at the current moment is abnormal and the position signal at the previous moment is normal, taking the position signal of the disconnecting link at the previous moment as the position signal before the disconnecting link is abnormal.
Preferably, the position signal recording module is further configured to:
when the virtual differential flow of the first bus is unbalanced and the virtual differential flow of the second bus is unbalanced, judging whether a position signal of a knife switch on a branch circuit at the current moment is abnormal or not and whether a position signal at the previous moment is normal or not, if the position signal of the knife switch at the current moment is abnormal and the position signal at the previous moment is normal, calculating a virtual differential flow of a first bus and a virtual differential flow of a second bus corresponding to the time of closing the knife switch, judging that a position signal before the knife switch is abnormal corresponds to a closing state when only one of the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch is zero and the other is not zero, and judging that the position signal before the knife switch is abnormal corresponds to the closing state and a position before other knife switches of the branch circuit where the knife switch is abnormal when the knife switch is closed is not zero The set signal also corresponds to a closed state.
Preferably, the bus bar protection device further includes:
the first abnormity judgment module is used for judging the position abnormity of the disconnecting link when the position signal of the disconnecting link is not received and the lasting time reaches the set maximum time of the disconnecting link operation, automatically identifying the position of the disconnecting link according to the tide, and controlling all disconnecting links on a branch where the disconnecting link is located to be switched on after the position of the disconnecting link is identified so as to enable the branch to be converted into double-bus operation.
Preferably, the bus bar protection device further includes:
and the second abnormity judgment module is used for judging the position abnormity of the disconnecting link when receiving the closing contact signal and the opening contact signal of two disconnecting links on the same branch at the same time, and controlling one disconnecting link on the branch to be switched on and the other disconnecting link to be switched off so that the branch is converted into single bus operation.
The implementation of the invention has the following beneficial effects: when the virtual differential current of one bus is unbalanced, determining the position of the abnormal disconnecting link and the position signal of the disconnecting link before the abnormity occurs according to the position signal of each disconnecting link on each branch at the current moment, the position signal of each disconnecting link on each branch at the last moment and the current sampling value of each branch, and recording the position signal of the disconnecting link before the abnormity occurs so as to cut off the fault branch according to the position signal of the disconnecting link before the abnormity occurs. The method provided by the invention can judge the fault according to the virtual differential calculation result, and can remove the related fault by adopting corresponding measures without enlarging the accident, thereby avoiding the occurrence of the malignant consequence of the power failure of the total station and ensuring the normal operation of the transformer substation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic view of a bus bar system and a plurality of branch circuits provided by the present invention.
Fig. 2 is a flowchart of a bus protection method for adaptive switching of a substation provided by the invention.
FIG. 3 is a basic logic diagram of the virtual difference amount provided by the present invention.
FIG. 4 is a schematic diagram of the virtual differential logic of the knife switch from on to off provided by the present invention.
Fig. 5a and 5b are schematic diagrams of error correction logic for the abnormal knife-switch position under two different situations provided by the present invention.
Fig. 6 is a schematic block diagram of a bus bar protection device provided by the present invention.
Detailed Description
The invention provides a bus protection method for self-adaptive switching of a transformer substation, which is applied to a bus system and a plurality of branches of the transformer substation (as shown in figure 1), wherein the bus system comprises a first bus (I bus for short) and a second bus (II bus for short), and each branch is respectively connected into the first bus and the second bus through two disconnecting switches.
As shown in fig. 2, the bus protection method for the self-adaptive switching of the substation includes the following steps:
and S1, receiving the current sampling value of the first bus and the current sampling value of the second bus which are acquired in real time through the bus protection device, and the current sampling value of each branch circuit and the position signal of the disconnecting link on each branch circuit which are acquired in real time, wherein the position signal of the disconnecting link comprises a closing contact signal and a separating contact signal of the disconnecting link.
S2, the bus protection device calculates a virtual differential current (i.e. a virtual differential current, also called a virtual large differential current) of the bus system, and a virtual differential current of the first bus and a virtual differential current of the second bus (a virtual differential current of a single bus is also called a virtual small differential current) according to the collected current sampling values and the position signals of the knife switches on each branch.
And S3, the bus protection device judges whether the virtual differential flow of the bus system is balanced, and if the virtual differential flow of the bus system is balanced, the bus protection device further judges whether the virtual differential flow of the first bus and the virtual differential flow of the second bus are balanced.
S4, when the virtual differential current of at least one of the first bus and the second bus is unbalanced, determining the position of the knife switch with the abnormality (it should be noted that the "position of the knife switch with the abnormality" refers to the position of the knife switch on which branch and which bus the knife switch is connected to, and is not the same as the position signal of the knife switch) and the position signal of the knife switch before the abnormality occurs according to the position signal of each knife switch on each branch at the present time, the position signal of the knife switch before the abnormality occurs, and recording the position signal of the knife switch before the abnormality occurs, so as to cut off the fault branch according to the position signal before the abnormality occurs.
Generally, when the knife switch is not in fault and abnormal state, when the knife switch is switched on, the on contact of the knife switch outputs a high level signal (represented by a numeral "1") to the bus protection device, and the off contact of the knife switch outputs a low level signal (represented by a numeral "0") to the bus protection device; when the knife switch is opened, the closing contact of the knife switch outputs a low level signal (represented by a numeral "0") to the bus protection device, and the opening contact of the knife switch outputs a high level signal (represented by a numeral "1") to the bus protection device. When the bus protection device receives that the contact signal of the disconnecting link is 11 or 00, the bus protection device indicates that the disconnecting link is abnormal.
Under normal conditions, in the switching process, the position of the disconnecting link is changed from closing (10) to opening (01), if a fault or abnormal disconnecting link condition occurs in the process, such as the abnormal state 11 or 00 of the position of the disconnecting link, the method provided by the invention can judge the position of the fault according to the virtual differential calculation result, and can adopt corresponding measures to remove the related fault without enlarging the accident, thereby avoiding the malignant consequence of the power failure of the whole station, and further ensuring the normal operation of the transformer substation.
The classical current differential principle of bus protection is as follows: i1+i2+…+in|≥I0(in the formula i1、i2、…、inIs a branch current, I0Is the differential current threshold). The bus differential protection is to connect all current transformers of all connecting elements on the bus to a differential circuit according to the same name and the same polarity to form a differential quantity with a tripping outlet. And (3) eliminating the conditions of unbalanced current of the bus system and current flow during bus fault, and if the bus system has no fault, enabling the large difference flow and the small difference flow of the bus differential protection to both satisfy the condition that the sigma I is equal to 0.
For the double-bus main connection, the bus protection large difference criterion is to ensure the reliability of protection action when the bus fails, and the bus protection large difference criterion is only used as a bus protection fault judging and starting element without considering the positions of the isolation switches. The differential criterion determines the discrimination of the fault property and the damage strength, the selectivity of the bus section and the formation of a tripping outlet according to the current differential formed at the position of the disconnecting link of the interval of each section of bus as the main fault discrimination logic, and finally the fault is removed.
The existing bus protection forms two operation mode words (I bus and II bus) according to the section, wherein the I bus is a first bus, and the II bus is a second bus, because each interval actual operation state has 4 conditions, if the operation mode words are wrong, the mode words of the I bus and the II bus cannot be mutually and directly checked, the current differential logic formed according to the mode words is tripped to an outlet, no precaution is available, and the reliability of the existing bus protection is seriously reduced; if the bus protection can identify obvious abnormity through current verification, the double buses are often simply forced to be single buses, and the protection loses selectivity. The importance of knife-switch position in existing bus protection differential logic is seen.
After the bus protection device is accessed at the two positions of the disconnecting link, 6 temporary operation mode words and 6 corresponding virtual differential flows are added. The whole bus forms two virtual large-difference differential flows (which are calculated according to a normally open node and a normally closed node respectively); each section of bus forms two temporary operation mode words and two corresponding virtual small difference streams; 4 temporary operation mode words of the two sections of buses form 4 virtual differential currents for mutual correction and are checked with the two virtual large differential currents. The basic logic diagram of the virtual differential amount is shown in FIG. 3 below.
As shown in FIG. 4, FIG. 4 is a schematic diagram of the virtual differential logic of the knife switch from on to off.
According to the virtual differential flow formed at the two positions of the disconnecting link, the large-differential virtual differential flow is zero when the bus system has no fault; if there is a gap in which the knife-switch position is lost, the large-difference virtual difference stream is not equal to zero. For each section of bus virtual differential flow, due to the fact that the conditions that the disconnecting link double spans exist, the position node of the disconnecting link does not normally reflect the actual state of the disconnecting link and the like, the condition that the I/II bus virtual differential flow is unbalanced can occur, and at the moment, the prejudgment and positioning of the abnormal disconnecting link position and accurate alarm can be achieved through the comprehensive comparison of the disconnecting link memory and the virtual differential flow.
As shown in the following table, taking a switching operation of a branch from mother i to mother ii as an example, after switching is completed, a virtual differential comparison table is formed according to the virtual differential of mother i and mother ii and the position of each knife switch virtual device.
Each virtual differential flow indication table in switching operation process
Further, step S4 specifically includes the following steps:
when the virtual differential current of only one bus in the first bus and the second bus is unbalanced, judging whether a branch with a current sampling value of zero exists according to the current sampling value of each branch, if so, judging whether a position signal of a disconnecting link on the branch with the current sampling value of zero at the current moment is abnormal and a position signal at the previous moment is normal, and if the position signal of the disconnecting link at the current moment is abnormal and the position signal at the previous moment is normal, taking the position signal of the disconnecting link at the previous moment as the position signal before the disconnecting link is abnormal. As shown in fig. 5a, fig. 5a shows a schematic diagram of the error correction logic when the knife switch is abnormally positioned and the corresponding branch has no current.
Further, step S4 specifically includes the following steps:
when the virtual differential flow of the first bus is unbalanced and the virtual differential flow of the second bus is unbalanced, judging whether a position signal of a knife switch on a branch circuit at the current moment is abnormal or not and whether a position signal at the previous moment is normal or not, if the position signal of the knife switch at the current moment is abnormal and the position signal at the previous moment is normal, calculating the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch, judging that a position signal before the knife switch is abnormal corresponds to a closing state when only one of the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch is zero and the other is not zero, and judging that the position signal before the knife switch is abnormal corresponds to the closing state and position signals before other knife switches of the branch circuit are abnormal when the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch are not zero Corresponding to the closing state. As shown in fig. 5b, fig. 5b shows a schematic diagram of error correction logic when the position of the knife switch is abnormal and the virtual small differences of the two buses are not balanced.
Further, step S4 may further include the steps of: when the position signal of the disconnecting link on the branch at the current moment is abnormal and the position signal at the previous moment is normal, the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the disconnecting link during the disconnecting link are calculated, and whether the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the disconnecting link during the switching on are correct is verified according to the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the disconnecting link during the switching off.
Generally, when the virtual differential flow of the first bus corresponding to the closing of the knife switch is zero, the virtual differential flow of the first bus corresponding to the opening of the knife switch is not zero, and when the virtual differential flow of the second bus corresponding to the closing of the knife switch is zero, the virtual differential flow of the second bus corresponding to the opening of the knife switch is not zero.
The bus protection method for the self-adaptive switching of the transformer substation further comprises the following steps:
when the bus protection device does not receive the position signal of the disconnecting link and the duration time reaches the set maximum time of the disconnecting link operation, judging that the position of the disconnecting link is abnormal, automatically identifying the position of the disconnecting link according to the tide, and controlling all disconnecting links on a branch where the disconnecting link is located to be switched on after identifying the position of the disconnecting link so as to enable the branch to be converted into double-bus operation. When the bus protection device does not receive the position signal of the disconnecting link and the duration time does not reach the set maximum time of the disconnecting link operation, the bus protection device controls the branch circuit to be converted into a single bus to operate.
When the bus protection device judges that signals of a normally open contact (closing contact) and a normally closed contact (dividing into contacts) of the disconnecting link are both sometimes on a certain branch, the position of the disconnecting link is judged to be abnormal, the position of the disconnecting link is automatically identified according to the tide, and whether the disconnecting link is in a closing position or a separating position is judged.
The bus protection method for the self-adaptive switching of the transformer substation further comprises the following steps:
when the bus protection device receives closing contact signals and opening contact signals of two disconnecting switches on the same branch at the same time, the position of the disconnecting switch is judged to be abnormal, and one disconnecting switch on the branch is controlled to be closed and the other disconnecting switch on the branch is controlled to be opened, so that the branch is converted into single bus operation.
The invention also provides a bus protection system for the self-adaptive switching of the transformer substation, which comprises the following components: the bus system comprises a first bus and a second bus, and each branch is respectively connected into the first bus and the second bus through two disconnecting links.
The current transformer is used for acquiring a current sampling value of a first bus and a current sampling value of a second bus in real time, acquiring a current sampling value of each branch in real time, and uploading the acquired current sampling values to the bus protection device.
As shown in fig. 6, the bus bar protecting device includes: the device comprises a signal acquisition module, a difference flow calculation module, a balance judgment module and a position signal recording module.
The signal acquisition module is used for receiving a current sampling value of a first bus and a current sampling value of a second bus which are acquired in real time, and a current sampling value of each branch circuit and a position signal of a disconnecting link on each branch circuit which are acquired in real time, wherein the position signal of the disconnecting link comprises a closing contact signal and a separating contact signal of the disconnecting link.
And the differential flow calculation module is used for calculating the virtual differential flow of the bus system, the virtual differential flow of the first bus and the virtual differential flow of the second bus according to the collected current sampling value and the position signal of the disconnecting link on each branch.
The balance judging module is used for judging whether the virtual differential flow of the bus system is balanced or not, and if the virtual differential flow of the bus system is balanced, further judging whether the virtual differential flow of the first bus is balanced with the virtual differential flow of the second bus or not.
The position signal recording module is used for determining the position of the abnormal disconnecting link and the position signal of the disconnecting link before the abnormity occurs according to the position signal of each disconnecting link on each branch at the current moment, the position signal of each disconnecting link on each branch at the last moment and the current sampling value of each branch when the virtual differential current of at least one bus in the first bus and the second bus is unbalanced, and recording the position signal of the disconnecting link before the abnormity occurs so as to cut off the fault branch according to the position signal of the disconnecting link before the abnormity occurs.
The position signal recording module is further configured to:
when the virtual differential current of only one bus in the first bus and the second bus is unbalanced, judging whether a branch with a current sampling value of zero exists according to the current sampling value of each branch, if so, judging whether a position signal of a disconnecting link on the branch with the current sampling value of zero at the current moment is abnormal and a position signal at the previous moment is normal, and if the position signal of the disconnecting link at the current moment is abnormal and the position signal at the previous moment is normal, taking the position signal of the disconnecting link at the previous moment as the position signal before the disconnecting link is abnormal.
A position signal recording module, further configured to:
when the virtual differential flow of the first bus is unbalanced and the virtual differential flow of the second bus is unbalanced, judging whether a position signal of a knife switch on a branch circuit at the current moment is abnormal or not and whether a position signal at the previous moment is normal or not, if the position signal of the knife switch at the current moment is abnormal and the position signal at the previous moment is normal, calculating the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch, judging that a position signal before the knife switch is abnormal corresponds to a closing state when only one of the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch is zero and the other is not zero, and judging that the position signal before the knife switch is abnormal corresponds to the closing state and position signals before other knife switches of the branch circuit are abnormal when the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch are not zero Corresponding to the closing state.
And, the position signal recording module may be further configured to: when the position signal of the disconnecting link on the branch at the current moment is abnormal and the position signal at the previous moment is normal, the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the disconnecting link during the disconnecting link are calculated, and whether the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the disconnecting link during the switching on are correct is verified according to the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the disconnecting link during the switching off.
Generally, when the virtual differential flow of the first bus corresponding to the closing of the knife switch is zero, the virtual differential flow of the first bus corresponding to the opening of the knife switch is not zero, and when the virtual differential flow of the second bus corresponding to the closing of the knife switch is zero, the virtual differential flow of the second bus corresponding to the opening of the knife switch is not zero.
The bus bar protection device further comprises: the device comprises a first abnormity judgment module and a second abnormity judgment module.
The first abnormity judgment module is used for judging the position abnormity of the disconnecting link when the position signal of the disconnecting link is not received and the lasting time reaches the set maximum time of the disconnecting link operation, automatically identifying the position of the disconnecting link according to the tide, and controlling all disconnecting links on a branch where the disconnecting link is located to be switched on after the position of the disconnecting link is identified so as to enable the branch to be converted into double-bus operation.
The second abnormity judgment module is used for judging the position abnormity of the disconnecting link when receiving closing contact signals and opening contact signals of two disconnecting links on the same branch at the same time, and controlling one disconnecting link on the branch to be closed and the other disconnecting link to be opened so that the branch is converted into single bus operation.
In summary, the invention can ensure that the position state of the knife switch is wrong in the switching process, and the fault can still be reliably and quickly removed under the condition of light load or no flow at abnormal intervals.
The method is applied to the relay protection of the transformer substation, can effectively judge the switching operation state of each branch according to the received double-position information of the disconnecting link in the switching operation process of the transformer substation, adaptively processes the faults occurring in the switching, does not eliminate the faults without selection, leads to accident enlargement, has simple and reliable logic, and is convenient for operators to operate.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (10)
1. A bus protection method for self-adaptive switching of a transformer substation is characterized by being applied to a bus system and a plurality of branches of the transformer substation, wherein the bus system comprises a first bus and a second bus, each branch is respectively connected to the first bus and the second bus through two disconnecting switches,
the bus protection method for the self-adaptive switching of the transformer substation comprises the following steps:
s1, receiving the current sampling value of the first bus and the current sampling value of the second bus which are acquired in real time, the current sampling value of each branch circuit which is acquired in real time and the position signal of the disconnecting link on each branch circuit through a bus protection device, wherein the position signal of the disconnecting link comprises a closing contact signal and a separating contact signal of the disconnecting link;
s2, the bus protection device calculates the virtual differential current of the bus system, the virtual differential current of the first bus and the virtual differential current of the second bus according to the collected current sampling value and the position signal of the disconnecting link on each branch circuit;
s3, the bus protection device judges whether the virtual differential flow of the bus system is balanced, and if the virtual differential flow of the bus system is balanced, the bus protection device further judges whether the virtual differential flow of the first bus and the virtual differential flow of the second bus are balanced;
s4, when the virtual differential current of at least one of the first bus and the second bus is unbalanced, determining the position of the abnormal disconnecting link and the position signal of the disconnecting link before the abnormality according to the position signal of each disconnecting link on each branch at the current moment, the position signal of each disconnecting link on each branch at the previous moment and the current sampling value of each branch, and recording the position signal of the disconnecting link before the abnormality so as to cut off the fault branch according to the position signal of the disconnecting link before the abnormality.
2. The bus protection method for the substation adaptive switching according to claim 1, wherein the step S4 specifically includes the following steps:
when the virtual differential current of only one of the first bus and the second bus is unbalanced, judging whether a branch with a current sampling value of zero exists according to the current sampling value of each branch, if so, judging whether a position signal of a disconnecting link on the branch with the current sampling value of zero at the current moment is abnormal and a position signal at the previous moment is normal, and if the position signal of the disconnecting link at the current moment is abnormal and the position signal at the previous moment is normal, taking the position signal of the disconnecting link at the previous moment as the position signal before the disconnecting link is abnormal.
3. The bus protection method for the self-adaptive switching of the substation according to claim 2, wherein the step S4 specifically includes the following steps:
when the virtual differential flow of the first bus is unbalanced and the virtual differential flow of the second bus is unbalanced, judging whether a position signal of a knife switch on a branch circuit at the current moment is abnormal or not and whether a position signal at the previous moment is normal or not, if the position signal of the knife switch at the current moment is abnormal and the position signal at the previous moment is normal, calculating a virtual differential flow of a first bus and a virtual differential flow of a second bus corresponding to the time of closing the knife switch, judging that a position signal before the knife switch is abnormal corresponds to a closing state when only one of the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch is zero and the other is not zero, and judging that the position signal before the knife switch is abnormal corresponds to the closing state and a position before other knife switches of the branch circuit where the knife switch is abnormal when the knife switch is closed is not zero The set signal also corresponds to a closed state.
4. The bus protection method for substation adaptive switching according to claim 1, further comprising the steps of:
when the bus protection device does not receive the position signal of the disconnecting link and the duration time reaches the set maximum time of the disconnecting link operation, judging that the position of the disconnecting link is abnormal, automatically identifying the position of the disconnecting link according to the tide, and controlling all disconnecting links on a branch where the disconnecting link is located to be switched on after identifying the position of the disconnecting link so as to enable the branch to be converted into double-bus operation.
5. The bus protection method for substation adaptive switching according to claim 1, further comprising the steps of:
when the bus protection device receives closing contact signals and opening contact signals of two disconnecting switches on the same branch at the same time, the position of the disconnecting switch is judged to be abnormal, and one disconnecting switch on the branch is controlled to be closed and the other disconnecting switch on the branch is controlled to be opened, so that the branch is converted into single bus operation.
6. The utility model provides a busbar protection system of self-adaptation switching of transformer substation which characterized in that includes: the bus protection device comprises a bus system, a plurality of branches, a current transformer and a bus protection device, wherein the bus system comprises a first bus and a second bus, and each branch is respectively connected to the first bus and the second bus through two disconnecting links;
the current transformer is used for acquiring a current sampling value of the first bus, a current sampling value of the second bus and a current sampling value of each branch circuit in real time, and uploading the acquired current sampling values to the bus protection device;
the bus bar protection device includes:
the signal acquisition module is used for receiving the current sampling value of the first bus and the current sampling value of the second bus which are acquired in real time, and the current sampling value of each branch and the position signal of the disconnecting link on each branch which are acquired in real time, wherein the position signal of the disconnecting link comprises a closing contact signal and a separating contact signal of the disconnecting link;
the differential current calculation module is used for calculating the virtual differential current of the bus system, the virtual differential current of the first bus and the virtual differential current of the second bus according to the collected current sampling value and the position signal of the disconnecting link on each branch circuit;
the balance judging module is used for judging whether the virtual differential flow of the bus system is balanced or not, and further judging whether the virtual differential flow of the first bus is balanced or not and the virtual differential flow of the second bus is balanced if the virtual differential flow of the bus system is balanced;
and the position signal recording module is used for determining the position of the abnormal disconnecting link and the position signal of the disconnecting link before the abnormity occurs according to the position signal of each disconnecting link on each branch at the current moment, the position signal of each disconnecting link on each branch at the last moment and the current sampling value of each branch when the virtual differential current of at least one of the first bus and the second bus is unbalanced, and recording the position signal of the disconnecting link before the abnormity occurs so as to cut off the fault branch according to the position signal of the disconnecting link before the abnormity occurs.
7. The bus protection system for substation adaptive switching according to claim 6, wherein the position signal recording module is further configured to:
when the virtual differential current of only one of the first bus and the second bus is unbalanced, judging whether a branch with a current sampling value of zero exists according to the current sampling value of each branch, if so, judging whether a position signal of a disconnecting link on the branch with the current sampling value of zero at the current moment is abnormal and a position signal at the previous moment is normal, and if the position signal of the disconnecting link at the current moment is abnormal and the position signal at the previous moment is normal, taking the position signal of the disconnecting link at the previous moment as the position signal before the disconnecting link is abnormal.
8. The bus protection system for substation adaptive switching according to claim 7, wherein the position signal recording module is further configured to:
when the virtual differential flow of the first bus is unbalanced and the virtual differential flow of the second bus is unbalanced, judging whether a position signal of a knife switch on a branch circuit at the current moment is abnormal or not and whether a position signal at the previous moment is normal or not, if the position signal of the knife switch at the current moment is abnormal and the position signal at the previous moment is normal, calculating a virtual differential flow of a first bus and a virtual differential flow of a second bus corresponding to the time of closing the knife switch, judging that a position signal before the knife switch is abnormal corresponds to a closing state when only one of the virtual differential flow of the first bus and the virtual differential flow of the second bus corresponding to the time of closing the knife switch is zero and the other is not zero, and judging that the position signal before the knife switch is abnormal corresponds to the closing state and a position before other knife switches of the branch circuit where the knife switch is abnormal when the knife switch is closed is not zero The set signal also corresponds to a closed state.
9. The substation adaptive-switching bus bar protection system according to claim 6, wherein the bus bar protection device further comprises:
the first abnormity judgment module is used for judging the position abnormity of the disconnecting link when the position signal of the disconnecting link is not received and the lasting time reaches the set maximum time of the disconnecting link operation, automatically identifying the position of the disconnecting link according to the tide, and controlling all disconnecting links on a branch where the disconnecting link is located to be switched on after the position of the disconnecting link is identified so as to enable the branch to be converted into double-bus operation.
10. The substation adaptive-switching bus bar protection system according to claim 6, wherein the bus bar protection device further comprises:
and the second abnormity judgment module is used for judging the position abnormity of the disconnecting link when receiving the closing contact signal and the opening contact signal of two disconnecting links on the same branch at the same time, and controlling one disconnecting link on the branch to be switched on and the other disconnecting link to be switched off so that the branch is converted into single bus operation.
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| CN111896866A (en) * | 2020-07-06 | 2020-11-06 | 广东电网有限责任公司 | Method and device for detecting disconnecting link of hot bus-bar reversing operation bus |
| CN111900701A (en) * | 2020-08-05 | 2020-11-06 | 华自科技股份有限公司 | Isolation switch abnormity processing method and device, bus protection device and storage medium |
| CN112630582B (en) * | 2021-03-09 | 2021-06-08 | 广东电网有限责任公司佛山供电局 | GIS loop defect diagnosis method and system based on hot bus inversion operation |
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