CN111007439A - Transformer substation bus protection secondary circuit commissioning on-load test method - Google Patents
Transformer substation bus protection secondary circuit commissioning on-load test method Download PDFInfo
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Abstract
The invention provides a load test method for a commissioning zone of a bus protection secondary circuit of a transformer substation, which comprises the steps of detecting the commissioning and decommissioning state of a protection function connecting sheet on a bus differential protection device; when the protection function connecting sheet is in an exit state, executing a preset power transmission scheme on the double-bus wiring circuit; acquiring a voltage value of a connecting terminal corresponding to each three-phase voltage transformer on the bus differential protection device after the power transmission scheme is executed, and judging whether a current loop phase error and a current loop secondary open circuit exist in a bus protection secondary loop; and if the phase difference error of the current loop and the secondary open circuit of the current loop do not exist, acquiring the current value flowing on each three-phase current transformer to judge whether the transformation ratio is correct or not, and judging whether the polarity is correct or not based on the transformation ratio. By implementing the method, potential safety hazards such as polarity errors of the current transformer, phase errors of the current loop, secondary open circuit of the current loop and the like in the bus protection secondary loop can be detected in time, and safe operation of a power grid is ensured.
Description
Technical Field
The invention relates to the technical field of substation bus protection testing, in particular to a method for testing load of a substation bus protection secondary circuit during operation.
Background
The bus bar of a substation is an important component in an electrical power system. If the bus fails to cut the fault in time, multi-interval power equipment can be damaged and the stability of the system can be damaged, so that the whole plant or the whole station has a blackout and the whole power system is broken down. Therefore, the bus protection device has reliable action and good performance, can quickly detect the fault on the bus and timely and selectively remove the fault.
In order to meet the requirements of speed and selectivity, the bus protection is constructed according to the differential principle. The bus protection cannot be realized only by simple wiring because the bus protection must be realized by considering that more spaced electrical elements (such as lines, transformers, generators, buses and the like) are connected on the bus and judging whether a fault exists based on kirchhoff current law, namely, judging whether the fault exists by calculating the sum of the currents of all the connecting elements on the bus.
As shown in fig. 1, a double bus bar connection will be described as an example. The 1M bus and the 2M bus are respectively connected with an element, namely a branch 1 and a branch 2, and are connected through a bus coupler switch. Bus protection requires only the calculation of the sum of the current vectors of all the elements connected to each bus, i.e. a differential current of
In the formula IjIs the current of each branch.
First, when the bus is normal or out of the bus range is failed, the current flowing in and the current flowing out of all the connecting elements on the bus are completely equal. For example, when a fault occurs outside of leg 1 (as shown in position a1 in FIG. 1), there is leg 2 providing an I1The fault current of the magnitude flows to a fault point through the bus tie interval and the branch circuit 1. At this time, for the 2M bus, one I flows from the branch 21The fault current of magnitude flows out of the bus-tie again by I1Magnitude of fault current, such that one goes in and one goes out, and both currents are equal in magnitude, thus 2M bus current Id＝I1-I10, i.e. the 2M bus current is zero.
Secondly, when the bus fails, all the elements connected with the bus supply fault current to a fault point, and the differential current of the bus protection is the sum of the branch currents. For example, when a 1M bus bar fails (as shown in FIG. 1 at position a 2), branch 1 provides an I1Magnitude of fault current, branch 2 providing an I2The magnitude of the fault current flows through the buscouple interval to the fault point. At this time, for the 2M bus, one I flows from the branch 21The fault current of magnitude flows out of the bus-tie again by I1Magnitude of fault current, such that one goes in and one goes out, and both currents are equal in magnitude, thus 2M bus current Id＝I1-I10, i.e. the 2M bus current is zero. For 1M bus, one I flows from branch 11The fault current of magnitude flows into I from the bus coupler1Magnitude of fault current, thus 1M bus current Id＝I1+I1＝2I1I.e. the 1M bus current is not zero.
As can be seen from the above analysis, if any current loop on any element connected to the bus has a problem, the bus protection will malfunction due to the occurrence of differential current when the bus is normal or has an external fault, or the bus protection will fail due to the absence of differential current when the bus has a fault. Therefore, the relay protection operating regulations stipulate that the bus protection must be subjected to an on-load test before commissioning in order to verify that all current loops connected to the bus protection meet the requirements.
In the practical application process, the common problems of the bus protection current loop include polarity error of the interval current transformer, phase error of the current loop, secondary open circuit of the current loop and the like. For example, the current transformer has a polarity so as to be able to distinguish the flow of the primary current, and when the polarity is reversed, the current flow is reversed. If the polarity of the branch 1 is reversed, when a fault occurs at the position a1 outside the branch 1 shown in fig. 1, the current sensed by the current transformer of the branch 1 will not flow out from the 1M bus, but flows from the branch 1 to the 1M bus, and the obtained bus protection differential current I is obtainedt＝I1+I1＝2I1And the bus protection cuts off the 1M bus by misoperation, so that the bus protection action results are completely different. For another example, when all the interval current loops of the bus protection are in phase error and the current loops are in secondary open circuit, when a fault occurs outside the bus area, the branch with the problem in the current loop collects the continuous fault current, so that differential action is generated and the bus protection malfunctions. If the phase difference of the current loop of the branch 1 is wrong or the current loop is open, when a fault occurs at the position a1 outside the branch 1 shown in fig. 1, the current transformer of the branch 1 cannot sense the fault current at this time, and at this time, the fault current actually flows to the fault point through the branch 1, so as to obtain the bus protection differential current It＝I1+0＝I1And the bus protection cuts off the 1M bus by misoperation, so that the bus protection action results are completely different.
Therefore, a method for testing the load of the operation of the bus protection secondary circuit of the transformer substation is urgently needed, which can detect potential safety hazards such as polarity errors of a current transformer, phase errors of the current circuit, secondary open circuit of the current circuit and the like in the bus protection secondary circuit in time and ensure safe operation of a power grid.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a load test method for commissioning a bus protection secondary circuit of a transformer substation, which can detect potential safety hazards such as polarity error of a current transformer, phase difference error of a current circuit, secondary open circuit of the current circuit and the like in the bus protection secondary circuit in time and ensure safe operation of a power grid.
In order to solve the technical problem, the embodiment of the invention provides a method for testing the load of a transformer substation bus protection secondary circuit during operation, which is used for a bus protection secondary circuit formed by a double-bus wiring circuit and a bus differential protection device; wherein the content of the first and second substances,
the double-bus wiring circuit is composed of a 1M bus, a 2M bus and a bus coupler switch for connecting the 1M bus and the 2M bus together, and a power transmission scheme for receiving power supply from a transformer substation through a branch circuit 1, enabling the 1M bus to enter the 2M bus through the bus coupler switch, and then transmitting the power supply to a user end through the branch circuit 2 is preset on the double-bus wiring circuit; the bus coupler switch, the branch 1 and the branch 2 are respectively provided with a corresponding three-phase current transformer, and the 1M bus and the 2M bus are respectively connected to the bus differential protection device through a corresponding three-phase voltage transformer;
the bus differential protection device is preset with a connecting terminal corresponding to each three-phase voltage transformer, so that the ABC three phases of the 1M bus and the 2M bus can correspond to the corresponding connecting terminals, and the bus differential protection device is also preset with a protection function connecting sheet and a protection logic action loop;
the method comprises the following steps:
detecting the on-off state of a protective function connecting sheet on the busbar differential protection device;
when the protection function connecting sheet on the bus differential protection device is detected to be in an exit state, executing a power transmission scheme preset on the double-bus wiring circuit;
acquiring a voltage value of a connecting terminal corresponding to each three-phase voltage transformer on the bus differential protection device after the power transmission scheme is executed, and judging whether a current loop phase error and a current loop secondary open circuit exist in the bus protection secondary loop or not according to the acquired voltage value of the connecting terminal on the bus differential protection device;
if the fact that the bus protection secondary circuit is not provided with the current circuit phase difference error and the current circuit secondary open circuit is judged, the current value flowing through each three-phase current transformer is obtained, whether the transformation ratio of each three-phase current transformer is correct or not is judged according to the obtained current value flowing through each three-phase current transformer, and whether the polarity of each three-phase current transformer is correct or not is further judged.
The specific steps of acquiring the voltage value of the connecting terminal corresponding to each three-phase voltage transformer on the bus differential protection device after the power transmission scheme is executed, and judging whether a current loop phase error and a current loop secondary open circuit exist in the bus protection secondary circuit according to the acquired voltage value of the connecting terminal on the bus differential protection device include:
after a preset power transmission scheme on the double-bus connecting circuit is executed, acquiring a voltage value of a connecting terminal corresponding to each three-phase voltage transformer on the bus differential protection device;
if the voltage values of the connection terminals corresponding to the ABC three phases in the same three-phase voltage transformer are equal, and the difference value formed by the voltage values of any one of the ABC three phases in the different three-phase voltage transformers corresponding to the connection terminals is 0, judging that no current loop phase error or current loop secondary open circuit exists in the bus protection secondary loop; and otherwise, judging that the current loop phase error and the current loop secondary open circuit exist in the bus protection secondary loop.
If it is determined that the bus protection secondary circuit has no current circuit phase difference error and no current circuit secondary open circuit, acquiring a current value flowing through each three-phase current transformer, determining whether the transformation ratio of each three-phase current transformer is correct according to the acquired current value flowing through each three-phase current transformer, and further determining whether the polarity of each three-phase current transformer is correct, the specific steps include:
when the fact that no current loop phase error or current loop secondary open circuit exists in the bus protection secondary loop is judged, the current value flowing through each three-phase current transformer is obtained;
comparing the obtained current value flowing through each three-phase current transformer with the primary power flow loaded on the 1M bus and the 2M bus after the power transmission scheme is executed, so as to obtain the transformation ratio value of each three-phase current transformer;
if the obtained transformation ratio value of each three-phase current transformer is within the preset transformation ratio range, judging that the transformation ratio of each three-phase current transformer is correct, and further judging that the polarity of each three-phase current transformer is correct;
and if the obtained transformation ratio value of a certain three-phase current transformer is not in the preset transformation ratio range, judging that the transformation ratio of the three-phase current transformer of which the transformation ratio value is not in the preset transformation ratio range is incorrect, and further judging that the polarity of the three-phase current transformer of which the transformation ratio value is not in the preset transformation ratio range is incorrect.
Wherein the method further comprises:
and after the 1M bus current value, the 2M bus current value and the large differential current value detected on the bus differential protection device are respectively and correspondingly located in respective preset normal ranges, the polarity of a three-phase current transformer arranged on the bus coupling switch is verified to be correct or not by adjusting the current on the bus coupling switch.
The specific steps of obtaining the 1M bus current value, the 2M bus current value and the large differential current value detected on the bus differential protection device, and verifying whether the polarity of the three-phase current transformer arranged on the bus coupling switch is correct by adjusting the current on the bus coupling switch after the obtained 1M bus current value, the obtained 2M bus current value and the large differential current value are respectively and correspondingly located in respective preset normal ranges include:
after the obtained 1M bus current value, 2M bus current value and large differential difference current value are respectively and correspondingly located in respective preset normal ranges, if the current on the bus-coupled switch is determined to be 0, whether the loads of the 1M bus and the 2M bus are balanced needs to be further detected;
when the load imbalance of one of the 1M bus and the 2M bus is detected, applying for load reversing operation on the 1M bus and the 2M bus, and further obtaining a current value flowing through a three-phase current transformer arranged on the bus-bar switch to judge whether the transformation ratio of the three-phase current transformer arranged on the bus-bar switch is correct after the current on the bus-bar switch exceeds a preset CT disconnection fixed value;
if the transformation ratio of the three-phase current transformer arranged on the bus tie switch is correct, verifying that the polarity of the three-phase current transformer arranged on the bus tie switch is correct; and otherwise, verifying the error of the three-phase current transformer arranged on the bus tie switch.
The embodiment of the invention has the following beneficial effects:
the invention is used for a bus protection secondary circuit formed by a double-bus wiring circuit and a bus differential protection device, judges whether a current circuit phase difference error and a current circuit secondary open circuit exist in the bus protection secondary circuit by detecting each phase voltage of double buses (1M and 2M), and judges whether the polarity set by an isolated current transformer in the bus protection secondary circuit is correct by detecting the phase current of the double buses and a bus link switch under the premise of determining that the current circuit phase difference error and the current circuit secondary open circuit do not exist, thereby being capable of quickly and timely detecting potential safety hazards such as the current transformer polarity error, the current circuit phase difference error and the current circuit secondary open circuit in the bus protection secondary circuit, ensuring the safe operation of a power grid and improving the working efficiency and the safety.
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, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is within the scope of the present invention for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic diagram of a prior art connection of a dual bus bar connection;
fig. 2 is a flowchart of a method for testing a load of a substation bus protection secondary circuit during operation according to an embodiment of the present invention;
fig. 3 is a schematic connection diagram of a bus protection secondary circuit in the method for testing the load of the operation of the bus protection secondary circuit of the substation according to the embodiment of the present invention;
fig. 4 is a schematic diagram of logical connection of the internal protection function of the protection function connection pad on the bus differential protection device in fig. 3.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 2, the method for testing the load of the transformer substation bus protection secondary circuit during operation provided in the embodiment of the present invention is used for a bus protection secondary circuit formed by a double-bus connection circuit and a bus differential protection device (as shown in fig. 3); wherein the content of the first and second substances,
the double-bus connection circuit is composed of a 1M bus, a 2M bus and a bus coupler switch for connecting the 1M bus and the 2M bus together, and a power transmission scheme (shown by an arrow in figure 3) is preset on the double-bus connection circuit, wherein the power transmission scheme is used for receiving power supply from a transformer substation through a branch 1, enabling the 1M bus to enter the 2M bus through the bus coupler switch and then transmitting the power supply to a user side through the branch 2; a corresponding three-phase current transformer (as shown in fig. 3) is arranged on each of the bus coupler switch, the branch 1 and the branch 2
) And the 1M bus and the 2M bus are respectively connected to the bus differential protection device through a corresponding three-phase voltage transformer (○ shown in figure 3);
a connection terminal corresponding to each three-phase voltage transformer is preset in the busbar differential protection device, so that three ABC phases of the 1M busbar and the 2M busbar can correspond to the corresponding connection terminal (such as 1Ua, 1Ub, 1Uc, 1N, 2Ua, 2Ub, 2Uc, 2N shown in fig. 3), and a protection function connection sheet (such as LP shown in fig. 3 and 4) and a protection logic action loop (not shown) are also preset in the busbar differential protection device; it should be noted that the protection logic action loop is used to initiate a protection action;
the method comprises the following steps:
step S1, detecting the throwing and retreating state of a protective function connecting sheet on the bus differential protection device;
step S2, when detecting that the protection function connecting sheet on the bus differential protection device is in an exit state, executing a power transmission scheme preset on the double-bus wiring circuit;
step S3, obtaining a voltage value of a connection terminal corresponding to each three-phase voltage transformer on the bus differential protection device after the power transmission scheme is executed, and determining whether a current loop phase error and a current loop secondary open circuit exist in the bus protection secondary loop according to the obtained voltage value of the connection terminal on the bus differential protection device;
step S4, if it is determined that there is no current loop phase error or current loop secondary open circuit in the bus protection secondary circuit, obtaining a current value flowing through each three-phase current transformer, determining whether the transformation ratio of each three-phase current transformer is correct according to the obtained current value flowing through each three-phase current transformer, and further determining whether the polarity of each three-phase current transformer is correct.
Specifically, in step S1, before the power transmission scheme preset on the dual bus link circuit is executed, the protection function connection pad on the bus differential protection device needs to be ensured to be in the withdrawing state, so that the withdrawing state of the protection function connection pad on the bus differential protection device needs to be detected.
In step S2, when the protection function connection pad on the busbar differential protection device is in the exit state, the power transmission scheme preset on the double-bus line circuit is executed. It should be noted that the power transmission scheme may be arranged on a substation, or may be arranged on a device for executing the method for testing the load of commissioning the bus protection secondary circuit of the substation, and the method is implemented by controlling a master switch or other devices only through the device for executing the method for testing the load of commissioning the bus protection secondary circuit of the substation.
In step S3, it is necessary to ensure that there is no current loop phase error or current loop secondary open circuit in the bus protection secondary loop, so the step specifically includes:
after a preset power transmission scheme on the double-bus connection circuit is executed, acquiring a voltage value of a connection terminal, corresponding to each three-phase voltage transformer, on the bus differential protection device;
if the voltage values (which are a constant) of the connection terminals corresponding to the ABC three phases in the same three-phase voltage transformer are equal, and the difference value formed by the voltage values of any one of the ABC three phases in the different three-phase voltage transformers corresponding to the connection terminals corresponding to the ABC three phases is 0, it is determined that no current loop phase error or current loop secondary open circuit exists in the bus protection secondary loop; and otherwise, judging that the current loop phase error and the current loop secondary open circuit exist in the bus protection secondary loop.
It can be understood that if the voltage values of the respective corresponding connection terminals of the three ABC phases in the same three-phase voltage transformer are not equal, or the difference value formed by the voltage values of the corresponding connection terminals of one of the three ABC phases in the different three-phase voltage transformers is not 0, there may be a current loop phase error or a current loop secondary open circuit.
In one embodiment, the three-phase alternating current phase voltage values of 1 Ua-1N, 1 Ub-1N and 1 Uc-1N on corresponding connecting terminals in a three-phase voltage transformer connected with a 1M bus are measured to be 57.7V normally, and the three-phase alternating current phase voltage values of 2 Ua-2N, 2 Ub-2N and 2 Uc-2N on corresponding connecting terminals in a three-phase voltage transformer connected with a 2M bus are measured to be 57.7V normally; simultaneously measuring the difference of alternating current phase-to-phase voltage values of 1Ua to 2Ua, 1Ub to 2Ub and 1Uc to 2Uc on the same corresponding connecting terminal in the two three-phase voltage transformers to be 0; at this time, it can be determined that there is no current loop phase error and current loop secondary open circuit in the bus protection secondary loop.
In step S4, it is only necessary to detect whether the polarity of each three-phase current transformer is correct under the precondition that it is ensured that there is no current circuit phase error and current circuit secondary open circuit in the bus protection secondary circuit, and therefore the step specifically includes:
when the fact that no current loop phase error or current loop secondary open circuit exists in the bus protection secondary loop is judged, the current value flowing through each three-phase current transformer is obtained;
comparing the obtained current value flowing through each three-phase current transformer with the primary power flow loaded on the 1M bus and the 2M bus after the power transmission scheme is executed, and obtaining the transformation ratio value of each three-phase current transformer; it should be noted that the power flow magnitude is set according to the power transmission scheme, and the value is a fixed value;
if the obtained transformation ratio value of each three-phase current transformer is within the preset transformation ratio range, judging that the transformation ratio of each three-phase current transformer is correct, and further judging that the polarity of each three-phase current transformer is correct;
and if the obtained transformation ratio value of a certain three-phase current transformer is not in the preset transformation ratio range, judging that the transformation ratio of the three-phase current transformer of which the transformation ratio value is not in the preset transformation ratio range is incorrect, and further judging that the polarity of the three-phase current transformer of which the transformation ratio value is not in the preset transformation ratio range is wrong.
In one embodiment, the primary power flow is 800A, the value of the current flowing through each three-phase current transformer is measured to be 0.8A, the transformation ratio value of each three-phase current transformer is calculated to be 1000/1, the transformation ratio value is within a preset range (such as 999/1-1100/1), and then the polarity of each three-phase current transformer can be judged to be correct by referring to the primary power flow directions (such as the arrow directions shown in fig. 3) of the current 1M bus and the current 2M bus.
In the embodiment of the invention, after the current, the voltage and the polarity are checked, whether the 1M bus current value, the 2M bus current value and the large differential current value in the bus differential protection device are in a normal range or not needs to be checked, and whether the polarity of the three-phase current transformer arranged on the bus differential switch is correct or not is further verified by adjusting the current on the bus differential switch. For example, if the current on the buscouple switch is small or even no current when the two buses are in load balance; if all units are inverted to the same bus to operate, no current exists on the bus tie switch, and the polarity of the three-phase current transformer arranged on the bus tie switch cannot be determined at the moment, so that the correctness of the bus difference cannot be really represented.
Accordingly, the method further comprises:
the method comprises the steps of obtaining a 1M bus current value, a 2M bus current value and a large differential current value detected on a bus differential protection device, and verifying whether the polarity of a three-phase current transformer arranged on a bus coupler switch is correct or not by adjusting the current on the bus coupler switch after the obtained 1M bus current value, 2M bus current value and large differential current value are respectively and correspondingly located in respective preset normal ranges.
After the obtained 1M bus current value, 2M bus current value and large differential difference current value are respectively and correspondingly located in respective preset normal ranges, if the current on the bus-coupled switch is determined to be 0, whether the loads of the 1M bus and the 2M bus are balanced needs to be further detected;
when the load imbalance of one of the 1M bus and the 2M bus is detected, the load imbalance of the 1M bus and the 2M bus is applied, so that after the current on the bus tie switch exceeds a preset CT disconnection constant value, the current value flowing through a three-phase current transformer arranged on the bus tie switch is further obtained to judge whether the transformation ratio of the three-phase current transformer arranged on the bus tie switch is correct or not;
if the transformation ratio of the three-phase current transformer arranged on the bus tie switch is correct, verifying that the polarity of the three-phase current transformer arranged on the bus tie switch is correct; otherwise, the error of the three-phase current transformer arranged on the bus tie switch is verified.
Based on fig. 3, an application scenario of the transformer substation bus protection secondary circuit commissioning load testing method in the embodiment of the present invention is further described:
step 1: before power transmission, the protection function connecting sheet LP on the bus protection device is withdrawn;
step 2: and transmitting power according to a power transmission starting scheme prepared in advance. If the power flow is sent to the user side from the opposite-side substation of the branch 1 through the branch 1, the power flow is sent to the user side from the opposite-side substation of the branch 1 through the branch 1 and the 1M bus, then to the bus coupler switch and the 2M bus, and finally from the branch 2;
and 3, step 3: respectively measuring whether three-phase alternating-current phase voltage values of 1M bus and 2M bus Ua-N, Ub-N, Uc-N are normal (the normal values are 57.7V) by an automatic instrument (a phase voltmeter) and the like; respectively measuring whether the alternating-current interphase voltage values of the 1M bus, the 2M buses 1 Ua-2 Ua, 1 Ub-2 Ub and 1 Uc-2 Uc are normal (the normal values are all 0V) or not, and recording;
and 4, step 4: after the fact that no current loop phase error or current loop secondary open circuit exists in a bus protection secondary loop is ensured, referring to the primary power flow size (such as 800A) of a current 1M bus and a current 2M bus at the time, and combining the transformation ratio requirements (such as 1000/1) of three-phase current transformers arranged on a branch 1, a branch 2 and a bus tie switch respectively, measuring the values of all A, B, C three-phase current secondary loops of bus protection by using an automatic instrument (a phase current meter), and converting whether the transformation ratio of the current transformers is correct or not (the transformation ratio is 1000/1, and the measured actual 0.8, wherein the primary power flow size is 800A, namely 1000/1 is 800/0.8), and the N-line current is measured to be correct or not and is recorded;
in the measuring process, the reason that the conversion ratio converted by a certain group of current values is incorrect needs to be immediately searched until the processing is normal;
and 5, step 5: on the basis that the transformation ratios of three-phase current transformers arranged on the branch 1, the branch 2 and the bus coupler switch are correct, the polarities of all interval current transformers of bus protection are determined by referring to the primary tide directions of the 1M bus and the 2M bus at the time and combining the polarity requirements of the three-phase current transformers arranged on the branch 1, the branch 2 and the bus coupler switch;
at the moment, the branch 1 flows in from the non-polar end of the three-phase current transformer connected with the branch, and flows out from the polar end; the branch 2 and the bus coupler switch respectively flow in from the polar end and flow out from the non-polar end of the three-phase current transformer which are connected with each other;
and 6, step 6: A. b, C, N, checking whether the 1M, 2M and large differential current values in the bus differential protection device are in a normal range after the current, voltage and polarity of the phases are correct;
and 7, step 7: if the load of the two buses is balanced, the current on the bus-coupled switch is very small or even no current exists; if all the units are inverted to the same bus to operate, no current exists on the bus-coupled switch, the polarity of a three-phase current transformer arranged on the bus-coupled switch cannot be determined, so that the correctness of the bus difference cannot be really represented, the application for load inversion is required under the condition, the current on the bus-coupled is larger than the CT disconnection fixed value, the test is carried out, and after all the test results are correct, the test results are recorded.
The embodiment of the invention has the following beneficial effects:
the invention is used for a bus protection secondary circuit formed by a double-bus wiring circuit and a bus differential protection device, judges whether a current circuit phase difference error and a current circuit secondary open circuit exist in the bus protection secondary circuit by detecting each phase voltage of double buses (1M and 2M), and judges whether the polarity set by an isolated current transformer in the bus protection secondary circuit is correct by detecting the phase current of the double buses and a bus link switch under the premise of determining that the current circuit phase difference error and the current circuit secondary open circuit do not exist, thereby being capable of quickly and timely detecting potential safety hazards such as the current transformer polarity error, the current circuit phase difference error and the current circuit secondary open circuit in the bus protection secondary circuit, ensuring the safe operation of a power grid and improving the working efficiency and the safety.
It will be understood by those skilled in the art that all or part of the steps in the method for implementing the above embodiments may be implemented by relevant hardware instructed by a program, and the program may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.
Claims (5)
1. A transformer substation bus protection secondary circuit operation load test method is characterized in that the method is used on a bus protection secondary circuit formed by a double-bus wiring circuit and a bus differential protection device; wherein the content of the first and second substances,
the double-bus wiring circuit is composed of a 1M bus, a 2M bus and a bus coupler switch for connecting the 1M bus and the 2M bus together, and a power transmission scheme for receiving power supply from a transformer substation through a branch circuit 1, enabling the 1M bus to enter the 2M bus through the bus coupler switch, and then transmitting the power supply to a user end through the branch circuit 2 is preset on the double-bus wiring circuit; the bus coupler switch, the branch 1 and the branch 2 are respectively provided with a corresponding three-phase current transformer, and the 1M bus and the 2M bus are respectively connected to the bus differential protection device through a corresponding three-phase voltage transformer;
the bus differential protection device is preset with a connecting terminal corresponding to each three-phase voltage transformer, so that the ABC three phases of the 1M bus and the 2M bus can correspond to the corresponding connecting terminals, and the bus differential protection device is also preset with a protection function connecting sheet and a protection logic action loop;
the method comprises the following steps:
detecting the on-off state of a protective function connecting sheet on the busbar differential protection device;
when the protection function connecting sheet on the bus differential protection device is detected to be in an exit state, executing a power transmission scheme preset on the double-bus wiring circuit;
acquiring a voltage value of a connecting terminal corresponding to each three-phase voltage transformer on the bus differential protection device after the power transmission scheme is executed, and judging whether a current loop phase error and a current loop secondary open circuit exist in the bus protection secondary loop or not according to the acquired voltage value of the connecting terminal on the bus differential protection device;
if the fact that the bus protection secondary circuit is not provided with the current circuit phase difference error and the current circuit secondary open circuit is judged, the current value flowing through each three-phase current transformer is obtained, whether the transformation ratio of each three-phase current transformer is correct or not is judged according to the obtained current value flowing through each three-phase current transformer, and whether the polarity of each three-phase current transformer is correct or not is further judged.
2. The method for testing the commissioning load of the bus protection secondary circuit of the substation according to claim 1, wherein the specific step of obtaining the voltage value of the connection terminal corresponding to each three-phase voltage transformer on the bus differential protection device after the power transmission scheme is executed, and determining whether a current circuit phase error and a current circuit secondary open circuit exist in the bus protection secondary circuit according to the obtained voltage value of the connection terminal on the bus differential protection device comprises:
after a preset power transmission scheme on the double-bus connecting circuit is executed, acquiring a voltage value of a connecting terminal corresponding to each three-phase voltage transformer on the bus differential protection device;
if the voltage values of the connection terminals corresponding to the ABC three phases in the same three-phase voltage transformer are equal, and the difference value formed by the voltage values of any one of the ABC three phases in the different three-phase voltage transformers corresponding to the connection terminals is 0, judging that no current loop phase error or current loop secondary open circuit exists in the bus protection secondary loop; and otherwise, judging that the current loop phase error and the current loop secondary open circuit exist in the bus protection secondary loop.
3. The method for testing the on-load of the commissioning of the bus protection secondary circuit of the substation according to claim 1, wherein if it is determined that there is no phase error of the current circuit and no secondary open circuit of the current circuit in the bus protection secondary circuit, the method comprises the specific steps of obtaining a current value flowing through each three-phase current transformer, determining whether a transformation ratio of each three-phase current transformer is correct according to the obtained current value flowing through each three-phase current transformer, and further determining whether the polarity of each three-phase current transformer is correct:
when the fact that no current loop phase error or current loop secondary open circuit exists in the bus protection secondary loop is judged, the current value flowing through each three-phase current transformer is obtained;
comparing the obtained current value flowing through each three-phase current transformer with the primary power flow loaded on the 1M bus and the 2M bus after the power transmission scheme is executed, so as to obtain the transformation ratio value of each three-phase current transformer;
if the obtained transformation ratio value of each three-phase current transformer is within the preset transformation ratio range, judging that the transformation ratio of each three-phase current transformer is correct, and further judging that the polarity of each three-phase current transformer is correct;
and if the obtained transformation ratio value of a certain three-phase current transformer is not in the preset transformation ratio range, judging that the transformation ratio of the three-phase current transformer of which the transformation ratio value is not in the preset transformation ratio range is incorrect, and further judging that the polarity of the three-phase current transformer of which the transformation ratio value is not in the preset transformation ratio range is incorrect.
4. The substation busbar protection secondary circuit commissioning on-load testing method of claim 1, further comprising:
and after the 1M bus current value, the 2M bus current value and the large differential current value detected on the bus differential protection device are respectively and correspondingly located in respective preset normal ranges, the polarity of a three-phase current transformer arranged on the bus coupling switch is verified to be correct or not by adjusting the current on the bus coupling switch.
5. The method for testing the load on the commissioning of the secondary loop for protecting the bus of the transformer substation according to claim 4, wherein the specific step of obtaining the 1M bus current value, the 2M bus current value and the large differential current value detected on the bus differential protection device, and verifying whether the polarity of the three-phase current transformer arranged on the bus coupled switch is correct by adjusting the current on the bus coupled switch after determining that the obtained 1M bus current value, the obtained 2M bus current value and the obtained large differential current value are respectively and correspondingly located in respective preset normal ranges comprises the following steps:
after the obtained 1M bus current value, 2M bus current value and large differential difference current value are respectively and correspondingly located in respective preset normal ranges, if the current on the bus-coupled switch is determined to be 0, whether the loads of the 1M bus and the 2M bus are balanced needs to be further detected;
when the load imbalance of one of the 1M bus and the 2M bus is detected, applying for load reversing operation on the 1M bus and the 2M bus, and further obtaining a current value flowing through a three-phase current transformer arranged on the bus-bar switch to judge whether the transformation ratio of the three-phase current transformer arranged on the bus-bar switch is correct after the current on the bus-bar switch exceeds a preset CT disconnection fixed value;
if the transformation ratio of the three-phase current transformer arranged on the bus tie switch is correct, verifying that the polarity of the three-phase current transformer arranged on the bus tie switch is correct; and otherwise, verifying the error of the three-phase current transformer arranged on the bus tie switch.
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