CN112363085A - Intelligent substation PT disconnection identification method and device - Google Patents
Intelligent substation PT disconnection identification method and device Download PDFInfo
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Abstract
A PT disconnection identification method and a PT disconnection identification device for an intelligent substation are disclosed, wherein the method comprises the steps of collecting bus voltages of all sections, currents of all intervals of bus section connection, breaker positions of all intervals and the positions of section breakers in real time; judging whether to start PT disconnection identification of the voltage transformer according to preset conditions; judging whether the PT disconnection identification meets the judgment condition, if so, sending a PT disconnection warning signal in a delayed mode, and closing in the synchronous period and closing in a non-voltage mode in a locking detection mode. The invention adopts the comprehensive judgment of multi-interval voltage and current magnitude acquired by the cluster measurement and control device, identifies PT broken line according to the characteristics of PT broken line and system fault, can judge according to the voltage on another section of bus when in parallel operation, introduces other interval currents on the same bus to assist in judging, locks PT broken line judgment when the current changes, solves the problem of false alarm or incorrect identification of PT broken line, and improves the reliability of PT broken line identification.
Description
Technical Field
The invention relates to the technical field of intelligent substations, in particular to a PT disconnection identification method and device for an intelligent substation.
Background
In recent years, intelligent transformer substations begin to be constructed and gradually popularized and applied in a large scale, and compared with traditional transformer substations, the intelligent transformer substations have a plurality of advantages, and are mainly embodied as follows: (1) and digital signal transmission and processing are adopted, so that the method is wide in application range, high in precision, stable and efficient, and convenient for data sharing. The optical fiber is used as a digital transmission carrier and has the advantages of large transmission capacity, low loss, long distance, strong anti-interference capability, good lightning protection performance, economy, environmental protection and the like. (2) The IEC61850 protocol is comprehensively adopted, information and communication models are unified, a three-layer two-network layered architecture is adopted, digital acquisition and networked information exchange of transformer substation information are realized, single-set configuration is adopted for measurement and control and protection of voltage levels of 110kV and below, the hidden danger of function failure caused by single-point faults exists, the overall reliability is low, the requirement of unattended transformer substations cannot be completely met, and the safe and stable operation of a power system is seriously influenced.
In order to better adapt to the unattended requirement of a transformer substation, improve the safe and stable operation level of a power grid, improve the operation efficiency of the power grid and reduce the construction and operation costs, in the aspect of a transformer substation automation system, a transformer substation measurement and control device belongs to bay level equipment in a transformer substation secondary system and is core equipment of a bay level of the transformer substation automation system. The upper connection station control layer equipment comprises a monitoring background, a telecontrol device and the like; the lower connection process layer equipment comprises an intelligent terminal, a merging unit and the like, and plays a role in starting and stopping.
With the rapid development of power grid and computer technologies, data acquisition and processing capabilities are continuously enhanced, system functions are developed greatly, but the requirements of various levels of main substation systems on the reliability and timeliness of various types of information are not met completely. At present, the configuration requirements of secondary equipment in intelligent substations with different voltage grades in China are different, the substations with the voltage grades of 110kV and below adopt protection and measurement integrated configuration, and the substations with the voltage grades of 220kV and above adopt independently configured measurement and control devices. Generally, most transformer substations adopt a single set of measurement and control in consideration of cost factors, namely, only one set of measurement and control device is arranged at each interval. This brings certain hidden trouble for the safe and stable operation of transformer substation, has following problem.
(1) Low reliability of single set mode operation
Under the single set configuration mode, all interval measurement and control are not standby. When the interval measurement and control fails or the maintenance quits operation, the interval measurement and control function is lost due to no standby measurement and control, and serious threat is generated to the safety of remote centralized monitoring of the unattended transformer substation. In addition, a single set of mode has a large defect in the aspect of data reliability, and because only a single set of equipment is used for information acquisition, if abnormal data or data errors occur in a certain measurement and control, the error data cannot be found due to the fact that no data is compared. Therefore, the current single-set operation mode cannot fully support the rapid development of a future power grid. There is a strong need for development and innovation in information providing mechanisms.
(2) Measurement and control method for failure detection
For a single set of measurement and control operation mode, if the measurement and control fails, the failure needs to be found quickly, and the network operation time of the failure measurement and control is reduced. However, at present, no equipment or method for rapidly finding alarm fault measurement and control exists, and whether the equipment has a fault or not is judged only by a manual mode. If faults such as network disconnection and the like are easy to find, the judgment time is short, and if faults such as error data and the like are difficult to find, the judgment time completely depends on the technical level and experience of operators, so that the safe operation of a remote regulation and control center and a transformer substation monitoring system is seriously influenced.
As main equipment for collecting operation data information of the intelligent substation and executing primary equipment operation control, the measurement and control device is an important basis for realizing safe and stable operation of the system. However, in the aspect of improving the reliability of the measurement and control function of the transformer substation, the industry mainly refers to the idea of protection dualization, discusses and researches a double-set configuration scheme of the measurement and control device, but due to the problems of insufficient equipment standardization, overhigh double-set configuration cost, complex system operation and maintenance and the like, a scheme for engineering implementation and popularization and application is not formed all the time, and the problem of the loss of the redundancy standby mechanism of the measurement and control device of the transformer substation is not solved effectively.
At present, the measurement and control devices of the intelligent transformer substation which are operated at home are all configured in a single set, the measurement and control functions are realized at intervals, and functional redundancy is lacked. The current measurement and control function PT disconnection judgment only adopts single-interval voltage and current magnitude for judgment, when any one of the following two conditions is met, PT disconnection alarm is reported after 10s of delay, and if the condition is not met for 10s, the PT disconnection alarm returns:
1. current in any phase greater than 0.005INWhile any phase of voltage is less than 0.3UNAnd the positive sequence voltage is less than 0.7UN；
2. Negative sequence voltage or zero sequence voltage (self-generating) greater than 0.1UN。
Wherein INFor CT quadratic rating (1A or 5A), UNPT quadratic rating (57.7V).
Because the current measurement and control function PT disconnection judgment only adopts single-interval voltage and current magnitude for judgment, when the interval no-load or load current is less than 0.005INWhen the PT is in three-phase disconnection, the PT cannot be correctly identified. In addition, for the high-resistance earth fault with slow climbing, due to the long fault duration, when the negative sequence voltage or the zero sequence voltage is more than 0.1UNPT disconnection is also falsely reported.
Disclosure of Invention
The invention aims to provide a PT disconnection recognition method and a PT disconnection recognition device for an intelligent substation, which aim to solve the problems that the current substation bay level measurement and control function adopts single-bay voltage and current magnitude for judgment, the PT three-phase disconnection cannot be correctly recognized when the bay is in no-load or small in load current, and the PT disconnection can be mistakenly reported for a high-resistance grounding fault which slowly climbs.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a first aspect of an intelligent substation PT disconnection identification method, which comprises the following steps;
collecting bus voltage of all sections, current of all intervals of bus section wiring, breaker positions of all intervals and the positions of the section breakers in real time;
judging whether to start PT disconnection identification of the voltage transformer according to preset conditions;
if the preset condition is met, starting PT disconnection recognition; otherwise, continuing to carry out the step of real-time acquisition;
if the PT disconnection identification meets the judgment condition, a PT disconnection warning signal is sent in a delayed mode, and synchronous closing and non-voltage closing are detected in a locking mode; otherwise, continuing to carry out the step of real-time acquisition.
Further, the preset conditions for starting the PT disconnection identification of the voltage transformer include:
UΦ1(t-2T)-UΦ1(t)＞0.1UN (1)
if the formula (1) is established, starting the PT disconnection identification of the voltage transformer;
wherein, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnectionΦ1(T-2T) is A, B, C phase voltage amplitude before two cycles of the bus where PT is located when the line is disconnected and started; u shapeNIs the PT quadratic rating.
Further, the PT disconnection recognition includes sequential judgment: (1) the values of positive sequence voltage, negative sequence voltage or zero sequence voltage of the bus where the PT is located, the positions of circuit breakers at all intervals on the bus where the PT is located or whether current exists; (2) PT disconnection identification is carried out to judge whether all interval currents on the bus change during starting; (3) and judging the position of the sectionalized circuit breaker, and judging whether the voltage values of the sectionalized buses are different or not at the switching-on position.
Further, the value of positive sequence voltage, negative sequence voltage or zero sequence voltage of the bus where the PT is located, the position of the circuit breaker at all intervals on the bus where the PT is located or whether there is current or not is judged according to the condition (1), including:
judging whether any phase voltage of the bus where the PT is located is low, the positive sequence voltage is low, and whether a current or a breaker is in a closed position exists in any interval of the corresponding bus or whether the PT has negative sequence voltage or zero sequence voltage, wherein the judgment equation is as follows:
or
U2.1(t)＞0.1UN (3)
Or
3U0.1(t)＞0.1UN (4)
If one of the above equations (2), (3) or (4) is satisfied, continuing to judge the judgment condition (2), otherwise, ending the judgment of PT disconnection identification;
wherein, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnection1.1(t) is the positive sequence voltage amplitude, U, of the bus where PT is located when PT disconnection identification starts2.1(t) is the negative sequence voltage amplitude, U, of the bus where PT is located when PT disconnection identification starts0.1(t) zero sequence voltage amplitude, I, of the bus where PT is located when PT disconnection identification startsΦ1(t) A, B, C phase current amplitude values corresponding to any interval of the bus when PT disconnection recognition is started, and DL is the position of the circuit breaker corresponding to any interval of the bus when PT disconnection recognition is started; i isNAnd protecting the secondary rated value of the CT for the corresponding bus.
Further, judging whether all interval currents on the bus change when the PT disconnection recognition of the condition (2) is started includes:
when PT disconnection identification starts, all intervals of corresponding buses have no zero sequence current, phase currents have no change, and a discrimination equation is as follows:
if the formula (5) is satisfied, continuing to judge the judgment condition (3), otherwise, finishing the judgment of PT disconnection identification;
in the above formula IΦ1(t) A, B, C phase current amplitude corresponding to any interval of the bus when PT disconnection identification starts, IΦ1(T-2T) is the A, B, C phase current amplitude value before the interval of two weeks of the corresponding bus when PT disconnection starts, I0.1(t) is the amplitude of the corresponding bus interval three-phase self-produced zero-sequence current when starting with broken line, INAnd protecting the secondary rated value of the CT for the corresponding bus.
Further, judge condition (3) and judge the position of segmentation circuit breaker, judge whether the bus voltage value of segmentation is different when the position of closing the floodgate, include:
if the sectional breaker is at the switching-on position, the bus voltage amplitudes at two sides of the sectional breaker are the same, the PT of the other section of bus has no zero sequence voltage and negative sequence voltage when the PT is broken, the amplitudes of the two sections of bus voltages are different, and the discriminant equation is as follows:
if the PT line break identification meets the formula (6), sending a PT line break alarm signal, and otherwise, finishing the judgment of the PT line break identification;
wherein, U2.2(t) is the negative sequence voltage amplitude of another section of bus when the line is broken and started, U0.2(t) zero sequence voltage amplitude of another bus when starting up with broken line, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnectionΦ2(t) is the A, B, C phase voltage amplitude of the other section of bus when the disconnection is started, UNTo PT secondary rating
And if the section breaker is not in the switching-on position, directly sending a PT disconnection warning signal.
Further, the delaying sending of the PT disconnection warning signal includes delaying sending of the PT disconnection warning signal by 10 s.
The invention provides a PT disconnection recognition device of an intelligent substation, which performs PT disconnection recognition and judgment according to the PT disconnection recognition method of the intelligent substation, and the PT disconnection recognition device comprises:
the acquisition module is used for acquiring bus voltages of all sections, currents of all intervals of bus section wiring, positions of circuit breakers of all intervals and positions of section circuit breakers in real time;
the PT disconnection identification and starting judgment module judges whether to start PT disconnection identification of the voltage transformer according to preset conditions; if the preset condition is met, starting PT disconnection recognition;
and the PT disconnection identification and judgment module is used for judging whether the PT disconnection identification meets the judgment condition or not, and sending a PT disconnection alarm signal in a delayed manner if the PT disconnection identification meets the judgment condition, and closing at the same time and closing at no pressure in a locking detection period.
Furthermore, the intelligent substation comprises an entity measurement and control module and a cluster measurement and control module, wherein each virtual measurement and control unit in the cluster measurement and control module corresponds to each entity measurement and control unit in the entity measurement and control module one by one, and when the entity measurement and control unit fails, the virtual measurement and control unit is automatically switched to the corresponding virtual measurement and control unit in the cluster measurement and control module at intervals of 1 to 1.
Further, the virtual measurement and control unit uses an ICD model, CID configuration, interlocking rules and operation parameters of the entity measurement and control unit; when the virtual measurement and control unit starts to operate, the APPID of the communication parameter, the IP address, the multicast address and the GOOSE control block of the entity measurement and control unit is used.
In conclusion, the invention provides a PT (potential transformer) disconnection identification method and a PT disconnection identification device for an intelligent substation, wherein the method comprises the steps of collecting bus voltages of all sections, currents of all intervals of bus section connection, breaker positions of all intervals and the positions of section breakers in real time; judging whether to start PT disconnection identification of the voltage transformer according to preset conditions; judging whether the PT disconnection identification meets the judgment condition, if so, sending a PT disconnection warning signal in a delayed mode, and closing in the synchronous period and closing in a non-voltage mode in a locking detection mode. The invention adopts the comprehensive judgment of multi-interval voltage and current magnitude acquired by the cluster measurement and control device, identifies PT broken line according to the characteristics of PT broken line and system fault, can judge according to the voltage on another section of bus when in parallel operation, introduces other interval currents on the same bus to assist in judging, locks PT broken line judgment when the current changes, solves the problem of false alarm or incorrect identification of PT broken line, and improves the reliability of PT broken line identification.
Drawings
Fig. 1 is a schematic flow chart of a PT disconnection recognition method of an intelligent substation according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a bus structure of an intelligent substation according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a judging process of the PT disconnection recognition method according to the embodiment of the present invention;
fig. 4 is a schematic diagram of a framework of an intelligent substation PT disconnection recognition device according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a mode of single-interval entity measurement and control plus cluster measurement and control adopted by the measurement and control function of the intelligent substation according to the embodiment of the present invention.
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 in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
The invention provides a method for identifying PT disconnection of an intelligent substation, which is shown in FIG. 1 and comprises the following steps;
and step S100, collecting the bus voltage of all the sections, the current of all the intervals of the bus section connection, the positions of the circuit breakers of all the intervals and the positions of the section circuit breakers in real time.
A Potential Transformer (PT) is an instrument for converting voltage, similar to a Transformer. As shown in fig. 2, the intelligent substation includes two sections of busbars I, II (the number of busbars is not limited to two sections of busbars), a section breaker DL1 is disposed between the two sections of busbars, voltage transformers PT1 and PT2 are disposed on the busbars, and breakers DL2, DL3, DL4 and DL5 are disposed in all the intervals. The cluster measurement and control device collects currents TA1, TA2, TA3, TA4 and TA5 at all intervals of single-bus section wiring, two-section bus voltages PT1 and PT2, and breaker positions DL1, DL2, DL3, DL4 and DL5 at all intervals, wherein DL1 is a section breaker, DL2 and DL3 are located in mother I, and DL4 and DL5 are located in mother II. DL1 is the closing position when two sections of buses run in parallel.
Step S200, judging whether to start PT disconnection recognition of the voltage transformer according to preset conditions: if the preset condition is met, starting PT disconnection recognition; otherwise, the step S100 of real-time acquisition is continued.
Specifically, the preset conditions for starting the PT disconnection identification of the voltage transformer include:
UΦ1(t-2T)-UΦ1(t)＞0.1UN (1)
if the formula (1) is established, starting the PT disconnection identification of the voltage transformer; wherein, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnectionΦ1(T-2T) is A, B, C phase voltage amplitude before two cycles of the bus where PT is located when the line is disconnected and started; u shapeNFor secondary PT rating, preferably, UNIt may be taken to be 57.7V.
Step S300, if the PT disconnection identification meets the judgment condition, a PT disconnection warning signal is sent in a delayed manner (preferably, the PT disconnection warning signal can be sent in a delayed manner for 10S), and synchronous closing and non-voltage closing are locked and detected; otherwise, continuing to carry out the step of real-time acquisition.
Further, the PT disconnection recognition includes sequential judgment: (1) the values of positive sequence voltage, negative sequence voltage or zero sequence voltage of the bus where the PT is located, the positions of circuit breakers at all intervals on the bus where the PT is located or whether current exists; (2) PT disconnection identification is carried out to judge whether all interval currents on the bus change during starting; (3) and judging the position of the sectionalized circuit breaker, and judging whether the voltage values of the sectionalized buses are different or not at the switching-on position. As shown in fig. 3, in the PT disconnection recognition method for the intelligent substation cluster measurement and control function, PT disconnection discrimination is started after a voltage has a sudden change, when PT positive-sequence voltage is low and an interval breaker is in an on position or has a current, or has a negative-sequence voltage or a zero-sequence voltage, all interval currents on a bus are not changed during starting, if a segmented breaker DL1 is in an on position, it is also required to discriminate that two segments of bus voltage values are different, all conditions meet a delay time and a PT disconnection warning signal is sent, and simultaneous closing and non-voltage closing functions are locked and detected.
Specifically, the value of positive sequence voltage, negative sequence voltage or zero sequence voltage of the bus where the PT belongs to the judgment condition (1), and the position of the circuit breaker at all intervals on the bus where the PT belongs to or whether there is current, include:
judging whether any phase voltage of the bus where the PT is located is low, the positive sequence voltage is low, and whether a current or a breaker is in a closed position exists in any interval of the corresponding bus or whether the PT has negative sequence voltage or zero sequence voltage, wherein the judgment equation is as follows:
or
U2.1(t)＞0.1UN (3)
Or
3U0.1(t)＞0.1UN (4)
If one of the above equations (2), (3) or (4) is satisfied, continuing to judge the judgment condition (2), otherwise, ending the judgment of PT disconnection identification; wherein, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnection1.1(t) is the positive sequence voltage amplitude, U, of the bus where PT is located when PT disconnection identification starts2.1(t) is the negative sequence voltage amplitude, U, of the bus where PT is located when PT disconnection identification starts0.1(t) zero sequence voltage amplitude, I, of the bus where PT is located when PT disconnection identification startsΦ1(t) A, B, C phase current amplitude values corresponding to any interval of the bus when PT disconnection recognition is started, and DL is the position of the circuit breaker corresponding to any interval of the bus when PT disconnection recognition is started; i isNFor the corresponding bus bar protection CT secondary rating (specifically, 1A or 5A may be selected). The interval current corresponding to the I-section bus PT1 is TA1, TA2 and TA3, and the interval breaker corresponding to the I-section bus PT1 is DL1, DL2 and DL 3; the interval currents corresponding to the II-section bus PT2 are TA1, TA4 and TA5, and the interval breakers corresponding to the II-section bus PT2 are DL1, DL4 and DL 5.
Specifically, judging whether all interval currents on the bus change when the PT disconnection recognition of the condition (2) is started includes:
when PT disconnection identification starts, all intervals of corresponding buses have no zero sequence current, phase currents have no change, and a discrimination equation is as follows:
if the formula (5) is satisfied, continuing to judge the judgment condition (3), otherwise, finishing the judgment of PT disconnection identification; in the above formula IΦ1(t) A, B, C phase current amplitude corresponding to any interval of the bus when PT disconnection identification starts, IΦ1(T-2T) is the A, B, C phase current amplitude value before the interval of two weeks of the corresponding bus when PT disconnection starts, I0.1(t) is the amplitude of the corresponding bus interval three-phase self-produced zero-sequence current when starting with broken line, INAnd protecting the secondary rated value of the CT for the corresponding bus.
Specifically, judge condition (3) and judge the position of segmentation circuit breaker, judge whether the bus voltage value of segmentation is different when the position of closing the floodgate, include:
if the sectional breaker is at the switching-on position, the bus voltage amplitudes at two sides of the sectional breaker are the same, the PT of the other section of bus has no zero sequence voltage and negative sequence voltage when the PT is broken, the amplitudes of the two sections of bus voltages are different, and the discriminant equation is as follows:
if the PT line break identification meets the formula (6), sending a PT line break alarm signal, and otherwise, finishing the judgment of the PT line break identification; wherein, U2.2(t) is the negative sequence voltage amplitude of another section of bus when the line is broken and started, U0.2(t) zero sequence voltage amplitude of another bus when starting up with broken line, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnectionΦ2(t) is the A, B, C phase voltage amplitude of the other section of bus when the disconnection is started, UNIs the PT secondary rating;
and if the section breaker is not in the switching-on position, directly sending a PT disconnection warning signal.
Further, the delaying sending of the PT disconnection warning signal includes delaying sending of the PT disconnection warning signal by 10 s.
The second aspect of the present invention provides an intelligent substation PT disconnection recognition apparatus, which performs PT disconnection recognition and determination according to the intelligent substation PT disconnection recognition method, as shown in fig. 4, including: the acquisition module is used for acquiring bus voltages of all sections, currents of all intervals of bus section wiring, positions of circuit breakers of all intervals and positions of section circuit breakers in real time; the PT disconnection identification and starting judgment module judges whether to start PT disconnection identification of the voltage transformer according to preset conditions; if the preset condition is met, starting PT disconnection recognition; and the PT disconnection identification and judgment module is used for judging whether the PT disconnection identification meets the judgment condition or not, and sending a PT disconnection alarm signal in a delayed manner if the PT disconnection identification meets the judgment condition, and closing at the same time and closing at no pressure in a locking detection period.
Furthermore, the intelligent substation comprises an entity measurement and control module and a cluster measurement and control module, wherein each virtual measurement and control unit in the cluster measurement and control module corresponds to each entity measurement and control unit in the entity measurement and control module one by one, and when the entity measurement and control unit fails, the virtual measurement and control unit is automatically switched to the corresponding virtual measurement and control unit in the cluster measurement and control module at intervals of 1 to 1. Specifically, as shown in fig. 5, the measurement and control function of the intelligent substation adopts a mode of single-interval entity measurement and control plus cluster measurement and control, each virtual measurement and control unit in the cluster measurement and control corresponds to a single-interval entity measurement and control unit of the intelligent substation one by one, and when an entity measurement and control unit fails, the virtual measurement and control unit is automatically switched to the corresponding virtual measurement and control unit in the cluster measurement and control according to the interval 1 to 1. The cluster measurement and control module can simultaneously operate a plurality of virtual measurement and control modules, and the virtual measurement and control modules are backup of the entity measurement and control modules and are only put into operation when the entity measurement and control modules are in fault or abnormal. The virtual measurement and control module uses an ICD model, CID configuration, interlocking rules and operation parameters of the entity measurement and control device. When the virtual measurement and control module starts to run, the communication parameters, the IP address, the multicast address, the APPID of the GOOSE control block of the process layer and the like of the entity measurement and control module are used, and therefore the client side communicating with the virtual measurement and control module can regard the virtual measurement and control module as the original entity measurement and control module.
In conclusion, the invention provides a PT (potential transformer) disconnection identification method and a PT disconnection identification device for an intelligent substation, wherein the method comprises the steps of collecting bus voltages of all sections, currents of all intervals of bus section connection, breaker positions of all intervals and the positions of section breakers in real time; judging whether to start PT disconnection identification of the voltage transformer according to preset conditions; judging whether the PT disconnection identification meets the judgment condition, if so, sending a PT disconnection warning signal in a delayed mode, and closing in the synchronous period and closing in a non-voltage mode in a locking detection mode. The invention adopts the comprehensive judgment of multi-interval voltage and current magnitude acquired by the cluster measurement and control device, identifies PT broken line according to the characteristics of PT broken line and system fault, can judge according to the voltage on another section of bus when in parallel operation, introduces other interval currents on the same bus to assist in judging, locks PT broken line judgment when the current changes, solves the problem of false alarm or incorrect identification of PT broken line, and improves the reliability of PT broken line identification.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (10)
1. A PT disconnection identification method of an intelligent substation is characterized by comprising the following steps;
collecting bus voltage of all sections, current of all intervals of bus section wiring, breaker positions of all intervals and the positions of the section breakers in real time;
judging whether to start PT disconnection identification of the voltage transformer according to preset conditions;
if the preset condition is met, starting PT disconnection recognition; otherwise, continuing to carry out the step of real-time acquisition;
if the PT disconnection identification meets the judgment condition, a PT disconnection warning signal is sent in a delayed mode, and synchronous closing and non-voltage closing are detected in a locking mode; otherwise, continuing to carry out the step of real-time acquisition.
2. The intelligent substation PT disconnection identification method according to claim 1, wherein the preset conditions for starting the PT disconnection identification of the voltage transformer include:
UΦ1(t-2T)-UΦ1(t)＞0.1UN (1)
if the formula (1) is established, starting the PT disconnection identification of the voltage transformer;
wherein, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnectionΦ1(T-2T) is A, B, C phase voltage amplitude before two cycles of the bus where PT is located when the line is disconnected and started; u shapeNIs the PT quadratic rating.
3. The intelligent substation PT disconnection identification method according to claim 1 or 2, wherein the PT disconnection identification includes sequentially judging: (1) the values of positive sequence voltage, negative sequence voltage or zero sequence voltage of the bus where the PT is located, the positions of circuit breakers at all intervals on the bus where the PT is located or whether current exists; (2) PT disconnection identification is carried out to judge whether all interval currents on the bus change during starting; (3) and judging the position of the sectionalized circuit breaker, and judging whether the voltage values of the sectionalized buses are different or not at the switching-on position.
4. The intelligent substation PT line breakage identification method according to claim 3, wherein judging the values of positive sequence voltage, negative sequence voltage or zero sequence voltage of the bus where the PT is located under the condition (1), the positions of the circuit breakers at all intervals on the bus where the PT is located or whether current exists comprises:
judging whether any phase voltage of the bus where the PT is located is low, the positive sequence voltage is low, and whether a current or a breaker is in a closed position exists in any interval of the corresponding bus or whether the PT has negative sequence voltage or zero sequence voltage, wherein the judgment equation is as follows:
or
U2.1(t)＞0.1UN (3)
Or
3U0.1(t)＞0.1UN (4)
If one of the above equations (2), (3) or (4) is satisfied, continuing to judge the judgment condition (2), otherwise, ending the judgment of PT disconnection identification;
wherein, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnection1.1(t) is the positive sequence voltage amplitude, U, of the bus where PT is located when PT disconnection identification starts2.1(t) is the negative sequence voltage amplitude, U, of the bus where PT is located when PT disconnection identification starts0.1(t) zero sequence voltage amplitude, I, of the bus where PT is located when PT disconnection identification startsΦ1(t) A, B, C phase current amplitude values corresponding to any interval of the bus when PT disconnection recognition is started, and DL is the position of the circuit breaker corresponding to any interval of the bus when PT disconnection recognition is started; i isNAnd protecting the secondary rated value of the CT for the corresponding bus.
5. The intelligent substation PT disconnection identification method according to claim 3 or 4, wherein judging whether all interval currents on the bus change when the PT disconnection identification of condition (2) is started comprises:
when PT disconnection identification starts, all intervals of corresponding buses have no zero sequence current, phase currents have no change, and a discrimination equation is as follows:
if the formula (5) is satisfied, continuing to judge the judgment condition (3), otherwise, finishing the judgment of PT disconnection identification;
in the above formula IΦ1(t) A, B, C phase current amplitude corresponding to any interval of the bus when PT disconnection identification starts, IΦ1(T-2T) is the A, B, C phase current amplitude value before the interval of two weeks of the corresponding bus when PT disconnection starts, I0.1(t) is the amplitude of the corresponding bus interval three-phase self-produced zero-sequence current when starting with broken line, INAnd protecting the secondary rated value of the CT for the corresponding bus.
6. The intelligent substation PT disconnection identification method according to any one of claims 3-5, wherein the determining condition (3) determines the position of a sectionalizing breaker, and determines whether the bus voltage values of the sections are different when the breaker is in a closed position, including:
if the sectional breaker is at the switching-on position, the bus voltage amplitudes at two sides of the sectional breaker are the same, the PT of the other section of bus has no zero sequence voltage and negative sequence voltage when the PT is broken, the amplitudes of the two sections of bus voltages are different, and the discriminant equation is as follows:
if the PT line break identification meets the formula (6), sending a PT line break alarm signal, and otherwise, finishing the judgment of the PT line break identification;
wherein, U2.2(t) is the negative sequence voltage amplitude of another section of bus when the line is broken and started, U0.2(t) zero sequence voltage amplitude of another bus when starting up with broken line, UΦ1(t) identifying A, B, C phase voltage amplitude, U, of the bus where PT is located at the time of PT disconnectionΦ2(t) is the A, B, C phase voltage amplitude of the other section of bus when the disconnection is started, UNIs the PT secondary rating;
and if the section breaker is not in the switching-on position, directly sending a PT disconnection warning signal.
7. The intelligent substation PT disconnection identification method of any one of claims 1-6, wherein delaying sending of a PT disconnection warning signal includes delaying sending of a PT disconnection warning signal by 10 s.
8. An intelligent substation PT disconnection recognition device, wherein the PT disconnection recognition judgment is carried out according to the intelligent substation PT disconnection recognition method of any one of claims 1-7, and the method comprises the following steps:
the acquisition module is used for acquiring bus voltages of all sections, currents of all intervals of bus section wiring, positions of circuit breakers of all intervals and positions of section circuit breakers in real time;
the PT disconnection identification and starting judgment module judges whether to start PT disconnection identification of the voltage transformer according to preset conditions; if the preset condition is met, starting PT disconnection recognition;
and the PT disconnection identification and judgment module is used for judging whether the PT disconnection identification meets the judgment condition or not, and sending a PT disconnection alarm signal in a delayed manner if the PT disconnection identification meets the judgment condition, and closing at the same time and closing at no pressure in a locking detection period.
9. The intelligent substation PT disconnection recognition device of claim 8, wherein the intelligent substation comprises an entity measurement and control module and a cluster measurement and control module, each virtual measurement and control unit in the cluster measurement and control module corresponds to each entity measurement and control unit in the entity measurement and control module one by one, and when an entity measurement and control unit fails, the intelligent substation PT disconnection recognition device is automatically switched to the corresponding virtual measurement and control unit in the cluster measurement and control module at an interval of 1 to 1.
10. The intelligent substation PT disconnection identification device of claim 9, wherein the virtual measurement and control unit uses ICD model, CID configuration, interlocking rules and operating parameters of the entity measurement and control unit; when the virtual measurement and control unit starts to operate, the APPID of the communication parameter, the IP address, the multicast address and the GOOSE control block of the entity measurement and control unit is used.
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