CN113612190A - Method and system for executing alternating current line reclosing based on safety margin index - Google Patents

Method and system for executing alternating current line reclosing based on safety margin index Download PDF

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CN113612190A
CN113612190A CN202110863038.1A CN202110863038A CN113612190A CN 113612190 A CN113612190 A CN 113612190A CN 202110863038 A CN202110863038 A CN 202110863038A CN 113612190 A CN113612190 A CN 113612190A
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time
preset
safety margin
reclosing
value
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CN113612190B (en
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曹虹
王兴国
杜丁香
夏秋
谢民
俞斌
戴长春
章昊
汪伟
张骏
邵庆祝
于洋
孙辉
许旵鹏
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China Electric Power Research Institute Co Ltd CEPRI
State Grid Anhui Electric Power Co Ltd
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China Electric Power Research Institute Co Ltd CEPRI
State Grid Anhui Electric Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/06—Details with automatic reconnection
    • H02H3/066—Reconnection being a consequence of eliminating the fault which caused disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention discloses a method and a system for executing alternating current line reclosing based on safety margin indexes, and belongs to the technical field of relay protection. The method comprises the following steps: acquiring direct current bipolar power, taking the breaker breaking time as 0 time, judging the safety margin of the direct current system according to the acquired direct current bipolar power and a commutation failure signal after receiving the commutation failure signal of the direct current system, and acquiring a first judgment result; determining the safety margin index of the alternating current system according to the first judgment result; according to the safety margin index of the alternating current system, carrying out alternating current line reclosing operation or non-reclosing operation; the invention can reduce the influence of secondary impact caused by superposition on a direct current system and avoid direct current locking caused by continuous commutation failure.

Description

Method and system for executing alternating current line reclosing based on safety margin index
Technical Field
The invention relates to the technical field of relay protection, in particular to a method and a system for executing reclosing of an alternating current circuit based on safety margin indexes.
Background
With the rapid development of the ultra-high voltage direct current transmission technology, China enters the operation era of an ultra-high voltage alternating current and direct current series-parallel power grid, the characteristic of strong weak alternating current is increasingly prominent, faults of an ultra-high voltage direct current near-region alternating current system can possibly induce phase commutation failure of the direct current system, especially permanent faults of the ultra-high voltage direct current near-region alternating current transmission line, if the faults are superposed on the permanent faults, secondary impact is brought to the direct current system, continuous phase commutation failure is easy to cause direct current blocking, once the direct current blocking faults occur, the shortage of large power can occur in a receiving-end power grid, and the frequency and voltage stability of the power grid can be affected. Therefore, correct reclosing of the extra-high voltage direct current near-region alternating current line is very important for safe and stable operation of the whole power grid.
Reclosing technology is widely applied to alternating current transmission lines to reclose transient faults and quickly recover power supply. However, the conventional automatic reclosing technology does not distinguish permanent faults from transient faults, and the circuit breaker is reclosed after fixed time delay, and then the fault is judged to determine whether to trip again, so that adverse effects are easily caused on an electrical system.
Disclosure of Invention
In view of the above problems, the present invention provides a method for performing an ac line reclosing based on a safety margin index, comprising:
acquiring direct current bipolar power, taking the breaker breaking time as 0 time, judging the safety margin of the direct current system according to the acquired direct current bipolar power and a commutation failure signal after receiving the commutation failure signal of the direct current system, and acquiring a first judgment result;
determining the safety margin index of the alternating current system according to the first judgment result;
and executing reclosing operation or non-reclosing operation of the alternating current line according to the safety margin index of the alternating current system.
Optionally, the determining the safety margin of the dc system includes:
step 111, when the DC bipolar power is less than or equal to the boundary transmission power P0Determining a first time period according to reclosing time T;
step 112, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 113, judging whether the value of the updated counter is greater than or equal to a first preset time threshold value N1; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 114;
step 114, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 113;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively a first preset time, a second preset time, a third preset time and a fourth preset time.
Optionally, the determining the safety margin of the dc system includes:
step 121, when the DC bipolar power is larger than the boundary transmission power P0Determining a first time period according to reclosing time T;
step 122, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 123, judging whether the value of the updated counter is greater than or equal to a second preset time threshold value N2; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 124;
step 124, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 123;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively at the first preset timeThe time, the second preset time, the third preset time and the fourth preset time.
Optionally, the determining, according to the first determination result, an alternating current system safety margin index includes:
Figure BDA0003186461870000031
wherein, UsetAs an index of safety margin on the AC side, b1And b0Positive and zero sequence susceptances, k, respectively, of unit length of the ac line1Is the first margin coefficient, k2Is the second margin coefficient and is the second margin coefficient,
Figure BDA0003186461870000032
and
Figure BDA0003186461870000033
is the current phasor of the two healthy phases,
Figure BDA0003186461870000034
and
Figure BDA0003186461870000035
is a voltage phasor of two healthy phases, ZmIs the mutual inductance of the line per unit length, ZlIs the self-inductance of the line per unit length, l is the fault distance; k is a radical of3To adjust the coefficient, wherein 0<k3<1, when the safety margin of the direct current system is judged as a safe state, k3Is a first preset coefficient threshold; when the safety margin of the direct current system is judged to be an unsafe state, k3Is a second predetermined coefficient threshold.
Optionally, according to the safety margin index of the ac system, performing an ac line reclosing operation or a non-reclosing operation includes:
if U ism<UsetIf the reclosing time is T, determining to execute the reclosing operation, simultaneously sending a reclosing permission signal to the opposite side, and executing reclosing after the opposite side receives the permission signal;
if U ism>UsetIf the reclosing time is T, determining to execute non-coincident operation, simultaneously sending a coincident locking signal to the opposite side, and not executing reclosing after the opposite side receives the locking signal;
wherein, UmVoltage amplitude of fault relative to ground; u shapesetAnd the safety margin index of the communication system is obtained.
The invention also provides a system for executing the reclosing of the alternating current line based on the safety margin index, which comprises the following steps:
the first judgment unit is used for acquiring the direct-current bipolar power, taking the breaker breaking time as 0 time, judging the safety margin of the direct-current system according to the acquired direct-current bipolar power and the commutation failure signal after receiving the commutation failure signal of the direct-current system, and acquiring a first judgment result;
the second judgment unit is used for determining the safety margin index of the alternating current system according to the first judgment result;
and the execution unit is used for executing the reclosing operation or the non-reclosing operation of the alternating current line according to the safety margin index of the alternating current system.
Optionally, the determining the safety margin of the dc system by the first determination result obtaining unit includes:
step 111, when the DC bipolar power is less than or equal to the boundary transmission power P0Determining a first time period according to reclosing time T;
step 112, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 113, judging whether the value of the updated counter is greater than or equal to a first preset time threshold value N1; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 114;
step 114, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4And when inWhen any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 113;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively a first preset time, a second preset time, a third preset time and a fourth preset time.
Optionally, the determining the safety margin of the dc system by the first determination result obtaining unit includes:
step 121, when the DC bipolar power is larger than the boundary transmission power P0Determining a first time period according to reclosing time T;
step 122, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 123, judging whether the value of the updated counter is greater than or equal to a second preset time threshold value N2; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 124;
step 124, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 123;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively at a first preset time, a second preset time and a third preset timeAnd a fourth preset time.
Optionally, the determining unit of the safety margin index of the alternating current system, which determines the safety margin index of the alternating current system according to the first determination result, includes:
Figure BDA0003186461870000051
wherein, UsetAs an index of safety margin on the AC side, b1And b0Positive and zero sequence susceptances, k, respectively, of unit length of the ac line1Is the first margin coefficient, k2Is the second margin coefficient and is the second margin coefficient,
Figure BDA0003186461870000052
and
Figure BDA0003186461870000053
is the current phasor of the two healthy phases,
Figure BDA0003186461870000054
and
Figure BDA0003186461870000055
is a voltage phasor of two healthy phases, ZmIs the mutual inductance of the line per unit length, ZlIs the self-inductance of the line per unit length, l is the fault distance; k is a radical of3To adjust the coefficient, wherein 0<k3<1, when the safety margin of the direct current system is judged as a safe state, k3Is a first preset coefficient threshold; when the safety margin of the direct current system is judged to be an unsafe state, k3Is a second predetermined coefficient threshold.
Optionally, the executing unit executes an ac line reclosing operation or a non-reclosing operation according to the safety margin index of the ac system, and includes:
if U ism<UsetIf the reclosing time is T, determining to execute the reclosing operation, simultaneously sending a reclosing permission signal to the opposite side, and executing reclosing after the opposite side receives the permission signal;
if U ism>UsetIf the reclosing time is T, the non-coincident operation is determined to be executed, a coincident locking signal is sent to the opposite side, and reclosing is not executed after the opposite side receives the locking signal.
According to the method and the system for executing the reclosing of the alternating current line based on the safety margin index, the direct current bipolar power is obtained, the circuit breaker breaking time is taken as 0 time, after a commutation failure signal of the direct current system is received, the safety margin of the direct current system is judged according to the obtained direct current bipolar power and the commutation failure signal, and a first judgment result is obtained; determining the safety margin index of the alternating current system according to the first judgment result; according to the safety margin index of the alternating current system, the reclosing operation or the non-reclosing operation of the alternating current line is executed, the influence of secondary impact caused by reclosing on the direct current system can be reduced, and direct current locking caused by continuous commutation failure is avoided.
Drawings
Fig. 1 is a flow diagram of a method 100 for performing ac line reclosing based on a safety margin indicator in accordance with an embodiment of the present invention;
FIG. 2 is a reclosing logic diagram of the method embodiment of the present invention;
fig. 3 is a schematic diagram of a system 300 for performing ac line reclosing based on a safety margin indicator according to an embodiment of the invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
The invention provides a method 100 for executing reclosing of an alternating current line based on a safety margin index, which comprises the following steps of:
step 101, acquiring direct current bipolar power, taking the breaker breaking time as 0 time, judging the safety margin of the direct current system according to the acquired direct current bipolar power and a commutation failure signal after receiving the commutation failure signal of the direct current system, and acquiring a first judgment result;
step 102, determining a safety margin index of the alternating current system according to the first judgment result;
and 103, executing reclosing operation or non-reclosing operation of the alternating current line according to the safety margin index of the alternating current system.
Wherein, the determining the safety margin of the direct current system includes:
step 111, when the DC bipolar power is less than or equal to the boundary transmission power P0Determining a first time period according to reclosing time T;
step 112, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 113, judging whether the value of the updated counter is greater than or equal to a first preset time threshold value N1; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 114;
step 114, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 113;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively a first preset time, a second preset time, a third preset time and a fourth preset time.
Wherein, the determining the safety margin of the direct current system includes:
step 121, when the DC bipolar power is larger than the boundary transmission power P0Determining a first time period according to reclosing time T;
step 122, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 123, judging whether the value of the updated counter is greater than or equal to a second preset time threshold value N2; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 124;
step 124, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 123;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively a first preset time, a second preset time, a third preset time and a fourth preset time.
Wherein, the determining the safety margin index of the communication system according to the first judgment result comprises:
Figure BDA0003186461870000081
wherein, UsetAs an index of safety margin on the AC side, b1And b0Positive and zero sequence susceptances, k, respectively, of unit length of the ac line1Is the first margin coefficient, k2Is the second margin coefficient and is the second margin coefficient,
Figure BDA0003186461870000082
and
Figure BDA0003186461870000083
is the current phasor of the two healthy phases,
Figure BDA0003186461870000084
and
Figure BDA0003186461870000085
is a voltage phasor of two healthy phases, ZmIs the mutual inductance of the line per unit length, ZlIs the self-inductance of the line per unit length, l is the fault distance; k is a radical of3To adjust the coefficient, wherein 0<k3<1, when the safety margin of the direct current system is judged as a safe state, k3Is a first preset coefficient threshold; when the safety margin of the direct current system is judged to be an unsafe state, k3Is a second predetermined coefficient threshold.
Wherein, according to the safety margin index of the alternating current system, the method for executing the reclosing operation or the non-reclosing operation of the alternating current line comprises the following steps:
if U ism<UsetIf the reclosing time is T, determining to execute the reclosing operation, simultaneously sending a reclosing permission signal to the opposite side, and executing reclosing after the opposite side receives the permission signal;
if U ism>UsetIf the reclosing time is T, determining to execute non-coincident operation, simultaneously sending a coincident locking signal to the opposite side, and not executing reclosing after the opposite side receives the locking signal;
wherein, UmVoltage amplitude of fault relative to ground; u shapesetIs a stand forAnd the safety margin index of the communication system is described.
The invention is further illustrated by the following examples:
wherein the preset step length is 1, T1Is 200ms, T2500ms, a preset self-holding time of 200ms, T3Is 200ms, T4400ms, the first preset time is 3, and the second preset time is 2;
the specific implementation process comprises the following steps:
1. the method for judging the safety margin of the direct current system comprises the following steps:
and acquiring direct current transmission power and a commutation failure signal, and taking the breaker breaking moment as 0 moment.
When the DC bipolar power is less than or equal to P0When judging that the time T belongs to a first time period T-200 ms-T-500 ms, when receiving any bridge commutation failure signal, the counter counts 1 and keeps 200 ms; the counter counts 1 update time Tdate200ms to 400ms ahead (i.e. T)date-200ms～Tdate-400ms) and the counter counts 2 and self-holds for 200 ms; the counter 2 receives any bridge commutation failure in the previous 200ms to 400ms period, and the counter 3; wherein if any one of the above conditions is not satisfied, the counter is cleared by 0. And T is reclosing time.
When the counter reaches 3, the system is determined to be in an unsafe state.
And when the counter is less than 3, the system is judged to be in a safe state.
DC bipolar power>P0When the judgment time T is T-200 ms-T-500 ms, when any bridge commutation failure signal is received, the counter counts 1 and is self-maintained for 200 ms; the counter counts 1 update time Tdate200ms to 400ms ahead (i.e. T)date-200ms～Tdate-400ms) and the counter counts 2, when any bridge commutation failure signal is received, and the counter clears 0 when any of the above conditions is not met.
When the counter reaches 2, the system is determined to be in an unsafe state.
And when the counter is less than 2, the system is judged to be in a safe state.
Wherein, P0Power is delivered to the boundary.
2. The method for judging the safety margin of the communication system comprises the following steps:
Figure BDA0003186461870000101
in the formula, wherein, UsetAs an index of safety margin on the AC side, b1And b0Positive and zero sequence susceptances, k, respectively, of unit length of the ac line1Is the first margin coefficient, k2Is a second margin coefficient, the value range is 0.7-0.9,
Figure BDA0003186461870000102
and
Figure BDA0003186461870000103
is the current phasor of the two healthy phases,
Figure BDA0003186461870000104
and
Figure BDA0003186461870000105
is a voltage phasor of two healthy phases, ZmIs the mutual inductance of the line per unit length, ZlIs the self-inductance of the line per unit length, l is the fault distance; k is a radical of3To adjust the coefficient, wherein 0<k3<1, when the safety margin of the direct current system is judged as a safe state, k3Is a first preset coefficient threshold; when the safety margin of the direct current system is judged to be an unsafe state, k3Is a second preset coefficient threshold value, k is more than 031＜k32＜1。
3. And executing reclosing operation or non-reclosing operation of the alternating current line according to the safety margin index of the alternating current system.
In the invention, as shown in fig. 2, the intelligent reclosing logic of the ac line executes different dc system safety margin determination logics according to the magnitude of dc transmission power, adjusts the coefficient of the ac safety margin index according to the determination result, and finally determines whether the converter station side executes the reclosing command according to the adjusted coefficient. If the coincidence command is executed, when the reclosing time is T, the coincidence command is executed, meanwhile, coincidence allowing signals are sent to the opposite side, and the opposite side receives the allowing signals and then coincides. If the non-coincident command is executed, when reclosing time T is reached, the non-coincident command is executed, a coincident blocking signal is sent to the opposite side, and the opposite side does not coincide after receiving the blocking signal.
In the invention, the first preset time threshold is larger than the second preset time threshold.
The values of the parameters defined in the above embodiments are only examples, and may be defined as required in actual operation, and are not limited to the values in the above examples. The present invention further provides a system 300 for performing ac line reclosing based on a safety margin indicator, as shown in fig. 3, including:
a first determination result obtaining unit 301, configured to obtain the dc bipolar power, and when the circuit breaker open time is taken as 0 time, after receiving a commutation failure signal of the dc system, determine a safety margin of the dc system according to the obtained dc bipolar power and the commutation failure signal, and obtain a first determination result.
Optionally, the determining the safety margin of the dc system by the first determining result obtaining unit 301 includes:
step 111, when the DC bipolar power is less than or equal to the boundary transmission power P0Determining a first time period according to reclosing time T;
step 112, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 113, judging whether the value of the updated counter is greater than or equal to a first preset time threshold value N1; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 114;
step 114, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 113;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively a first preset time, a second preset time, a third preset time and a fourth preset time.
Optionally, the determining the safety margin of the dc system by the first determining result obtaining unit 301 includes:
step 121, when the DC bipolar power is larger than the boundary transmission power P0Determining a first time period according to reclosing time T;
step 122, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 123, judging whether the value of the updated counter is greater than or equal to a second preset time threshold value N2; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 124;
step 124, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 123;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Are respectively the first presetTime, a second preset time, a third preset time and a fourth preset time.
An alternating current system safety margin index determining unit 302, configured to determine an alternating current system safety margin index according to the first determination result.
Optionally, the determining unit 302 for determining the safety margin index of the ac system according to the first determination result includes:
Figure BDA0003186461870000121
wherein, UsetAs an index of safety margin on the AC side, b1And b0Positive and zero sequence susceptances, k, respectively, of unit length of the ac line1Is the first margin coefficient, k2Is the second margin coefficient and is the second margin coefficient,
Figure BDA0003186461870000122
and
Figure BDA0003186461870000123
is the current phasor of the two healthy phases,
Figure BDA0003186461870000124
and
Figure BDA0003186461870000125
is a voltage phasor of two healthy phases, ZmIs the mutual inductance of the line per unit length, ZlIs the self-inductance of the line per unit length, l is the fault distance; k is a radical of3To adjust the coefficient, wherein 0<k3<1, when the safety margin of the direct current system is judged as a safe state, k3Is a first preset coefficient threshold; when the safety margin of the direct current system is judged to be an unsafe state, k3Is a second predetermined coefficient threshold.
And the executing unit 303 is configured to execute an ac line reclosing operation or a non-reclosing operation according to the ac system safety margin index.
Optionally, the executing unit 303 executes an ac line reclosing operation or a non-reclosing operation according to the ac system safety margin index, including:
if U ism<UsetIf the reclosing time is T, determining to execute the reclosing operation, simultaneously sending a reclosing permission signal to the opposite side, and executing reclosing after the opposite side receives the permission signal;
if U ism>UsetIf the reclosing time is T, determining to execute non-coincident operation, simultaneously sending a coincident locking signal to the opposite side, and not executing reclosing after the opposite side receives the locking signal;
wherein, UmVoltage amplitude of fault relative to ground; u shapesetAnd the safety margin index of the communication system is obtained.
The reclosing method is combined with different judgment results of the safety margin of the direct current system and the safety margin of the alternating current system, the reclosing scheme is optimized, the influence of secondary impact caused by reclosing on the direct current system is reduced, and direct current locking caused by continuous commutation failure is avoided.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein. The scheme in the embodiment of the application can be implemented by adopting various computer languages, such as object-oriented programming language Java and transliterated scripting language JavaScript.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (10)

1. A method for executing AC line reclosing based on safety margin indexes is characterized by comprising the following steps:
acquiring direct current bipolar power, taking the breaker breaking time as 0 time, judging the safety margin of the direct current system according to the acquired direct current bipolar power and a commutation failure signal after receiving the commutation failure signal of the direct current system, and acquiring a first judgment result;
determining the safety margin index of the alternating current system according to the first judgment result;
and executing reclosing operation or non-reclosing operation of the alternating current line according to the safety margin index of the alternating current system.
2. The method of claim 1, wherein the determining a safety margin of the dc system comprises:
step 111, when the DC bipolar power is less than or equal to the boundary transmission power P0Determining a first time period according to reclosing time T;
step 112, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 113, judging whether the value of the updated counter is greater than or equal to a first preset time threshold value N1; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 114;
step 114, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 113;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively being a first preset time, a second preset time, a third preset time and a fourth preset timeAnd setting time.
3. The method of claim 1, wherein the determining a safety margin of the dc system comprises:
step 121, when the DC bipolar power is larger than the boundary transmission power P0Determining a first time period according to reclosing time T;
step 122, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 123, judging whether the value of the updated counter is greater than or equal to a second preset time threshold value N2; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 124;
step 124, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 123;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively a first preset time, a second preset time, a third preset time and a fourth preset time.
4. The method of claim 1, wherein determining an AC system safety margin indicator based on the first determination comprises:
Figure FDA0003186461860000021
wherein, UsetAs an index of safety margin on the AC side, b1And b0Positive and zero sequence susceptances, k, respectively, of unit length of the ac line1Is the first margin coefficient, k2Is the second margin coefficient and is the second margin coefficient,
Figure FDA0003186461860000022
and
Figure FDA0003186461860000023
is the current phasor of the two healthy phases,
Figure FDA0003186461860000024
and
Figure FDA0003186461860000025
is a voltage phasor of two healthy phases, ZmIs the mutual inductance of the line per unit length, ZlIs the self-inductance of the line per unit length, l is the fault distance; k is a radical of3For adjusting the coefficient, where 0 < k3< 1, when the DC system safety margin is judged as safe, k3Is a first preset coefficient threshold; when the safety margin of the direct current system is judged to be an unsafe state, k3Is a second predetermined coefficient threshold.
5. The method of claim 1, wherein performing an ac line reclosing operation or a non-reclosing operation according to the ac system safety margin indicator comprises:
if U ism＜UsetIf the reclosing time is T, determining to execute the reclosing operation, simultaneously sending a reclosing permission signal to the opposite side, and executing reclosing after the opposite side receives the permission signal;
if U ism＞UsetIf the reclosing time is T, determining to execute non-coincident operation, simultaneously sending a coincident locking signal to the opposite side, and not executing reclosing after the opposite side receives the locking signal;
wherein, UmVoltage amplitude of fault relative to ground; u shapesetAnd the safety margin index of the communication system is obtained.
6. A system for performing ac line reclosing based on safety margin indicator, the system comprising:
the first judgment result acquisition unit is used for acquiring the direct-current bipolar power, taking the breaker breaking time as 0 time, judging the safety margin of the direct-current system according to the acquired direct-current bipolar power and the commutation failure signal after receiving the commutation failure signal of the direct-current system, and acquiring a first judgment result;
the alternating current system safety margin index determining unit is used for determining an alternating current system safety margin index according to the first judgment result;
and the execution unit is used for executing the reclosing operation or the non-reclosing operation of the alternating current line according to the safety margin index of the alternating current system.
7. The system of claim 6, wherein the first determination result obtaining unit determines a safety margin of the dc system, and comprises:
step 111, when the DC bipolar power is less than or equal to the boundary transmission power P0Determining a first time period according to reclosing time T;
step 112, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 113, judging whether the value of the updated counter is greater than or equal to a first preset time threshold value N1; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 114;
step 114, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4And updating the counter value to the current count when any bridge commutation failure signal is received within a second time periodThe sum of the value of the device and the preset step length is self-maintained according to the preset self-maintaining time; and returns to step 113;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively a first preset time, a second preset time, a third preset time and a fourth preset time.
8. The system of claim 6, wherein the first determination result obtaining unit determines a safety margin of the dc system, and comprises:
step 121, when the DC bipolar power is larger than the boundary transmission power P0Determining a first time period according to reclosing time T;
step 122, at the judgment time T, the time is in a first time period T-T1～T-T2If any bridge commutation failure signal is received, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time;
step 123, judging whether the value of the updated counter is greater than or equal to a second preset time threshold value N2; if yes, judging that the direct current system is in an unsafe state; otherwise, go to step 124;
step 124, updating the time T according to the counterdateDetermining a second time period Tdate-T3～Tdate-T4When any bridge commutation failure signal is received in a second time period, updating the value of the counter to be the sum of the current value of the calculator and the preset step length, and carrying out self-holding according to preset self-holding time; and returns to step 123;
if the bridge commutation failure signal is not received, clearing the value of the counter and judging that the direct current system is in a safe state;
wherein, T1、T2、T3And T4Respectively being a first preset time, a second preset time, a third preset time and a fourth preset timeAnd setting time.
9. The system according to claim 6, wherein the ac system safety margin index determining unit that determines an ac system safety margin index according to the first determination result includes:
Figure FDA0003186461860000041
wherein, UsetAs an index of safety margin on the AC side, b1And b0Positive and zero sequence susceptances, k, respectively, of unit length of the ac line1Is the first margin coefficient, k2Is the second margin coefficient and is the second margin coefficient,
Figure FDA0003186461860000042
and
Figure FDA0003186461860000043
is the current phasor of the two healthy phases,
Figure FDA0003186461860000051
and
Figure FDA0003186461860000052
is a voltage phasor of two healthy phases, ZmIs the mutual inductance of the line per unit length, ZlIs the self-inductance of the line per unit length, l is the fault distance; k is a radical of3For adjusting the coefficient, where 0 < k3< 1, when the DC system safety margin is judged as safe, k3Is a first preset coefficient threshold; when the safety margin of the direct current system is judged to be an unsafe state, k3Is a second predetermined coefficient threshold.
10. The system of claim 6, wherein the execution unit, according to the AC system safety margin indicator, executes an AC line reclosing operation or a non-reclosing operation, comprising:
if U ism＜UsetIf the reclosing time is T, determining to execute the reclosing operation, simultaneously sending a reclosing permission signal to the opposite side, and executing reclosing after the opposite side receives the permission signal;
if U ism＞UsetIf the reclosing time is T, determining to execute non-coincident operation, simultaneously sending a coincident locking signal to the opposite side, and not executing reclosing after the opposite side receives the locking signal;
wherein, UmVoltage amplitude of fault relative to ground; u shapesetAnd the safety margin index of the communication system is obtained.
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