CN115800213B - Distributed power distribution automation measurement and control terminal - Google Patents
Distributed power distribution automation measurement and control terminal Download PDFInfo
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- CN115800213B CN115800213B CN202211505296.3A CN202211505296A CN115800213B CN 115800213 B CN115800213 B CN 115800213B CN 202211505296 A CN202211505296 A CN 202211505296A CN 115800213 B CN115800213 B CN 115800213B
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Abstract
The invention relates to a distributed power distribution automation measurement and control terminal which comprises a protection module, a distributed FA, an out-of-limit alarm module, a double-voltage lock and an operation detection module, wherein the protection module comprises differential protection, three-phase reclosing and inrush current blocking, the difference of the electric quantity between two ends of a transmission line is compared through the differential protection, exciting inrush current and internal fault current can be rapidly distinguished, the fault occurrence place is rapidly determined, fault cutting is executed according to a distinguishing result, the exciting current is rapidly increased when the voltage of a transformer is increased or the frequency is reduced through the inrush current blocking, a fifth harmonic component in the three-phase differential current is used as an over-excitation blocking basis, when the line breaks down, a three-phase reclosing power protector can immediately start a protection program, give out an instruction to cut off the transmission line, and alarm is sent to remind the current accident type; when the power supply line is out of order, the three-phase reclosing power protector resumes the power supply again, so that the operation reliability and safety of the whole terminal are greatly improved.
Description
Technical Field
The invention relates to the technical field of power distribution automation, in particular to a distributed power distribution automation measurement and control terminal.
Background
The power distribution automation measurement and control terminal has functions of measuring, protecting and controlling a switch, and has the advantages of adopting advanced digital signal processing technology, high-speed industrial network communication technology, embedded industrial chip set and multitasking real-time operation system, along with strong stability, high reliability, good instantaneity, wide environment, strong functions, being matched with a switch of a ring main unit, being capable of combining intelligent distribution network functions such as voltage time type, voltage current time type, protection type and the like, and realizing the function of on-site power distribution automation. The terminal is matched with an outgoing line switch, a branch switch and the like, so that fault removal and fault recovery of a distribution transmission line can be realized, and the distribution automation remote terminal device integrates functions of remote measurement, remote signaling, remote control, protection, communication and the like.
The power distribution automation measurement and control terminal is a protection facility which is used for the safety of a step-down transformer for the power distribution of a transformer substation, a power plant, high-low voltage power distribution and the power consumption of a station power system, and can ensure the normal and stable operation of a power grid system after the equipment is used, so that the damage caused by power faults can be avoided to a great extent. At present, the main functions of the power distribution automation measurement and control terminal include PT wire breakage detection, control loop wire breakage detection, reclosing, current limiting protection, acceleration tripping after closing and the like. However, when the system equipment (such as a transformer) is normally operated and the external failure occurs, the current flowing through the differential relay is zero, but for various reasons, even when the system equipment is normally operated, an unbalanced current flows through the differential circuit, so that the setting operation value of the longitudinal differential protection is forced to be increased, and the sensitivity of the protection is reduced. Therefore, the influence of unbalanced current on the measurement and control terminal is reduced.
The main factors for generating unbalanced current are many, wherein the influence of exciting inrush current generated when a transformer is closed under no load or when power is restored after external faults are removed is the most serious. Therefore, the core problem of the protection of the power distribution automatic measurement and control terminal is how to correctly judge the excitation current and the internal fault current, and execute fault cut-off according to the judging result.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a distributed power distribution automatic measurement and control terminal.
In order to achieve the above purpose, the technical scheme of the invention is specifically realized as follows: the utility model provides a distributed distribution automation measurement and control terminal, includes protection module, distributed FA, out of limit alarm module, dual pressure lock and operation detection module, protection module includes differential protection, three-phase reclosing and gushing current shutting, differential protection: the two ends of the power transmission line are connected by a communication channel and a DTU, the ground of the fault is rapidly determined and the fault is isolated according to the differential comparison of the electric quantity between the two ends of the power transmission line, and the judgment basis is as follows:
1) Starting up a criterion: id is greater than or equal to Idz
2) Ratio braking criterion: when Ir is less than or equal to Ickz, id is less than or equal to k1Ir; id-Id'. Gtoreq.k2 (Ir-Ickz) when Ir > Ickz
Wherein Id is differential current, id= |im+in|, id' =k1×ickz;
ir is the braking current, ir= |im-in|;
idz is a differential threshold and Ickz is a brake inflection point current constant;
k1 K2 is the ratio brake coefficient, 0.3 for the single power supply line k1, k2 is 0.5; for a double-power supply line k1 of 0.3-0.5 and k2 of 0.5-0.8;
the three-phase reclosing power protector can immediately start a protection program when the line is in electric leakage, overload, short circuit, overvoltage, undervoltage and phase failure, gives out an instruction to cut off the power supply line and gives out an alarm to remind the current accident type; when the power supply line fails to remove, the three-phase reclosing power protector resumes the power supply again;
when the voltage of the transformer is increased or the frequency of the inrush current is reduced, the exciting current is increased sharply, and the fifth harmonic component in the three-phase differential current is used as the basis of the overexcitation locking.
Preferably, the inrush current blocking performs feature recognition on the exciting inrush current in the current loop, and when the terminal operates normally, |Ig- [ K1.I1+K2.I2+K5.I5 ] | < 0.1, the differential protection does not act during normal operation; when the fifth harmonic wave generated during over-excitation is larger than a preset braking value, locking three-phase differential protection;
the surge current locking action equation is as follows:
I 5 ＞K 5 ·I o
in the formula I g For working current, I 1 As the first harmonic in the difference stream, I 2 Is the second harmonic in the second difference stream, I 5 Five in the difference streamSubharmonic, I o Fundamental wave, K in differential flow 1 For first harmonic braking coefficient, K 2 For second harmonic braking coefficient, K 5 Is a fifth harmonic braking coefficient.
Preferably, when reclosing is put into operation, the power transmission line is in a normal state, the breaker switch is at the closing position, the spring does not store energy, protection is not started, the three-phase reclosing is completed after 15 seconds of operation when all conditions are met, any one of the following conditions is met, and the three-phase reclosing is immediately discharged while delayed locking reclosing:
1) Reclosing and exiting;
2) Manual tripping (manual tripping, remote tripping);
3) Tripping protection;
4) No three-phase flow exists;
5) The switch gives an alarm on two positions;
6) Before reclosing is started, the spring is received to store no energy or low-pressure locking signal, and the discharge is performed for 400ms after time delay.
The terminal is internally provided with overcurrent acceleration protection and three-section zero sequence acceleration protection, and the reclosing acceleration selects pre-reclosing acceleration or post-reclosing acceleration, and is input before reclosing action when the pre-reclosing acceleration is selected; when acceleration is carried out after reclosing is selected, current within 15 seconds is input after manual switching-on, remote control switching-on or reclosing action, if any phase current is larger than a fixed value, tripping is carried out after short delay.
Preferably, the distributed FA and the adjacent distribution terminals in the same power supply loop interact through information, when faults occur on the distribution lines, the faults are rapidly removed under the condition of not depending on communication of a master station, and power supply of a non-fault area is recovered, and the distributed FA consists of fault detection logic, fault removal logic, fault isolation logic, initial switch voltage loss protection logic, switch failure jump logic, power supply recovery logic and slow-moving logic.
Preferably, the out-of-limit alarm module gives an alarm when the terminal generates an upper limit of current, a lower limit of current, an upper limit of voltage and a lower limit of voltage, and the SOE is recorded after the event is generated.
Preferably, the double press lock includes:
the two sides are provided with pressure locks: when the switch is in the split position, the two sides are pressed to prohibit automatic closing;
closing rings and closing gates: checking the voltage at two sides of the circuit breaker when the circuit breaker is in the trip position, wherein no voltage (no-voltage threshold 40% Un) is arranged at any side to allow closing; the two sides are provided with pressure (the pressure threshold is 50% Un) and are converted into synchronous detection, the angle between the angle after the busbar voltage correction and the line voltage is calculated, the angle difference is smaller than an angle difference fixed value, the pressure difference is smaller than a pressure difference fixed value, and the closing is allowed.
Preferably, the operation detection module includes control loop detection, the control loop detection is used for collecting and recording current values of x periods before the fault, and then subtracting the current values from the current sampling values after the fault, and the collection algorithm is as follows:
Ip(t)＝I(t)-I(t-nT),Ip(k)＝I(k)-I(k-xN)
wherein: ip (t) is the fault component current; i (t) is the measured current; t is the power frequency period; n is the number of weekly samples; k is sample number 1,2,3, …; n=1, 2,3, ….
When the control circuit breaks down, the switching-on position relay HWJ and the tripping position relay TWJ lose magnetism at the same time, ip (t) is larger than Ig, and the switching-on position relay HWJ and the tripping position relay TWJ close at the same time, so that an alarm signal of abnormality of the control circuit is sent.
Preferably, the operation detection module comprises PT wire breakage detection, and criteria and signal resetting conditions of the PT wire breakage detection are as follows: (1) The negative sequence voltage of the line is more than 12V, and the bus PT is broken after 10 seconds of delay;
(2) The sum of the three-phase voltage amplitudes of the line is smaller than rated voltage Un, any phase of any outgoing line has current >0.04 rated current In or any phase voltage of the bus is larger than 0.3Un, and the line PT is reported to be broken after delay for 10 seconds;
(3) After the three-phase voltage is recovered to be normal, all the three-phase voltage is recovered to be normal after 10s delay;
PT broken line detection is switched by PT broken line detection control word.
Preferably, the fault-removal logic: when the system fails, the failure node is not a final switch, the phase current is larger than a setting value or the zero sequence current is larger than the setting value, and nodes on one side and only one side of the bus side and the line side do not send out a node failure GOOSE signal, and the system acts after setting delay; if the fault node is a last switch, the phase current is larger than the setting value or the zero sequence current is larger than the setting value, and a node fault GOOSE signal of any node on the bus side and the line side is received, the node switch is jumped after setting delay.
Preferably, the switch failure skip logic: after the node switch is tripped, after failure judgment time, judging that the switch fails and refuses, triggering a 'switch refuses' GOOSE output signal, and starting a neighboring switch; when the node switch receives a bus side or line side node switch refusing jump GOOSE signal and the node switch is in a closed position and not tripped, the node switch fails to jump in a continuous mode and acts instantaneously; and if the node switch does not detect the fault and the tripping is successful, triggering a GOOSE output signal of 'successful fault isolation'.
The invention has the beneficial effects that:
compared with the prior art, the distributed power distribution automatic measurement and control terminal compares the electric quantity difference between two ends of a power transmission line through differential protection, can rapidly judge excitation surge current and internal fault current, rapidly determine fault occurrence places and execute fault cutting according to judging results, rapidly increase the excitation current when the voltage of a transformer is increased or the frequency is reduced through surge current locking, and utilize fifth harmonic components in three-phase differential current as over-excitation locking basis, when leakage, overload, short circuit, overvoltage, undervoltage and phase failure occur on a circuit, the three-phase reclosing power protector can immediately start a protection program, send out instructions to cut off the power transmission line and send out an alarm to remind the current accident type; when the power supply line is subjected to fault elimination, the three-phase reclosing power protector resumes power supply, so that the operation reliability and safety of the whole terminal are greatly improved, the system equipment can be monitored and managed in all directions, and the safety, stability and economic operation of the system equipment are ensured.
Drawings
The invention will now be described in further detail with reference to the drawings and to specific examples.
FIG. 1 is a schematic diagram of the connection of differential protection of a distributed power distribution automation measurement and control terminal according to the present invention;
FIG. 2 is a diagram of differential protection operation characteristics of a distributed power distribution automation measurement and control terminal according to the present invention;
FIG. 3 is a schematic diagram of the differential protection of a distributed power distribution automation measurement and control terminal according to the present invention;
FIG. 4 is a schematic diagram of the three-phase reclosing operation logic of the distributed power distribution automatic measurement and control terminal;
FIG. 5 is a schematic diagram of the I-stage operation logic of the overcurrent acceleration protection of the distributed power distribution automatic measurement and control terminal;
FIG. 6 is a schematic diagram of three-segment zero sequence acceleration protection operation logic of a distributed power distribution automation measurement and control terminal according to the present invention;
FIG. 7 is a schematic diagram of a distributed FA connection of a distributed power distribution automation measurement and control terminal according to the present invention;
FIG. 8 is a logic diagram of the upper limit operation of the current of the distributed power distribution automation measurement and control terminal according to the present invention;
FIG. 9 is a logic diagram of the lower limit operation of the distributed power distribution automation measurement and control terminal;
FIG. 10 is a logic diagram of the upper voltage limit operation of the distributed power distribution automation measurement and control terminal of the present invention;
FIG. 11 is a logic diagram of the lower limit operation of the voltage of the distributed power distribution automation measurement and control terminal.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
Referring to fig. 1-2, a distributed power distribution automation measurement and control terminal comprises a protection module, a distributed FA, an out-of-limit alarm module, a double-voltage lock and an operation detection module, wherein the protection module comprises a differential protection, a three-phase reclosing and a surge current locking, the differential protection adopts an optical fiber communication channel and two DTUs to respectively connect two ends of a power transmission line, the split-phase current differential of kirchhoff theorem is adopted as a main protection of the line protection, the two ends of the power transmission line are respectively a DTU1 and a DTU2, and the occurrence of faults and isolation of the faults are rapidly determined according to differential comparison of electric quantity between the two ends of the power transmission line. The electric quantity is differential current of two ends of the transmission line, and the judgment basis of the protection module is as follows:
1) Starting up a criterion: id is greater than or equal to Idz
2) Ratio braking criterion: when Ir is less than or equal to Ickz, id is less than or equal to k1Ir; id-Id'. Gtoreq.k2 (Ir-Ickz) when Ir > Ickz
Wherein Id is differential current, id 'is operating current, id= |im+In|, id' =k1×Ickz;
ir is the braking current, ir= |im-in|;
idz is a differential threshold and Ickz is a brake inflection point current constant;
k1 K2 is the ratio brake coefficient, 0.3 for the single power supply line k1, k2 is 0.5; for a double-power supply line k1 of 0.3-0.5 and k2 of 0.5-0.8; typically for dual supply lines k1 is 0.4 and k2 is 0.6.
The slope of the slope in fig. 2 is the ratio of the braking coefficient, and the short-circuit current contains a large amount of non-periodic components when the area fails, and the intersection of the braking current Ir and the operating current Id 'falls within the braking area when the operating current Id' is greater than the differential threshold Idz; when the fault occurs in the region, the differential current, that is, the operation current is the total short-circuit current, the braking current Ir is the short-circuit current flowing through the non-power supply side, the value is small, and the intersection point of two straight lines parallel to the longitudinal axis and the transverse axis must fall in the operation region, so that the differential protection reliably operates.
When the CT transformation ratios at the two ends of the transmission line are unequal, the contralateral current can be compensated by the set contralateral current balance coefficient. When the current balance coefficient is regulated, the ratio obtained by using the CT transformation ratio of the side and the CT transformation ratio of the upper side is taken as a reference, and the ratio is the 'side current balance coefficient' of the side. And setting the difference flow constant values at two sides by taking the CT transformation ratio at the side as a reference.
With reference to fig. 3, when an optical fiber communication abnormality occurs, the terminal records the optical fiber communication abnormality, protects the outlet, lights the alarm lamp, locks the differential protection, and outputs an alarm signal, the signal outlet can be set, and the alarm returns after the optical fiber communication is recovered; when the current is normal, the sum of three-phase current is zero, when the CT is broken, three-phase voltage is symmetrical (zero-sequence voltage), the sum of three-phase current is not zero, when the CT is broken on the side or the CT is broken on the opposite side, the CT is broken and warned and the CT is broken and is blocked to be simultaneously input, and when the CT is broken, the differential protection is blocked, so that the differential protection is distinguished from the ground fault, and the judgment basis of the CT is as follows: (1) Of the three-phase currents, the phase with the smallest current has zero value; (2) The phase with larger current has a current value which is not zero and is smaller than the maximum load current.
In addition, the three-phase reclosing power protector can immediately start a protection program when the line is in electric leakage, overload, short circuit, overvoltage, undervoltage and open phase, send out an instruction to cut off the power supply line and send out an alarm to remind the current accident type; when the power supply line fails to be removed, the three-phase reclosing power protector resumes power supply again. The three-phase reclosing selection XHB-APS/3-63A three-phase intelligent safety electricity protector is connected to a power transmission line and has the functions of overvoltage protection, undervoltage protection, overload protection, short-circuit protection, electric leakage protection, automatic reclosing, inspection before closing and remote monitoring.
It should be noted that in this embodiment, the protection control word may be set to exit when reclosing is not performed. The reclosing can be performed through a delay outlet under the conditions that the circuit breaker is in a separated position, charging is completed and no locking condition exists, and after overcurrent or time-limited quick-break tripping and reclosing, if the reclosing is in a permanent fault, the tripping can be accelerated later, and the reclosing is not carried out after the tripping. In addition, when reclosing and charging, after closing, judging that the circuit breaker is at the closing position, and charging after the set time is finished; the reclosing locking condition is to accelerate tripping after manual opening and closing in a fault state.
Referring to fig. 4, the operation logic of the three-phase recloser is set as follows: when reclosing is put into operation, the power transmission line is in a normal state, the breaker switch is at the closing position, the spring does not store energy, protection is not started, the operation is carried out for 15 seconds when all conditions are met, three-phase reclosing charging is completed, any of the following conditions is met, and immediately discharging is carried out while delay locking reclosing:
1) Reclosing and exiting;
2) Manual tripping (manual tripping, remote tripping);
3) Tripping protection;
4) No three-phase flow exists;
5) The switch gives an alarm on two positions;
6) Before reclosing is started, the spring is received to store no energy or low-pressure locking signal, and the discharge is performed for 400ms after time delay.
The terminal is internally provided with overcurrent acceleration protection and three-section zero sequence acceleration protection, and the reclosing acceleration selects pre-reclosing acceleration or post-reclosing acceleration, and is input before reclosing action when the pre-reclosing acceleration is selected; when acceleration is carried out after reclosing is selected, current within 15 seconds is input after manual switching-on, remote control switching-on or reclosing action, if any phase current is larger than a fixed value, tripping is carried out after short delay.
The over-current acceleration protection is three-phase three-section time-limiting over-current protection, the three-section time-limiting over-current protection is identical, different delay actions are set under different over-current values to avoid work peak current and enable a breaker with the nearest accident point to act so as to reduce the influence range of power failure when short circuit faults occur, wherein section I is time-limiting current quick-break protection and is set according to the maximum short circuit current at the tail end of the section; the current quick-break when the section II is limited is set according to the maximum action range of the current quick-break protection of each adjacent element of the lower stage, and can be used as the backup protection of the section I of the power transmission line of the section II; the III section is overcurrent protection, is set according to the maximum load current of the element, has longer time limit than the II section, can be used as backup protection of the I section and the II section, and has the largest protection range and the longest time limit. Each section is provided with independent input or withdrawal, and the input/withdrawal can be selected through a soft pressing plate. The I section operation logic is shown in fig. 5, the II section operation logic and the III section operation logic are the same as the I section operation logic, the three-phase current of the transmission line is detected, when the maximum current of the line is larger than the fixed value of the current of the overcurrent I section, the overcurrent I section starting element is started, after a settable delay, an overcurrent I section alarming and tripping (circuit breaker) command is output, an overcurrent signal lamp is lightened, and the protection can be selectively input/output through a soft pressing plate; overcurrent power failure tripping input, no line current, no line voltage, and no delay outlet tripping of an overcurrent section I.
The three-section zero sequence acceleration protection is used for detecting the ground fault, the protection action is performed by utilizing the zero sequence current generated during the ground, the operation logic is referred to fig. 6, and the three-section zero sequence acceleration protection has the same constitution principle as the overcurrent acceleration protection. When a ground fault occurs, a short-circuit path is formed by grounding the line, and a large short-circuit current flows in the fault phase. When the maximum current in the circuit is larger than the zero-sequence overcurrent fixed value, the zero-sequence overcurrent starting element is started, and after the zero-sequence overcurrent time delay is set, a zero-sequence overcurrent alarm and tripping command is sent out, and the protection can be selectively put in/out through the soft pressing plate.
When the transformer is closed under no load or the differential protection cuts off the external fault recovery voltage, a large number of magnetizing inrush currents may occur. The inrush current blocking performs characteristic identification on the exciting inrush current in the current loop so as to prevent misoperation when the high-capacity transformer is switched on. The function is used in combination with differential protection, and the surge blocking constant value can be set. The protection may be selectively put in/out by a soft platen.
When the voltage of the transformer increases or the frequency decreases, the exciting current increases sharply, and a differential protection malfunction may occur, so that the fifth harmonic component in the three-phase differential current is used as the basis of overexcitation locking. The inrush current blocking performs characteristic recognition on exciting inrush current in a current loop, and when a terminal normally operates, |Ig- [ K1.I1+K2.I2+K5.I5 ] | < 0.1, differential protection does not act during normal operation; when the fifth harmonic wave generated during over-excitation is larger than a preset braking value, locking three-phase differential protection;
the surge current locking action equation is as follows:
I 5 ＞K 5 ·I o
in the formula I g For working current, I 1 As the first harmonic in the difference stream, I 2 Is the second harmonic in the second difference stream, I 5 As fifth harmonic in difference stream, I o Fundamental wave, K in differential flow 1 For first harmonic braking coefficient, K 2 For second harmonic braking coefficient, K 5 Is a fifth harmonic braking coefficient.
Further, in this embodiment, the distributed FA is formed by an intelligent terminal, a peer-to-peer communication system, and a power distribution automation master station, and the structure of the distributed FA is shown in fig. 7, and the distributed FA interacts with an adjacent power distribution terminal in the same power supply loop through peer-to-peer communication (61850+goose), when a fault occurs on the power transmission line, the fault is quickly removed under the condition of not depending on the master station communication, and the power supply of a non-fault area is recovered, so that the self-healing function of the power distribution network is realized, and the fault isolation time and the self-healing time of the non-fault area are shortened to millisecond level. The distributed FA comprises fault detection logic, fault removal logic, fault isolation logic, head switch voltage loss protection logic, switch failure jump logic, power supply recovery logic and slow-moving logic.
The fault detection logic: the characteristic differences of short-circuit current and ground faults on two sides of a fault section are detected, so that the fault is located in the corresponding section, when a distribution network breaks down, the phase current flowing through the node is larger than a set value or the zero sequence current is larger than the set value, and when the node fault is judged, a node fault GOOSE output signal is triggered instantaneously.
The fault-removal logic: when the system fails, if the node is not a last switch and the phase current is greater than a setting value or the zero sequence current is greater than a setting value, nodes on one side and only one side of the bus side and the line side do not send out a node fault GOOSE signal, the node switch is jumped after setting delay; if the node is a final switch and the phase current is larger than the setting value or the zero sequence current is larger than the setting value, and a node fault GOOSE signal of any node on the bus side and the line side is received, the node switch is jumped after setting delay.
The fault isolation logic: and if the node does not detect the fault and receives a 'node fault' GOOSE signal of one node at the bus side or the line side, the node switch is jumped after the setting delay.
The head switch voltage loss protection logic: when the node is the first switch and the GOOSE communication of the node is normal, if the switch is closed and the line is under pressure for 3 seconds, the first switch is automatically put into the voltage-loss protection, so that the fault can be rapidly isolated when the fault occurs between the power supply point and the first switch. And after the initial switch is subjected to voltage-loss protection, if both sides of the node are not pressed and the node is not flowing, tripping the node switch through setting delay, and meanwhile starting the tripping failure judgment of the switch.
The switch failure trip logic: after the node switch is tripped, after failure judgment time, judging that the switch fails and refuses, triggering a 'switch refuses' GOOSE output signal, and starting a neighboring switch; when the node switch receives a bus side or line side node switch refusing jump GOOSE signal and the node switch is in a closed position and not tripped, the node switch fails to jump in a continuous mode and acts instantaneously; and if the node switch does not detect the fault and the tripping is successful, triggering a GOOSE output signal of 'successful fault isolation'.
The power restoration logic: after successful fault isolation, each node in the area forwards 'successful fault isolation' GOOSE signals to two sides in sequence, when the power supply recovery and charging of the node are completed and the 'successful fault isolation' GOOSE signals are received after the voltage is lost on one side of a bus side or a line side, the node switch is started to be switched on after setting delay, and the power supply conversion process is completed.
The slow-moving logic: after fault positioning is finished, after fault is removed by feeder line protection action of the transformer substation, corresponding fault sections are isolated by delay, then whether a transfer condition of a connecting power supply is met or not is judged, if yes, a connecting switch is closed to finish power supply recovery of a non-fault power failure area, the fault removal and fault isolation are required to be carried out by adding a no-voltage no-current condition on the basis of quick-action logic judgment, and the no-voltage no-current duration time is required to be greater than a set value to act and trigger corresponding GOOSE output signals.
The snap-action logic: and cutting off the fault area before the action of the outlet circuit breaker, isolating the corresponding fault section before the feeder line protection action after the fault positioning is completed in the zero power outage of the circuit, then judging whether the transfer condition of the contact power supply is met or not, and if so, closing the contact switch to complete the power restoration of the non-fault power outage area.
In more detail, the out-of-limit alarm module gives an alarm when the terminal generates current with higher limit, current with lower limit, voltage with higher limit and voltage with lower limit, and the SOE is recorded after the event is generated. Specifically, referring to fig. 8, when the current of any phase in the power transmission line is greater than the current upper limit value, a current upper limit alarm is sent out through the set out-of-limit time delay; the lower limit running logic of the current refers to fig. 9, and when the current of any phase in the power transmission line is smaller than the lower limit value of the current, a lower limit alarm is sent out by the set out-of-limit time delay; the operation logic of the voltage exceeding the upper limit refers to fig. 10, and when the voltage of any phase in the power transmission line is larger than the overvoltage alarm fixed value, an overvoltage alarm is sent out through the set out-of-limit time delay; and the lower voltage operation logic refers to fig. 11, and when the voltage of any phase in the power transmission line is larger than 10V and smaller than the low voltage alarm fixed value, the low voltage alarm is sent out through the set out-of-limit time delay.
In addition, the double-pressure lock comprises a pressure lock block and a ring-closing brake block at two sides, wherein the pressure lock block is arranged at two sides: when the switch is in the split position, the two sides are pressed to prohibit automatic closing; closing rings and closing gates: checking the voltage at two sides of the circuit breaker when the circuit breaker is in the trip position, wherein no voltage (no-voltage threshold 40% Un) is arranged at any side to allow closing; the two sides are provided with pressure (the pressure threshold is 50% Un) and are converted into synchronous detection, the angle between the angle after the busbar voltage correction and the line voltage is calculated, the angle difference is smaller than an angle difference fixed value, the pressure difference is smaller than a pressure difference fixed value, and the closing is allowed.
The operation detection module comprises control loop detection, the control loop detection is used for collecting and recording current values of x periods before the fault, and subtracting the current values from the current sampling values after the fault, and the collection algorithm is as follows:
Ip(t)＝I(t)-I(t-nT),Ip(k)＝I(k)-I(k-xN)
wherein: ip (t) is the fault component current; i (t) is the measured current; t is the power frequency period; n is the number of weekly samples; k is sample number 1,2,3, …; n=1, 2,3, ….
When the control circuit breaks down, the switching-on position relay HWJ and the tripping position relay TWJ lose magnetism at the same time, ip (t) is larger than Ig, and the switching-on position relay HWJ and the tripping position relay TWJ close at the same time, so that an alarm signal of abnormality of the control circuit is sent.
The operation detection module comprises PT wire breakage detection, wherein the criteria and the signal resetting conditions of the PT wire breakage detection are as follows:
(1) The negative sequence voltage of the line is more than 15V, and the bus PT is broken after 10 seconds of delay;
(2) The sum of the three-phase voltage amplitudes of the line is smaller than rated voltage Un, any phase of any outgoing line has current >0.05 rated current In or any phase voltage of the bus is larger than 0.5Un, and the line PT is reported to be broken after delay of 10 s;
(3) After the three-phase voltage is recovered to be normal, all the three-phase voltage is recovered to be normal after 10s delay;
PT broken line detection is switched by PT broken line detection control word.
According to the distributed power distribution automation measurement and control terminal, the electrical differences between two ends of a power transmission line are compared through differential protection, exciting inrush current and internal fault current can be rapidly judged, fault occurrence places can be rapidly determined, fault cutting is performed according to judging results, exciting current is rapidly increased when voltage of a transformer is increased or frequency is reduced through inrush current locking, a fifth harmonic component in three-phase differential current is used as a basis for over-excitation locking, when leakage, overload, short circuit, overvoltage, undervoltage and phase failure occur on a line, a three-phase reclosing power protector can immediately start a protection program, an instruction is sent to cut off the power transmission line, and an alarm is sent to remind of the current accident type; when the power supply line is subjected to fault elimination, the three-phase reclosing power protector resumes power supply, so that the operation reliability and safety of the whole terminal are greatly improved, the system equipment can be monitored and managed in all directions, and the safety, stability and economic operation of the system equipment are ensured.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.
Claims (8)
1. The utility model provides a distributed distribution automation measurement and control terminal which characterized in that, including protection module, distributed FA, warning module that limits beyond limit, double pressure lock and operation detection module, protection module includes differential protection, three-phase reclosure and gush current shutting, differential protection: the two ends of the power transmission line are connected by a communication channel and a DTU, the ground of the fault is rapidly determined and the fault is isolated according to the differential comparison of the electric quantity between the two ends of the power transmission line, and the judgment basis is as follows:
1) Starting up a criterion: id is more than or equal to Idz;
2) Ratio braking criterion: when Ir is less than or equal to Ickz, id is less than or equal to k1Ir; when Ir > Ickz, id-Id'. Gtoreq.k2 (Ir-Ickz);
wherein Id is differential current, id= |im+in|, id' =k1×ickz;
ir is the braking current, ir= |im-in|;
idz is a differential threshold and Ickz is a brake inflection point current constant;
k1 K2 is the ratio brake coefficient, 0.3 for the single power supply line k1, k2 is 0.5; for a dual-power supply circuit k1 of 0.3-0.5 and k2 of 0.5-0.8;
the three-phase reclosing power protector can immediately start a protection program when the line is in electric leakage, overload, short circuit, overvoltage, undervoltage and phase failure, gives out an instruction to cut off the power supply line and gives out an alarm to remind the current accident type; when the power supply line fails to remove, the three-phase reclosing power protector resumes the power supply again;
when the voltage of the transformer is increased or the frequency of the inrush current is reduced, the exciting current is increased sharply, and the fifth harmonic component in the three-phase differential current is used as the basis of overexcitation locking;
the inrush current blocking is used for exciting inrush current in a current loopLine characteristic identification, I when the terminal operates normally g -［K 1 ·I 1 ＋K 2 ·I 2 + K 5 ·I 5 The value of the differential protection is less than 0.1, and the differential protection does not act during normal operation; when the fifth harmonic wave generated during over-excitation is larger than a preset braking value, locking three-phase differential protection;
the surge current locking action equation is as follows:
I 5 ＞K 5 ·I o
in the formula I g For working current, I 1 As the first harmonic in the difference stream, I 2 Is the second harmonic in the second difference stream, I 5 As fifth harmonic in difference stream, I o Fundamental wave, K in differential flow 1 For first harmonic braking coefficient, K 2 For second harmonic braking coefficient, K 5 Is a fifth harmonic braking coefficient;
when reclosing is put into operation, the power transmission line is in a normal state, the breaker switch is at the closing position, the spring does not store energy, protection is not started, the operation is carried out for 15 seconds when all conditions are met, three-phase reclosing charging is completed, any of the following conditions is met, and immediately discharging is carried out while delay locking reclosing:
1) Reclosing and exiting;
2) The manual tripping comprises manual tripping and remote control tripping;
3) Tripping protection;
4) No three-phase flow exists;
5) The switch gives an alarm on two positions;
6) Before reclosing is started, a spring non-energy storage or low-pressure locking signal is received, and the discharge is performed for 400ms after time delay;
the terminal is internally provided with overcurrent acceleration protection and three-section zero sequence acceleration protection, and the reclosing acceleration selects pre-reclosing acceleration or post-reclosing acceleration, and is input before reclosing action when the pre-reclosing acceleration is selected; when acceleration is carried out after reclosing is selected, current within 15 seconds is input after manual switching-on, remote control switching-on or reclosing action, if any phase current is larger than a fixed value, tripping is carried out after short delay.
2. The distributed power distribution automation measurement and control terminal according to claim 1, wherein the distributed FA is in information interaction with an adjacent power distribution terminal in the same power supply loop, when a fault occurs on a power distribution line, the fault is rapidly removed under the condition of not depending on communication of a master station, and power supply of a non-fault area is recovered, and the distributed FA is composed of fault detection logic, fault removal logic, fault isolation logic, head switch voltage loss protection logic, switch failure jump logic, power supply recovery logic and slow-moving logic.
3. The distributed power distribution automation measurement and control terminal according to claim 1, wherein the out-of-limit alarm module gives an alarm when the terminal generates an upper limit current, a lower limit current, an upper limit voltage and a lower limit voltage, and the SOE is recorded after the event.
4. The distributed power distribution automation measurement and control terminal of claim 1, wherein the dual pressure lock comprises:
the two sides are provided with pressure locks: when the switch is in the split position, the two sides are pressed to prohibit automatic closing;
closing rings and closing gates: when the circuit breaker is in trip, checking the voltages at two sides of the circuit breaker, and allowing closing on any side without voltage, wherein the non-voltage threshold is 40% of rated voltage Un; the two sides are converted into synchronous detection, the angle between the corrected angle of the bus voltage and the line voltage is calculated, the angle difference is smaller than an angle difference fixed value, the pressure difference is smaller than a pressure difference fixed value, and closing is allowed, wherein the voltage threshold is 50% of rated voltage Un.
5. The distributed power distribution automation measurement and control terminal of claim 1, wherein: the operation detection module comprises control loop detection, the control loop detection is used for collecting and recording current values of x periods before the fault, and subtracting the current values from the current sampling values after the fault, and the collection algorithm is as follows:
Ip(t) =I(t) - I( t - nT), Ip ( k) = I (k) - I( k - xN)
wherein: ip (t) is the fault component current; i (t) is the measured current; t is the power frequency period; n is the number of weekly samples; k is sample number 1,2,3, …; n=1, 2,3, …;
when the control circuit breaks down, the switching-on position relay HWJ and the tripping position relay TWJ lose magnetism at the same time, ip (t) is larger than Ig, and the switching-on position relay HWJ and the tripping position relay TWJ close at the same time, so that an alarm signal of abnormality of the control circuit is sent.
6. The distributed power distribution automation measurement and control terminal of claim 1, wherein: the operation detection module comprises PT wire breakage detection, wherein the criteria and the signal resetting conditions of the PT wire breakage detection are as follows:
(1) The negative sequence voltage of the line is more than 12V, and the bus PT is broken after 10 seconds of delay;
(2) The sum of the three-phase voltage amplitudes of the line is smaller than rated voltage Un, any phase of any outgoing line has current >0.04 rated current In or any phase voltage of the bus is larger than 0.3Un, and the line PT is delayed by time delay 10s to be broken;
(3) After the three-phase voltage is recovered to be normal, all the three-phase voltage is recovered to be normal after 10s delay;
PT broken line detection is switched by PT broken line detection control word.
7. The distributed power distribution automation measurement and control terminal according to claim 2, wherein: the fault-removal logic: when the system fails, the failure node is not a final switch, the phase current is larger than a setting value or the zero sequence current is larger than the setting value, and nodes on one side and only one side of the bus side and the line side do not send out a node failure GOOSE signal, and the system acts after setting delay; if the fault node is a last switch, the phase current is larger than the setting value or the zero sequence current is larger than the setting value, and a node fault GOOSE signal of any node on the bus side and the line side is received, the node switch is jumped after setting delay.
8. The distributed power distribution automation measurement and control terminal according to claim 2, wherein: the switch failure trip logic: after the node switch is tripped, after failure judgment time, judging that the switch fails and refuses, triggering a 'switch refuses' GOOSE output signal, and starting a neighboring switch; when the node switch receives a bus side or line side node switch refusing jump GOOSE signal and the node switch is in a closed position and not tripped, the node switch fails to jump in a continuous mode and acts instantaneously; and if the node switch does not detect the fault and the tripping is successful, triggering a GOOSE output signal of 'successful fault isolation'.
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| CN1558486A (en) * | 2004-02-13 | 2004-12-29 | 浙江大学 | Integrated differential flow brake device for preventing voltage transformer differential protection unwanted operation |
| CN102035178A (en) * | 2010-12-29 | 2011-04-27 | 许继集团有限公司 | Method for transformer excitation surge current latching |
| CN104779705A (en) * | 2015-05-06 | 2015-07-15 | 特变电工湖南智能电气有限公司 | Line protection measurement and control method and device |
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