CN115800213A - Distributed distribution automation measurement and control terminal - Google Patents
Distributed distribution automation measurement and control terminal Download PDFInfo
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- CN115800213A CN115800213A CN202211505296.3A CN202211505296A CN115800213A CN 115800213 A CN115800213 A CN 115800213A CN 202211505296 A CN202211505296 A CN 202211505296A CN 115800213 A CN115800213 A CN 115800213A
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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-pressure lock and an operation detection module, wherein the protection module comprises differential protection, a three-phase reclosing lock and an inrush current lock, the differential protection is used for differentially comparing the electric quantity between two ends of a power transmission line, so that the inrush current and the internal fault current can be rapidly judged, a fault place is rapidly determined, fault cut-off is performed according to the judgment result, the inrush current lock is used for rapidly increasing the excitation current when the voltage of a transformer is increased or the frequency of the transformer is reduced, a quintic harmonic component in the three-phase differential current is used as an overexcitation lock basis, when a circuit has a fault, a three-phase reclosing electricity protector can immediately start a protection program, send an instruction to cut off a power supply wire, and send an alarm to remind the current accident type; after the fault of the power supply and transmission line is eliminated, the three-phase reclosing power utilization protector recovers power supply again, so that the operation reliability and the safety of the whole terminal are greatly improved.
Description
Technical Field
The invention relates to the technical field of distribution automation, in particular to a distributed distribution automation measurement and control terminal.
Background
The distribution automation measurement and control terminal has the functions of measurement, protection and control of the switch and distribution automation, adopts the advanced digital signal processing technology, the high-speed industrial network communication technology, the embedded industrial chip set and the multi-task real-time operating system, has strong stability, high reliability, good real-time performance, wide environmental scope and powerful functions, can be combined into the distribution network functions of intelligent distribution, voltage time type, voltage current time type, protection type and the like by being matched with the ring main unit switch, and realizes the local distribution automation function. The terminal is matched with an outgoing switch, a branch switch and the like, can realize fault removal and fault recovery of the distribution and transmission line, and is a distribution automation remote terminal device integrating functions of remote measurement, remote signaling, remote control, protection, communication and the like.
Distribution automation measurement and control terminal is to transformer substation, power plant, high-low voltage distribution and the protection facility that step-down transformer safety adopted of station power system self power consumption, can ensure grid system's normal even running after the equipment uses, and harm that can to a great extent avoid power failure to bring. At present, main functions of a distribution automation measurement and control terminal include PT disconnection detection, control loop disconnection detection, reclosing, current limiting protection, accelerated tripping after closing and the like. However, when a system device (such as a transformer) is operating normally or an external fault occurs, the current flowing through the differential relay is zero, but for various reasons, an unbalanced current flows through the differential circuit even during normal operation, and the setting operation value of the longitudinal differential protection is increased, which lowers the sensitivity of the protection. Therefore, the influence of the unbalanced current on the measurement and control terminal is reduced.
There are many main factors generating unbalanced current, and the influence of magnetizing inrush current generated when the transformer is switched on in a no-load state or when power is restored after an external fault is removed is the most serious. Therefore, the core problem of protection of the current distribution automation measurement and control terminal is how to correctly judge the magnetizing inrush current and the internal fault current, and execute fault disconnection according to the judgment result.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a distributed power distribution automation measurement and control terminal.
In order to achieve the purpose, the technical scheme of the invention is realized as follows: the utility model provides a distribution automation measurement and control terminal, includes protection module, distributed FA, transfinites warning module, double-pressure lock and operation detection module, protection module includes differential protection, three-phase reclosing lock and inrush current shutting, differential protection: the two ends of the transmission line are connected by a communication channel and a DTU (data transfer unit), the fault occurrence place is quickly determined and the fault is isolated according to the differential comparison of the electric quantity between the two ends of the transmission line, and the judgment basis is as follows:
1) Starting criterion: id is not less than Idz
2) Ratio braking criterion: when Ir is less than or equal to Ickz, id is more than or equal to k1Ir; id-Id' ≧ k2 (Ir-Ickz) when Ir > Ickz
Wherein Id is a differential current, id = | Im + In |, id' = k1 × Ickz;
ir is braking current, and Ir = | Im-In |;
idz is a differential threshold, ickz is a braking inflection point current constant value;
k1 K2 is the ratio braking coefficient, k1 is 0.3 for the single power supply line, k2 is 0.5; for a circuit k1 powered by a double power supply, the voltage is 0.3-0.5, and k2 is 0.5-0.8;
the three-phase reclosing lock monitors the running condition of the power supply and transmission line on line, when the line has electric leakage, overload, short circuit, overvoltage, undervoltage and open phase, the three-phase reclosing electricity utilization protector can immediately start a protection program, send an instruction to cut off the power supply and transmission line and send an alarm to remind the current accident type; when the fault of the power supply and transmission line is eliminated, the three-phase reclosing power utilization protector restores power supply again;
when the voltage of the transformer is increased or the frequency of the transformer is reduced, the excitation current is increased sharply, and fifth harmonic components in the three-phase differential current are used as the basis of overexcitation blocking.
Preferably, the inrush current lock performs characteristic identification on the excitation inrush current in the current loop, when the terminal normally operates, | Ig- [ K1 · I1+ K2 · I2+ K5 · I5] | is less than 0.1, and the differential protection does not act when the terminal normally operates; when the fifth harmonic wave generated in the process of overexcitation surge is larger than a preset braking value, the three-phase differential protection is locked at the same time;
the inrush current blocking action equation is as follows:
I 5 ＞K 5 ·I o
in the formula I g As operating current, I 1 Is the first harmonic of the difference stream, I 2 Is the second harmonic in the stream of two differences, I 5 Fifth harmonic in the difference stream, I o Fundamental wave in the difference stream, K 1 Is the first harmonic braking coefficient, K 2 Is the second harmonic braking coefficient, K 5 Is the fifth harmonic braking coefficient.
Preferably, when the reclosure is put into use, the power transmission line is in a normal state, the breaker switch is in an on position, the spring does not store energy, the protection is not started, the operation is carried out for 15 seconds when all conditions are met, the three-phase reclosure charging is completed, any one of the following conditions is met, and the reclosure is immediately discharged and locked in a delayed mode at the same time:
1) The reclosing exits;
2) Manual tripping (manual tripping, remote tripping);
3) Protection tripping;
4) Three phases are all free of flow;
5) Switching on and off double-position alarm;
6) Before the reclosing is started, a signal that the spring does not store energy or the low-pressure locking signal is received, and discharging is carried out after 400ms of delay.
The terminal is internally provided with overcurrent acceleration protection and three-section zero sequence acceleration protection, the reclosing acceleration selects acceleration before reclosing or acceleration after reclosing, and when the acceleration before reclosing is selected, the terminal is put into use before reclosing action; when the speed is accelerated after the reclosing is selected, current is input within 15 seconds after manual closing, remote control closing or reclosing action, and if any phase current is larger than a fixed value, tripping is carried out after short time delay.
Preferably, the distributed FA interacts with adjacent power distribution terminals in the same power supply loop through information, when a fault occurs on a power distribution line, the fault is rapidly removed under the condition of not depending on master station communication, and non-fault area power supply is recovered, and the distributed FA comprises fault detection logic, fault removal logic, fault isolation logic, first switch voltage loss protection logic, switch failure joint tripping logic, power supply recovery logic and slow-acting logic.
Preferably, the out-of-limit alarm module gives an alarm when the terminal generates time when the current is higher than the upper limit, the current is lower than the lower limit, the voltage is higher than the upper limit and the voltage is lower than the lower limit, and the SOE is recorded after the event is generated.
Preferably, the double compression lock comprises:
and two sides are locked by pressing: when the switch is positioned at a separating position, automatic closing is forbidden under the pressure at two sides;
closing a loop and closing a switch: checking the voltage on both sides of the circuit breaker when the circuit breaker is in a jump position, allowing closing without any voltage (non-voltage threshold 40%; and (4) converting the voltage (50 percent Un) on both sides into a synchronization period, calculating the angle between the corrected angle of the bus voltage and the line voltage, wherein the angle difference is smaller than an angle difference fixed value, and the differential pressure is smaller than a differential pressure fixed value, so that the switch-on is allowed.
Preferably, the operation detection module comprises a control loop detection module, the control loop detection module is used for collecting and recording current values of x periods before the fault, and subtracting the current sampling value after the fault, and the collection algorithm is as follows:
Ip(t)＝I(t)-I(t-nT),Ip(k)＝I(k)-I(k-xN)
in the formula: ip (t) is the fault component current; i (t) is the measured current; t is the power frequency period; n is the number of samples per week; k is sampling serial number 1,2,3, \8230; n =1,2,3, \8230.
When the control circuit is in fault, the switching-on position relay HWJ and the tripping position relay TWJ are simultaneously de-energized, ip (t) > Ig, and two normally closed contacts of the switching-on position relay HWJ and the tripping position relay TWJ are simultaneously closed, and a warning signal of 'control circuit abnormity' is sent out.
Preferably, the operation detection module includes PT disconnection detection, and the criterion of the PT disconnection detection and the condition of signal resetting are as follows: (1) The negative sequence voltage of the line is more than 12V, and the time delay is 10s to report the bus PT disconnection;
(2) The sum of the three-phase voltage amplitudes of the circuit is less than the rated voltage Un, any phase of any outgoing line has current larger than 0.04 rated current In or any phase voltage of a bus is larger than 0.3Un, and the circuit PT is reported to be broken In a delayed time of 10 s;
(3) After the three-phase voltage is recovered to be normal, the three-phase voltage is delayed for 10s and then is completely recovered to be normal;
PT disconnection detection controls the switching of the word by PT disconnection detection.
Preferably, the fault removal logic: when the system has a fault, a fault node is not a last switch, the phase current is greater than a setting fixed value or the zero sequence current is greater than the setting fixed value, and nodes on one side and only one side of the nodes on the bus side and the line side do not send out a 'node fault' GOOSE signal, then the node fault acts after setting delay; and if the fault node is a last switch, the phase current is greater than the setting fixed value or the zero-sequence current is greater than the setting fixed value, and a node fault GOOSE signal of any node of the bus side and the line side is received, the node switch is tripped after setting delay.
Preferably, the switch failure joint trip logic: after the node switch acts and trips, judging that the switch fails and rejects after failure judgment time, triggering a 'switch reject tripping' GOOSE output signal, and starting an adjacent side switch; when the node switch receives a 'switch rejection trip' GOOSE signal of a bus side or line side node, and the node switch is in a closed position and is not tripped, the instantaneous action of failure and joint tripping is carried out; if the node switch does not detect the fault and the trip is successful, a fault isolation success GOOSE output signal is triggered.
The invention has the beneficial effects that:
compared with the prior art, the distributed distribution automatic measurement and control terminal performs differential comparison on the electric quantity between two ends of a power transmission line through differential protection, can quickly judge the excitation inrush current and the internal fault current, quickly determine the fault occurrence place and execute fault cut-off according to the judgment result, and also rapidly increases the excitation current when the voltage of a transformer rises or the frequency of the transformer decreases through inrush current lock-up, utilizes the quintic harmonic component in the three-phase differential current as the over-excitation lock-up basis, when the line has electric leakage, overload, short circuit, overvoltage, undervoltage and open phase, the three-phase reclosing power utilization protector can immediately start a protection program, sends an instruction to cut off the power supply line, and sends an alarm to remind the current accident type; after the fault of the power supply and transmission line is eliminated, the three-phase reclosing electricity protector recovers power supply again, so that the operational reliability and safety of the whole terminal are greatly improved, the system equipment can be monitored and managed in an all-round manner, and the safety, stability and economic operation of the system equipment are guaranteed.
Drawings
The invention is described in further detail below with reference to the figures and the specific embodiments.
Fig. 1 is a schematic connection diagram of differential protection of a distributed power distribution automation measurement and control terminal according to the present invention;
fig. 2 is a diagram of the differential protection action characteristic of a distributed power distribution automation measurement and control terminal according to the present invention;
fig. 3 is a schematic diagram of the operation logic of the differential protection of the distributed distribution automation measurement and control terminal according to the present invention;
fig. 4 is a schematic diagram of a three-phase reclosing operation logic of a distributed power distribution automation measurement and control terminal according to the present invention;
fig. 5 is a schematic diagram of a section i operation logic of overcurrent acceleration protection of a distributed power distribution automation measurement and control terminal according to the present invention;
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 distribution automation measurement and control terminal according to the present invention;
fig. 8 is a logic diagram of the current over-limit operation of the distributed power distribution automation measurement and control terminal according to the present invention;
fig. 9 is a logic diagram of lower limit-crossing current operation of a distributed power distribution automation measurement and control terminal according to the present invention;
fig. 10 is a logic diagram of the voltage over-limit operation of a distributed power distribution automation measurement and control terminal according to the present invention;
fig. 11 is a logic diagram of lower-limit operation of the voltage of the distributed power distribution automation measurement and control terminal according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-2, a distributed distribution automation measurement and control terminal includes a protection module, a distributed FA, an out-of-limit alarm module, a dual-voltage lock, and an operation detection module, where the protection module includes a differential protection, a three-phase reclosing and an inrush current lock, the differential protection uses an optical fiber communication channel and two DTUs to respectively connect two ends of a power transmission line, uses kirchhoff's theorem split-phase current differential as a main protection of line protection, the two ends of the power transmission line are respectively DTU1 and DTU2, and according to an electrical quantity differential comparison between the two ends of the power transmission line, a fault occurrence place is quickly determined and a fault is isolated. The electric quantity is the differential current of the two ends of the power transmission line, and the judgment basis of the protection module is as follows:
1) Starting criterion: id is not less than Idz
2) Ratio braking criterion: when Ir is less than or equal to Ickz, id is more than or equal to k1Ir; id-Id' ≧ k2 (Ir-Ickz) when Ir > Ickz
Wherein Id is a differential current, id 'is an operating current, id = | Im + In |, id' = k1 × Ickz;
ir is braking current, and Ir = | Im-In |;
idz is a differential threshold, ickz is a braking inflection point current constant value;
k1 K2 is the rate brake coefficient, k1 is 0.3 and k2 is 0.5 for a single power supply line; for a circuit k1 powered by a double power supply, the voltage is 0.3-0.5, and k2 is 0.5-0.8; typically, k1 is 0.4 and k2 is 0.6 for a dual power supply line.
The slope of the slope in fig. 2 is a ratiometric braking coefficient, the presence of a mass production non-periodic component in the short-circuit current at out-of-zone faults, and the molding device falls within the braking zone at the intersection of the braking current Ir and the actuation current Id 'when the actuation current Id' is greater than the differential threshold Idz; when the fault occurs in the area, the differential current, namely the action 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 is bound to fall in the action area, so that the reliable action of the differential protection is realized.
When the CT transformation ratios at two ends of the transmission line are not equal, the current at the opposite side can be compensated through the set opposite side current balance coefficient. And during the setting, the CT transformation ratio of the current side is taken as a reference, and the ratio obtained by the CT transformation ratio of the opposite side and the CT transformation ratio of the previous side is the opposite side current balance coefficient of the current side. And the differential flow fixed values on the two sides are set by taking the CT transformation ratio on the side as a reference.
Referring to fig. 3, when the optical fiber communication is abnormal, the terminal records "optical fiber communication is abnormal", the "alarm" lamp is turned on to protect the outlet, and the differential protection is locked, and simultaneously the alarm signal is output, the signal outlet can be set, and the alarm returns after the optical fiber communication is recovered; when the CT disconnection alarm is switched on simultaneously with CT disconnection locking, locking differential protection is carried out when the CT disconnection alarm is switched on, and in order to be distinguished from ground fault, the CT disconnection judgment basis is as follows: (1) In three-phase currents, the value of one phase with the minimum current is zero; (2) The current value of the phase with larger current is not zero and is smaller than the maximum load current.
In addition, the three-phase reclosing on-line monitoring power supply and transmission line operation condition, when the line has electric leakage, overload, short circuit, overvoltage, undervoltage and open phase, the three-phase reclosing electricity utilization protector can immediately start a protection program, send an instruction to cut off the power supply and transmission line, and send an alarm to remind the current accident type; when the fault of the power supply and transmission line is eliminated, the three-phase reclosing power utilization protector recovers power supply again. The three-phase reclosing selection XHB-APS/3-63A three-phase intelligent safety electricity utilization protector is connected to a power transmission line and has the functions of overvoltage protection, undervoltage protection, overload protection, short-circuit protection, leakage protection, automatic reclosing, check before closing and remote monitoring.
It should be noted that in this embodiment, the protection control word can be set to exit when the reclosing switch is not turned on. The reclosing can act through a delay outlet under the condition that the circuit breaker is in an off position, charging is completed and no locking condition is judged, after overcurrent or time-limited quick-break tripping and reclosing, if the circuit breaker is in a permanent fault, the circuit breaker can be tripped in a later accelerated mode, and the reclosing is not charged any more after tripping. In addition, during reclosing charging, after the circuit breaker is closed, the circuit breaker is judged to be in a closed position, and charging is completed after set time; the reclosing locking condition is accelerated tripping after manual opening and closing in a fault state.
Referring to fig. 4, the operating logic of the three-phase reclosing lock is set as follows: when the reclosing is put into operation, the power transmission line is in a normal state, the breaker switch is in a closed position, the spring does not store energy, the protection is not started, the protection circuit operates for 15 seconds when all conditions are met, the three-phase reclosing is charged, any one of the following conditions is met, and the reclosing is immediately discharged and locked in a delayed manner at the same time:
1) The reclosing is exited;
2) Manual tripping (manual tripping, remote tripping);
3) Protection tripping;
4) Three phases are all free of flow;
5) Switching on and off double-position alarm;
6) Before the reclosing is started, a signal that the spring does not store energy or the low-pressure locking signal is received, and discharging is carried out after 400ms of delay.
The terminal is internally provided with overcurrent acceleration protection and three-section zero sequence acceleration protection, the reclosing acceleration selects acceleration before reclosing or acceleration after reclosing, and when the acceleration before reclosing is selected, the terminal is put into use before reclosing action; when the speed is accelerated after the reclosing is selected, current is input within 15 seconds after manual closing, remote control closing or reclosing action, and if any phase current is larger than a fixed value, tripping is carried out after short time delay.
The overcurrent accelerated protection is three-phase three-section type timing time-limited overcurrent protection which is completely the same, different time-delay actions are set to avoid work peak current and only the circuit breaker closest to an accident point acts to reduce the influence range of power failure when short-circuit fault occurs by utilizing different overcurrent values, wherein the I section is non-time-limited current quick-break protection and is set according to the maximum short-circuit current avoiding the tail end of the section; the second section is time-limited current quick-break, is set according to the maximum action range of current quick-break protection of each adjacent element which is kept away from the next stage, and can be used as backup protection of the first section of the power transmission line of the section; the section III is overcurrent protection, is set according to the maximum load current which avoids the element, has longer time limit than the section II, can be used as backup protection of the section I and the section II, and has the largest protection range and the longest time limit. Each section is provided with independent input or output, and the input/output can be selected through a soft pressure plate. The I section of operation logic is shown in figure 5, the II section of operation logic and the III section of operation logic are the same as the I section of operation logic, the three-phase current of the power transmission line is detected, when the maximum current of the line is larger than the current fixed value of the overcurrent I section, an overcurrent I section starting element is started, an overcurrent I section alarm and tripping (circuit breaker) command is output after settable delay, an overcurrent signal lamp is lightened, and protection can be selectively put in or withdrawn through a soft pressing plate; when overcurrent power failure tripping is input, the circuit has no current and no voltage, and the overcurrent I section has no delay outlet tripping.
The three-section zero sequence acceleration protection is used for detecting the ground fault, the zero sequence current generated during grounding is used for protecting the ground fault, the operation logic of the three-section zero sequence acceleration protection refers to the graph 6, and the composition principle of the three-section zero sequence acceleration protection is the same as that of 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 through 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 a zero sequence overcurrent alarm and tripping command is sent out after the delay of the set zero sequence overcurrent time.
When the transformer is switched on in no-load or external fault recovery voltage is removed by differential protection, excitation inrush current with a large value may occur. And the inrush current lock identifies the characteristics of the magnetizing inrush current in the current loop so as to prevent misoperation when the large-capacity transformer is switched on. The function is matched with differential protection for use, and the inrush current blocking constant value can be set. The protection can be selectively put in/out through a soft pressure plate.
When the voltage of the transformer increases or the frequency of the transformer decreases, the exciting current sharply increases, and the differential protection malfunction may be caused. The inrush current lock identifies the characteristics of the excitation inrush current in the current loop, when the terminal normally operates, | Ig- [ K1 · I1+ K2 · I2+ K5 · I5] | is less than 0.1, and the differential protection does not act during normal operation; when the fifth harmonic wave generated during the over-excitation surge is greater than a preset braking value, the three-phase differential protection is locked;
the inrush current blocking action equation is as follows:
I 5 ＞K 5 ·I o
in the formula I g For operating current, I 1 Being the first harmonic of the difference stream, I 2 Is the second harmonic in the stream of two differences, I 5 Fifth harmonic in the difference stream, I o Fundamental wave in differential flow, K 1 Is the first harmonic braking coefficient, K 2 Is the second harmonic braking coefficient, K 5 Is the fifth harmonic braking coefficient.
Furthermore, in this embodiment, the distributed FA is composed of an intelligent terminal, a peer-to-peer communication system, and a distribution automation master station, and the structure of the distributed FA is as shown in fig. 7, the distributed FA interacts with an adjacent distribution terminal in the same power supply loop through information through peer-to-peer communication (61850 + goose), when a fault occurs on a transmission line, the fault is quickly removed without relying on master station communication, power supply in a non-fault area is recovered, a self-healing function of a distribution network is realized, and fault isolation time and 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, first switch voltage loss protection logic, switch failure joint tripping logic, power supply recovery logic and slow-acting logic.
The failure detection logic: and when the distribution network has a fault, the phase current flowing through the node is greater than a setting fixed value or the zero-sequence current is greater than the setting fixed value, and the node fault is judged, and a node fault GOOSE output signal is triggered instantaneously.
The fault removal logic: when the system has a fault, if the node is not a last switch, the phase current is greater than a setting fixed value or the zero-sequence current is greater than the setting fixed value, and nodes on one side and only one side of the nodes on the bus side and the line side do not send out a 'node fault' GOOSE signal, the node is tripped through the action after setting delay; if the node is a final switch, the phase current is greater than the setting fixed value or the zero-sequence current is greater than the setting fixed value, and a node fault GOOSE signal of any node of the bus side and the line side is received, the node is tripped after setting delay.
The fault isolation logic: and if the node does not detect the fault and receives a 'node fault' GOOSE signal of only one node on the bus side or the line side, the node switch is tripped after setting delay.
The first switch voltage loss protection logic: when the node is a first switch and GOOSE communication of the node is normal, if the switch is closed and the voltage of the line is 3s, the first switch is automatically switched into for voltage loss protection, and the fault can be quickly isolated when the fault occurs between a power supply point and the first switch. After the first switch voltage loss protection is put into operation, if both sides of the node have no voltage and the node has no current, the node is tripped through setting delay, and meanwhile, the judgment of the tripping failure of the switch is started.
The switch failure jump logic: after the node switch acts and trips, judging that the switch fails and rejects after failure judgment time, triggering a 'switch reject tripping' GOOSE output signal, and starting an adjacent side switch; when the node switch receives a 'switch rejection trip' GOOSE signal of a bus side or line side node, and the node switch is in a closed position and is not tripped, the instantaneous action of failure and joint tripping is carried out; if the node switch does not detect the fault and the trip is successful, triggering a fault isolation success GOOSE output signal.
The power restoration logic: after the fault isolation is successful, each node in the area sequentially forwards a 'fault isolation success' GOOSE signal to two sides, and after the power supply recovery charging of the node is completed and the voltage of the bus side or the single side of the line side is lost, the 'fault isolation success' GOOSE signal is received, and the switch of the node is started to be switched on after setting delay, so that the power supply transfer process is completed.
The slow-motion logic: after fault positioning is completed, after a transformer substation feeder line protection action removes a fault, a corresponding fault section is isolated in a delayed mode, whether a switching condition of an interconnection power supply is met or not is judged, if the switching condition is met, an interconnection switch is closed to complete power supply recovery of a non-fault power failure area, a non-voltage no-current condition needs to be added on the basis of quick-acting logic judgment, the non-voltage no-current duration time needs to be longer than a setting fixed value, then action is performed, and a corresponding GOOSE output signal is triggered.
The snap-action logic: and cutting off a fault area before the action of the outlet breaker, realizing the zero power failure of the line after the fault positioning is finished, isolating a corresponding fault section before the action of feeder protection, then judging whether the switching condition of the contact power supply is met, and closing the contact switch to finish the power supply recovery of the non-fault power failure area if the switching condition is met.
More specifically, the out-of-limit alarm module gives an alarm when the terminal generates time when the current is higher than the upper limit, the current is lower than the lower limit, the voltage is higher than the upper limit and the voltage is lower than the lower limit, and the SOE is recorded after an event is generated. Specifically, referring to fig. 8, when the current of any phase in the transmission line is greater than the current upper limit fixed value, the set upper limit time delay sends out a current upper limit alarm; referring to fig. 9, when the current of any phase in the transmission line is smaller than the lower limit current threshold, the lower limit current alarm is issued after the set out-of-limit time delay; referring to fig. 10, when the voltage of any phase in the transmission line is greater than the overvoltage alarm fixed value, the overvoltage alarm is sent out after the set out-of-limit time delay; referring to fig. 11, when the voltage of any phase in the transmission line is greater than 10V and smaller than the low-voltage alarm fixed value, the low-voltage alarm is issued after the set out-of-limit time delay.
In addition, the double-pressure lock comprises a two-side pressure lock and a closed loop switch, wherein the two-side pressure lock comprises: when the switch is positioned at a separating position, automatic closing is forbidden under the pressure at two sides; closing a loop and closing a switch: when the breaker is in a jump position, the voltage on two sides of the breaker is checked, and the closing is allowed when no voltage is applied to any side (the non-voltage threshold is 40 percent) Un; and (4) converting the voltage (50 percent Un) on the two sides into a detection synchronization period, calculating the angle between the corrected angle of the bus voltage and the line voltage, wherein the angle difference is smaller than an angle difference fixed value, and the differential pressure is smaller than a differential pressure fixed value, so that closing is allowed.
The operation detection module comprises a control loop detection module, the control loop detection module is used for collecting and recording current values of x periods before the fault and subtracting 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)
in the formula: ip (t) is the fault component current; i (t) is the measured current; t is the power frequency period; n is the number of samples per week; k is sampling number 1,2,3, \ 8230; n =1,2,3, \8230.
When the control circuit is in fault, the switching-on position relay HWJ and the tripping position relay TWJ are simultaneously de-magnetized, ip (t) > Ig, two normally closed contacts of the switching-on position relay HWJ and the tripping position relay TWJ are simultaneously closed, and a warning signal of 'abnormal control circuit' is sent out.
The operation detection module comprises PT disconnection detection, and the criteria of the PT disconnection detection and the signal resetting conditions are as follows:
(1) The negative sequence voltage of the line is more than 15V, and the time delay is 10s to report the bus PT disconnection;
(2) The sum of the three-phase voltage amplitude values of the line is less than the rated voltage Un, any phase of any outgoing line has the current greater than 0.05 rated current In or any phase voltage of the bus is greater than 0.5Un, and the PT disconnection of the line is reported In a delayed mode by 10 s;
(3) After the three-phase voltage is recovered to be normal, the three-phase voltage is delayed for 10s and then is completely recovered to be normal;
PT disconnection detection controls the switching of the word by PT disconnection detection.
According to the distributed distribution automatic measurement and control terminal, through differential protection, electrical quantities between two ends of a power transmission line are differentially compared, excitation inrush current and internal fault current can be rapidly judged, a fault occurrence place is rapidly determined, fault cutoff is executed according to a judgment result, the excitation current is rapidly increased when the voltage of a transformer is increased or the frequency of the transformer is reduced through inrush current locking, quintuple harmonic components in three-phase differential current are used as overexcitation locking bases, when a circuit has electric leakage, overload, short circuit, overvoltage, undervoltage and phase loss, a three-phase reclosing power utilization protector can immediately start a protection program, an instruction is sent to cut off a power supply line, and an alarm is given out to remind the current accident type; after the power supply and transmission line fault is eliminated, the three-phase reclosing power protector recovers power supply again, so that the operation reliability and safety of the whole terminal are greatly improved, system equipment can be monitored and managed in an all-round mode, and safety, stability and economic operation of the system equipment are guaranteed.
Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.
Claims (10)
1. The utility model provides a distribution automation measurement and control terminal, its characterized in that, including protection module, distributed FA, transfinite warning module, two pressure locks and operation detection module, protection module includes differential protection, three-phase reclosing lock and inrush current shutting, differential protection: connecting two ends of a transmission line by using a communication channel and a DTU (data transfer unit), quickly determining a fault occurrence place and isolating the fault according to the electrical quantity differential comparison between the two ends of the transmission line, and judging according to the following steps:
1) Starting criterion: idz is not less than or equal to Idz
2) Ratio braking criterion: when Ir is less than or equal to Ickz, id is more than or equal to k1Ir; id-Id' ≧ k2 (Ir-Ickz) when Ir > Ickz
Wherein Id is a differential current, id = | Im + In |, id' = k1 × Ickz;
ir is braking current, and Ir = | Im-In |;
idz is a differential threshold, ickz is a braking inflection point current constant value;
k1 K2 is the ratio braking coefficient, k1 is 0.3 for the single power supply line, k2 is 0.5; for a circuit k1 powered by a double power supply, the power supply voltage is 0.3-0.5, and k2 is 0.5-0.8;
the three-phase reclosing lock monitors the running condition of the power supply and transmission line on line, when the line has electric leakage, overload, short circuit, overvoltage, undervoltage and open phase, the three-phase reclosing electricity utilization protector can immediately start a protection program, send an instruction to cut off the power supply and transmission line and send an alarm to remind the current accident type; when the fault of the power supply and transmission line is eliminated, the three-phase reclosing power utilization protector restores power supply again;
when the voltage of the transformer is increased or the frequency of the transformer is reduced, the excitation current is increased sharply, and fifth harmonic components in the three-phase differential current are used as the basis of overexcitation blocking.
2. The distributed power distribution automation measurement and control terminal of claim 1, wherein the inrush current lock performs characteristic identification on an inrush current in a current loop, and when the terminal operates normally, | I g -[K 1 ·I 1 +K 2 ·I 2 +K 5 ·I 5 ]If the absolute value is less than 0.1, the differential protection does not act during normal operation; when the fifth harmonic wave generated in the process of overexcitation surge is larger than a preset braking value, the three-phase differential protection is locked at the same time;
the inrush current blocking action equation is as follows:
I 5 ＞K 5 ·I o
in the formula I g As operating current, I 1 Is the first harmonic of the difference stream, I 2 Is the second harmonic of the two difference streams, I 5 Fifth harmonic in the difference stream, I o Fundamental wave in differential flow, K 1 Is the first harmonic braking coefficient, K 2 Is the second harmonic braking coefficient, K 5 Is the fifth harmonic braking coefficient.
3. The distributed power distribution automation measurement and control terminal of claim 1, wherein when a reclosing switch is turned on, the power transmission line is in a normal state, a breaker switch is in a closed position, a spring does not store energy, protection is not started, the operation is carried out for 15 seconds when all conditions are met, the three-phase reclosing switch is charged, any one of the following conditions is met, and the reclosing switch is immediately discharged and is locked in a delayed mode at the same time:
1) The reclosing exits;
2) Manual tripping (manual tripping, remote tripping);
3) Protection tripping;
4) Three phases are all free of flow;
5) Switching on and off double-position alarm;
6) Before the reclosing is started, a signal that the spring does not store energy or the low-pressure locking signal is received, and discharging is carried out after 400ms of delay.
The terminal is internally provided with overcurrent acceleration protection and three-section zero sequence acceleration protection, the reclosing acceleration selects acceleration before reclosing or acceleration after reclosing, and when the acceleration before reclosing is selected, the terminal is put into use before reclosing action; when the speed is accelerated after the reclosing is selected, current is input within 15 seconds after manual closing, remote control closing or reclosing action, and if any phase current is larger than a fixed value, tripping is carried out after short time delay.
4. The distributed power distribution automation measurement and control terminal of claim 1, wherein the distributed FA interacts with adjacent power distribution terminals in the same power supply loop through information, when a fault occurs on a power distribution line, the fault is rapidly removed without depending on master station communication, and non-fault area power supply is recovered, and the distributed FA comprises fault detection logic, fault removal logic, fault isolation logic, first switch no-voltage protection logic, switch failure joint tripping logic, power supply recovery logic and slow-action type logic.
5. 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 time when the current is higher than the upper limit, the current is lower than the lower limit, the voltage is higher than the upper limit and the voltage is lower than the lower limit, and the SOE is recorded after the event is generated.
6. The distributed power distribution automation measurement and control terminal of claim 1 wherein the dual-pressure lock comprises:
and two sides are locked by pressing: when the switch is in a separating position, automatic closing is forbidden under the pressure of two sides;
closing a loop and closing a switch: when the breaker is in a jump position, the voltage on two sides of the breaker is checked, and the closing is allowed when no voltage is applied to any side (the non-voltage threshold is 40 percent) Un; and (4) converting the voltage (50 percent Un) on the two sides into a detection synchronization period, calculating the angle between the corrected angle of the bus voltage and the line voltage, wherein the angle difference is smaller than an angle difference fixed value, and the differential pressure is smaller than a differential pressure fixed value, so that closing is allowed.
7. The distributed power distribution automation measurement and control terminal of claim 1, characterized in that: the operation detection module comprises a control loop detection module, the control loop detection module is used for collecting and recording current values of x periods before the fault and subtracting 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)
in the formula: ip (t) is the fault component current; i (t) is the measured current; t is the power frequency period; n is the number of samples per week; k is sampling serial number 1,2,3, \8230; n =1,2,3, \ 8230;.
When the control circuit is in fault, the switching-on position relay HWJ and the tripping position relay TWJ are simultaneously de-energized, ip (t) > Ig, and two normally closed contacts of the switching-on position relay HWJ and the tripping position relay TWJ are simultaneously closed, and a warning signal of 'control circuit abnormity' is sent out.
8. The distributed power distribution automation measurement and control terminal of claim 1, characterized in that: the operation detection module comprises PT disconnection detection, and the criteria of the PT disconnection detection and the signal resetting conditions are as follows:
(1) The negative sequence voltage of the line is more than 12V, and the time delay is 10s to report the PT disconnection of the bus;
(2) The sum of the three-phase voltage amplitudes of the circuit is less than the rated voltage Un, any phase of any outgoing line has current larger than 0.04 rated current In or any phase voltage of a bus is larger than 0.3Un, and the circuit PT is reported to be broken In a delayed time of 10 s;
(3) After the three-phase voltage is recovered to be normal, the three-phase voltage is delayed for 10s and then is completely recovered to be normal;
PT disconnection detection controls the switching of the word by PT disconnection detection.
9. The distributed power distribution automation measurement and control terminal of claim 4, characterized in that: the fault removal logic: when the system has a fault, a fault node is not a last switch, the phase current is greater than a setting fixed value or the zero sequence current is greater than the setting fixed value, and nodes on one side and only one side of the nodes on the bus side and the line side do not send out a 'node fault' GOOSE signal, then the node fault acts after setting delay; and if the fault node is a last switch, the phase current is greater than the setting fixed value or the zero-sequence current is greater than the setting fixed value, and a node fault GOOSE signal of any node of the bus side and the line side is received, the node switch is tripped after setting delay.
10. The distributed power distribution automation measurement and control terminal of claim 4, characterized in that: the switch failure joint trip logic: after the node switch acts and trips, judging that the switch fails and rejects after failure judgment time, triggering a switch rejection GOOSE output signal, and starting an adjacent side switch; when the node switch receives a 'switch tripping rejection' GOOSE signal of a bus side or line side node and the node switch is in an on position and is not tripped, the node switch does not work and performs a tripping instantaneous action; if the node switch does not detect the fault and the trip is successful, a fault isolation success GOOSE output signal is triggered.
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