CN111224388B

CN111224388B - Node interlocking protection method suitable for multiple power supply modes

Info

Publication number: CN111224388B
Application number: CN202010102645.1A
Authority: CN
Inventors: 李钢; 吴永文; 朱微维
Original assignee: Nari Technology Co Ltd
Current assignee: Nari Rail Transit Technology Co ltd; Nari Technology Co Ltd
Priority date: 2020-02-19
Filing date: 2020-02-19
Publication date: 2022-02-15
Anticipated expiration: 2040-02-19
Also published as: CN111224388A

Abstract

The invention discloses a node interlocking protection method suitable for various power supply modes. The positive direction directions of various protections are regulated, the current positive direction and the current reverse direction are determined through positive direction judgment, allowable protection and reverse blocking protection are provided, the problem of failure of the non-directional blocking protection in a multi-power system is solved, the method is suitable for various power supply modes, the interlocking protection of the whole power grid can be realized only by mutually interlocking the protection of the local station and the protection of the opposite ends of the incoming and outgoing lines entering and exiting the local station, and the difficulty in implementation and maintenance of the method is reduced. If the optical fiber longitudinal differential protection between the lines is not operated or set, complete protection can still be provided for faults under various power supply modes. When the GOOSE network is adopted to transmit the interlocking signal mode, network grouping can be carried out according to one station in a GOOSE switch, and the situation that network abnormal messages possibly cause by a network mode of a whole line and the whole line are affected is avoided.

Description

Node interlocking protection method suitable for multiple power supply modes

Technical Field

The invention relates to a relay protection method for node interlocking, and belongs to the field of protection control.

Background

In a ring network power supply system, such as an urban rail transit alternating current medium voltage power supply system, an optical fiber longitudinal difference is usually set between two stations as main protection, and meanwhile, timing limit overcurrent protection is set according to a stepped principle as backup protection, and the two are combined to form complete protection. Because of the requirement of all maximum allowable time limits of main transformer for supplying power to urban rail transit, the number of the timing limit overcurrent protection stages set according to the step principle cannot be too many, so as to ensure that the time limit cannot exceed the requirement of the main transformer.

Relay protection manufacturers have taken measures to prevent overcurrent protection malfunctions, typically by sending blocking signals to each other. The mutual transmission of signals takes place by means of cable transmission contacts, but also by means of communication, for example GOOSE. Typical logic diagrams of criteria for sending blocking signals and protection actions to each other are shown in fig. 1 and 6. For simplicity, the block diagram only depicts phase a.

However, in the way of sending the locking signals to each other, when the interlocking adopts a cable transmission contact mode, the situation that the locking signals are not received by the protection device due to the fact that a cable is loosened or broken, and the relay fault for controlling the opening and closing of the contacts is considered; when the interlocking adopts a communication mode, the protection device does not receive the locking signal due to the possible faults of the switch, the loosening or the breakage of the network connecting line and the like, and under the conditions, the protection device can malfunction if the locking signal is not received. If the limit value of the 'latching trip time limit' needs to be set for a long time in order to prevent misoperation, the protection action is slow, and the fault is slowly cut off.

By adopting the patented technical scheme, as shown in fig. 3, when the low pressure does not flow, the quick action and the selectivity of protection are both increased by mutually sending the permission signals. And the optical fiber longitudinal differential protection can be replaced between stations so as to realize the rapid removal of line faults between stations.

However, the above method is only suitable for a single power supply system, and if the method is used for a multi-power supply system, the protection will have the problem of refusing action, but in real life, more and more multi-power supply situations exist.

In order to not affect operation, the subway sometimes adopts an uninterrupted switching mode, namely, a section switch and a connection switch in a looped network are closed for a short time, so that the situation of double power supplies in a short time is caused.

In order to save energy and protect environment, the subway increasingly adopts an energy feedback device, namely, when a train brakes, the kinetic energy of the train is converted into electric energy to feed back power to a medium-voltage ring network, and as a plurality of trains run on one line, a plurality of power supplies dynamically appear in the system.

Distributed power generation has a multi-power supply situation, and power supply points and power supply directions can dynamically change. The power distribution network and the power grid also have the problems.

For the above multiple power supply situations, no systematic solution exists at present, and new challenges are brought to primary system design, relay protection function design and fixed value setting. .

Disclosure of Invention

In order to solve the problem of multiple power supplies, the invention provides a node interlocking protection method suitable for multiple power supply modes, the method is suitable for various power supply modes, the node is used as a core, and the method is suitable for various power supply modes and all protection.

The invention can adopt the following technical scheme:

a node interlocking protection method suitable for multiple power supply modes comprises the following steps:

defining a node; the node is a point in a primary system of a power grid, which is in direct electrical connection, and comprises a segmented left bus, a segmented right bus, a non-segmented bus and a line, wherein the line comprises a power transmission line or a T-connection and bifurcated multi-branch line;

defining node protection; a circuit breaker directly connected with a node is arranged as a protection device corresponding to the node, and the protection device is called as the protection of the node; the protections directly connected to the same node are adjacent to each other;

each protection is connected with at most two nodes; the protection corresponding to the circuit breaker which is sometimes opened and sometimes closed between the nodes is still the protection on the node; for the sectional protection, no matter the bus sectional breaker is opened or closed, the sectional protection is adjacent to the protection on the bus node on the left side of the section, and the sectional protection is also adjacent to the protection on the bus node on the right side of the section; the line protection is hung on the bus, and no matter whether the line breaker is opened or closed, the line protection is adjacent to the protection on the opposite side of the line node where the line protection is located, and the line protection is also adjacent to the protection on the bus node where the line protection is located;

setting node interlocking protection in a relay protection device, wherein the node interlocking protection comprises locking protection, allowable protection, failure protection and joint tripping, and each protection comprises a criterion for sending a signal by the interlocking protection and an action criterion; the locking type protection is divided into non-directional locking type protection and reverse locking type protection;

the criteria for transmitting the signal include: sending a phase-based non-directional locking signal, sending a phase-based reverse locking signal, sending a phase-based allowing signal, sending a phase-based starting failure signal and sending a jump signal;

criterion for sending lock-up signals in phase-non-direction: if a certain phase current of a certain protection is greater than the 'interlocked locking type signaling current', the protection sends a non-directional locking signal of the certain phase to all adjacent protections of the protection, and the non-directional locking means that the current flow direction is not judged;

criterion for sending a phase-reversed blocking signal: if a certain phase current of a certain protection is larger than the 'interlocking locking type signaling current', the protection sends a reverse locking signal of the phase to give the adjacent protection of the node to which the current of the protection reversely points;

the criterion for sending the phase-allowed signal comprises two conditions that the current is less than an interlocking threshold current and greater than a forward allowed sending current; the sending of the current less than the "interlock threshold current" is based on the criterion of the phase enable signal: when the circuit breaker corresponding to a certain protection is in a closed position and a certain phase voltage is smaller than a rated voltage, or the protection receives a phase non-directional blocking signal sent by an adjacent protection as a condition, and the phase current of the protection is smaller than an 'interlocking threshold current', the protection sends an allowable signal of the phase to all the adjacent protections of the protection; the sending of the current larger than the forward allowable sending current is determined according to the phase allowable signal: if a certain phase current of a certain protection is larger than a forward allowable transmitting current, the protection sends an allowable signal of the phase to the adjacent protection of which the current of the protection points to the node in the forward direction; for the segment protection, a certain phase current of a certain protection is larger than a forward allowable transmitting current, and when the current flows to the left side of the segment, the protection transmits an allowable signal to an adjacent protection on a bus on the left side of the segment; when the current flows to the right side of the segment, the protection sends an enabling signal to the adjacent protection on the bus on the right side of the segment; for the line protection on the bus, a certain phase current of a certain protection is greater than a forward allowable transmitting current, and when the current flows to the bus, the protection transmits an allowable signal to an adjacent protection on the bus; when the current flows to the line, the protection sends an enabling signal to the adjacent protection on the line;

criterion for sending phase-wise start-up failure signal: the fault phase current of a certain protection is greater than the 'interlocking threshold current', the protection has sent a tripping command, and after the time delay of 'starting failure time limit', a starting failure signal of the phase is sent to all adjacent protections of the protection;

criterion for sending the joint jump signal: after a certain protection is tripped, a joint tripping signal is sent through optical fibers or carriers laid on two sides of a line to protect the opposite side of the line to be protected;

the action criterion comprises: according to the action criteria of phase directionless locking protection, phase reverse locking protection, phase permission protection, phase failure protection and jump-connection;

according to the phase non-direction locking type protection action criterion: the fault phase current of a certain protection is greater than the non-directional blocking tripping current, the non-fault phase current is less than the non-directional blocking tripping current, at least the fault phase non-directional blocking signal sent by any adjacent protection of a node connected with the protection is not received, and the tripping is protected after the time delay of the non-directional blocking tripping time limit; for the sectional protection, the fault phase current of a certain protection is greater than the non-directional locking tripping current, the non-fault phase current is less than the non-directional locking tripping current, at least the fault phase non-directional locking signal sent by any adjacent protection of the left side node or the right side node of the section connected with the protection is not received, and the trip is protected after the time delay of the non-directional locking tripping time limit; for the line protection on the bus, the fault phase current of a certain protection is greater than the non-directional blocking tripping current, the non-fault phase current is less than the non-directional blocking tripping current, at least the fault phase non-directional blocking signal sent by any adjacent protection of the line node or the bus node connected with the protection is not received, and the protection tripping is carried out after the time delay of the non-directional blocking tripping time limit;

according to the criterion of opposite locking type protection action: the current of a fault phase of a certain protection is greater than 'reverse blocking type tripping current', the current of a non-fault phase is less than 'reverse blocking type tripping current', any adjacent protection fault phase reverse blocking signal of a node connected with the protection and pointed by the current of the fault phase in the forward direction is not received, and tripping is protected after 'reverse blocking type tripping time limit' time delay; for the sectional protection, the fault phase current of a certain protection is greater than 'reverse blocking type tripping current', the non-fault phase current is less than 'reverse blocking type tripping current', if the fault phase current points to the left node of the section in the forward direction, the protection does not receive any adjacent protection fault phase reverse blocking signal of the left node of the section, and tripping is protected after 'reverse blocking type tripping time limit' time delay; if the fault phase current is forward to the node on the right side of the segment, the protection does not receive any adjacent protection fault phase reverse blocking signal of the node on the right side of the segment, and tripping is protected after time delay of reverse blocking type tripping time limit; for the line protection on the bus, the fault phase current of a certain protection is greater than 'reverse blocking type tripping current', the non-fault phase current is less than 'reverse blocking type tripping current', if the fault phase current points to a line node in the forward direction, the protection does not receive any adjacent protection fault phase reverse blocking signal of the line node, and tripping is protected after 'reverse blocking type tripping time limit' time delay; if the fault phase current is forward to the bus node, the protection does not receive any adjacent protection fault phase reverse blocking signal of the bus node, and the trip is protected after the time delay of reverse blocking type trip time limit;

protecting action criterion according to a phase allowance formula: the fault phase current of a certain protection is greater than the interlocking allowable tripping current, the non-fault phase current is less than the interlocking allowable tripping current, all adjacent protection fault phase allowable signals of the node connected with the protection and pointed by the fault phase current in the forward direction are received, and the tripping operation is protected after the time delay of the interlocking allowable tripping time limit; for the segment protection, the fault phase current of a certain protection is greater than the interlocking allowable tripping current, the non-fault phase current is less than the interlocking allowable tripping current, if the fault phase current points to the node on the left side of the segment in the forward direction, the protection receives all adjacent protection fault phase allowable signals of the node on the left side of the segment, and the tripping is protected after the time delay of the interlocking allowable tripping time limit; if the fault phase current is forward to the node on the right side of the segment, the protection receives all adjacent protection fault phase permission signals of the node on the right side of the segment, and the trip is protected after the time delay of 'interlock permission type trip time limit'; for the line protection on the bus, the fault phase current of a certain protection is greater than the interlocking allowable tripping current, the non-fault phase current is less than the interlocking allowable tripping current, if the fault phase current points to the line node in the forward direction, the protection receives all adjacent protection fault phase allowable signals of the line node, and the tripping is protected after the time delay of the interlocking allowable tripping time limit; if the fault phase current is forward to the bus node, the protection receives all adjacent protection fault phase permission signals of the bus node, and the tripping is protected after the time delay of 'interlock permission type tripping time limit';

according to the criterion of phase failure protection action: the fault phase current of a certain protection is greater than the interlocking failure tripping current, the non-fault phase current is less than the interlocking failure tripping current, the fault phase starting failure signal sent by any adjacent protection of the node connected with the protection is received, and the tripping is protected after the time delay of the failure tripping time limit;

the criterion of the jump action is as follows: a certain protection receives a joint tripping signal sent by optical fibers or carriers laid on two sides of the line through opposite-side protection of the line, and tripping is protected;

the phase-by-phase means both a failure phase judged by protection and a signal of a transmission and reception failure phase consistent with the judged failure phase; the signals of the fault phase are transmitted and received according to the phase and are divided into a single signal and a combined signal: transmitting and receiving A, B, C a single signal of one of three phases when a single-phase fault occurs; sending and receiving A, B, C two single signals of two of the three phases in the event of a two-phase fault; one combined signal of two phases of AB, BC and CA can be transmitted and received; when three-phase fault occurs, three single signals of three phases are sent and received A, B, C; the ABC phase combined signal may also be transmitted and received; in the method adopting single signals, a plurality of received single signals are combined before action judgment is carried out; the method of combining signals is adopted, and before the signals are sent, fault phase signals are combined to be sent as a signal;

the forward pointing and the reverse pointing of the current refer to the fact that the current is compared with a bus reference voltage in real time to judge the current flow direction, the current forward pointing is called along the current flow direction, and the current reverse pointing is called against the current flow direction;

the current is compared with the bus reference voltage in real time for judging the current direction, the line protection positive direction points to the line, the transformer protection positive direction points to the transformer, the subsection protection positive direction points to the left bus, the rest protection positive directions point to the line, and if the regulations are contradictory, the priority is sequentially decreased; the positive direction judgment adopts a 90-degree wiring power direction principle, the system impedance angle pointed by the positive direction is set to be phi, the positive direction action range and the negative direction action range are set to be 180 degrees, and the following steps are sequentially judged: when Ia, Ib and Ic exceed the fixed value and Uc is more than 0.1 times of rated voltage, the angle of Uc ahead of Iab is positive between phi and (phi +180 DEG); when Ia, Ib and Ic exceed the fixed value and Uc is not more than 0.1 time of rated voltage, the angle of the memory voltage before Uc short circuit ahead Iab is positive between phi and (phi +180 DEG); when only Ia and Ib exceed the fixed values, the angle of Uc ahead of Iab is a positive direction between phi and (phi +180 DEG); when only Ib and Ic exceed the fixed values, the angle of Ua leading Ibc is a positive direction between phi and (phi +180 degrees); when only Ic and Ia exceed the fixed value, the angle of Ub ahead Ica is positive between phi and (phi +180 DEG); when only Ia exceeds a fixed value, the angle of Ubc leading Ia is a positive direction between phi-180 DEG and phi; when only Ib exceeds a fixed value, the angle of Uca leading Ib is a positive direction between phi and 180 degrees; when only Ic exceeds a fixed value, the angle of Uab leading Ic is positive between phi-180 DEG and phi; when PT disconnection occurs, namely voltage is lost, sending a phase-based reverse locking signal, sending a phase-based permission signal, carrying out phase-based reverse locking protection and carrying out phase-based permission protection exit; when the direction is determined to be the positive direction, the forward pointing direction of the current is the specified positive direction, and the reverse pointing direction of the current is the direction opposite to the specified positive direction; when the forward direction element does not act, the element acts in the reverse direction, and the forward pointing direction of the current is the direction opposite to the specified forward direction; the reverse pointing direction of the current is the direction of the prescribed positive direction; for safety, if the range of motion in the forward and reverse directions is reduced from 180 degrees to less than 180 degrees, the range of motion in the forward direction of the non-single-phase fault is changed between phi and phi +180 degrees to (phi + a) and (phi +180 ° -b), the range of motion in the forward direction of the single-phase fault is changed between phi-180 degrees and phi to (phi-180 ° + c) and (phi-d), in this case, when the forward direction element does not move, the reverse direction element does not act, and the motion determination of the reverse direction element is required, the range of motion in the reverse direction of the non-single-phase fault is changed between phi-180 degrees and phi-180 ° + e) and (phi-f), and the range of motion in the reverse direction of the single-phase fault is changed between phi and phi +180 ° +180 degrees to (phi + g) and (phi +180 ° -h), where a, b, c, d, e, f, g, h are positive numbers and are angles at which the range of motion is narrowed; when the direction is determined to be the positive direction, the forward pointing direction of the current is the specified positive direction, and the reverse pointing direction of the current is the direction opposite to the specified positive direction; when the forward direction element does not act, but the reverse direction element acts, the forward pointing direction of the current is the direction opposite to the prescribed forward direction; the reverse pointing direction of the current is the direction of the prescribed positive direction; when the elements in the positive direction and the negative direction do not act, the protection criterion related to the direction does not act;

all adjacent protections connected with the nodes connected with the protection, to which the current points in the positive direction, are configured in advance in the protection, and all adjacent protections connected with the nodes connected with the protection, to which the current points in the reverse direction, are configured in advance in the protection;

at the end of the powerless circuit, the feeder line protection device does not access a locking signal, and the current quick-break protection with the input time limit of zero second is carried out;

if the protection quits operation, the protection is set to a 'maintenance position', the adjacent protection of the protection is stored after receiving the information, the protection quitting operation does not participate in the judgment of the locking signal and the allowing signal of the adjacent protection any more, or the adjacent protection sets the locking signal of the protection quitting operation to '0', namely, the locking is not carried out any more; the enable signal is set to "1", i.e. always enabled;

the interlocking signals are transmitted between adjacent protections in modes of transmitting contact signals through a GOOSE network, a local area network, hard wiring and the like, and the interlocking signals are transmitted through optical fibers and carrier waves for the protections on the two sides of the power transmission line;

the protection of the station and the protection of the opposite ends of the incoming and outgoing lines entering and exiting the station are mutually interlocked without the protection information of other stations;

the method of transmitting the interlocking signals by adopting the GOOSE network can perform network grouping according to a station or perform network grouping according to nodes in a GOOSE switch in a more detailed manner;

the foregoing discussion of the segments applies equally to the bus tie;

the aforementioned "interlock lock signaling current", "forward allowed signaling current", "directionless lock trip current", "reverse lock trip current", "interlock allowed trip current", "interlock threshold current", "interlock failure trip current" are current-fixed values, and the aforementioned "directionless lock trip time limit", "reverse lock trip time limit", "interlock allowed trip time limit", "start failure time limit", "failure trip time limit" are time-fixed values.

Further, the interval between sending and receiving two GOOSE signals is less than 10 ms.

Further, the sending of the current less than the "interlock threshold current" is based on the criterion of the phase enable signal: the circuit breaker is in a closed position, a certain phase voltage is smaller than a rated voltage, and the certain phase voltage is smaller than the rated voltage and is set to be smaller than 70% of the rated voltage.

Further, the "no direction latch trip time limit" is 250 msec, the "reverse latch trip time limit" is 380 msec, and the "interlock allowed trip time limit" is 20 msec.

Further, "directionless latch trip current", "reverse latch trip current", "interlock allowed trip current", "interlock failure trip current" are set to be greater than the maximum load current, or slightly lower than the maximum load current, respectively, and when set slightly lower than the maximum load current, "directionless latch trip time limit", "reverse latch trip time limit", "interlock allowed trip time limit", "failure trip time limit", are set to be greater than the duration of time that the load current exceeds the corresponding current limit value, respectively.

Further, the "interlock threshold current" is used to monitor the presence or absence of current on the line, and is set to 0.1 times the rated current.

Further, the "interlock locking type transmitting current" and the "forward direction allowing type transmitting current" are set to be larger than the rated current.

Further, the 'starting failure time limit' is used for avoiding the tripping time of the circuit breaker and is set to be larger than the tripping time of the circuit breaker.

Furthermore, the current criterion is changed into an impedance criterion, namely, the current constant values of 'interlock locking type signaling current', 'forward allowable signaling current', 'directionless locking type tripping current', 'reverse locking type tripping current', 'interlock allowable tripping current' and 'interlock failure tripping current' are changed into the directionless impedance values of 'interlock locking type signaling directionless impedance', 'forward allowable signaling directionless impedance', 'directionless locking type tripping directionless impedance', 'reverse locking type tripping directionless impedance', 'interlock allowable tripping directionless impedance', 'interlock failure tripping directionless impedance', and the current criterion is changed into the impedance criterion, because the current and the impedance are in inverse relation, the current in the criterion is replaced by the non-directional impedance, and the criterion is still applicable if the larger number is changed into the smaller number.

Further, the current direction judgment for determining the forward direction and the reverse direction of the current is changed into direction judgment by adopting directional impedance for determining the forward direction and the reverse direction of the current.

The node interlocking protection comprises allowable protection and locked protection, the allowable protection and the reverse locked protection are put into operation at ordinary times, the allowable protection and the reverse locked protection are suitable for various power supply modes, and when multi-path current flows into the same node, the adjacent protection of the node mistakenly sends a locking signal to cause that an action criterion is not necessarily met, action is possibly refused, but misoperation cannot be caused.

Since the adjacent protection blocking signal is not received, which may be an adjacent protection program problem, a hardware problem, a switch problem, a wire or network cable problem, the adjacent protection program cannot be tripped in a short time because the blocking signal is not received, so as to avoid the override trip and the misoperation, and the blocking trip time limit is usually set to be longer.

The allowed protection has no problem that the locked protection needs to wait for a locking signal, so when the allowed signals actively sent by all adjacent protections of the nodes connected with the allowed protections, to which the fault current points forward, are received, the rapid tripping can be realized. The allowed protection action is fast and the latched protection action is slow, so that the trip time limit "interlocked allowed trip current" can be set higher than the "directionless latched trip current" and the "reverse latched trip current" according to the stepped protection principle.

The directionless latching protection and the reverse latching protection have the action criteria that the corresponding current constant values are the directionless latching tripping current and the reverse latching tripping current respectively, if the setting is the same, the directionless latching protection receives any adjacent protection fault phase latching signal of a node pointed by the fault phase current in the forward direction, the latching signal comprises the reverse latching signal and the forward latching signal, and from this point, the directionless latching protection is easier to latch and more difficult to trip than the reverse latching protection, so that according to the stepped protection principle, the directionless latching tripping time limit can be set to be smaller than the reverse latching tripping time limit, the directionless latching tripping time limit is 250 milliseconds, and the reverse latching tripping time limit is 380 milliseconds. However, the non-directional locking protection has more functions than the reverse locking protection in receiving any adjacent protection fault phase locking signal of a node to which the fault phase current is directed reversely, and can act if the locking signal is not received, so that the non-directional locking protection is easy to act than the reverse locking protection in this respect, and certainly, the action state is abnormal, but the non-directional locking protection does not need to judge the current flow direction, namely, the voltage does not need to participate, so that the protection criterion is simple and direct, the PT disconnection is avoided, and the application can still be realized.

The interval between two GOOSE signals is less than 10 ms, so as to ensure that the sending and receiving are discrete signals, but the signals can be regarded as continuous signals when the resolution is not less than 10 ms, if the time interval between the two GOOSE signals is too long, the signals change during the time, and the signals are not sent and received in time, which can cause the error of protection judgment, action delay and even false tripping, therefore, if the interval between the two GOOSE signals exceeds the set 10 ms, the protection action timing is cleared.

"directionless latch trip current", "reverse latch trip current", "interlock allowed trip current", "interlock failure trip current", are typically set to be greater than the maximum load current, or slightly less than the maximum load current, respectively, but "directionless latch trip time limit", "reverse latch trip time limit", "interlock allowed trip time limit", "failure trip time limit", are typically set to be greater than the duration of time that the load current exceeds the corresponding current setting, respectively, in order to prevent the load current from causing a protective false trip.

The interlocking logic of the line protection is also participated in the protection corresponding to the circuit breaker in the branch position at ordinary times, so that the interlocking logic after the corresponding circuit breaker is protected to be switched on is ensured to be correct.

The criterion of the jump action is as follows: and a certain protection receives a joint tripping signal sent by optical fibers or carriers laid on two sides of the line for opposite-side protection of the line, and protects tripping, so that the purpose of completely cutting off a fault line is realized.

Has the advantages that:

the invention uses the node theory to unify the relationship among various protections, is suitable for various node types, and defines the adjacent protection of each node so as to establish a unified node interlocking protection method. The positive direction directions of various protections are regulated, and the current forward direction and the current reverse direction are determined through positive and negative direction judgment, on the basis, allowable protection and reverse blocking protection are provided, the problem of failure of non-directional blocking protection in a multi-power system is solved, the power supply device is suitable for various power supply modes, including multiple power supplies, double power supplies and a single power supply, power supply points and power supply directions are allowed to dynamically change, and the multiple power supplies include multiple power supplies which run for a long time and multiple power supplies which are temporarily generated in the switching process. The invention provides a systematic overall solution, which is suitable for various protection devices and various application occasions, including the field of rail transit power supply and energy feedback application thereof, the field of power distribution, the field of power utilization and the field of distributed power generation. The invention can realize the interlocking protection of the whole power grid only by interlocking the protection of the station and the protection of the opposite ends of the incoming and outgoing lines entering and exiting the station without the participation of the protection of other stations in interlocking, thereby reducing the difficulty of implementing and maintaining the method. If the optical fiber longitudinal differential protection between the lines is not operated or set, complete protection can still be provided for faults under various power supply modes. When the GOOSE network is adopted to transmit the interlocking signal mode, network grouping can be carried out according to one station in a GOOSE switch, and the situation that network abnormal messages possibly cause by a network mode of a whole line and the whole line are affected is avoided. The non-directional impedance is adopted to replace the current in the criterion, the directional impedance is adopted to carry out direction judgment, the forward direction and the reverse direction of the current are determined, and an alternative impedance method is provided.

Drawings

Fig. 1 is a logic diagram of criteria for transmitting a phase a non-directional blocking signal.

Fig. 2 is a logic diagram of criteria for transmitting an a-phase reverse blocking signal.

Fig. 3 is a logic diagram of a criterion for transmitting an a-phase enable signal with a current less than the "interlock threshold current".

Fig. 4 is a logic diagram of the criterion of transmitting a-phase enable signal when the current is larger than the forward enable signaling current.

Fig. 5 is a logic diagram of criteria for transmitting phase a start-up failure signals.

FIG. 6 is a logic diagram of the criterion of the A-phase directionless latch type protection action.

FIG. 7 is a logic diagram of the criterion of the A-phase reverse locking protection action.

FIG. 8 is a logic diagram of the A-phase allowable protection action criterion.

FIG. 9 is a logic diagram of the A-phase malfunction protection action criterion.

The above figures take the phase A fault as an example, and are also applicable to the phase B, C, AB, BC, CA and ABC faults.

Fig. 10 is a diagram of an ac medium-voltage power supply system for urban rail transit. In the figure, A, B, C, D is four stations, and station E is a load for supplying power to station B. For simplicity, the corresponding protection of the circuit breaker is also named by the name of this circuit breaker.

The access protection DL1(B1), the access protection DL2(B1), the feeder DL4(B1) and the segment protection DL3(B) are all adjacent protections of the B station 1 mother node;

the ingress and egress protection DL1(B2), the ingress and egress protection DL2(B2) and the segment protection DL3(B) are all adjacent protections of the B station 2 mother node;

the incoming and outgoing line protection DL2(B1) and the incoming and outgoing line protection DL1(C1) are lines L_BC1All neighbor protection of a node;

here, the segment protection DL3(B) is not only an adjacent protection of the B station 1 mother node but also an adjacent protection of the B station 2 mother node no matter the corresponding breaker DL3(B) is in a closing state or an opening state;

here, the incoming and outgoing line protection DL2(B1) is not only the adjacent protection of the B station 1 mother node, but also the line L_BC1Adjacent protection of nodes;

here, the ingress and egress protection DL1(C1) is not only the adjacent protection of the parent node of the C station 1, but also the line L_BC1Neighbor protection of the node.

Detailed Description

The following specifically analyzes and explains various protection actions of various fault points under various power supply modes by combining the ac medium-voltage power supply system of the urban rail transit shown in fig. 10.

It is assumed here that the fiber longitudinal differential protection at the two ends of the line between the two stations is not working or provided.

1. Line L_BC1The point k1 has a fault (line fault)

1) When only a single power supply 1 is present

The DL1(C1) fault phase low-voltage no-current system does not send a blocking signal and sends an allowance signal to all adjacent protection DL2(B1) and DL2 (C1).

DL2(B1) fault phase current is greater than 'no direction locking type tripping current', and is not received by the connected line L_BC1The only adjacent protection DL1 of the node (C1) sends no direction blocking signal, trips correctly, and jumps the DL1 of the C station (C1) through the optical fiber between the B station and the C station.

DL2(B1) fault phase current is larger than 'reverse blocking tripping current', and the line to which the current is directed in the forward direction is not received L_BC1The only adjacent protection DL1 of the node (C1) sends a reverse blocking signal, and correctly trips and leaps the DL1 of the C station through the optical fiber between the B station and the C station (C1).

DL2(B1) fault phase current is greater than "interlock-allowed trip current", line L is received with its current directed in the forward direction_BC1The only adjacent protection DL1(C1) of the node sends an allow signal, which is tripped correctly, and the DL1(C1) of the C station is jumped through the optical fiber between the B station and the C station.

All other protections DL1(A1), DL2(A1) and DL1(B1) with the fault phase current larger than the 'directionless latching tripping current' receive the directionless latching signal sent by at least one adjacent protection of the connected nodes of the protections, and the protections do not trip by mistake.

All other protections DL1(A1), DL2(A1) and DL1(B1) with the fault phase current larger than the reverse blocking tripping current receive the reverse blocking signal sent by at least one adjacent protection of the node to which the current of the other protections points forward, and the protections do not trip by mistake.

All other protections DL1(A1), DL2(A1) and DL1(B1) with the fault phase current larger than the 'interlocking allowable tripping current' have at least one adjacent protection which points to the nodes in the current forward direction and do not send out an allowable signal, so that the protections do not trip by mistake.

Besides, the protection has the current less than the 'directionless latching type tripping current', 'reverse latching type tripping current', 'interlocking allowable type tripping current', and the protection cannot trip by mistake.

A list of action behaviors. Writing an entry in A/B mode, if both A and B are the same, then only A is written.

2) In the case of power supply 1 and power supply 2

a) Analyzing the situation of directionless locking type protection action

The DL1(C1) fault phase current is larger than the 'interlocking lock signaling current', and sends a non-direction locking signal to all adjacent protections DL2(B1) and DL2 (C1).

The DL1(B1) fault phase current is larger than the 'interlock locking type signaling current', and sends a non-direction locking signal to all adjacent protections DL2(A1), DL2(B1), DL4(B1) and DL3 (B).

DL2(B1) fault phase current is greater than 'no direction locking type tripping current', and is received by the line L connected with the same_BC1The non-directional blocking signal sent by the adjacent protection DL1(C1) of the node receives the non-directional blocking signal sent by the adjacent protection DL1(B1) of the parent node of the B station 1, and the protection refuses to operate.

The action behavior of DL1(C1) is the same as that of DL2(B1), and the action rejection is protected.

All other protections DL1(A1), DL2(A1), DL2(C1), DL1(D1) and DL2(D1) with the fault phase current larger than the 'non-directional blocking tripping current' receive the non-directional blocking signal sent by at least one adjacent protection of the nodes connected with the protections, and the protections cannot be tripped by mistake.

Besides, the protection is that the current is less than the 'directionless latching type tripping current', and the error tripping is avoided.

b) Analyzing reverse blocking type protection action situation

DL1(C1) fault phase current is larger than 'interlocking lock type signaling current', then the phase reversal locking signal is sent to the adjacent protection DL2(C1) of which the current is reversely directed to the C station 1 mother node, and the phase reversal locking signal is not sent to the line L of which the current is forwardly directed_BC1Neighbor protection DL2(B1) of the node;

DL2(B1) fault phase current is larger than 'reverse blocking tripping current', and line L which does not receive current and points to in the forward direction_BC1The node unique adjacent protection DL1(C1) sends reverse blocking signals, and the node is correctly tripped and carries out fiber optic link hopping between the B station and the C station to the DL1(C1) of the C station.

The action behavior of DL1(C1) is the same as that of DL2(B1), and the correct tripping is protected.

All other protections DL1(A1), DL2(A1), DL1(B1), DL2(C1), DL1(D1) and DL2(D1) with the fault phase current larger than the reverse blocking tripping current receive the reverse blocking signal sent by at least one adjacent protection of the node to which the current of the other protections points forward, and the protections cannot trip by mistake.

Besides, the current of the protection is smaller than the reverse blocking type tripping current, and the protection cannot be tripped by mistake.

c) Analyzing allowed protection action conditions

DL1(C1) fault phase current is greater than forward direction allowable signaling current, then the allowable signal of this phase is sent to the forward direction pointing line L_BC1The node's neighbor protection DL2 (B1).

DL2(B1) fault phase current is greater than "interlock-allowed trip current", line L is received with its current directed in the forward direction_BC1The node unique adjacent protection DL1(C1) sends an allow signal, is tripped correctly, and is linked to jump the DL1(C1) of the C station through the optical fiber between the B station and the C station.

The fault phase current is larger than the 'interlocking allowable tripping current' and is larger than all other protections DL1(A1), DL2(A1), DL1(B1), DL2(C1), DL1(D1) and DL2(D1), and at least one adjacent protection of the nodes to which the current is forward points does not send out an allowable signal, so that the protections cannot be tripped mistakenly.

Besides, the current of the protection is smaller than the 'interlocking allowable tripping current', and the protection cannot be tripped by mistake.

3) When there are power supply 1, power supply 2, and power supply 3

a) Analyzing the situation of directionless locking type protection action

The DL2(B1) fault phase current is larger than the 'interlock locking type signaling current', and sends a non-direction locking signal to all adjacent protections DL1(C1), DL1(B1), DL4(B1) and DL3 (B).

The DL4(B1) fault phase current is larger than the 'interlock locking signaling current', and sends a non-direction locking signal to all adjacent protections DL2(B1), DL1(B1) and DL3 (B).

DL2(B1) fault phase current is greater than 'no direction locking type tripping current', and is received by the line L connected with the same_BC1The non-directional blocking signal sent by the adjacent protection DL1(C1) of the node receives the non-directional blocking signal sent by the adjacent protection DL1(B1) and DL4(B1) of the parent node of the B station 1, and the protection refuses to operate.

Actions of DL1(C1) and DL4(B1) are similar to actions of DL2(B1), and are protected against actions.

All other protections DL1(A1), DL2(A1), DL1(B1) and DL4(B1) with the fault phase current larger than the 'directionless latching type tripping current' receive the directionless latching signal sent by at least one adjacent protection of the connected nodes of the protections, and the protections do not trip by mistake.

Besides, the current of the protection is smaller than the 'directionless latching type tripping current', and the protection cannot be tripped by mistake.

b) Analyzing reverse blocking type protection action situation

If the DL2(B1) fault phase current is larger than the 'interlocking lock type signaling current', the phase reversal locking signal is sent to the adjacent protection DL1(B1), DL4(B1) and DL3(B) of which the current is reversely directed to the B station 1 mother node, and the phase reversal locking signal is not sent to the line L of which the current is forwardly directed_BC1The node's neighbor protection DL1 (C1).

DL1(C1) fault phase current is larger than 'reverse blocking tripping current', and line L which does not receive current and points to in the forward direction_BC1The node unique adjacent protection DL2(B1) sends reverse blocking signals, and the node is correctly tripped and carries out the optical fiber link hopping between the B station and the C station to the DL2(B1) of the B station.

The action behavior of DL2(B1) is the same as that of DL1(C1), and the correct tripping is protected.

The DL4(B1) fault phase current is larger than 'reverse blocking type tripping current', and a reverse blocking signal sent by the adjacent protection DL2(B1) of the B station 1 mother node to which the current is directed forward is received, so that the protection cannot be tripped by mistake.

c) Analyzing allowed protection action conditions

DL2(B1) fault phase current is greater than forward direction allowable signaling current, then the allowable signal of the phase is sent to the forward direction pointing line L_BC1The adjacent protection DL1(C1) of the node does not send the enable signal of the phase, and the current is reversely directed to the adjacent protection DL1(B1), DL4(B1) and DL3(B) of the parent node of the B station 1.

DL1(C1) fault phase current is greater than "interlock-allowed trip current", line L is received with its current directed in the forward direction_BC1The node unique adjacent protection DL2(B1) sends an allow signal, is tripped correctly, and is linked to hop DL2(B1) of the B station through the optical fiber between the B station and the C station.

The DL4(B1) fault phase current is larger than the 'interlocking permission type tripping current', and the protection does not receive the permission signal sent by the adjacent protection DL2(B1) of the B station 1 mother node to which the current is directed forward, so that the protection cannot be tripped by mistake.

Failure at point k2 in bus of station B1 (bus failure)

1) When only a single power supply 1 is present

DL2(B1), DL4(B1) and DL3(B) fail phase low voltage no-flow, do not send blocking signal, send permission signal to all its adjacent protection.

The DL1(B1) fault phase current is larger than the 'directionless latching type tripping current', and the fault phase current does not receive directionless latching signals sent by any adjacent protection DL2(B1), DL4(B1) and DL3(B) of the B station 1 mother node connected with the fault phase current, is tripped correctly, and passes through the DL2(A1) of the optical fiber multi-hop A station between the A station and the B station.

The DL1(B1) fault phase current is larger than 'reverse blocking type tripping current', and a reverse blocking signal sent by any adjacent protection DL2(B1), DL4(B1) and DL3(B) of a B station 1 mother node to which the current is directed forward is not received, so that the station is tripped correctly and passes through a DL2(A1) of an optical fiber joint tripping A station between the A station and the B station.

The DL1(B1) fault phase current is larger than the 'interlocking-allowed tripping current', and the fault phase current is correctly tripped by receiving an allowance signal sent by all adjacent protection DL2(B1), DL4(B1) and DL3(B) of a B station 1 mother node to which the current is forwardly directed, and is subjected to fiber optic link tripping between the B station and the C station to carry out DL1(C1) of the C station.

All other protections DL1(A1) and DL2(A1) with the fault phase current larger than the 'directionless latching type tripping current' receive the directionless latching signal sent by at least one adjacent protection of the connected nodes of the protections, and the protections do not trip by mistake.

All other protections DL1(A1) and DL2(A1) with the fault phase current larger than the reverse blocking tripping current receive the reverse blocking signal sent by at least one adjacent protection of the node to which the current of the other protections is directed forward, and the protections are not tripped by mistake.

All other protections DL1(A1) and DL2(A1) with the fault phase current larger than the 'interlocking allowable tripping current' have at least one adjacent protection node to which the current is directed forward, and do not send out an allowable signal, so that the protections do not trip by mistake.

2) In the case of power supply 1 and power supply 2

a) Analyzing the situation of directionless locking type protection action

The DL2(A1) fault phase current is larger than the 'interlocking lock signaling current', and sends a non-direction locking signal to all adjacent protections DL1(B1) and DL1 (A1).

DL1(B1) fault phase current is larger than 'non-directional blocking type tripping current', receives a non-directional blocking signal transmitted by the adjacent protection DL2(B1) of the B station 1 mother node connected with the same and receives a line L_AB1The adjacent protection DL2(A1) of the node sends a non-directional blocking signal to protect the refusal of action.

The action behavior of DL2(B1) is the same as that of DL2(B1), and the action rejection is protected.

All other protections DL1(A1), DL2(A1), DL1(C1), DL2(C1), DL1(D1) and DL2(D1) with the fault phase current larger than the 'non-directional blocking tripping current' receive the non-directional blocking signal sent by at least one adjacent protection of the nodes connected with the protections, and the protections cannot be tripped mistakenly.

b) Analyzing reverse blocking type protection action situation

DL1(B1) fault phase current is greater than 'interlock lock signaling current', then the phase reverse lock signal is sent to give its current reverse direction to line L_AB1The node's neighbor protection DL2(a1) does not send this phase reverse blocking signal to all the neighbor protections DL2(B1), DL4(B1), DL3(B) of the B station 1 parent node to which its current is forward directed.

The DL2(B1) fault phase current is larger than 'reverse blocking type tripping current', and a reverse blocking signal sent by adjacent protection DL1(B1), DL4(B1) and DL3(B) of a B station 1 mother node to which the current is directed forward is not received, so that the station is tripped correctly and passes through DL1(C1) of an optical fiber joint tripping C station between the B station and the C station.

The action behavior of DL1(B1) is the same as that of DL2(B1), and the correct tripping is protected.

All other protections DL1(A1), DL2(A1), DL1(C1), DL2(C1), DL1(D1) and DL2(D1) with the fault phase current larger than the reverse blocking tripping current receive the reverse blocking signal sent by at least one adjacent protection of the node to which the current of the other protections points forward, and the protections cannot trip by mistake.

c) Analyzing allowed protection action conditions

DL4(B1) and DL3(B) fault phase low-voltage no-flow send permission signals to adjacent protection DL1(B1) and DL2 (B1).

If the DL1(B1) fault phase current is larger than the forward direction allowable signaling current, an allowable signal of the phase is sent, and the current of the phase is forward directed to all adjacent protection DL2(B1), DL4(B1) and DL3(B) of the B station 1 mother node.

The DL2(B1) fault phase current is larger than the 'interlocking-allowed tripping current', and the fault phase current is correctly tripped by receiving an allowance signal sent by all adjacent protection DL1(B1), DL4(B1) and DL3(B) of a B station 1 mother node to which the current is forwardly directed, and is subjected to fiber optic link tripping between the B station and the C station to carry out DL1(C1) of the C station.

The fault phase current is larger than the 'interlocking allowable tripping current' and is larger than all other protections DL1(A1), DL2(A1), DL1(C1), DL2(C1), DL1(D1) and DL2(D1), and at least one adjacent protection of the nodes to which the current is forward points does not send out an allowable signal, so that the protections cannot be tripped mistakenly.

3) When there are power supply 1, power supply 2, and power supply 3

a) Analyzing the situation of directionless locking type protection action

Actions of DL1(B1) and DL4(B1) are similar to actions of DL2(B1), and are protected against actions.

All other protections DL1(A1), DL2(A1), DL1(C1), DL2(C1), DL1(D1) and DL2(D1) with the fault phase current larger than the 'non-directional blocking tripping current' receive the non-directional blocking signal sent by at least one adjacent protection of the nodes connected with the protections, and the protections cannot be tripped by mistake.

b) Analyzing reverse blocking type protection action situation

DL1(B1) fault phase current is greater than 'interlock lock signaling current', then the phase reverse lock signal is sent to give its current reverse direction to line L_AB1The adjacent protection DL2(a1) of the node does not send the phase reverse blocking signal to the adjacent protection DL2(a1), DL4(B1) and DL3(B) of the B station 1 mother node to which the current is forward directed.

DL2(B1) fault phase current is greater than 'interlock lock signaling current', then the phase reverse lock signal is sent to give its current reverse direction to line L_BC1The adjacent protection DL1(C1) of the node does not send the phase reverse blocking signal to the adjacent protection DL1(a1), DL4(B1) and DL3(B) of the B station 1 mother node to which the current is directed forward.

If the DL4(B1) fault phase current is larger than the 'interlocking lock type signaling current', the phase reverse locking signal is sent to the adjacent protection with the current in the reverse direction, and the phase reverse locking signal is not sent to the adjacent protection DL1(A1), DL2(B1) and DL3(B) with the current in the forward direction directed to the B station 1 mother node.

The DL2(B1) fault phase current is larger than 'reverse blocking type tripping current', and a reverse blocking signal sent by adjacent protection DL1(A1), DL4(B1) and DL3(B) of a B station 1 mother node to which the current is directed forward is not received, so that the station is tripped correctly and passes through DL1(C1) of an optical fiber joint tripping C station between the B station and the C station.

The action behaviors of DL1(B1) and DL4(B1) are the same as DL2(B1), and the correct tripping is protected.

c) Analyzing allowed protection action conditions

DL3(B) fault phase low voltage no-flow, sending permission signal to its adjacent protection DL1(B1), DL2(B1), DL4 (B1).

If the DL1(B1) fault phase current is larger than the forward direction allowable signaling current, an allowable signal of the phase is sent, and the current of the phase is forward directed to adjacent protection DL2(A1), DL4(B1) and DL3(B) of the B station 1 mother node.

If the DL2(B1) fault phase current is larger than the forward direction allowable signaling current, an allowable signal of the phase is sent, and the current of the phase is forward directed to adjacent protection DL1(A1), DL4(B1) and DL3(B) of the B station 1 mother node.

If the DL4(B1) fault phase current is larger than the forward direction allowable signaling current, an allowable signal of the phase is sent, and the current of the phase is forward directed to adjacent protection DL2(A1), DL1(B1) and DL3(B) of the B station 1 mother node.

The DL2(B1) fault phase current is larger than the 'interlocking-allowed tripping current', and the fault phase current is correctly tripped by receiving an allowance signal sent by all adjacent protection DL1(B1), DL4(B1) and DL3(B) of a B station 1 mother node to which the current is directed forward, and passes through DL1(C1) of an optical fiber multi-hop C station between the B station and the C station.

Failure occurs at point k3 in the bus of station E1 (failure of bus fed out)

1) When only a single power supply 1 is present

The DL1(E1) fault phase has no low voltage and no current, does not send a blocking signal, and sends an allowance signal to the adjacent protection DL2 (E1).

The DL2(E1) fault phase current is larger than the 'directionless latching type tripping current', and the directionless latching signal sent by the only adjacent protection DL1(E1) of the E station 1 mother node connected with the fault phase current is not received, so that the fault phase current is correctly tripped.

The DL2(E1) fault phase current is larger than 'reverse blocking type tripping current', and a reverse blocking signal sent by the only adjacent protection DL1(E1) of the E station 1 mother node to which the current is directed in the forward direction is not received, so that the protection is tripped correctly.

The DL1(E1) fault phase current is larger than the 'interlocking permission type tripping current', and the fault is correctly tripped by receiving a permission signal sent by the E station 1 mother node to which the current is directed forward and only the adjacent protection DL1 (E1).

All other protections DL1(A1), DL2(A1), DL1(B1) and DL4(B1) with the fault phase current larger than the reverse blocking tripping current receive the reverse blocking signal sent by at least one adjacent protection of the node pointed to by the current forward direction, and the protections do not trip by mistake.

All other protections DL1(A1), DL2(A1), DL1(B1) and DL4(B1) with the fault phase current larger than the 'interlocking allowable tripping current' have at least one adjacent protection which points to the nodes in the current forward direction and do not send out an allowable signal, and the protections do not trip by mistake.

2) In the case of power supply 1 and power supply 2

The DL1(B1) fault phase current is larger than the 'interlocking permission type tripping current', and the fault is correctly tripped by receiving a permission signal sent by the E station 1 mother node to which the current is directed forward and only the adjacent protection DL1 (E1).

All other protections with the fault phase current larger than the 'non-directional blocking tripping current' are DL1(A1), DL2(A1), DL1(B1), DL2(B1), DL1(C1), DL2(C1), DL1(D1), DL2(D1) and DL4(B1), and the protection cannot be tripped by mistake by receiving a non-directional blocking signal sent by at least one adjacent protection of the nodes connected with the protections.

All other protections with the fault phase current larger than the reverse blocking tripping current are DL1(A1), DL2(A1), DL1(B1), DL2(B1), DL1(C1), DL2(C1), DL1(D1), DL2(D1) and DL4(B1), and the protection cannot be tripped by mistake by receiving a reverse blocking signal sent by at least one adjacent protection of a node to which the current of the other protections points forward.

All other protections with the fault phase current larger than the 'interlocking allowable tripping current' are DL1(A1), DL2(A1), DL1(B1), DL2(B1), DL1(C1), DL2(C1), DL1(D1), DL2(D1) and DL4(B1), and at least one adjacent protection of the nodes pointed by the current forward direction does not send out an allowable signal, so that the protections cannot be tripped mistakenly.

3) When there are power supply 1, power supply 2, and power supply 3

The DL1(E1) and DL4(B1) fault phase currents are larger than the 'interlocking lock signaling current', and a non-directional lock signal is sent to the adjacent protection DL2 (E1).

DL2(E1) fault phase current is larger than 'non-directional blocking type tripping current', receives a non-directional blocking signal sent by the adjacent protection DL1(E1) of the E station 1 mother node connected with the non-directional blocking type tripping current, and receives a line L connected with the non-directional blocking signal_BE1And the node adjacent protection DL4(B1) sends a non-directional blocking signal to protect the refusal of action.

DL1(E1) fault phase current is greater than "interlock lock signaling current", then this phase reverse lock signal is sent to its current reverse direction to the power supply 3 and not to its current forward direction to the adjacent protection DL2(E1) of the E station 1 parent node to which it is directed.

The DL2(E1) fault phase current is larger than 'reverse blocking type tripping current', and a reverse blocking signal sent by the adjacent protection DL1(E1) of the E station 1 mother node, the current of which is directed forward, is not received, so that the protection is tripped correctly.

DL1(E1) fault phase current is greater than "forward allowed signaling current", then the allow signal for this phase is sent to its current forward directed to the adjacent protection DL2(E1) of the E station 1 mother node.

The DL2(E1) fault phase current is larger than the 'interlocking permission type tripping current', and the fault is correctly tripped by receiving a permission signal sent by the only adjacent protection DL1(E1) of the E station 1 mother node to which the current is directed forward.

4, a point k4 in the bus of the B station 2 fails (bus failure in a sectional closing state)

Whether only a single power supply 1, a power supply 1 and a power supply 2, or a power supply 1, a power supply 2 and a power supply 3,

DL1(B2) and DL2(B2) fault phases are low-voltage and no current, do not send blocking signals and send permission signals to all adjacent protection.

The DL3(B) fault phase current is larger than the 'directionless locking tripping current', and the fault phase current does not receive directionless locking signals sent by any adjacent protection DL1(B2) and DL2(B2) of the B station 2 mother node connected with the fault phase current, so that the fault phase current is correctly tripped.

The DL3(B) fault phase current is larger than 'reverse blocking type tripping current', and the reverse blocking signals sent by any adjacent protection DL1(B2) and DL2(B2) of the B station 2 mother node to which the current is directed in the forward direction are not received, so that the system trips correctly.

The DL3(B) fault phase current is larger than the 'interlocking allowable tripping current', and the fault is correctly tripped by receiving the allowable signals sent by all adjacent protection DL1(B2) and DL2(B2) of the B station 2 mother node to which the current is forward directed.

All other protections with fault phase current larger than the 'directionless blocking tripping current' receive the directionless blocking signal sent by at least one adjacent protection of the connected nodes of the protections, and the protections do not trip by mistake.

All other protections with fault phase current larger than 'reverse blocking tripping current' receive reverse blocking signals sent by at least one adjacent protection of the node pointed to by the current forward, and the protections can not be tripped by mistake.

The fault phase current is larger than all other protections of 'interlocking allowable tripping current', the nodes of which the current is directed forward have at least one adjacent protection which does not send out an allowable signal, and the protection does not trip by mistake.

The foregoing has described the general principles, essential features, and advantages of this patent. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to explain the principles of the invention, and that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The scope of protection sought by the present patent is defined by the claims appended hereto and their equivalents.

Claims

1. A node interlocking protection method applicable to multiple power supply modes is characterized by comprising the following steps:

the phase-by-phase means both a failure phase judged by protection and a signal of a transmission and reception failure phase consistent with the judged failure phase; the signals of the fault phase are transmitted and received according to the phase and are divided into a single signal and a combined signal: transmitting and receiving A, B, C a single signal of one of three phases when a single-phase fault occurs; sending and receiving A, B, C two single signals of two of the three phases in the event of a two-phase fault; or transmitting and receiving one combined signal of two phases of AB, BC and CA; when three-phase fault occurs, three single signals of three phases are sent and received A, B, C; or transmitting and receiving a combined signal of ABC phases; in the method adopting single signals, a plurality of received single signals are combined before action judgment is carried out; the method of combining signals is adopted, and before the signals are sent, fault phase signals are combined to be sent as a signal;

the interlocking signals are transmitted between adjacent protections in a mode of transmitting contact signals through a GOOSE network, a local area network and hard wiring, and the interlocking signals are transmitted through optical fibers and carrier waves for the protections on the two sides of the power transmission line;

adopting a GOOSE network to transmit an interlocking signal mode, and carrying out network grouping according to a station or carrying out network grouping according to nodes in a GOOSE switch;

the foregoing discussion of the segments applies equally to the bus tie;

2. The node interlock protection method of claim 1 wherein the interval between sending and receiving two GOOSE signals is less than 10 milliseconds.

3. A node interlock protection method as claimed in claim 1, wherein the sending of the current less than the interlock threshold current is based on the criterion of the phase enable signal: the circuit breaker is in the closed position and some phase voltage is set to less than 70% of the rated voltage.

4. The node interlock protection method of claim 1 wherein the "no direction latch trip time limit" is 250 milliseconds, the "reverse latch trip time limit" is 380 milliseconds, and the "interlock allowed trip time limit" is 20 milliseconds.

5. The node interlock protection method of claim 1 wherein the "undirected latch trip current", "reverse latch trip current", "interlock allowed trip current", "interlock failure trip current" are set to be greater than the maximum load current or slightly less than the maximum load current, respectively, and when set slightly less than the maximum load current, the "undirected latch trip time limit", "reverse latch trip time limit", "interlock allowed trip time limit", "failure trip time limit", are set to be greater than the duration of time that the load current exceeds the corresponding current limit, respectively.

6. A node interlock protection method according to claim 1, wherein the interlock threshold current is used to monitor the presence or absence of current on the line and is set to 0.1 times the rated current.

7. The node interlock protection method of claim 1 wherein the interlock locking signaling current and the forward direction enabling signaling current are set to be greater than the rated current.

8. The node interlock protection method of claim 1 wherein the "startup failure time limit" is used to avoid the circuit breaker trip time and is set greater than the circuit breaker trip time.

9. The node interlock protection method according to claim 1, wherein the current criterion is changed to an impedance criterion, i.e., the current constants of "interlock lock signaling current", "forward allowed signaling current", "directionless lock trip current", "reverse lock trip current", "interlock allowed trip current", "interlock failure trip current", are changed to the directionless impedance constants of "interlock signaling directionless impedance", "forward allowed signaling directionless impedance", "directionless lock trip undirected impedance", "reverse lock trip undirected impedance", "interlock allowed trip undirected impedance", "interlock failure trip undirected impedance", and the current criterion is changed to an impedance criterion, respectively, because the current and the impedance are inverse, the current in the criterion is replaced by the undirected impedance, accordingly, if the greater than sign is changed to the less than sign, the criterion still applies.

10. The node interlock protection method according to claim 1, wherein the direction discrimination of the current for determining the forward direction and the reverse direction of the current is performed by using a directional impedance instead for determining the forward direction and the reverse direction of the current.