CN117394286A - Relay protection system and method suitable for lengthening T zone - Google Patents

Abstract

The invention discloses a relay protection system and a relay protection method suitable for an lengthened T zone, wherein the system comprises a host computer and a plurality of sub-computers which are arranged in the lengthened T zone, and the host computer and the sub-computers are connected through optical fibers and internally pair; the host computer is used for carrying out relay protection logic discrimination of a lengthening T zone based on data acquired by each sub-computer and issuing a protection tripping command to the corresponding sub-computer, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection discrimination, remote transmission and CT saturation discrimination; the sub-machine is used for collecting and uploading analog quantity and switching value data, receiving and executing a protection tripping command and cutting off faults, and has the functions of signal and mutual remote transmission of the linkage tripping. The invention does not depend on external clock and long cable secondary current and switching value transmission, and can reach 32 ends at most, thereby solving the technical problem of the existing T zone protection.

Description

Relay protection system and method suitable for lengthening T zone

Technical Field

The invention belongs to the technical field of relay protection of power systems, and relates to a relay protection system and method suitable for a lengthened T zone.

Background

With the development of the power grid, large-scale thermal power plants, hydropower plants, nuclear power plants, pumped storage power stations and the like at the source end are generally connected into a main network through a T area after being boosted to a voltage level of 500kV or higher. The bus of the booster station is far away from the main machine equipment due to the restriction of the geographical position and the reconstruction and extension condition, and a long-distance lengthening T zone different from a conventional power station appears, and the branch line of an access system is far more than 300 meters and even more than a few kilometers. As typical 500kV voltage class 3/2 wiring, the unit is incorporated into a high voltage system by a combination unit wiring; also, the installation position of the host equipment is far, the lead distance of the high-voltage side is long, and a T area is arranged on one side of the unit, so that a double T connection area of the reinforced plate is formed; in addition, the internal bridge, the angular electric connection wire or the connection through a lead wire and the like are adopted, and when the device is applied to occasions with a long distance between main equipment and a system power grid, the situation that the coverage distance of an interconnection connection wire area is long and the area is large can also occur.

The length of the secondary loop cable of the conventional transformer for T-zone protection is increased, so that secondary transmission signals are easy to decay, and analog quantity obtained by a protection device is possibly distorted; the length of the cable for driving the remote switch to trip increases, and the cable is influenced by the distributed capacitance along the cable during long-distance transmission, so that the instability risk of the transmission signal can be caused; moreover, a system with a voltage level of 500kV or higher has higher requirements on protection of CT saturation resistance and timeliness of an action outlet, more than 6 ends of a lengthened T zone exist, and the conventional three-end T zone protection scheme cannot meet the relay protection requirements of the lengthened T zone in the aspects of port number, current cable access length, action speed, data acquisition and the like.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides a relay protection system and a relay protection method suitable for lengthening a T zone, which are characterized in that optical fibers are connected between main and sub machines, relay protection functions and logic discrimination such as differential protection, overcurrent protection, failure jump and the like are completed by the main machine, the sub machines are responsible for analog quantity and switching quantity data acquisition, protection tripping and fault removal are executed, the sub machines have the functions of signal and jump mutual remote transmission, the protection differential protection adopts a bus protection ratio braking scheme, the action speed is high, the CT saturation resistance is high, the invention does not depend on external clocks and long cable secondary current and switching quantity transmission, and the maximum reaches 32 ends, and the technical problem of the existing T zone protection is solved.

The invention adopts the following technical scheme.

The relay protection system suitable for the lengthened T zone comprises a host machine and a plurality of sub-machines which are arranged in the lengthened T zone, wherein the lengthened T zone comprises a bus side and an element or circuit side, and an interconnection wiring area of the bus side and the element or circuit side is of a T-shaped structure;

the main machine is arranged at one half-circuit breaker wiring end at the bus side, and an edge switch CT and a middle switch CT are respectively arranged at two sides of the one half-circuit breaker wiring end;

the plurality of sub-machines comprise a sub-machine 1 and a sub-machine 2 which are respectively distributed according to an edge switch CT and a middle switch CT, and n-2 sub-machines which are distributed according to each branch CT at the side of an element or a line, wherein n is smaller than or equal to 32;

the main machine is connected with the plurality of sub-machines through optical fibers, and the internal time is set;

the host computer is used for carrying out relay protection logic discrimination of a lengthening T zone based on data acquired by each sub-computer and issuing a protection tripping command to the corresponding sub-computer, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection discrimination, remote transmission and CT saturation discrimination;

the sub-machine is used for collecting and uploading analog quantity and switching value data, receiving and executing a protection tripping command and cutting off faults, and has the functions of signal and mutual remote transmission of the linkage tripping.

Preferably, the host and the sub-machines are configured according to double CPU plug-ins, and the host double CPUs are respectively connected with the double CPUs of each sub-machine in a point-to-point mode; and the host and the sub-machine adopt IEEE1588 for internal time synchronization.

Preferably, the relay protection system dynamically tracks the operation condition of the site by introducing the state of the primary isolation switch, and specifically:

the interval of the bus side is free of an isolation disconnecting link, and the current value is fixedly counted into differential and braking currents;

the outlet intervals of the branches are provided with isolation disconnecting links, whether the current value accounts for small-difference differential current or not is determined by the state of the isolation disconnecting link G1, and the small-difference differential current and the braking current do not account for the outlet intervals of the isolation disconnecting link G1 which are in split positions.

Preferably, a line outlet interval of 'isolation disconnecting link position TWJ' opening and 'isolation disconnecting link forced separation' hard pressing plate is configured on a sub-machine arranged according to branch CT so as to judge the abnormal position of the isolation disconnecting link, and the method is specific:

the on state of the isolating knife switch position TWJ is inconsistent with the hard pressing plate state of the isolating knife switch strong separation, or when the on state of the isolating knife switch position TWJ is 1 and current exists in an outlet interval, the isolating knife switch position TWJ is abnormal, and the abnormal alarming of the knife switch position is carried out;

under the condition that the position of the disconnecting link is abnormal, the disconnecting link is in a state of being separated from the hard pressing plate by a strong force.

Preferably, the action equation of the ratio brake differential protection is:

wherein I is _i The current of the ith branch of the T area;

n is the total number of branches in the T area;

I _d0 is a threshold value of differential action current;

k is the brake coefficient.

Preferably, the action equation of the overcurrent protection is:

T＞T _SETⅠ

T＞T _SETⅡ

wherein I is _t.φ.max Maximum phase current for element or line side CT;

I _gldzⅠ 、I _gldzⅡ the constant value of the current of the I section and the II section of the overcurrent protection is respectively obtained;

T _SETⅠ /T _SETⅡ the time constant value of the first section and the second section of the overcurrent protection is respectively set;

t is overcurrent protection time;

after branch current provided with side switch CT and middle switch CT on bus side is converted to element or line sidePhase currents of (a);

for element or line side current.

Preferably, the breaker failure trip protection refers to that when the failure of the breaker in the T area is judged by the host, the breaker connected to the trip T area is specifically:

when detecting that the external failure starting device provides two failure starting starts to the sub-machine, detecting whether the current discriminating element is open:

if the bus is opened, the side switch CT fails to jump to protect the start, and the side switch connected to the bus is jumped off after time delay;

the current discriminating element comprises phase current, zero sequence current and negative sequence current, and the three or logic is open;

the phase current is opened by adopting AND logic of a phase current steady-state quantity and a abrupt quantity; the phase current mutation measures any phase current of the branch, is opened when the phase current mutation is larger than a threshold value of the mutation, and is effectively fixed and widened for 15 seconds after the opening; the phase current steady-state measures the maximum of the phase currents of all the branches, and opens when the maximum of the phase currents is larger than a steady-state quantity threshold value;

the zero sequence current and the negative sequence current are steady state quantity criteria, and the maximum one of the zero sequence current and the negative sequence current of all branches is taken and opened when the maximum one is larger than a set threshold value.

Preferably, the CT disconnection discrimination is divided into CT disconnection discrimination based on an alarm section differential current out-of-limit value and a latch section differential current out-of-limit value, wherein the alarm section differential current out-of-limit value is lower than the latch section differential current out-of-limit value; specific:

when the differential current in the T area exceeds the alarm section differential current out-of-limit value but does not exceed the locking section differential current out-of-limit value, an alarm signal is sent after fixed delay;

when the differential current exceeds the limit value of the differential current of the locking section, an alarm signal is sent out after fixed time delay, and differential protection is locked according to the phase.

Preferably, the remote transmission means multiplexing communication network links between the main machine and the sub machine, and transmitting remote jump command or information of required switching value in two directions.

Preferably, the transient CT saturation discrimination logic is:

within a first time threshold T1 of Δif > Id0, when the ratio brake condition Id > k×if is not satisfied and the time of Δif > Id0 is greater than T1, the ratio brake condition is satisfied, which indicates that the transient CT is saturated;

the steady state CT saturation discrimination logic is:

after Δif > Id0 reaches the second time threshold T2, within a third time threshold T3 where Δ DId < ks×Δ DIf is reached, the ratio brake condition Id > k×if is not satisfied, Δ DId < ks×Δ DIf is longer than T3, and then the ratio brake condition is satisfied, indicating steady state CT saturation;

wherein Δif is the brake current abrupt amount, I _d Is a differential current, I _f For braking current, K is the ratio braking differential protection braking coefficient, id0 is the differential threshold, ΔDI _d ΔDI for differential current differential value _f Ks is a current differential ratio brake coefficient, which is a brake current differential value.

A relay protection method suitable for lengthening a T zone comprises the following steps:

each sub-machine collects analog quantity and switching value data of the branch circuit and uploads the analog quantity and switching value data to the host;

the method comprises the steps that a host computer carries out relay protection logic discrimination of a lengthening T zone based on data collected by each sub-computer and issues a protection tripping command to a corresponding sub-computer, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection discrimination, remote transmission and CT saturation discrimination;

after each sub-machine receives the protection tripping command, the protection tripping command is executed, and faults are removed.

The invention has the beneficial effects that compared with the prior art:

the invention adopts a split design of a main machine and a sub machine, wherein the main machine and the sub machines are connected in a point-to-point manner by adopting a star network and optical fibers, the main machine is shared, the sub machines are correspondingly configured according to a circuit breaker CT, the main machine maximally supports the access of 32 sub machines, wherein the main machine carries out relay protection logic judgment of a lengthening T area based on data collected by each sub machine and issues a protection tripping command to the corresponding sub machine, and relay protection comprises ratio braking differential protection, overcurrent protection, circuit breaker failure joint tripping protection, CT disconnection judgment, remote transmission and CT saturation judgment; the sub-machines collect and upload analog quantity and switching value data, receive and execute protection tripping commands and remove faults, and have the functions of signal and mutual remote transmission of the combined tripping.

The invention solves the interference problem caused by long cables by utilizing the optical fiber communication of the main and sub machines, can use a multi-terminal T region, adopts the ratio differential protection similar to bus protection, has high action speed and strong CT saturation resistance, and increases the stability of a power system; the remote transmission function among the sub-machines solves the problems that the existing remote transmission function cannot be operated in the opposite direction and cannot be used for weak links in many-to-many mode; the self-adaptive overcurrent protection can prevent dead zones of the circuit breaker from losing protection; the failure jump function of the invention can prevent the external failure of the T area and enlarge the failure range caused by the failure of the circuit breaker; the invention thoroughly solves the defect of the existing T region protection, shortens the time for cutting off the T region fault, and improves the reliability of the T region protection. The invention can accurately judge the steady CT saturation and the transient CT saturation, and the action outlet for protecting the differential current can prevent the protection misoperation through CT saturation judgment.

Drawings

FIG. 1 is a main and sub-machine arrangement of the present invention;

FIG. 2 is a diagram of the interconnections between the main and sub-computer chassis of the present invention;

FIG. 3 is a diagram showing the determination of abnormal positions of a disconnecting link in an embodiment of the invention;

FIG. 4 illustrates the protection ranges of the T area corresponding to different isolation switch positions in the embodiment of the present invention;

FIG. 5 is isolation switch position anomaly discrimination logic in an embodiment of the present invention;

FIG. 6 is CT saturation determination logic in accordance with an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The embodiments described herein are merely some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art without making any inventive effort, are within the scope of the present invention.

In a preferred but non-limiting embodiment of the present invention, the relay protection system includes a host and a plurality of sub-machines disposed in an elongated (more than 300 m) T-zone, wherein the elongated T-zone includes a bus side and an element or line side, and the bus side and an interconnection area of the element or line side are in a "T" structure;

the main machine is arranged at one half-circuit breaker wiring end at the bus side, and an edge switch CT and a middle switch CT are respectively arranged at two sides of the one half-circuit breaker wiring end;

the plurality of sub-machines comprise a sub-machine 1 and a sub-machine 2 which are respectively distributed according to an edge switch CT and a middle switch CT, and n-2 sub-machines which are distributed according to each branch CT at the side of an element or a line, wherein n is smaller than or equal to 32;

the main machine is connected with the plurality of sub-machines through optical fibers, and the internal time is set;

the host computer is used for carrying out relay protection logic discrimination of a lengthening T zone based on data acquired by each sub-computer and issuing a protection tripping command to the corresponding sub-computer, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection discrimination, remote transmission and CT saturation discrimination, and the host computer is also communicated with the station control layer to realize information display and processing uploaded by the sub-computer;

the sub-machine is used for collecting analog quantity (CT current) and switching quantity (isolating knife switch, remote jump and remote transmission) data, converting the data into data in a stipulated format, uploading the data to the host machine, receiving and executing a protection tripping command and cutting faults, and having the functions of signal and remote transmission of the combined jump mutually between the sub-machines, and the sub-machines comprise signals such as electric quantity, non-electric quantity, shutdown, failure start and the like. The sub-machine provides the required conventional relay output contact, is connected with the control circuit of the operation box to trip, is compatible with the function of a LOCOUT relay, is used for being connected with a direct tripping circuit, and sends necessary tripping alarm information to the host machine.

In specific implementation, the arrangement mode of the main and sub-machine devices is shown in fig. 1, the sub-machines are arranged according to CT, the main machine is generally arranged at one half wiring terminal, the sub-machine 1 and the sub-machine 2 respectively collect an edge switch CT and a middle switch CT of one half wiring terminal, and the rest sub-machines are respectively arranged according to T-division branch, and collect CT and an isolation knife switch; and judging the logic function of the host computer, and executing data acquisition and tripping commands by the sub-computer.

In fig. 2, the main and sub computers are configured according to double-CPU plug-in units, and the main computers CPU1 and CPU2 are respectively connected with the CPU1 and CPU2 of each sub computer in a point-to-point manner, so that the independence and reliability of sampling and tripping of the two CPUs are ensured. The damage of any CPU will not cause the protection malfunction.

The host case comprises a CPU plug-in, an on plug-in, an off plug-in, a power plug-in, a management plug-in and the like. The sub-machine case comprises a CPU plug-in, an alternating current plug-in, an opening plug-in, a LOCOUT plug-in, a power plug-in and the like. The host management plug-in is provided with a time setting function and supports a GMRP network multicast protocol. The device provides a hard pulse time-setting mode (including an IRIG-B time-setting mode, a second pulse time-setting mode), a network time-setting mode and an IEEE1588 time-setting mode. The main machine and the auxiliary machine adopt IEEE1588 and are not influenced by external clocks. Correspondingly, the main and sub-computer hardware system comprises a power supply module, a communication and management module, a processor module, an opening and closing module and an opening and closing module; the communication and management module, the processor, the opening and closing module and the opening and closing module realize information interaction through buses; the processor module comprises a first processor CPU1, a second processor CPU2 and an alternating current converter; the alternating current converter converts alternating current and alternating voltage and then respectively inputs the alternating current and the alternating voltage to the first processor and the second processor through the analog-to-digital converter; the opening module comprises an opening plug-in unit, and the opening plug-in unit receives the hard pressing plate signal and the external opening signal; the opening module comprises a plurality of opening plug-ins, and the opening plug-ins send tripping and closing signals; the communication and management module is internally provided with a MASTER plug-in, and is also connected with a man-machine interface; the power module provides power to the communication and management module, the processor module, the switching-in module and the switching-out module.

The differential current calculation of the relay protection system in the T zone system is changed from static calculation to dynamic tracking, the operation condition of the site is dynamically tracked by introducing a primary isolating switch state, and software can select 32 branches at most by taking a three-side T zone as an example. The exiting slave units do not account for differential and braking currents; the bus side is provided with no isolation disconnecting link, and the current value is fixedly counted into differential and braking currents; the outlet interval determines whether the current value is counted into small difference current through the state of the isolating switch G1, and the small difference differential current and the braking current do not count the outlet interval of the isolating switch G1 in a split mode.

The protection ranges of the T areas corresponding to the positions of the different isolating knife switches are shown in figure 4. Because the isolation disconnecting link position may be abnormal, the problem can be solved by adopting a hard pressing plate which is configured on the sub-machine and is provided with an isolation disconnecting link position TWJ for opening and an isolation disconnecting link for strong separation, and the specific scheme is as follows:

the opening of the isolating switch position TWJ represents the state that the isolating switch position is separated, namely, when the switch is closed, the isolating switch position TWJ contacts are opened, and when the switch is opened, the isolating switch position TWJ contacts are closed.

In order to ensure that the isolating switch is correctly put in and out and the electrified switch is forbidden, the device is provided with a hard pressing plate for the 'isolating switch to be strongly separated', and operators must firstly conduct the switch-on and switch-off operation of the hard pressing plate before isolating the isolating switch.

The bus side interval has no isolation switch position, and does not need to input an isolation switch position TWJ to open and an isolation switch forced separation hard pressing plate, and bus processing is carried out according to default access.

The wire outlet interval is not required to be input into the isolation knife switch position TWJ and the isolation knife switch strong-separation hard pressing plate when the isolation knife switch is put in, and the isolation knife switch position TWJ and the isolation knife switch strong-separation hard pressing plate are required to be input when the isolation knife switch is withdrawn.

As shown in fig. 4, the extended T-zone protection configures isolation switch position anomaly discrimination logic for the outgoing line interval with isolation switch positions:

(1) The opening state of the TWJ at the position of the isolating knife switch at the corresponding interval is inconsistent with the state of the hard pressing plate for the strong separation of the isolating knife switch:

the TWJ of the isolating switch is opened to 0, and the isolating switch is forced to be separated into a hard pressing plate for input, so that the device can alarm that the position of the isolating switch is abnormal;

the TWJ of the isolating switch is opened to be 1, the isolating switch is forced to be separated from the hard pressing plate to be withdrawn, and the device can warn that the position of the isolating switch is abnormal.

(2) The isolating switch position TWJ is opened to be 1, and current is supplied to the outlet interval, so that the device can alarm the abnormal switch position.

Under the condition that the position of the disconnecting link is abnormal, the state of the disconnecting link is taken, namely the disconnecting link state is judged to be the split position (namely the G1 disconnecting link state is 0) when the disconnecting link is put in, and the disconnecting link state is judged to be the close position (namely the G1 disconnecting link state is 1) when the disconnecting link is withdrawn.

In the relay protection system, a host computer is used for judging relay protection logic of a lengthened T zone based on data collected by each sub-machine and issuing a protection tripping command to a corresponding sub-machine, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection judgment, remote transmission and CT saturation judgment, and the method specifically comprises the following steps of:

(1) The following relation is adopted to judge the action of the T zone ratio brake differential protection function:

in the method, in the process of the invention,

I _i a branch current for the ith subunit branch;

n is the total number of the sub-unit branches of the T area;

I _d0 is the threshold value of differential action current, I _d0 The value of (2) is in the range of 0.05 to 20I _n ，I _n Is the secondary rating of the current transformerA current value;

k is a braking coefficient, and the value range is 0.2 to 0.9.

(2) Two sections of overcurrent protection are arranged at intervals of each sub-machine, and the starting and tripping of the overcurrent protection are matched with the differential protection, and taking three-side T areas as an example:

when the isolating switch G1 of the outgoing line is disconnected, the three-side ratio braking type current differential protection is automatically converted into two-side ratio braking type current differential protection, the outgoing line of the T area is not protected any more, meanwhile, two sections of overcurrent protection on the outgoing line side are opened to serve as the outgoing line protection, and when the outgoing line fails, the two sections of overcurrent protection actions send out a far jump signal to the opposite side.

The overcurrent protection is provided with two sections, and the action equation is as follows:

T＞T _SETⅠ

T＞T _SETⅡ

wherein I is _t.φ.max Maximum phase current for element or line side CT;

I _gldzⅠ 、I _gldzⅡ the constant value of the current of the I section and the II section of the overcurrent protection is respectively obtained;

T _SETⅠ /T _SETⅡ the time constant value of the first section and the second section of the overcurrent protection is respectively set;

t is overcurrent protection time;

the branch current of the side switch CT and the middle switch CT arranged on the bus side is converted into the phase after the element or the line sideA current;

for the element or line side current, each was composed of A, B, C three phases.

Overcurrent protection I section current fixed value setting range: 0.000A to 20 (In) A;

overcurrent protection II section current fixed value setting range: 0.000A to 20 (In) A;

overcurrent protection I section time definite value setting scope: 0.01 s-10.00 s;

overcurrent protection II period time fixed value setting range: 0.01 s-10.00 s.

(3) The circuit breaker failure trip protection, namely the failure trip protection through the bus difference, is arranged for realizing the trip bus connected side circuit breaker when the side circuit breaker of the wiring system of the half circuit breaker fails, and the external failure starting device of each branch circuit provides two nodes for the bus protection device. The device detects that two failure links of the branch X are tripped in at the same time, and when no failure trip-in abnormal alarm is generated, whether the current discriminating element of the branch X is opened or not is checked. If the bus is open, the failure is started through the bus-bar tripping protection, and the side circuit breaker connected on the bus bar is tripped through the 50ms delay. Whether the failure of the side breaker occurs is mainly judged by a breaking control unit, and the current judging element which is used for preventing the failure of the device from tripping into errors after the failure of the device is subjected to the trip protection of a bus differential.

The current discriminating element comprises phase current, zero sequence current and negative sequence current, and the three or logic is open.

The phase current is opened by and logic of the steady-state amount and the abrupt amount of the phase current.

The phase current abrupt change quantity starts to judge under the condition that the failure is input by the differential trip protection control word and the pressing plate, and the arbitrary phase current of the branch is taken to be larger than the abrupt change quantity threshold value of 0.06In, and then the opening is opened, and the fixed widening is effective for 15 s.

The maximum phase current of all branches is measured In a steady state, and the phase current is opened when the maximum phase current is larger than a threshold value of 0.08 In.

The zero sequence current and the negative sequence current are steady state quantity criteria, and the maximum one of the zero sequence current and the negative sequence current of all branches is taken and opened when the maximum one is larger than a threshold value of 0.06 In.

The failure linkage trip-in continuously exists for 10 seconds, the alarm failure trip-in is abnormal, and the failure is blocked through the bus differential trip protection function.

(4) Under the condition of the input of a differential protection function, the device performs CT disconnection detection without considering three-phase CT disconnection.

The CT disconnection judgment of the device is divided into two sections: an alarm section and a locking section, wherein the alarm section, namely the differential current out-of-limit value is lower than the locking section differential current out-of-limit value.

The alarm section and the locking section send alarm signals through fixed delay of 10 s.

When the CT disconnection locking condition is met, the device executes phase locking differential protection, and when the CT disconnection locking condition disappears, the locking is automatically released.

CT disconnection warning fixed value (differential current out-of-limit value) setting range: 0.000A to 20 (In) A; recommended tuning range: 0.06In to 0.2In;

CT broken line locking fixed value setting range: 0.000A to 20 (In) A; recommended tuning range: 0.06In to 0.2In;

(5) The remote transmission function can be suitable for the application occasions such as tripping the power station side breaker switch, starting the side switch breaker failure, tripping the group in a combined way, and three-phase inconsistent tripping of the side switch. The function multiplexes the communication network links between the main machine and the sub machine, and transmits remote jump orders or information of needed auxiliary switching value such as electric quantity, non-electric quantity, shutdown, failure start and the like in a bidirectional way, thereby reducing the risk of long cable switching value transmission. Setting range of the far outgoing time set value: 0s to 10.00s.

(6) In order to prevent bus protection from generating out-of-zone faults at the near end of the bus, the bus protection malfunction is caused by differential current formed by severe CT saturation, and a CT saturation detection assembly is arranged on a host machine and used for CT saturation judgment and is divided into steady CT saturation judgment and transient CT saturation judgment.

As shown in fig. 6, the transient CT saturation discrimination logic is:

within a first time threshold T1 of Δif > Id0, when the ratio brake condition Id > k×if is not satisfied and the time of Δif > Id0 is greater than T1, the ratio brake condition is satisfied, which indicates that the transient CT is saturated;

the steady state CT saturation discrimination logic is:

after Δif > Id0 reaches the second time threshold T2, within the third time threshold T3 of Δ DId < ks×Δ DIf, the ratio brake condition Id > k×if is not satisfied, the time Δ DId < ks×Δ DIf is greater than T3, and the ratio brake condition is satisfied, indicating steady state CT saturation.

Wherein Δif is the brake current abrupt amount, I _d Is a differential current, I _f For braking current, K is the ratio braking differential protection braking coefficient (generally 0.3-0.8), id0 is the differential threshold, ΔDI _d ΔDI for differential current differential value _f Ks is a current differential ratio brake coefficient, which is typically 0.2, for braking current differential values (typically 0.3 to 0.8).

The T area is a node of one current, and any T area system can be simplified into two currents to flow in and out of the current i under the external fault condition at the moment T ₁ (t) and i ₂ (t) can be expressed as

Wherein φ is a constant related to CT time; ω=2pi f, f being the frequency of the alternating current;

ts and Tp are the system primary and secondary time constants, respectively, N is the sampling frequency, θ is the fault initiation angle,ω=2pi f, f being the frequency of the alternating current, is an angle related to the CT time constant.

I _max The maximum secondary current at the moment of failure.

Let T be the sampling time interval, let t=nt, digitize formula (1) into formula (2) according to the sampling value:

differential current I of intra-zone fault _d And a braking current I _f Is i ₁ (n) and |i ₁ (n) |, in case of out-of-zone failure, the differential is zero, the braking current is twice |i, in case of no CT error ₁ (n)|。

When the fault occurs in the area, the differential value of the differential current is the differential current of the current point minus the differential current of the previous point:

where n is the nth sample point.

Considering a CT error of 10%, the differential current is a CT error of 2 times, namely a differential value of 0.2 times, when the fault occurs outside the area, and the differential value is as follows:

when the fault happens outside the area, the differential value of the braking current is as follows:

the brake current abrupt amount is:

ΔI _f ＝|I _fx -I _dx-T |

I _fx braking currents respectively of the current period, I _fx-T The braking currents of the previous cycle are respectively, and T is the sampling period.

The out-of-zone fault CT saturation produces differential current but even the most severe CT saturation, there is still a linear transition zone at the zero crossing point of the current and the initial phase of the fault. The differential current is zero in the transition region, and a differential current is generated across this region. The CT saturation detection assembly utilizes the characteristics, forms a plurality of parallel CT saturation criteria by processing various variable relations in the linear transformation area in real time, including differential current, brake current abrupt change, differential current change rate, brake current change rate and the like, and endows different synchronous factors according to the characteristics of different criteria. The time of occurrence of CT saturation is accurately identified through the relation between the synchronous factor and the time variable, and the harmonic analysis of the harmonic quantity of the differential current is added, so that the CT saturation detection component has extremely strong CT saturation resistance and can identify 2msCT saturation.

The out-of-zone CT saturation can also be identified by waveform identification techniques, such as when a differential current waveform has a break angle, indicating out-of-zone CT saturation of the bus zone.

For faults in the transition region outside the saturated phase region, the fault can be rapidly cut off by adopting a waveform identification technology, and when a differential current waveform has no break angle, the fault in the bus region is indicated.

The embodiment 2 of the invention provides a relay protection method suitable for lengthening a T zone, which comprises the following steps:

each sub-machine collects analog quantity and switching value data of the branch circuit and uploads the analog quantity and switching value data to the host;

the method comprises the steps that a host computer carries out relay protection logic discrimination of a lengthening T zone based on data collected by each sub-computer and issues a protection tripping command to a corresponding sub-computer, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection discrimination, remote transmission and CT saturation discrimination;

after each sub-machine receives the protection tripping command, the protection tripping command is executed, and faults are removed.

The invention has the beneficial effects that compared with the prior art:

the invention adopts a split design of a main machine and a sub machine, wherein the main machine and the sub machines are connected in a point-to-point manner by adopting a star network and optical fibers, the main machine is shared, the sub machines are correspondingly configured according to a circuit breaker CT, the main machine maximally supports the access of 32 sub machines, wherein the main machine carries out relay protection logic judgment of a lengthening T area based on data collected by each sub machine and issues a protection tripping command to the corresponding sub machine, and relay protection comprises ratio braking differential protection, overcurrent protection, circuit breaker failure joint tripping protection, CT disconnection judgment, remote transmission and CT saturation judgment; the sub-machines collect and upload analog quantity and switching value data, receive and execute protection tripping commands and remove faults, and have the functions of signal and mutual remote transmission of the combined tripping.

The invention solves the interference problem caused by long cables by utilizing the optical fiber communication of the main and sub machines, can use a multi-terminal T region, adopts the ratio differential protection similar to bus protection, has high action speed and strong CT saturation resistance, and increases the stability of a power system; the remote transmission function among the sub-machines solves the problems that the existing remote transmission function cannot be operated in the opposite direction and cannot be used for weak links in many-to-many mode; the self-adaptive overcurrent protection can prevent dead zones of the circuit breaker from losing protection; the failure jump function of the invention can prevent the external failure of the T area and enlarge the failure range caused by the failure of the circuit breaker; the invention thoroughly solves the defect of the existing T region protection, shortens the time for cutting off the T region fault, and improves the reliability of the T region protection.

The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.

The computer readable storage medium may be a tangible device that can hold and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: portable computer disks, hard disks, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static Random Access Memory (SRAM), portable compact disk read-only memory (CD-ROM), digital Versatile Disks (DVD), memory sticks, floppy disks, mechanical coding devices, punch cards or in-groove structures such as punch cards or grooves having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media, as used herein, are not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., optical pulses through fiber optic cables), or electrical signals transmitted through wires.

The computer readable program instructions described herein may be downloaded from a computer readable storage medium to a respective computing/processing device or to an external computer or external storage device over a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers and/or edge servers. The network interface card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium in the respective computing/processing device.

Computer program instructions for performing the operations of the present disclosure can be assembly instructions, instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, c++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions may be executed entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, aspects of the present disclosure are implemented by personalizing electronic circuitry, such as programmable logic circuitry, field Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), with state information of computer readable program instructions, which can execute the computer readable program instructions.

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.

Claims (11)

1. Relay protection system suitable for add long T district, including laying in add long T district's host computer and a plurality of child machine, wherein add long T district including generating line side and component or circuit side, the interconnection wiring area of generating line side and component or circuit side is "T" shape structure, its characterized in that:

the main machine is arranged at one half-circuit breaker wiring end at the bus side, and an edge switch CT and a middle switch CT are respectively arranged at two sides of the one half-circuit breaker wiring end;

the plurality of sub-machines comprise a sub-machine 1 and a sub-machine 2 which are respectively distributed according to an edge switch CT and a middle switch CT, and n-2 sub-machines which are distributed according to each branch CT at the side of an element or a line, wherein n is smaller than or equal to 32;

the main machine is connected with the plurality of sub-machines through optical fibers, and the internal time is set;

the host computer is used for carrying out relay protection logic discrimination of a lengthening T zone based on data acquired by each sub-computer and issuing a protection tripping command to the corresponding sub-computer, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection discrimination, remote transmission and CT saturation discrimination, and the CT saturation discrimination is divided into steady CT saturation discrimination and transient CT saturation discrimination;

the sub-machine is used for collecting and uploading analog quantity and switching value data, receiving and executing a protection tripping command and cutting off faults, and has the functions of signal and mutual remote transmission of the linkage tripping.

2. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

the host and the sub-machines are configured according to double CPU plug-ins, and the host double CPUs are respectively connected with the double CPUs of each sub-machine in a point-to-point mode; and the host and the sub-machine adopt IEEE1588 for internal time synchronization.

3. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

the relay protection system dynamically tracks the on-site operation condition by introducing a primary isolation switch state, and specifically:

the interval of the bus side is free of an isolation disconnecting link, and the current value is fixedly counted into differential and braking currents;

the outlet intervals of the branches are provided with isolation disconnecting links, whether the current value accounts for small-difference differential current or not is determined by the state of the isolation disconnecting link G1, and the small-difference differential current and the braking current do not account for the outlet intervals of the isolation disconnecting link G1 which are in split positions.

4. A relay protection system for an extended T-zone according to claim 3, wherein:

the sub-machines distributed according to branch CT are provided with wire outlet intervals of 'isolation disconnecting link position TWJ' opening and 'isolation disconnecting link forced separation' hard pressing plates so as to judge the abnormal position of the isolation disconnecting link, and the method is specific:

the on state of the isolating knife switch position TWJ is inconsistent with the hard pressing plate state of the isolating knife switch strong separation, or when the on state of the isolating knife switch position TWJ is 1 and current exists in an outlet interval, the isolating knife switch position TWJ is abnormal, and the abnormal alarming of the knife switch position is carried out;

under the condition that the position of the disconnecting link is abnormal, the disconnecting link is in a state of being separated from the hard pressing plate by a strong force.

5. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

the action equation of the ratio brake differential protection is as follows:

wherein I is _i The current of the ith branch of the T area;

n is the total number of branches in the T area;

I _d0 is a threshold value of differential action current;

k is the brake coefficient.

6. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

the action equation of the overcurrent protection is as follows:

T＞T _SETⅠ

T＞T _SETⅡ

wherein I is _t.φ.max Maximum phase current for element or line side CT;

I _gldzⅠ 、I _gldzⅡ the constant value of the current of the I section and the II section of the overcurrent protection is respectively obtained;

T _SETⅠ /T _SETⅡ the time constant value of the first section and the second section of the overcurrent protection is respectively set;

t is overcurrent protection time;

the branch current of the side switch CT and the middle switch CT arranged on the bus side is converted into the phase current after the element or the line side;

for element or line side current.

7. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

the breaker failure jump protection refers to the breaker connected to the jump T area when the failure of the breaker in the T area is judged by the host, and specifically comprises the following steps:

when detecting that the external failure starting device provides two failure starting starts to the sub-machine, detecting whether the current discriminating element is open:

if the bus is opened, the side switch CT fails to jump to protect the start, and the side switch connected to the bus is jumped off after time delay;

the current discriminating element comprises phase current, zero sequence current and negative sequence current, and the three or logic is open;

the phase current is opened by adopting AND logic of a phase current steady-state quantity and a abrupt quantity; the phase current mutation measures any phase current of the branch, is opened when the phase current mutation is larger than a threshold value of the mutation, and is effectively fixed and widened for 15 seconds after the opening; the phase current steady-state measures the maximum of the phase currents of all the branches, and opens when the maximum of the phase currents is larger than a steady-state quantity threshold value;

the zero sequence current and the negative sequence current are steady state quantity criteria, and the maximum one of the zero sequence current and the negative sequence current of all branches is taken and opened when the maximum one is larger than a set threshold value.

8. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

CT disconnection discrimination is divided into CT disconnection discrimination based on an alarm section differential current out-of-limit value and a locking section differential current out-of-limit value, wherein the alarm section differential current out-of-limit value is lower than the locking section differential current out-of-limit value; specific:

when the differential current in the T area exceeds the alarm section differential current out-of-limit value but does not exceed the locking section differential current out-of-limit value, an alarm signal is sent after fixed delay;

when the differential current exceeds the limit value of the differential current of the locking section, an alarm signal is sent out after fixed time delay, and differential protection is locked according to the phase.

9. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

the remote transmission refers to multiplexing communication network links between the main machine and the sub machine, and the remote jump command or the information of the required switching value is transmitted in a bidirectional way.

10. A relay protection system suitable for an extended T-zone according to claim 1, wherein:

the transient CT saturation discrimination logic is as follows:

within a first time threshold T1 of Δif > Id0, when the ratio brake condition Id > k×if is not satisfied and the time of Δif > Id0 is greater than T1, the ratio brake condition is satisfied, which indicates that the transient CT is saturated;

the steady state CT saturation discrimination logic is:

after Δif > Id0 reaches the second time threshold T2, within a third time threshold T3 where Δ DId < ks×Δ DIf is reached, the ratio brake condition Id > k×if is not satisfied, Δ DId < ks×Δ DIf is longer than T3, and then the ratio brake condition is satisfied, indicating steady state CT saturation;

wherein the method comprises the steps ofΔif is the brake current abrupt amount, I _d Is a differential current, I _f For braking current, K is the ratio braking differential protection braking coefficient, id0 is the differential threshold, ΔDI _d ΔDI for differential current differential value _f Ks is a current differential ratio brake coefficient, which is a brake current differential value.

11. A relay protection method suitable for lengthening a T zone, based on the relay protection system implementation of any one of claims 1-10, characterized in that: the method comprises the following steps:

each sub-machine collects analog quantity and switching value data of the branch circuit and uploads the analog quantity and switching value data to the host;

the method comprises the steps that a host computer carries out relay protection logic discrimination of a lengthening T zone based on data collected by each sub-computer and issues a protection tripping command to a corresponding sub-computer, wherein relay protection comprises ratio braking differential protection, overcurrent protection, breaker failure jump protection, CT disconnection discrimination, remote transmission and CT saturation discrimination;

after each sub-machine receives the protection tripping command, the protection tripping command is executed, and faults are removed.