CN114256814B - Multistage current limiting protection method and configuration system for segmented bus - Google Patents
Multistage current limiting protection method and configuration system for segmented bus Download PDFInfo
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- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
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Abstract
A multistage current limiting protection method and configuration system of a sectional bus, a main current limiter is arranged between a main breaker of a main transformer and a bus correspondingly connected with the main breaker, a tie line current limiter and a tie line breaker are arranged on a tie line between adjacent buses, a feeder line current limiter is arranged at one end of each feeder line breaker far away from the bus, each breaker and a quick breaker are in a closed state when a power grid is stable, and the current limiter and the breaker adopt sectional protection according to fault parts when a short circuit fault occurs in a circuit: the controller triggers the quick circuit breaker of the circuit breaker and the current limiter, and sends the short-circuit fault and address information to the upper-level controller, thereby realizing the current-limiting protection and the feed automation function of the fault line. The protection discrimination logic of the method is simple, and can perform fault current limiting isolation and power supply recovery more quickly.
Description
Technical Field
The invention belongs to the technical field of power grid protection, and particularly relates to a multistage current limiting protection method and a configuration system for a segmented bus.
Background
With the rapid development of national economy, the demand of society for electric power is continuously increased, the continuous development of electric power systems is driven, the capacities of single machines and power plants, the capacities of power substations and the loads of cities and industrial centers are continuously increased, the electric power systems are mutually connected, the short circuit current level in each stage of power grid is continuously improved, and the damage of short circuit faults to the electric power systems and electric equipment connected with the electric power systems is also increasingly greater. Moreover, while the demand for electric energy is increasing, higher demands are being made of electric energy quality, reliability and safety of power supply, etc. However, transient stability problems of large power grids are prominent, one of the most important reasons being due to the lack of effective short-circuit fault current limiting technology in conventional power technology.
The short-circuit fault current limiter provides a new idea for solving the problem. Currently, based on material properties and technological breakthroughs thereof, a variety of current limiters have been proposed and developed, including PTC current limiters, resonant current limiters, solid state current limiters, superconducting current limiters, and the like. The PTC current limiter has small current limiting capacity, so the PTC current limiter has no application prospect in an actual power grid. When the solid-state current limiter is applied to a high-voltage high-capacity system, a large number of solid-state switching tubes (IGBT, GTO and the like) are required to be connected in series and parallel, so that the solid-state current limiter has a complex structure, is high in price, has large steady-state loss and has low reliability; the superconductive current limiter has high cost and is difficult to practically popularize; the resonant current limiter requires a large number of solid-state switching devices such as capacitors and thyristors, and is large in size. Therefore, practical applications thereof have also a great limitation.
At present, the interconnection of the multiple sections of buses is convenient for collecting, distributing and transmitting electric energy. The bus is huge in transmission electric energy, and once a short-circuit fault occurs, the short-circuit current is seriously exceeded, so that the bus can bear great heating and electrodynamic effects, and the current limiting and breaking protection are very important. Meanwhile, as the power supply radius of the urban power distribution network is short, the short-circuit current along the line has little phase difference, and the satisfactory selectivity is difficult to realize by adopting the traditional level difference protection, so that the outlet protection delay time of the transformer substation is prolonged. The disadvantage of the protection mode appears along with the increase of the short-circuit current level of the urban distribution network, namely, before the circuit breaker effectively breaks the fault, the large short-circuit current easily causes the voltage sag of the bus to influence the load of the non-fault line; meanwhile, short-circuit current can impact on equipment in a station, and the safety of the equipment is affected. The contradiction between the two requirements of achieving distribution line level difference protection and protecting the primary equipment within the station is becoming more prominent.
Disclosure of Invention
In order to solve the defects existing in the prior art, the invention aims to provide a multistage current limiting protection method and a configuration system for a segmented bus. According to the invention, the circuit breakers and the current limiters are mutually matched at different positions of the multi-section bus, so that local sectional protection of the bus is realized, and the backup protection of the bus is formed by the controllers of the current limiters, so that the full protection of the power grid is realized, the override trip of the circuit breakers and the expansion of a power failure area are avoided, the short-circuit current of the power grid can be effectively limited, and the rapid breaking protection of the power grid is realized.
The invention adopts the following technical scheme.
1. A multistage current limiting protection method of a segmented bus comprises the following steps:
step 1: a main current limiter is arranged between a main breaker of a main transformer and a bus correspondingly connected with the main breaker, a tie line current limiter and a tie line breaker are arranged on tie lines between adjacent buses, and a feeder line current limiter is arranged at one end, far away from the bus, of each feeder line breaker;
step 2: when the power grid is in a steady state, the main circuit breaker, the tie line circuit breakers and the feeder circuit breakers of the buses are in a closed state, and the quick circuit breakers of all the current limiters are in a closed state;
Step 3: detecting a power grid fault state in real time, and entering a step 4 when a bus connected with the main current limiter fails; when the adjacent bus connected with the main current limiter fails, the step 5 is entered; when the feeder line of the bus connected with the main current limiter fails, the step 6 is entered; when the feeder line to which the adjacent bus of the bus connected with the main current limiter belongs fails, the step 7 is entered;
step 4: the controller of the main current limiter triggers the coordination action of the main breaker and the quick breaker of the main current limiter, so that the current limiting protection of a fault bus is realized;
step 7: the controller of the fault feeder current limiter triggers the coordination action of the fault feeder circuit breaker and the quick circuit breaker of the current limiter, and sends short-circuit fault and address information to the controller of the tie line current limiter and the controller of the main current limiter, so that the current limiting protection of the fault feeder is realized.
In step 3, detecting a short-circuit fault of a line where the current limiter is located through each current limiter;
a current sensor connected with a first winding of the current limiting unit and the quick breaker in series and a voltage sensor connected on a line in parallel are arranged in the current limiter, a second winding of the current limiting unit is connected with the first winding and a serial branch of the quick breaker in parallel, and the different name ends of the two windings are connected;
the current sensor and the voltage sensor respectively monitor the current signal and the voltage signal of the line where the current limiter is located in real time, upload the detected current signal and voltage signal to a controller in the current limiter, and judge whether the line has a short circuit fault or not by the controller.
The step 4 specifically comprises the following steps:
step 4.1, breaking a quick breaker of a controller of the main current limiter after a first zero crossing point of short-circuit current, and breaking the main breaker after a first time delay;
step 4.2, after the second time delay, the controller of the main current limiter sends a reclosing command to the main circuit breaker, if the fault is a transient short circuit fault, the main current limiter resumes a steady state operation state after the current limiting is finished, the reclosing of the main circuit breaker is successful, and the normal operation of the line is resumed; if the permanent short circuit fault exists, executing the step 4.3;
And 4.3, breaking the main breaker and isolating the fault section.
The step 5 specifically comprises the following steps:
step 5.1, breaking a quick breaker of the interconnecting line current limiter after a first zero crossing point of short-circuit current, and breaking the interconnecting line breaker after a first time delay;
step 5.2, after the second time delay, the controller of the tie line current limiter sends a reclosing command to the tie line circuit breaker, if the transient short circuit fault exists, the tie line current limiter restores the steady state operation state, the reclosing of the tie line circuit breaker is successful, and the normal operation of the circuit is restored; if the permanent short circuit fault exists, executing the step 5.3;
and 5.3, breaking the tie line breaker, and simultaneously informing the controller of the tie line current limiter to send a maintenance command to the main breaker by the controller of the tie line current limiter, wherein if the tie line breaker fails and cannot execute the breaking command of the controller of the tie line current limiter, the controller of the main current limiter knows that the tie line breaker is always in the closed position, and delays to send a breaking command to the main breaker so as to realize backup protection of a power grid.
The step 6 specifically comprises the following steps:
step 6.1, breaking a quick breaker of a controller of the fault feeder current limiter after a first zero crossing point of short-circuit current, and breaking the fault feeder current limiter after a first time delay;
Step 6.2, after the second time delay, the controller of the fault feeder current limiter sends a reclosing command to the fault feeder circuit breaker, and the controller of the main current limiter monitors the running states of the fault feeder current limiter and the fault feeder circuit breaker; if the fault is an instantaneous short-circuit fault, the fault feeder current limiter resumes a normal operation state, and the fault feeder current limiter recloses successfully to resume normal operation of the line; if the permanent short circuit fault exists, executing the step 6.3;
step 6.3, breaking the fault feeder circuit breaker, and simultaneously notifying a controller of the fault feeder current limiter to send a holding command to the main circuit breaker by the controller of the main current limiter; if the fault feeder circuit breaker fails, the controller of the main current limiter knows that the fault feeder circuit breaker is always in the on position, and delay sends an off command to the main circuit breaker to realize the backup protection of the power grid.
The step 7 specifically comprises the following steps:
step 7.1, breaking a quick breaker of a controller of the fault feeder current limiter after a first zero crossing point of short-circuit current, and breaking the fault feeder current limiter after a first time delay;
step 7.2, after the second delay, the controller of the fault feeder current limiter sends out a reclosing command, and the controllers of the tie line current limiter and the main current limiter monitor the operation states of the fault feeder current limiter and the fault feeder circuit breaker: if the fault is an instantaneous short-circuit fault, after the current limiting is finished, the fault feeder current limiter restores the steady-state operation state, the fault feeder circuit breaker is successfully reclosed, and the normal operation of the line is restored; if the permanent short circuit fault exists, executing the step 7.3;
Step 7.3, breaking the fault feeder circuit breaker, and simultaneously, the controller of the fault feeder current limiter informs the controller of the tie line current limiter to send a holding command to the tie line circuit breaker, and the controller of the fault feeder current limiter informs the controller of the main current limiter to send the holding command to the main circuit breaker; if the fault feeder circuit breaker fails, the controller of the tie line current limiter knows that the fault feeder circuit breaker is always in the on position, and a brake-off command is sent to the tie line circuit breaker in a delayed mode, so that backup protection of a power grid is realized.
Preferably, the value range of the first delay is 40ms-60ms; the second delay has a value ranging from 250ms to 350ms. A multistage current limiting protection configuration system of a sectional bus of a multistage current limiting protection method of the sectional bus comprises a main transformer, a main breaker, a main current limiter, a tie line breaker, a tie line current limiter, a bus, a feeder line to which the bus belongs, a feeder line breaker, a feeder line current limiter and a feeder load,
a main breaker and a main current limiter are sequentially arranged between the main transformer and the bus correspondingly connected;
a tie line current limiter and a tie line breaker are arranged on the tie lines between adjacent buses;
and the bus is connected with a feeder, and a feeder breaker and a feeder current limiter are sequentially arranged at the head end of each feeder.
Each current limiter in the system comprises a quick breaker, a current limiting unit, a controller, a current sensor, a voltage sensor and a signal wire;
a current sensor connected with a first winding of the current limiting unit and the quick breaker in series and a voltage sensor connected on a line in parallel are arranged in the current limiter, a second winding of the current limiting unit is connected with the first winding and a serial branch of the quick breaker in parallel, and the different name ends of the two windings are connected;
the current sensor and the voltage sensor respectively monitor the current signal and the voltage signal of the line where the current limiter is located in real time, upload the detected current signal and voltage signal to a controller in the current limiter, and judge whether the line has a short circuit fault or not by the controller.
The controller acquires a line current signal through the current sensor, and acquires a voltage signal through the voltage sensor, so as to judge whether a short circuit fault occurs in the line;
the controller obtains a status signal of the quick breaker through a signal line and controls the quick breaker;
the controller obtains a state signal of the circuit breaker through a signal wire and controls the circuit breaker;
the controller realizes signal communication with other controllers through signal wires to form a distributed feed automation system.
Compared with the prior art, the invention has the advantages that the short-circuit current of the power grid can be effectively limited, and the rapid breaking protection of the power grid can be realized.
The beneficial effects of the invention also include:
1. according to the structural characteristics of the power grid, the current limiter and the circuit breaker are matched with each other, so that the rapid current limiting and breaking protection of the power grid are realized, and the full protection of the power grid is realized;
2. the current limiter is matched with the quick breaker through the double-split reactor, the breaker is quickly broken, the quick input of the reactor is realized, fault current is effectively limited, the current limiting capacity of the current limiter is improved, and therefore a better current limiting effect than that of the existing short-circuit fault current limiter is achieved. Meanwhile, overvoltage in the current limiting process is avoided, and the operation safety of the power grid is improved.
3. The controller of the current limiter not only realizes fault judgment and current limiting control, but also realizes a feed automation function, and the fault section can be accurately judged by utilizing the local current information and the position information and the current information of the downstream sectionalizing switch without participation of a main station or time limit cooperation, so that the judgment logic of protection is simple, fault current limiting isolation and power supply recovery can be faster, current limiting and protection are more convenient, and the design is more reasonable;
4. The controller of the current limiter forms a local feeder automation system, so that local control and upper and lower linkage are conveniently realized, the override actions of the upper current limiter and the circuit breaker are avoided, and the power failure area is prevented from being enlarged;
5. the current limiter is configured according to the power grid structure, so that the current limiting protection of the whole power grid is realized, an additional feed automation system is avoided, and the system cost is saved.
Drawings
FIG. 1 is a configuration diagram of a multistage current limiting protection configuration system for a segmented bus of the present invention;
FIG. 2 is a schematic flow chart of a multistage current limiting protection method for a segmented bus according to an embodiment of the present invention;
FIG. 3 is a partial configuration diagram of a multi-stage current limiting protection configuration system for a segmented bus in accordance with an embodiment of the present invention;
fig. 4 is a schematic diagram of the primary restrictor 103 according to an embodiment of the present invention.
The reference numerals are:
1. a main transformer; 102. a main breaker; 103. a primary restrictor;
2. a bus; 201. a feeder circuit breaker;
202. a feeder restrictor; 203. a feeder load;
4. a tie line current limiter; 5. a tie line breaker;
6. a current limiting unit; 601. a first winding; 602. a second winding;
7. a current sensor; 8. a voltage sensor; 9. a quick circuit breaker.
Detailed Description
The present application is further described below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical solutions of the present invention and are not intended to limit the scope of protection of the present application.
Fig. 1 is a configuration diagram of a multistage current limiting protection configuration system of a segmented bus bar (feeder load is omitted in the figure), which comprises a main transformer 1, a bus bar 2, a feeder to which the bus bar belongs, a main breaker 102, a main current limiter 103, a tie line breaker 5, a tie line current limiter 4, a feeder breaker 201, a feeder current limiter 202 and a feeder load 203, wherein the main breaker 102 and the main current limiter 103 are sequentially arranged between the main transformer 1 and the bus bar 2 correspondingly connected; a tie line current limiter 4 and a tie line breaker 5 are arranged on the tie lines between adjacent buses; each section of bus is connected with a feeder, and a feeder breaker 201 and a feeder current limiter 202 are sequentially arranged at the head end of each feeder.
Specifically, after the main transformer 1, the main breaker 102 and the main current limiter 103 are sequentially connected in series, wherein the other end of the main current limiter 103 is connected to a bus, the interconnecting line current limiter 4 and the interconnecting line current breaker 5 are connected in series and then bridge between two sections of buses, the feeder line current breaker, the feeder line current limiter and the feeder line load are sequentially connected in series to form a feeder line, one end of the feeder line, which is close to the feeder line breaker, is connected with the bus, each section of bus is connected with N feeder lines, and the parts and the connection mode thereof form a multistage current limiting protection configuration system of the segmented bus.
Each current limiter in the system comprises a quick breaker 9, a current limiting unit 6, a controller, a current sensor 7, a voltage sensor 8 and a signal wire;
a current sensor connected in series with a first winding 601 of the current limiting unit and a quick breaker 9 and a voltage sensor connected in parallel on a line are arranged in the current limiter, a second winding of the current limiting unit is connected in parallel with the first winding and a serial branch of the quick breaker, and the different name ends of the two windings are connected;
the current sensor and the voltage sensor respectively monitor the current signal and the voltage signal of the line where the current limiter is located in real time, upload the detected current signal and voltage signal to a controller in the current limiter, and judge whether the line has a short circuit fault or not by the controller.
The controller acquires a line current signal through the current sensor, and acquires a voltage signal through the voltage sensor, so as to judge whether a short circuit fault occurs in the line;
the controller obtains a status signal of the quick breaker through a signal line and controls the quick breaker;
the controller obtains a state signal of the circuit breaker through a signal wire and controls the circuit breaker;
the controller realizes signal communication with other controllers through signal wires to form a distributed feed automation system.
Fig. 2 is a schematic flow chart of a multistage current limiting protection method for a segmented bus according to an embodiment of the present invention:
step 1: a main current limiter is arranged between a main breaker of a main transformer and a bus correspondingly connected with the main breaker, a tie line current limiter and a tie line breaker are arranged on tie lines between adjacent buses, and a feeder line current limiter is arranged at one end, far away from the bus, of each feeder line breaker;
step 2: when the power grid is in a steady state, the main circuit breaker, the tie line circuit breakers and the feeder circuit breakers of the buses are in a closed state, and the quick circuit breakers of all the current limiters are in a closed state;
step 3: detecting a power grid fault state in real time, and entering a step 4 when a bus connected with the main current limiter fails; when the adjacent bus connected with the main current limiter fails, the step 5 is entered; when the feeder line of the bus connected with the main current limiter fails, the step 6 is entered; when the feeder line to which the adjacent bus of the bus connected with the main current limiter belongs fails, the step 7 is entered;
step 4: the controller of the main current limiter triggers the coordination action of the main breaker and the quick breaker of the main current limiter, so that the current limiting protection of a fault bus is realized;
the step 4 specifically comprises the following steps:
Step 4.1, breaking a quick breaker of a controller of the main current limiter after a first zero crossing point of short-circuit current, and breaking the main breaker after a first time delay;
step 4.2, after the second time delay, the controller of the main current limiter sends a reclosing command to the main circuit breaker, if the fault is a transient short circuit fault, the main current limiter resumes a steady state operation state after the current limiting is finished, the reclosing of the main circuit breaker is successful, and the normal operation of the line is resumed; if the permanent short circuit fault exists, executing the step 4.3;
and 4.3, breaking the main breaker and isolating the fault section.
the step 5 specifically comprises the following steps:
step 5.1, breaking a quick breaker of the interconnecting line current limiter after a first zero crossing point of short-circuit current, and breaking the interconnecting line breaker after a first time delay;
step 5.2, after the second time delay, the controller of the tie line current limiter sends a reclosing command to the tie line circuit breaker, if the transient short circuit fault exists, the tie line current limiter restores the steady state operation state, the reclosing of the tie line circuit breaker is successful, and the normal operation of the circuit is restored; if the permanent short circuit fault exists, executing the step 5.3;
And 5.3, breaking the tie line breaker, and simultaneously informing the controller of the tie line current limiter to send a maintenance command to the main breaker by the controller of the tie line current limiter, wherein if the tie line breaker fails and cannot execute the breaking command of the controller of the tie line current limiter, the controller of the main current limiter knows that the tie line breaker is always in the closed position, and delays to send a breaking command to the main breaker so as to realize backup protection of a power grid.
the step 6 specifically comprises the following steps:
step 6.1, breaking a quick breaker of a controller of the fault feeder current limiter after a first zero crossing point of short-circuit current, and breaking the fault feeder current limiter after a first time delay;
step 6.2, after the second time delay, the controller of the fault feeder current limiter sends a reclosing command to the fault feeder circuit breaker, and the controller of the main current limiter monitors the running states of the fault feeder current limiter and the fault feeder circuit breaker; if the fault is an instantaneous short-circuit fault, the fault feeder current limiter resumes a normal operation state, and the fault feeder current limiter recloses successfully to resume normal operation of the line; if the permanent short circuit fault exists, executing the step 6.3;
Step 6.3, breaking the fault feeder circuit breaker, and simultaneously notifying a controller of the fault feeder current limiter to send a holding command to the main circuit breaker by the controller of the main current limiter; if the fault feeder circuit breaker fails, the controller of the main current limiter knows that the fault feeder circuit breaker is always in the on position, and delay sends an off command to the main circuit breaker to realize the backup protection of the power grid.
Step 7: the controller of the fault feeder current limiter triggers the coordination action of the fault feeder circuit breaker and the quick circuit breaker of the current limiter, and sends short-circuit fault and address information to the controller of the tie line current limiter and the controller of the main current limiter, so that the current limiting protection of the fault feeder is realized.
The step 7 specifically comprises the following steps:
step 7.1, breaking a quick breaker of a controller of the fault feeder current limiter after a first zero crossing point of short-circuit current, and breaking the fault feeder current limiter after a first time delay;
step 7.2, after the second delay, the controller of the fault feeder current limiter sends out a reclosing command, and the controllers of the tie line current limiter and the main current limiter monitor the operation states of the fault feeder current limiter and the fault feeder circuit breaker: if the fault is an instantaneous short-circuit fault, after the current limiting is finished, the fault feeder current limiter restores the steady-state operation state, the fault feeder circuit breaker is successfully reclosed, and the normal operation of the line is restored; if the permanent short circuit fault exists, executing the step 7.3;
Step 7.3, breaking the fault feeder circuit breaker, and simultaneously, the controller of the fault feeder current limiter informs the controller of the tie line current limiter to send a holding command to the tie line circuit breaker, and the controller of the fault feeder current limiter informs the controller of the main current limiter to send the holding command to the main circuit breaker; if the fault feeder circuit breaker fails, the controller of the tie line current limiter knows that the fault feeder circuit breaker is always in the on position, and a brake-off command is sent to the tie line circuit breaker in a delayed mode, so that backup protection of a power grid is realized.
As shown in fig. 3 and fig. 4, a power grid structure and a current limiter partial configuration diagram of a multistage current limiting protection configuration system for a segmented bus according to an embodiment of the present invention are defined as a first bus and a second bus from left to right, and four feeders are defined as a first feeder, a second feeder, a third feeder and a fourth feeder, including a main transformer 1, a first bus, a second bus, a main breaker 102, a tie breaker 5, a first feeder breaker, a second feeder breaker, a third feeder breaker, a fourth feeder breaker, a main current limiter 103, a tie current limiter 4, a first feeder current limiter, a second feeder current limiter, a third feeder current limiter, a fourth feeder current limiter, a first feeder load, a second feeder load, a third feeder load and a fourth feeder load. After the main transformer 1, the main circuit breaker 102 and the main current limiter 103 are sequentially connected in series, wherein the other end of the main current limiter 103 is connected to a first bus, the interconnecting line current limiter 4 and the interconnecting line circuit breaker 5 are connected in series and then are bridged between the first bus and a second bus, the first feeder circuit breaker, the first feeder current limiter and a first feeder load are sequentially connected in series to form a first feeder, one end of the first feeder close to the first feeder circuit breaker is connected to the first bus, and the other end of the first feeder is grounded; the second feeder circuit breaker, the second feeder current limiter and the second feeder load are sequentially connected in series to form a second feeder, one end of the second feeder close to the second feeder circuit breaker is connected with the first bus, and the other end of the second feeder is grounded; the third feeder circuit breaker, the third feeder current limiter and the third feeder load are sequentially connected in series to form a third feeder, one end of the third feeder close to the third feeder circuit breaker is connected with the second bus, and the other end of the third feeder is grounded; the fourth feeder circuit breaker, the fourth feeder current limiter and the fourth feeder load are sequentially connected in series to form a fourth feeder, one end of the fourth feeder close to the fourth feeder circuit breaker is connected with the second bus 3, the other end of the fourth feeder is grounded, and the parts and the connection mode thereof form a multistage current limiting protection configuration system of the segmented bus.
Fig. 4 is a schematic diagram (within a broken line frame) of the main restrictor 103 according to embodiment 1 of the present invention. The main current limiter 103, which implements the main transformer 1 current limiting protection, includes a fast circuit breaker 99, a current limiting unit 6, a controller, a current sensor 7, and a voltage sensor 8. The controller acquires line current and voltage signals through a current sensor 7 and a voltage sensor 8 respectively for line fault judgment. The controller obtains a status signal of the quick breaker 9 through a signal line Sig04 and controls the quick breaker 9; the controller Ctr obtains a state signal of the main breaker 102 through a signal line Sig05 and controls the main breaker 102; the controllers realize signal communication among other controllers through a signal line Sig03 to form a distributed feed automation system. The main current limiter 103 and the main circuit breaker 102 (locally) realize main transformer fault current limiting and breaking protection.
In a preferred embodiment, the current limiting unit 6 is a double-split reactor consisting of a first winding 601 and a second winding 602, wherein the first winding 601 and the second winding 602 have the same number of turns, are connected by different name ends, and have opposite magnetic flux directions. The first winding 601 and the second winding 602 are coupled in either a hollow coupling manner or a closed magnetic circuit is formed by a closed iron core.
The main current limiter 103 of the present invention operates on the principle that in a steady state, the fast circuit breaker 9 is closed, and the current passing through the first winding 601 and the second winding 602 are equal, and the magnetic fluxes are equal to cancel each other, so that the main current limiter 103 presents a small impedance (leakage inductance) or zero impedance to the outside. Once a short circuit fault occurs, the controller triggers the quick breaker 9 to break, and in the breaking process, the line current is gradually transferred from the first winding 601 to the second winding 602, so that the currents of the first winding 601 and the second winding 602 are unequal, magnetic fluxes cannot be counteracted, larger magnetic fluxes are formed, and impedance is generated; when the quick breaker 9 is fully closed, the line current is all transferred to the second winding 602, thereby achieving short-circuit current limitation.
The main breaker 102 and the main current limiter 103 are matched with each other to realize fault current limiting and breaking protection of the main transformer 1 and the first bus; the interconnecting wire breaker 5 and the interconnecting wire current limiter 4 are mutually matched to realize fault current limiting and breaking protection of the second bus; the first feeder circuit breaker is matched with the first feeder current limiter to realize fault current limiting and breaking protection of the first feeder; the second feeder circuit breaker is matched with the second feeder current limiter to realize fault current limiting and breaking protection of the second feeder; the third feeder circuit breaker is matched with the third feeder current limiter to realize fault current limiting and breaking protection of the third feeder; the fourth feeder circuit breaker and the fourth feeder current limiter are mutually matched to realize fault current limiting and breaking protection of the fourth feeder, so that full-circuit current limiting protection is realized.
The tie line current limiter 4, the first feeder current limiter, the second feeder current limiter, the third feeder current limiter and the fourth feeder current limiter of the present invention have the same structural composition and the same working principle as the main current limiter 103. Wherein, in the fault handling process, the controller of the main current limiter 103 is an upper level controller of the controllers of the tie line current limiter 4 and the feeder line current limiter; the controller of the main current limiter 103 and the controller of the tie line current limiter 4 are superior controllers to the controllers of the third feeder current limiter and the fourth feeder current limiter.
The main breaker 102, the tie line breaker 5, the first feeder line breaker, the second feeder line breaker, the third feeder line breaker and the fourth feeder line breaker are conventional breakers, the breaking action time is 50-100ms, the quick breaker 9 is a quick breaker, and the breaking action time is 3-6ms.
When the power grid is in a steady state, the main circuit breaker 102, the tie line circuit breaker 5, the first feeder circuit breaker, the second feeder circuit breaker, the third feeder circuit breaker and the fourth feeder circuit breaker are all in a closed state, meanwhile, the quick circuit breakers 9 of all current limiters are in a closed state, and the current limiting unit 6 presents low impedance. Thus, low impedance or zero loss operation of all current limiters is achieved.
When a short-circuit fault occurs in the power grid, the adopted current limiting protection strategies are different according to the different positions of the short-circuit fault, and as shown in fig. 1, F2, F3 and F4 represent the short-circuit faults at different positions.
When a short-circuit fault occurs at the F1 position, the current of the first bus rapidly rises, the voltage rapidly drops, and the controller of the main current limiter 103 rapidly triggers the main circuit breaker 102 and the quick circuit breaker 9 of the main current limiter 103 after judging the short-circuit fault according to the current and the voltage change of the first bus. The quick breaker 9 breaks after the first zero crossing point of the short-circuit current, so that the second winding 602 is put into line current limiting, and the main breaker 102 breaks the first bus after 50ms, so that the short-circuit current limiting and fault current limiting breaking protection are realized. After 300ms of delay time, the controller of the main current limiter 103 sends out a reclosing command, if the fault is a transient short circuit fault, the main current limiter 103 resumes a steady state operation state after the current limiting is finished, the reclosing of the main circuit breaker 102 is successful, and the normal operation of the line is resumed. If the permanent short circuit fault exists, the main breaker 102 is disconnected, the isolation of a fault section is realized, the load of a non-fault area works normally, and the expansion of a power failure section is avoided. Therefore, when the first bus is short-circuited, the main transformer 1 is current limiting and breaking protection realized by the cooperation of the main breaker 102 and the main current limiter 103, and is local fast current limiting protection without backup protection.
When a short circuit fault occurs at F2, the second bus current rises rapidly while the voltage drops rapidly. After the controller of the tie-line current limiter 4 determines the short-circuit fault, the tie-line circuit breaker 5 and the quick circuit breaker 9 of the tie-line current limiter 4 are quickly triggered, and short-circuit fault and address information are sent to the upper-level controller, i.e., the controller of the main current limiter 103. The quick breaker 9 breaks after the first zero crossing point of the short-circuit current, so that the second winding 602 is put into line current limiting, and the tie line breaker 5 breaks the second bus after 50ms, thereby realizing current limiting and fault current limiting breaking protection. After a delay of 300ms, the controller of the tie-line current limiter 4 issues a reclosing command. In this process, the controller of the main current limiter 103 as the upper stage always monitors the operation states of the tie line current limiter 4 and the tie line breaker 5. If the fault is an instantaneous short-circuit fault, after the current limiting is finished, the interconnecting line current limiter 4 is restored to a normal running state, the interconnecting line breaker 5 is successfully reclosed, and the normal running of the line is restored. If the permanent short-circuit fault is present, the tie breaker 5 is disconnected and the controller of the main current limiter 103 is notified to issue a hold command to the main breaker 102. The isolation of the fault section is realized, so that the load of the non-fault section works normally, and the expansion of the power failure section is avoided. If the tie line breaker 5 fails and the breaking command of the controller of the main current limiter 103 cannot be executed, the controller of the main current limiter 103 knows that the tie line breaker 5 is always in the on position, and delays sending the breaking command to the main circuit breaker 102, so that the backup protection of the power grid is realized. Therefore, when the second bus bar has a short-circuit fault, the second bus bar can realize local fast current limiting protection through the cooperation of the tie line breaker 5 and the tie line current limiter 4, and realize backup protection of the main transformer 1 through the main breaker 102. Meanwhile, the current limiting function of the tie line current limiter 4 prevents power grid equipment from suffering large current impact, and improves the running reliability of the power grid.
When a short circuit fault occurs at F3, the first feeder current rises rapidly while the voltage drops rapidly. After the controller of the first feeder current limiter P determines the short-circuit fault, the first feeder circuit breaker and the fast circuit breaker 9 of the first feeder current limiter are rapidly triggered, and short-circuit fault and address information are transmitted to the upper controller, i.e., the controller of the main current limiter 103. The quick breaker 9 breaks after the first zero crossing point of the short-circuit current, so that the second winding 602 is put into line current limiting. The first feeder circuit breaker breaks the fault line after 50ms, thereby realizing current limiting and fault current limiting breaking protection. After 300ms of delay, the controller of the first feeder current limiter sends out a reclosing command. During this process, the controller of the main current limiter 103 is constantly monitoring the operation status of the first feeder current limiter and the first feeder circuit breaker. If the current is in the transient short-circuit fault, after the current limiting is finished, the first feeder current limiter resumes the normal operation state, and the reclosing of the first feeder current limiter is successful, so that the normal operation of the line is resumed. If the fault is a permanent short circuit fault, the first feeder circuit breaker is disconnected, and the controller of the main current limiter 103 is informed to send a holding command to the main circuit breaker 102, so that isolation of a fault section is realized, loads of a non-fault area work normally, and expansion of a power failure section is avoided. If the first feeder circuit breaker fails, the controller of the main current limiter 103 knows that the first feeder circuit breaker is always in the on position, and delays sending an off command to the main circuit breaker 102, so as to realize the backup protection of the power grid. Therefore, when the first feeder line has a short-circuit fault, the first bus bar can realize local fast current limiting protection through the cooperation of the first feeder line breaker and the first feeder line current limiter, and realize backup protection of the main transformer 1 through the main breaker 102. Meanwhile, the current limiting function of the first feeder current limiter prevents power grid equipment from suffering large current impact, and improves the running reliability of the power grid.
When a short circuit fault occurs at F4, the third feeder current rises rapidly while the voltage drops rapidly. After the controller of the third feeder line current limiter determines the short-circuit fault, the third feeder line circuit breaker and the fast circuit breaker of the third feeder line current limiter are triggered quickly, and the short-circuit fault and the address information are sent to the upper level controller, namely the controller of the tie line current limiter 4 and the controller of the main current limiter 103. The quick breaker 9 breaks after the first zero crossing point of the short-circuit current, so that the second winding 602 is put into line current limiting, and the third feeder breaker breaks the fault line after 50ms, so that current limiting and fault current limiting breaking protection are realized. After 300ms of delay, the controller of the third feeder current limiter sends out a reclosing command. In this process, the controller of the tie line current limiter 4 and the controller Ctr of the main current limiter 103 are constantly monitoring the operating states of the third feeder current limiter and the third feeder circuit breaker. If the current is in the transient short-circuit fault, after the current limiting is finished, the third feeder current limiter resumes the normal operation state, and the third feeder current limiter recloses successfully to resume the normal operation of the line. If the permanent short-circuit fault is detected, the third feeder circuit breaker is disconnected, and the controller of the tie-line current limiter 4 is informed to send a holding command to the tie-line circuit breaker 5, and the controller of the main current limiter 103 is informed to send a holding command to the main circuit breaker 102. Therefore, the isolation of the fault section is realized, the load of the non-fault area works normally, and the expansion of the power failure section is avoided. If the third feeder circuit breaker fails, the controller Ctr of the tie line current limiter 4 knows that the third feeder circuit breaker is always in the on position, and a brake-off command is sent to the tie line circuit breaker 5 in a delayed mode, so that the backup protection of the power grid is realized. Therefore, when the third feeder line has a short circuit fault, the main transformer 1, the first bus bar and the second bus bar can realize local quick current limiting protection through the cooperation of the third feeder line breaker and the third feeder line current limiter, and three-stage protection is formed through the tie line breaker 5 or the backup protection of the main transformer 1 and the first bus bar. Meanwhile, the current limiting function of the third feeder current limiter prevents power grid equipment from suffering large current impact, and improves the running reliability of the power grid.
Therefore, the mutual coordination of the current limiter and the circuit breaker realizes the rapid current limiting and breaking protection of the power grid, the controller of the current limiter not only realizes fault judgment and current limiting control, but also realizes the feed automation function, the fault section can be accurately judged by utilizing the local current information and the position information and the current information of the downstream sectionalized switch, the participation of a main station is not needed, the time limit coordination is not needed, the judgment logic of the protection is simple, and the fault current limiting isolation and the power supply recovery can be faster. The current limiters and the circuit breakers of all groups are mutually matched, so that the fault current limiting and breaking protection of the whole circuit are realized.
While the applicant has described and illustrated the embodiments of the present invention in detail with reference to the drawings, it should be understood by those skilled in the art that the above embodiments are only preferred embodiments of the present invention, and the detailed description is only for the purpose of helping the reader to better understand the spirit of the present invention, and not to limit the scope of the present invention, but any improvements or modifications based on the spirit of the present invention should fall within the scope of the present invention.
Claims (8)
1. The multistage current limiting protection method for the segmented bus is characterized by comprising the following steps of:
Step 1: a main current limiter is arranged between a main breaker of a main transformer and a bus correspondingly connected with the main breaker, a tie line current limiter and a tie line breaker are arranged on tie lines between adjacent buses, and a feeder line current limiter is arranged at one end, far away from the bus, of each feeder line breaker;
step 2: when the power grid is in a steady state, the main circuit breaker, the tie line circuit breakers and the feeder circuit breakers of the buses are in a closed state, and the quick circuit breakers of all the current limiters are in a closed state;
step 3: detecting a power grid fault state in real time, and entering a step 4 when a bus connected with the main current limiter fails; when the adjacent bus connected with the main current limiter fails, the step 5 is entered; when the feeder line of the bus connected with the main current limiter fails, the step 6 is entered; when the feeder line to which the adjacent bus of the bus connected with the main current limiter belongs fails, the step 7 is entered;
step 4: the controller of the main current limiter triggers the coordination action of the main breaker and the quick breaker of the main current limiter, so that the current limiting protection of a fault bus is realized; the step 4 specifically comprises the following steps:
step 4.1, breaking a quick breaker of a controller of the main current limiter after a first zero crossing point of short-circuit current, and breaking the main breaker after a first time delay;
Step 4.2, after the second time delay, the controller of the main current limiter sends a reclosing command to the main circuit breaker, if the fault is a transient short circuit fault, the main current limiter resumes a steady state operation state after the current limiting is finished, the reclosing of the main circuit breaker is successful, and the normal operation of the line is resumed; if the permanent short circuit fault exists, executing the step 4.3;
step 4.3, breaking the main circuit breaker and isolating a fault section;
step 5, the controller of the tie line current limiter triggers the coordination action of the tie line circuit breaker and the quick circuit breaker of the tie line current limiter, and sends short-circuit fault and address information to the controller of the main current limiter, so that fault current limiting protection of adjacent buses is realized; the step 5 specifically comprises the following steps:
step 5.1, breaking a quick breaker of the interconnecting line current limiter after a first zero crossing point of short-circuit current, and breaking the interconnecting line breaker after a first time delay;
step 5.2, after the second time delay, the controller of the tie line current limiter sends a reclosing command to the tie line circuit breaker, if the transient short circuit fault exists, the tie line current limiter restores the steady state operation state, the reclosing of the tie line circuit breaker is successful, and the normal operation of the circuit is restored; if the permanent short circuit fault exists, executing the step 5.3;
Step 5.3, breaking the tie line breaker, and simultaneously informing the controller of the tie line current limiter to send a maintenance command to the main breaker by the controller of the tie line current limiter, if the tie line breaker fails and cannot execute the breaking command of the controller of the tie line current limiter, the controller of the main current limiter knows that the tie line breaker is always in a closing position, and delays sending a breaking command to the main breaker so as to realize backup protection of a power grid;
step 6, the controller of the fault feeder current limiter triggers the coordination action of the fault feeder circuit breaker and the quick circuit breaker of the current limiter, and sends short-circuit fault and address information to the controller of the main current limiter to realize the current limiting protection of the fault feeder;
step 7: the controller of the fault feeder current limiter triggers the coordination action of the fault feeder circuit breaker and the quick circuit breaker of the current limiter, and sends short-circuit fault and address information to the controller of the tie line current limiter and the controller of the main current limiter, so that the current limiting protection of the fault feeder is realized.
2. The multi-stage current limiting protection method for a segmented bus according to claim 1, wherein:
in step 3, detecting a short-circuit fault of a line where the current limiter is located through each current limiter;
A current sensor connected with a first winding of the current limiting unit and the quick breaker in series and a voltage sensor connected on a line in parallel are arranged in the current limiter, a second winding of the current limiting unit is connected with the first winding and a serial branch of the quick breaker in parallel, and the different name ends of the two windings are connected;
the current sensor and the voltage sensor respectively monitor the current signal and the voltage signal of the line where the current limiter is located in real time, upload the detected current signal and voltage signal to a controller in the current limiter, and judge whether the line has a short circuit fault or not by the controller.
3. The method of multistage current limiting protection for a segmented bus according to claim 2, wherein,
the step 6 specifically comprises the following steps:
step 6.1, breaking a quick breaker of a controller of the fault feeder current limiter after a first zero crossing point of short-circuit current, and breaking the fault feeder current limiter after a first time delay;
step 6.2, after the second time delay, the controller of the fault feeder current limiter sends a reclosing command to the fault feeder circuit breaker, and the controller of the main current limiter monitors the running states of the fault feeder current limiter and the fault feeder circuit breaker; if the fault is an instantaneous short-circuit fault, the fault feeder current limiter resumes a normal operation state, and the fault feeder current limiter recloses successfully to resume normal operation of the line; if the permanent short circuit fault exists, executing the step 6.3;
Step 6.3, breaking the fault feeder circuit breaker, and simultaneously notifying a controller of the fault feeder current limiter to send a holding command to the main circuit breaker by the controller of the main current limiter; if the fault feeder circuit breaker fails, the controller of the main current limiter knows that the fault feeder circuit breaker is always in the on position, and delay sends an off command to the main circuit breaker to realize the backup protection of the power grid.
4. The method of multistage current limiting protection for a segmented bus according to claim 2, wherein,
the step 7 specifically comprises the following steps:
step 7.1, breaking a quick breaker of a controller of the fault feeder current limiter after a first zero crossing point of short-circuit current, and breaking the fault feeder current limiter after a first time delay;
step 7.2, after the second delay, the controller of the fault feeder current limiter sends out a reclosing command, and the controllers of the tie line current limiter and the main current limiter monitor the operation states of the fault feeder current limiter and the fault feeder circuit breaker: if the fault is an instantaneous short-circuit fault, after the current limiting is finished, the fault feeder current limiter restores the steady-state operation state, the fault feeder circuit breaker is successfully reclosed, and the normal operation of the line is restored; if the permanent short circuit fault exists, executing the step 7.3;
Step 7.3, breaking the fault feeder circuit breaker, and simultaneously, the controller of the fault feeder current limiter informs the controller of the tie line current limiter to send a holding command to the tie line circuit breaker, and the controller of the fault feeder current limiter informs the controller of the main current limiter to send the holding command to the main circuit breaker; if the fault feeder circuit breaker fails, the controller of the tie line current limiter knows that the fault feeder circuit breaker is always in the on position, and a brake-off command is sent to the tie line circuit breaker in a delayed mode, so that backup protection of a power grid is realized.
5. The multistage current limiting protection method for a segmented bus according to any one of claims 1, 3, and 4, wherein:
the value range of the first delay is 40ms-60ms;
the value range of the second delay is 250ms-350ms.
6. A multistage current limiting protection configuration system of a sectional bus based on a multistage current limiting protection method of a sectional bus according to any one of claims 1 to 5, comprising a main transformer, a main breaker, a main current limiter, a tie breaker, a tie current limiter, a bus, a feeder to which the bus belongs, a feeder breaker, a feeder current limiter and a feeder load,
the method is characterized in that:
a main breaker and a main current limiter are sequentially arranged between the main transformer and the bus correspondingly connected;
A tie line current limiter and a tie line breaker are arranged on the tie lines between adjacent buses;
and the bus is connected with a feeder, and a feeder breaker and a feeder current limiter are sequentially arranged at the head end of each feeder.
7. The multi-stage current limiting protection configuration system for a segmented bus according to claim 6, wherein:
each current limiter in the system comprises a quick breaker, a current limiting unit, a controller, a current sensor, a voltage sensor and a signal wire;
a current sensor connected with a first winding of the current limiting unit and the quick breaker in series and a voltage sensor connected on a line in parallel are arranged in the current limiter, a second winding of the current limiting unit is connected with the first winding and a serial branch of the quick breaker in parallel, and the different name ends of the two windings are connected;
the current sensor and the voltage sensor respectively monitor the current signal and the voltage signal of the line where the current limiter is located in real time, upload the detected current signal and voltage signal to a controller in the current limiter, and judge whether the line has a short circuit fault or not by the controller.
8. The multi-stage current limiting protection configuration system for a segmented bus according to claim 7, wherein:
The controller acquires a line current signal through the current sensor, and acquires a voltage signal through the voltage sensor, so as to judge whether a short circuit fault occurs in the line;
the controller obtains a status signal of the quick breaker through a signal line and controls the quick breaker;
the controller obtains a state signal of the circuit breaker through a signal wire and controls the circuit breaker;
the controller realizes signal communication with other controllers through signal wires to form a distributed feed automation system.
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