CN216489750U - Economic current limiter for deeply limiting short-circuit current - Google Patents

Abstract

The economical current limiter for deeply limiting the short-circuit current comprises a measurement and control unit, a Rock coil, a current limiter main body, a switching power supply, a control and isolation transformer and a current limiter base, wherein a shell of the current limiter main body is a hollow composite insulator, a device heat dissipation hole is formed in the top of the shell, a deep current limiting reactor and a high-speed switch are arranged in the current limiter main body, and the high-speed switch is connected with the deep current limiting reactor and arranged below the deep current limiting reactor; the measurement and control unit is connected with the Rock coil and the high-speed switch, a switching power supply and control are arranged below the current limiter main body, and the switching power supply and the control are arranged on a base of the current limiter through an isolation transformer. The device has good current limiting effect, can complete the switching-off and switching-on operations in a very short time, and has the advantages of strong switching-off capability, high reliability, long service life, economy and energy conservation. The system has almost zero loss in normal operation, small occupied area, low cost and simple maintenance, can be flexibly applied to various current-limiting occasions of the power system, and has safe and reliable operation.

Description

Economic current limiter for deeply limiting short-circuit current

Technical Field

The present invention relates to current fault current limiters, and more particularly to economical current limiters that deeply limit short circuit current.

Background

As is known, when a short-circuit fault occurs in an electric power system, the short-circuit current is generally ten times or more of the rated current, which causes great harm to electrical equipment such as transformers, generators, circuit breakers, transmission lines, and the like, while the breaking capacity of the existing economical and practical vacuum circuit breakers is below 40kA, and the breaking time needs tens of milliseconds. Along with the development and growth of various types of power utilization enterprises, the power load is greatly increased, the capacity of a main transformer is correspondingly increased, and power grid systems of various enterprises face the problems that the short-circuit current approaches and reaches the maximum use limit of a load vacuum circuit breaker, the on-off capacity of the load side vacuum circuit breaker is insufficient, the design of the short-circuit current impact resistance capacity of the transformer is insufficient, and the like, so that the safe operation of the enterprises is seriously threatened.

In the face of the increasingly serious problem that the short-circuit current exceeds the standard, many enterprises adopt a method of limiting the system short-circuit current by a high-impedance transformer, but the problem of current limiting depth is not finally solved by increasing impedance of the transformer, the electric power is reduced slightly, and a series of problems of active and reactive power loss, investment cost increase and the like are brought.

The problem of current-limiting depth is not fundamentally solved by adopting a common series current-limiting reactor (the reactance rate is about ten percent). When a system is short-circuited, the current-limiting depth is not enough, and main electrical equipment such as a generator and a transformer cannot be effectively protected, so that winding deformation and equipment damage are easily caused under the impact of huge short-circuit current, and further catastrophic accidents are caused.

The explosive type high-capacity high-speed cut-off device and the reactor used in the market run in parallel, although the problems of active and reactive power loss, voltage drop, magnetic leakage field and the like of the reactor are solved by the method, when a short-circuit fault occurs, the primary component acts, and the problem of current limiting depth is not solved when the reactor is put into operation. The spare parts of this type device action back needs to be changed newly, can drop into the operation again, and the operating cost of enterprise increases to increased the space of the installation cabinet body and the bus connection between the reactor device, artificial trouble hidden danger point that has set up.

SUMMERY OF THE UTILITY MODEL

In order to solve the problems, an economical current limiter for deeply limiting short-circuit current quickly and reliably is developed, and the technical scheme is as follows:

the economical current limiter for deeply limiting the short-circuit current comprises a measurement and control unit, a rogowski coil, a current limiter main body, a switching power supply, a control and isolation transformer and a current limiter base, wherein a shell of the current limiter main body is a hollow composite insulator, the top of the current limiter main body is provided with a device heat dissipation hole, a deep current limiting reactor and a high-speed switch are arranged in the current limiter main body, and the high-speed switch is connected with the deep current limiting reactor and arranged below the deep current limiting reactor; the measurement and control unit is connected with the rogowski coil and the high-speed switch, a switching power supply and control are arranged below the current limiter main body, and the switching power supply and the control are arranged on a base of the current limiter through an isolation transformer.

The measurement and control unit detects the system current through the rogowski coil and sends an opening/closing command to the high-speed switch.

A rogowski coil is mounted on the bus for monitoring the system current.

The high-speed switch consists of an energy storage capacitor and a high-speed eddy current driving switch, the energy storage capacitor is used for storing energy and then discharging to the coil, and the magnetic flux generated by the coil drives the eddy current to be induced in the eddy current disc and generate mutual repulsion action with a magnetic field to drive the high-speed eddy current driving switch to be switched on and off; the high-speed eddy current driving switch consists of an electromagnetic repulsion mechanism and a vacuum arc-extinguishing chamber, is in a closing state when a system normally operates so as to carry out short circuit on the current-limiting reactor without generating energy loss, and is rapidly opened within a set time after receiving an action signal of the measurement and control unit, and the deep current-limiting reactor is put into a fault loop so as to limit short-circuit current.

The deep current-limiting reactor consists of large inductance elements, is short-circuited by a switch when a system normally runs, and is connected into a fault loop to limit fault current and maintain normal bus voltage after the system breaks down.

The isolation transformer is used for electrically insulating the primary side and the secondary side, isolating the loop, inhibiting high-frequency noise waves from being transmitted into the control loop and ensuring the electricity safety

The flow restrictor base is used to provide support for flow restrictor placement.

The device heat dissipation hole is communicated with a heat dissipation channel arranged in the current limiter main body.

The main body of the current limiter is of a cylindrical structure.

The base of the current limiter is of a disc structure.

Compared with the prior art, its advantage effect lies in: the device current-limiting is effectual, accomplish separating brake and combined floodgate operation in the very short time, the breaking capacity is strong, the device reliability is high, long service life, at the almost zero loss of system normal operating, satisfy the energy-conserving demand of system, and area is little, it is simple to maintain, can be applied to various current-limiting occasions of electric power system in a flexible way, can not only guarantee electric power system's safety, the reliable operation, and have very important meaning to reducing the equipment cost of electrical equipment user, compare in traditional scheme series reactor, the explosion bridge scheme is more economical, it is more energy-conserving.

Drawings

FIG. 1 is a schematic diagram of an overall structure of an economical current limiter for deeply limiting short-circuit current;

FIG. 2 is an electrical schematic of an economical current limiter for deep limiting short circuit current;

FIG. 3 is a schematic diagram of the installation location of a current limiter in a power grid;

FIG. 4 is a waveform of bus voltage and fault current;

in the figure: 1. the device comprises heat dissipation holes, 2, a hollow composite insulator, 3, a deep current-limiting reactor, 4, an energy storage capacitor, 5, a high-speed eddy current driving switch, 6, a switching power supply and control unit, 7, an isolation transformer, 8 and a current limiter base.

Detailed Description

Embodiments for implementing the present invention are described in detail with reference to the accompanying drawings. The present invention is not limited to the contents described in the following embodiments. The following constituent elements include substantially the same elements that can be easily obtained by those skilled in the art. The following structures may be combined as appropriate. Various omissions, substitutions, and changes in the structure may be made without departing from the spirit of the utility model.

The dimensions of the components in the drawings do not strictly indicate the actual dimensions of the components, the dimensional ratios of the components, and the like, and are merely intended to schematically illustrate the principles and concepts of the present invention.

Example 1

As shown in fig. 1-2, when the power system is in normal operation, the high-speed eddy current driving switch 5 is in a closed state, and the high-speed eddy current driving switch 5, as a simple current guiding device, presents a zero-loss state to the outside. When the power system has short-circuit fault, the current collector rapidly transmits the short-circuit current information to the switching power supply and the control 6; the switching power supply and control unit 6 accurately and rapidly judges the zero crossing time of the three-phase current through a proper algorithm, respectively sends an action signal to the high-speed eddy current driving switch 5 before the zero-crossing time of each phase current, and puts the deep current-limiting reactor 3 into a fault loop; when the fault is detected to be relieved, namely the bus voltage rises, a current limiter exit signal is sent to the high-speed eddy current drive switch 5, the deep current limiting reactor 3 is in short circuit, and the current limiter exits from running.

Example 2

As shown in fig. 3, in order to effectively reduce the short-circuit current level of the system, the economical current limiter for deeply limiting the short-circuit current is mainly installed at the following four locations, which should be used on the premise that it should be cheaper than a large-sized circuit breaker, and the installation cost must be lower than the cost of upgrading the short-circuit breaker:

1) and the generator outlet protects a generator end bus.

2) And the generator-main transformer outlet protects a generator end bus and a main transformer.

3) And the feed line limits the short-circuit current of each feeder branch.

4) And the bus tie line is used for limiting the short-circuit current of the two system buses and maintaining the bus voltage.

When the economical current limiter for deeply limiting short-circuit current is arranged on the bus connecting line, the reliability of closed-network operation is enhanced. When in normal operation, the two buses run in parallel, and power can be exchanged through the bus coupler, so that reasonable distribution of power is facilitated. When the outgoing line of any bus has a fault, the economic current limiter which is arranged at the position connected with the bus and limits the short-circuit current deeply presents high impedance in response to overcurrent, the convergence of the other bus can be effectively inhibited, the short-circuit current level is lower than the breaking capacity of the outgoing line breaker, and the reliable power supply of the normal line is ensured. After the fault is removed, the economical current limiter for deeply limiting the short-circuit current returns to the normal operation state. In addition, when one transformer exits due to faults in normal operation, after the economical current limiter which is connected with the bus and used for limiting the short-circuit current deeply is installed and recovered, all outgoing lines can be supplied with power uninterruptedly by the other line, and the reliability of power supply is enhanced.

Example 3

As shown in fig. 4, when a short-circuit fault occurs near the generator outlet, the bus voltage drops instantaneously and approaches zero, the short-circuit current jitters, and the peak value reaches 35.69a in a half cycle. When the short-circuit current approaches zero, the economical current limiter for deeply limiting the short-circuit current acts, the high-speed eddy current drive switch 5 is tripped to rapidly switch the deep current limiting reactor 3 into a fault loop, the maximum amplitude of the short-circuit current is limited to 5.612A, and the bus voltage is increased to about 85% of the normal voltage; and then the bus protection acts, the voltage is recovered to be normal, and the fault loop breaking current is reduced to zero.

The embodiments of the present invention have been specifically described above. The above description is merely an explanation of one embodiment, and the scope of the present invention is not limited to this one embodiment, and should be interpreted broadly as a scope that can be grasped by a person skilled in the art based on the same technical idea.

Claims (7)

1. The economical current limiter for limiting the short-circuit current deeply is characterized by comprising a measurement and control unit, a rogowski coil, a current limiter main body, a switching power supply, a control unit (6), an isolation transformer (7) and a current limiter base (8), wherein the shell of the current limiter main body is a hollow composite insulator (2), the top of the current limiter main body is provided with a device heat dissipation hole (1), a deep current limiting reactor (3) and a high-speed switch are arranged in the current limiter main body, and the high-speed switch is connected with the deep current limiting reactor (3) and arranged below the deep current limiting reactor (3); the measurement and control unit is connected with the rogowski coil and the high-speed switch, a switching power supply and a control unit (6) are arranged below the current limiter main body, and the switching power supply and the control unit (6) are arranged on a current limiter base (8) through an isolation transformer (7).

2. A deep short circuit current limiting economical current limiter according to claim 1 characterized in that said rogowski coil is mounted on a bus bar.

3. A deep limiting short-circuit current economy current limiter according to claim 1 characterized in that the high-speed switch is composed of an energy storage capacitor (4) and a high-speed eddy current driven switch (5).

4. An economical current limiter to limit the short-circuit current deeply according to claim 1 characterized in that said deep current limiting reactor (3) is composed of a large inductance element.

5. Economical current limiter for deep limiting of short-circuit current according to claim 1 characterized by the device heat dissipation hole (1) communicating with a heat dissipation channel arranged in the current limiter body.

6. The economical current limiter for deeply limiting short-circuit current according to claim 1, wherein said current limiter body is a cylindrical structure.

7. Economical current limiter for deep limiting of short-circuit currents according to claim 1 characterized in that the base (8) of the current limiter is of disc structure.

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