KR102058400B1 - Apparatus for discriminating instantaneous current in power grid line - Google Patents

Abstract

The present invention relates to an apparatus for determining instantaneous current in a line of a power system, comprising: a voltage inducing unit for detecting a instantaneous current in each line of a power system and inducing a voltage; and dividing the voltage derived from the voltage inducing unit into a plurality of voltages. A voltage divider, a voltage detector for detecting a voltage of some of the voltages divided by the voltage divider, and an instantaneous current of each line in a sleep mode operated at a low power under a prescribed condition Receives the generated activation power and enters the wake-up mode and simultaneously converts the analog voltage detected from the voltage detector into a digital voltage to restore the original instantaneous current value, and restores the restored instantaneous current value and the Instantaneous high speed by including a control unit that compares the set reference current value and determines whether to disconnect the line according to the result You can respond quickly to determine the current for the instantaneous incident, there is an effect that can store a variety of information about the fault current.

Description

Instantaneous current discrimination device in power system line {APPARATUS FOR DISCRIMINATING INSTANTANEOUS CURRENT IN POWER GRID LINE}

The present invention relates to an instantaneous current discrimination apparatus in a line of a power system, and more particularly, to determine an instantaneous current at a high speed, to cope with an instantaneous accident quickly, and to store various types of information on an accidental current. An instantaneous current discrimination apparatus in a line.

Generally, all buildings such as industrial sites, apartments, warehouses, factories, schools, and lodging facilities are equipped with distribution boards, which are usually equipped with a molded case circuit breaker (MCCB). .

The circuit breaker (MCCB) can open and close the circuit in the normal state by manual or electrical operation, and automatically cuts off the circuit in the event of an accident such as an overload or a short circuit. .

In addition, such a circuit breaker does not have a detection function for an imaging accident, and therefore, a thermal overcurrent relay (THR) or an electronic motor protection relay (EMPR) is required to use a three-phase load, especially a three-phase motor. .

In other words, in a power system that uses three-phase power equipment such as three-phase motor load, one-phase or two-phase disconnection of power is referred to as one-phase or two-phase open phase. Most three-phase motors have one-phase open faults.

It is reported that the 1-phase image formation of the three-phase motor mainly occurs due to the contact failure due to the aging and frequent use of the electromagnetic contactor, which is responsible for starting and stopping the three-phase motor. When one phase of a three-phase motor is missing, three-phase motors have a current that is about 1.5 times the rated current, and deterioration of the internal winding of the three-phase motor is a cause of fire.

When starting and turning on the three-phase motor in the open phase, the starting current of about 6 to 8 times of the rated current flows, causing damage to the motor as well as serious disasters. Is not an obligation, and efforts are being made to prevent and prevent it in practice.

In other words, since the site manager of the power system using the three-phase power equipment is additionally installed as necessary, it is completely dependent on the recognition and needs of the site manager.

In addition, as described above, a thermal overcurrent relay (THR) or an electronic motor protection relay (EMPR) is used to protect the three-phase motor from an open phase accident. Detectable and designed to trip within 3 seconds at a voltage unbalance rate of more than about 70%, the response speed is slow, there is a problem of frequent malfunction and accuracy in the field.

On the other hand, the electrical control method of the circuit breaker used in the low-voltage distribution system is designed in a thermal, thermoelectric or electronic structure. First, in the case of the thermal type, when the effective value of the fault current for the occurrence of the accident is small, the heat generation amount (H = 0.24I ² Rt) is small, and the blocking operation fails. In the case of the electronic type, when the period of the abnormal current is short, It is impossible to excite and the blocking function is lost, which means that there is always a risk of an electrical disaster such as an electric fire.

1 is a view schematically showing the operation of a conventional thermal or electronic low voltage circuit breaker.

Referring to FIG. 1, the analog circuit unit 10 compares the instantaneous current value input from each phase (R, S, T, N) of the power system with a reference current value previously determined, and inputs the instantaneous current value. If it is larger than this preset reference current value, it is determined that instantaneous fault current has been input. If the analog circuit unit 10 determines that the instantaneous fault current has been input, the blocking signal is output (override output) 20 to block the relay 30.

However, in the related art, since the instantaneous current is determined by the analog circuit unit 10 and outputs the cutoff signal 20, information on the accident current is not stored, and the analog circuit is used for electromagnetic interference (Electro Magnetic Compatibility, EMC). There are vulnerable problems.

The present invention has been made to solve the above problems, an object of the present invention is to determine the instantaneous current at high speed to quickly cope with the instantaneous accident, the line of the power system to store a variety of information about the accidental current To provide an instantaneous current discrimination apparatus.

In order to achieve the above object, a first aspect of the present invention includes a voltage induction unit for inducing a voltage by detecting an instantaneous current in each line of a power system; A voltage divider dividing the voltage derived from the voltage inducing unit into a plurality of voltages; A voltage detector detecting a voltage of some of the voltages divided by the voltage divider; And receiving the activated power generated using the instantaneous current of each line in the sleep mode operated at a low power under a prescribed condition, switching to the wake-up mode and detecting the voltage from the voltage detector. Converts the analog voltage into a digital voltage and restores the original instantaneous current value, and compares the restored instantaneous current value with a preset reference current value and determines whether to cut off the line according to the result. It is to provide an instantaneous current discrimination device in the line.

Here, the voltage generation unit is connected to each line between the voltage induction unit and the load, and further comprises a voltage generation unit for generating an activation power by using the instantaneous current generated in each line, the control unit generates the activation power generated from the power generation unit It is desirable to switch to the activation mode.

Preferably, the control unit may receive a portion of the power divided by the voltage dividing unit and switch to the activation mode.

Preferably, the voltage induction part is made of the same number of coil turns regardless of the rated current flowing in each line, and made of a plurality of Rogowski coils that induce voltage by differentiating the instantaneous current detected in each line. This is preferred.

Preferably, the voltage divider may adjust the output voltage through a plurality of voltage divider resistors.

Preferably, the controller compares the restored instantaneous current value with a predetermined reference current value and determines that an accidental current is generated when the restored instantaneous current value is larger than a predetermined reference current value, and loads the load through the respective lines. The line opening control signal may be output to a breaker provided in each line so that the supplied power is cut off.

Preferably, the controller compares the restored instantaneous current value with a preset reference current value, and determines that an accident current is generated when the restored instantaneous current value is greater than a predetermined reference current value, thereby determining information related to the corresponding accident current. Can be controlled to be stored in a separate memory.

Preferably, the information related to the fault current may include at least one of the magnitude, time, and waveform information of the corresponding current.

Preferably, the controller compares the restored instantaneous current value with a predetermined reference current value and determines that an accident current is generated when the restored instantaneous current value is larger than a predetermined reference current value. Specific warning signals may be output to warn external users of the information visually or audibly.

Preferably, the controller compares the restored instantaneous current value with a predetermined reference current value and determines that an accident current is generated when the restored instantaneous current value is larger than a predetermined reference current value, thereby identifying a specific accident current. A warning message may be generated and transmitted to a preset user terminal.

Preferably, the control unit may be formed of a microprocessor control unit (Microprocessor Control Unit, MCU) to control the various components in accordance with a predetermined program by receiving the operating power.

According to the instantaneous current determination device in the line of the power system of the present invention as described above, instantaneous current at high speed through a Rogowski Coil and a microprocessor control unit (MCU) without signal saturation By judging it can not only quickly cope with instantaneous accidents, but also effectively prevent the malfunction of the relay, there is an advantage that can store a variety of information on the accident current.

1 is a view schematically showing the operation of a conventional thermal or electronic low voltage circuit breaker.
2 is a diagram illustrating an example of a start and stop circuit of a three-phase induction motor using a thermal overcurrent relay mainly used in an industrial site.
3 is a block diagram illustrating an overall instantaneous current discrimination apparatus in a line of a power system according to an exemplary embodiment of the present invention.
4 is a block diagram illustrating an overall instantaneous current discrimination apparatus in a line of a power system according to another embodiment of the present invention.

The above objects, features, and advantages will be described in detail with reference to the accompanying drawings, whereby those skilled in the art to which the present invention pertains may easily implement the technical idea of the present invention. In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention illustrated below may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. In addition, the same reference numerals are used in the drawings to indicate the same or similar components.

In general, a thermal overcurrent relay forms a magnetic switch (MS) together with a magnetic contactor (MC) to trip the circuit by tripping the circuit when the current supplied to the motor becomes higher than a preset current value. To prevent burning.

That is, in the case of an AC motor, an alternating current of three phases (R, S, T) normally flows inside of the alternating current motor. At this time, when one of the three phases (R, S, T) is cut off and no current flows. When the current is concentrated in the remaining phase or the temperature rises during overload or overcurrent, the winding is burned out. To prevent this, an overcurrent relay is generally used in the motor to prevent burnout during overload or phase loss.

2 is a diagram illustrating an example of a start and stop circuit of a three-phase induction motor using a thermal overcurrent relay mainly used in an industrial site.

Referring to FIG. 2, a thermal overcurrent relay THR, which is generally used as a protection device for a three phase induction motor IM, illustrates an internal relay when an overcurrent occurs due to an overload of the three phase induction motor IM. It operates on the principle of opening and closing the contact by using the bimetal (bending action) due to hot wire heating.

On the other hand, MCB is a circuit breaker, MC is a magnetic contactor, THR is a thermal overcurrent relay, T is a time relay, PB1 is a start pushbutton, PB2 is a stop pushbutton, and GL is an operation indicator. IM is a three-phase induction motor.

The thermal overcurrent relay of the prior art performs an instantaneous override function to protect the circuit breaker itself and the line as soon as possible by performing an interruption action as soon as an electric current exceeding the breaking capacity of the breaker causes damage to the breaker itself. Have.

However, a conventional thermal or electronic low voltage circuit breaker operates as a magnetic trip or has a separate analog circuit to operate independently of the existing microprocess control unit (MCU), and the microprocess control unit (MCU) provides instantaneous fault current. Operation information is not entered. In addition, the relay judged using an analog circuit has a disadvantage that it is vulnerable to electromagnetic interference (EMC).

In order to solve this problem, the present invention utilizes Rogowski Coil without signal saturation, and at high speed within a few usec (Microsecond, 10 ^-6 ) in the microprocess control unit (MCU) through the differential signal of current. The instantaneous current can be judged quickly to cope with the instantaneous accident, it is a characteristic technology that can store various information about the accidental current.

3 is a block diagram illustrating an overall instantaneous current discrimination apparatus in a line of a power system according to an embodiment of the present invention.

Referring to FIG. 3, the instantaneous current determination device in a line of a power system according to an embodiment of the present invention includes a voltage induction unit 100, a voltage divider 200, a voltage detector 300, and a power generator 400. ) And the control unit 500 and the like.

Here, the voltage inducing unit 100 detects the instantaneous current in each line (R, S, T, N) of the power grid to perform a function of inducing voltage.

In this case, the power system generally includes any power supply capable of supplying electricity to the load 600, including a power project for producing and supplying electricity or a means for producing and / or supplying electricity in addition to the power project. Used in the sense.

For example, the load 600 is a power system, operators receiving electricity generated from the power system and supplying electricity to railroads or urban railways, Small Hydropower, Photovoltaic, Solar Renewable energy that supplies electricity from renewable energy such as thermal, wind power, waste energy, bio energy, geo thermal, ocean energy, etc. At least one or more of the processing systems may be supplied with electricity from a power supply.

In addition, the power supply source and load 600 is a smart-grid (intelligent power grid), which means the next generation power system and its management system implemented through the convergence and complex of the modernized power technology and information communication technology that is emerging recently. ) Is also possible.

On the other hand, the load 600 is connected to a number of transformers (transformers) using a local power distribution cable as a final accommodating means of power factories, stores, homes, etc. to receive power.

The voltage induction part 100 is made of the same number of coil turns regardless of the rated current flowing in each line (R, S, T, N), and the instantaneous current detected by each line (R, S, T, N) It is preferably made of a plurality of Rogowski Coil to differentiate by inducing a voltage.

Unlike the current transformer (CT), the Rogowski coil is excited by using a plastic bobbin made of a special material forming an air core without using a magnetic core. When a current flows through a conductor that penetrates the core core, a voltage proportional to the current of the conductor is induced by the coil wound around the core core, thereby detecting the magnitude of the current flowing in the conductor. Have

That is, the Rogowski coil can be used in a wide range of areas such as opening and closing transient measurement of semiconductors, and can measure large currents of 100A to 100KA with the same size, and are separated from the primary side, and have excellent insulation and magnetic materials. It does not contain the excellent linearity, unlike the through-type current transformer has the advantage of forming an air core without internal iron core does not suffer overcurrent damage due to iron core saturation.

In addition, when a current flows in the conductor located inside the Rogowski coil, the induced voltage V _out induced by the Rogowski coil by the current is expressed by Equation 1 below.

(Equation 1)

Here, I is the current flowing through the conductor, the current to be measured, μ ₀ is the permeability of the vacuum, N is the winding density of the coil, and A is the cross-sectional area of the Rogowski coil.

As shown in Equation 1, when the sinusoidal current flows through the conductor, the waveform of the voltage detected as an output from the Rogowski coil becomes a derivative value of the sinusoidal wave and cannot be directly expressed as a current value.

Therefore, in order to obtain the measured current value, the induced voltage V _out output from the Rogowski coil must be integrated through the signal processor. The signal processing unit is preferably performed through the control unit 500, which will be described later. However, the signal processing unit is not limited thereto, and may include a passive integrating circuit unit or an operational amplifier composed of a separate signal amplifying circuit, a resistor, and a capacitance. It may be implemented through an active integrating circuit.

The voltage divider 200 is electrically connected to the voltage inducing unit 100 and divides the voltage derived from the voltage inducing unit 100 into a plurality of voltages. The voltage divider 200 may adjust the output voltage through a plurality of voltage divider resistors.

On the other hand, since the voltage derived from the voltage induction unit 100 cannot be immediately recognized by the control unit 500 due to a large instantaneous current value, it is necessary to reduce the voltage to an appropriate voltage so that the control unit 500 can recognize it. Therefore, the voltage derived from the voltage inducing unit 100 through the voltage divider 200 is divided into a plurality of voltages that the control unit 500 can recognize.

The voltage detector 300 is electrically connected to the voltage divider 200 and performs a function of detecting a voltage of some of the voltages divided by the voltage divider 200.

The power generation unit 400 is connected to the line of the load 600 side, and performs a function of generating an active power by using instantaneous current of each line (R, S, T, N).

In this case, the activation power means a minimum power supply (for example, current or voltage signal) for the control unit 500 to switch from the sleep mode to the wake-up mode.

The power generation unit 400 is configured to generate a predetermined active power by a large instantaneous current generated from each line R, S, T, N, that is, an instantaneous fault current, for example, a current converter. Transformer, CT), Shunt, Hall Sensor, Rogowski Sensor, etc. can be used.

In addition, the control unit 500 receives the activated power generated from the power generator 400 in the sleep mode operated at a low power under a prescribed condition, and switches to the wake-up mode. After converting the analog voltage detected by the voltage detector 300 into a digital voltage to restore the original instantaneous current value, compares the restored instantaneous current value with a preset reference current value and determines whether the line is blocked according to the result. Determining the function.

That is, the control unit 500 performs signal processing to restore the voltage induced by the voltage inducing unit 100 to the original instantaneous current, and includes amplifying means for amplifying a signal of the induced voltage detected by the voltage detecting unit 300. An integrating means for integrating the signal amplified by the amplifying means, an analog / digital (A / D) converting means for converting the analog signal integrated from the integrating means into a digital signal, and the A / D converting means And arithmetic control means for arithmetic processing of the digital signal.

In addition, the controller 500 compares the restored instantaneous current value with a predetermined reference current value, and when the restored instantaneous current value is larger than a predetermined reference current value, determines that an accident current is generated and causes each line (R, S). The line opening control signal may be output to the breakers 700 provided in the respective lines R, S, T, and N so that the power supplied to the load 600 is cut through the T and N. FIG.

At this time, the breaker 700 is installed so as to be connected between the input side for supplying electricity and the load 600 side of the consumer using electricity, the input power is supplied to the load 600 by the excitation operation of the trip coil. It performs the function of blocking.

In addition, the controller 500 compares the restored instantaneous current value with a preset reference current value, and when the restored instantaneous current value is greater than a predetermined reference current value, determines that an accident current is generated and related information regarding the accident current. May be controlled to be stored in itself or in a separate memory 550.

At this time, the information related to the fault current is preferably made of at least one of information of the magnitude, time, and waveform of the corresponding current.

In addition, the controller 500 compares the restored instantaneous current value with a predetermined reference current value, and when the restored instantaneous current value is larger than a predetermined reference current value, determines that an accident current is generated to generate the corresponding accident current. A specific warning signal may be output to warn an external user to a visual (eg, lamp or LED) or audible (eg, speaker).

In addition, the controller 500 compares the restored instantaneous current value with a predetermined reference current value, and when the restored instantaneous current value is larger than a predetermined reference current value, determines that an accident current is generated to identify a corresponding accident current. A warning message may be generated and transmitted to a preset user terminal (not shown).

In this case, the user terminal is generally a computer such as a desktop PC (Personal Computer, PC), notebook PC, etc., but is not limited thereto, and is connected to the control unit 500 through a wired / wireless communication network to transmit and receive data. It can be any kind of wired or wireless communication device.

For example, the user terminal may include various mobile terminals communicating through a wireless Internet or a portable Internet. In addition, a palm personal computer (SPC), a smart phone, and a digital multimedia broadcasting (DMB) having a communication function may be used. It can mean all wired / wireless home appliances / communication devices that can send and receive messages such as phones and tablet PCs.

The control unit 500 configured as described above is preferably made of a microprocessor control unit (Microprocessor Control Unit, MCU) for controlling various components according to a predetermined program by receiving the operating power, but is not limited thereto. It can be implemented with any control processor with a sleep mode function that operates at low power (preferably in the range of about 1 to 10mA).

On the other hand, the sleep mode (Sleep mode) refers to a state that reduces the power loss in the standby mode by applying the minimum power to the control unit 500. Of course, since the control unit 500 is not completely turned off, the sleep mode is switched to the wake-up mode as soon as a signal for activating the control unit 500 is input. To this end, in the sleep mode, it is possible to record information necessary for the operation of the controller 500 in the memory 550 and to load an optimal value according to the situation.

That is, when normal power is supplied to the controller 500 by self power, the controller 500 performs a normal operation. When no current is generated due to no load, the controller 500 enters the sleep mode and enters the standby mode. It works.

At this time, the power source uses a built-in battery (Battery), and in the sleep mode 3V power is used because about 1.3uA, the capacity of the used built-in battery is 1200mh can be used for 80 years. Since the controller 500 recognizes whether the current power state is a self power operation or a battery operation, the controller 500 may determine the normal operation and the sleep mode operation according to the power state.

4 is a block diagram illustrating an apparatus for determining instantaneous current in a line of a power system according to another embodiment of the present invention, in which the power generation unit 400 is omitted in comparison with the above-described embodiment of the present invention. In this case, the same components as those in the above-described embodiment of the present invention will be denoted by the same reference numerals and names.

Referring to FIG. 4, an instantaneous current determination device in a line of a power system according to another embodiment of the present invention includes a voltage induction unit 100, a voltage divider 200, a voltage detector 300, a controller 500, and the like. It is made, including.

Here, the voltage induction unit 100 detects the instantaneous current in each line (R, S, T, N) of the power grid as in the embodiment of the present invention to perform a function of inducing a voltage For a detailed description thereof, reference will be made to one embodiment of the present invention described above.

The voltage dividing unit 200 is electrically connected to the voltage inducing unit 100 and performs a function of dividing the voltage derived from the voltage inducing unit 100 into a plurality of voltages. Reference is made to one embodiment of the invention.

The voltage detector 300 is electrically connected to the voltage divider 200, and performs a function of detecting a voltage of some of the voltages divided by the voltage divider 200. Reference is made to one embodiment of the invention.

In particular, in another embodiment of the present invention, rather than using the activation power generated by the power generator 400 applied to the above-described embodiment of the present invention, some of the voltages divided by the voltage divider 200 are used. It is used as an active power source using the voltage of.

That is, the control unit 500 is supplied to the partial power divided by the voltage dividing unit 200 in the sleep mode (Sleep mode) operating under a prescribed condition is switched to the wake-up mode and At the same time, the analog voltage detected by the voltage detection unit 300 is converted into a digital voltage to restore the original instantaneous current value, and compares the restored instantaneous current value with a preset reference current value and disconnects the line according to the result. To determine the function.

In addition, the other functions of the control unit 500 applied to another embodiment of the present invention are the same as the above-described embodiment of the present invention, a detailed description thereof will be referred to the above-described embodiment of the present invention.

As described above, in the embodiments of the present invention, a high speed cutoff may be realized by using a differential signal of a Rogowski coil without signal saturation, and the differential signal may be used to quickly determine an accident current at the time of a short circuit accident. .

Accordingly, a quick boot-up of the control unit 500, that is, the microprocess control unit (MCU) is required, but a typical boot takes several msec, but the wake-up function of the microprocess control unit (MCU) is used. Therefore, it takes only about 8usec to convert from sleep mode to wake-up mode, so high-speed signal processing is possible.

On the other hand, the Rogowski coil output of about 400A is about 7.76mV. The Rogowski coil's output is about 9.3V at about 55KA current, which is the instantaneous override. The voltage is divided to determine the voltage input to the A / D conversion means of the controller 500 to perform an instantaneous operation. At this time, the operational starting point takes about 2.2 msec.

Although the preferred embodiment of the instantaneous current discrimination apparatus in the line of the power system according to the present invention has been described above, the present invention is not limited thereto, but the scope of the claims and the detailed description of the invention and the accompanying drawings are various. It is possible to carry out the transformation to this also belongs to the present invention.

100: voltage induction part, 200: voltage divider part,
300: voltage detector, 400: power generator,
500: control unit, 550: memory,
600: load, 700: breaker

Claims (11)

A voltage inducing unit including a plurality of Rogowski coils for inducing voltage by differentiating the instantaneous current detected in each line of the power system;
A voltage divider dividing the voltage derived from the voltage inducing unit into a plurality of voltages;
A voltage detector detecting a voltage of some of the voltages divided by the voltage divider; And
Amplifying the signal of the analog voltage detected by the voltage detector, integrating the amplified signal, converts the integrated signal into a digital voltage to restore the original instantaneous current value, the restored instantaneous current value and the predetermined reference current Comprising a control unit for comparing the value and determine whether the line is blocked according to the result,
The control unit
In the sleep mode operated at a low power under a prescribed condition, the activated power generated using the instantaneous current of each line is supplied to the wake-up mode, and the restored instantaneous current value When it is larger than the reference current value, it is determined that an accident current is generated and outputs a line opening control signal to a breaker provided in each line so that power supplied to the load is cut off through each line,
The activation power is
Supplied by the power generating unit or the voltage divider connected to each line between the voltage inducing unit and the load
Instantaneous current discrimination device in the line of power system.
delete delete delete According to claim 1,
The voltage divider, the instantaneous current determination device in the line of the power system, characterized in that for adjusting the output voltage through a plurality of voltage divider resistors.
delete According to claim 1,
The controller, if it is determined that an accident current is generated, the instantaneous current determination device in the line of the power system, characterized in that for controlling to store the information related to the accident current in a separate memory.
The method of claim 7, wherein
The information related to the accident current, instantaneous current determination device in the line of the power system, characterized in that made of at least one of the information of the magnitude, time and waveform information of the current.
According to claim 1,
The control unit, when it is determined that the accident current is generated, the instantaneous current determination device on the line of the power system, characterized in that for outputting a specific warning signal to warn the external user visually or audibly about the occurrence of the accident current.
According to claim 1,
The control unit, when it is determined that the accident current is generated, the instantaneous current determination device on the line of the power system, characterized in that for generating a specific warning message for the accident current and transmits it to a predetermined user terminal.
According to claim 1,
The control unit, the instantaneous current determination device in the line of the power system, characterized in that made of a microprocessor control unit (Microprocessor Control Unit, MCU) to control the various components in accordance with a predetermined program is supplied with operating power.

Images