KR102273351B1 - Ultra-precision ground detection system for energy storage system and switchgear pannel - Google Patents

Abstract

The present invention relates to a ground detection system for an energy storage device and an onsite switchboard. In an ultraprecision ground detection system having Option #1 IEC61850, Option #2 Modbus AGFR, Option #3 RS-485, Ethernet TCP/IP, and DGPS RS-485 functions, through a high-sensitivity direct current converter, which can precisely measure a direct low current of several mA through an output terminal of a main coil by changing an oscillation cycle of square waves of a square wave oscillator circuit by amplifying an induced electromotive force induced to a sub coil which is separate from the main coil to a ferromagnetic body core, a ground fault and a leakage current, which have to be detected at several mA, can be detected, and, as a result, the system can be beneficially used to prevent a big accident such as a fire, a short circuit or the like, which can happen later.

Description

{Ultra-precision ground detection system for energy storage system and switchgear pannel}

The present invention relates to an energy storage device and an ultra-precision grounding detection system for an in-house switchboard, and more particularly, to an energy storage device capable of measuring a low current of several mA and an ultra-precise grounding detection system for an in-house switchboard.

In order to reduce global warming through low-carbon policies around the world, coal-free power plants are being promoted, and solar power plants and wind power plants, which are new and renewable energy, are being expanded.

In order to generate such renewable energy, such as solar and wind power, an energy storage device is absolutely necessary. The energy storage device stores surplus power in the case of solar and wind power generation, which are renewable energy, and is used when the renewable energy is not generated. In addition, surplus power is stored in general power facilities and used during peak load.

Types of energy storage devices are commercialized as flywheels, pumped water power generation, air compression, supercapacitors, and lithium-ion batteries, and the lithium-ion battery is the most used. The lithium ion battery has a high energy density, no memory effect, good charging and discharging efficiency, and long life, so it is used the most, but recently, this lithium ion battery has become a social problem due to frequent fire accidents.

Among the causes of lithium-ion battery fire accidents, ground fault current and leakage current account for a fairly high proportion. Lithium ion battery is a DC power supply, and in order to detect ground fault and leakage current, a DC current transformer is used.

However, the DC current transformer has a low magnetic field at low current, that is, several mA, so it is difficult to measure.

In order to secure the fire and accident prevention of the on-site switchboard, where all power sources (protective monitoring equipment, lighting, and equipment) in the substation branch off, separate devices are configured on the DC line to monitor the on-site power and renewable energy storage system.

The DC substation switchboard is mainly used to supply power to various protection and monitoring devices in the substation, and when a failure occurs, the protection and monitoring devices stop working. Due to the nature of DC power, it is impossible to detect current through a general current transformer (CT), so a separate AC component current flows through the DC system to prevent an earth leakage accident through DCT (Detetive CT) that detects grounding when it occurs.

As a DC current transformer to measure the DC ground fault current and leakage current, a Hall sensor current transformer, a flux-gate current transformer, or the like is used. As related prior art, Patent Registration No. 10-2111489 (Reference 1), Registration Patent No. 10-1571369 (Reference 2), etc. have been proposed.

The Hall sensor current transformer measures DC current using an open loop method as shown in FIG. 1 and a closed loop method as shown in FIG. 2 .

The open-loop Hall sensor current transformer shown in FIG. 1 assembles the Hall sensor 2 between the ferromagnetic cores 1, measures the magnitude of magnetic flux Φ with the Hall sensor 2, and amplifies it through the amplifier 3 .

The closed-loop type Hall sensor current transformer shown in FIG. 2 is a method of measuring by adding a winding 4 to the open-loop Hall sensor current transformer. The magnetic flux Φ generated in the ferromagnetic core 1 by the DC current flowing through the conductor is removed. In order to do this, the secondary side feedback winding (4) is made and the shunt resistor (5) is connected thereto to measure the voltage applied to both ends of the shunt resistor (5) so that the secondary current flows.

On the other hand, in the flux gate DC current transformer shown in FIG. 3 , for example, a coil 6 is wound around a ferromagnetic core 1 , a square wave is applied to one end of the wound coil 6 , and a shunt resistor is located at the lower end of the coil 6 . (5) is connected. The voltage applied to the shunt resistor 5 is amplified through the amplifier 3 to measure the current I of the wire to be measured.

The flux gate DC current transformer applies a square wave as shown in FIG. 4 to the coil 6 wound around the ferromagnetic core 1 to amplify the voltage induced in the shunt resistor 5 and measure the current I in the wire to be measured. is measured, which is easy to measure as shown in FIG. 4 . When a square wave (A) is applied to the wound coil 6 and the current I to be measured is 0A, V _out becomes a vertical symmetrical waveform as shown in FIG. 4B .

At this time, when '+ number A' is applied to the current I to be measured, the upper part becomes magnetically saturated and protrudes from T1 as shown in FIG. 4C, and does not protrude due to non-magnetic saturation at T2. Conversely, when '-number A' is applied to the current I to be measured, the upper part is not magnetically saturated and there is no protrusion at T1, and the lower part becomes magnetically saturated and protrudes from T2 as shown in FIG. 4D.

By the way, the current to be measured is easy to measure at several A, but very difficult to measure at several mA because there is no difference in the area of the waveform because I has no change in the waveform at 0A(B) and is the same.

Therefore, ground fault and leakage current should be detected at several mA, but detection at several A may result in a large accident such as fire or short circuit due to late detection.

That is, at a very low DC current (several mA) as described above, there is no waveform change as shown in (C) and (D) of FIG. 4 and it is very insignificant, so DC current measurement becomes a problem.

Reference 1: Registered Patent No. 10-2111489 Reference 2: Registered Patent No. 10-1571369

Therefore, the present invention is to solve these problems, and in an energy storage device and a grounding detection device for an on-site switchboard, Option #1 IEC61850 is linked with the upper system, Option #2 is Modbus linked with AGFR, Option #3 RS- The purpose of providing an ultra-precise grounding detection system linking with DI, DO, CT/PT, AI with 485, linking with HMI with Ethernet TCP/IP, and linking with DC current transformers with DGPS (DC Ground Processing System) RS-485. There is this.

In particular, in the present invention, an auxiliary coil is additionally wound on a ferromagnetic core in DC ground detection connected from DGPS to RS-485, and the square wave cycle applied to the other main coil is changed with the induced electromotive force induced in the additionally wound auxiliary coil. Therefore, the purpose of this is to provide an ultra-precise grounding detection system to which a DC low current of several mA can be easily measured and a high-precision and high-sensitivity DC current transformer is applied.

The present invention in order to solve such a technical problem; Option #1 IEC61850, Option #2 Modbus AGFR, Option #3 RS-485, Ethernet TCP/IP, DGPS RS-485 function to be selectively installed according to the installation environment in energy storage devices and grounding detection devices for on-site switchboards. It features an ultra-precise ground detection system.

In particular, the present invention relates to a device in connection with a DGPS RS-485 DC current transformer, a ferromagnetic core through which feeder P and N phase conductors pass, a main coil wound around the ferromagnetic core, and a square wave applying a square wave to one end of the main coil. An oscillation circuit, a shunt resistor connected to the lower end of the main coil to measure a DC current in the form of a voltage, an auxiliary coil wound around the ferromagnetic core, and the auxiliary coil to change an oscillation period of a square wave of the square wave oscillation circuit It provides a high-sensitivity DC current transformer comprising a first amplifier for amplifying the induced electromotive force induced in the oscillation circuit and outputting the square wave oscillation circuit.

In addition, the arithmetic processing unit calculates the current value of the wire and transmits it to the ultra-precision grounding detection system through RS-485 communication, and the ultra-precise grounding detection system is characterized in that it determines whether the feeder has a ground fault or a leakage current.

According to the present invention, among Option #1 IEC61850, Option #2 Modbus AGFR, Option #3 RS-485, Ethernet TCP/IP, and DGPS RS-485 functions in the grounding detection system for energy storage devices and on-site switchboards, it is optional according to the installation environment In the ultra-precision ground detection system that can be installed as a ferromagnetic core, the induced electromotive force induced in the auxiliary coil separate from the main coil is amplified to change the oscillation period of the square wave of the square wave oscillation circuit, and a direct current of several mA through the output terminal of the main coil Low current can be measured accurately.

In addition, the high-sensitivity DC current transformer applied to the energy storage device and the ground detection system for on-site switchboards according to the present invention is very useful to prevent large accidents such as fires and short circuits that may occur after several mA ground faults and leakage currents occur. can

1 is a configuration diagram illustrating a general open-loop type Hall sensor current transformer.
2 is a block diagram illustrating a general closed-loop type Hall sensor current transformer.
3 is a block diagram illustrating a typical flux gate DC current transformer.
4 is a waveform diagram illustrating a typical flux gate DC current transformer.
5 is a block diagram of a high-sensitivity DC current transformer according to the present invention.
6 is a waveform diagram for explaining a high-sensitivity DC current transformer according to the present invention.
7 is a waveform diagram illustrating sampling of a high-sensitivity DC current transformer according to the present invention.
8 is a configuration diagram of a high-sensitivity DC current transformer in a case according to the present invention.
9 is an RJ-45 connection diagram applied to high-sensitivity DC current according to the present invention.
10 is a PCB configuration diagram of a high-sensitivity DC current transformer according to the present invention.
11 is a block diagram of an ultra-precise ground detection system to which a high-sensitivity DC current transformer according to the present invention is applied.
12 is a block diagram illustrating an ultra-precise grounding detection system of an in-house switchboard to which a high-sensitivity DC current transformer according to the present invention is applied.
13 is a block diagram illustrating a new renewable energy ultra-precision ground detection system to which a high-sensitivity DC current transformer according to the present invention is applied.

Hereinafter, the characteristics of the energy storage device and the ultra-precision grounding detection system for in-house switchboard according to the present invention will be understood by the embodiments described in detail with reference to the accompanying drawings.

Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all the technical ideas of the present invention, so at the time of the present application, they can be replaced with various It should be understood that there may be equivalents and variations.

Referring to FIG. 5, the high-sensitivity DC current transformer applied to the energy storage device and the ultra-precision grounding detection system for the switchgear in the house according to the present invention additionally winds an auxiliary coil in addition to the main coil wound on the ferromagnetic core, and the induced electromotive force generated here It is possible to measure DC low current in the form of voltage at the output terminal of the main coil by amplifying it with an amplifier and applying it to the square wave oscillation circuit to change the oscillation period of the square wave.

The high-sensitivity DC current transformer 100 of the present invention as described above includes a ferromagnetic core 110, a main coil 120 wound on one side of the ferromagnetic core 110, and applying a square wave to one end of the main coil 120. A square wave oscillation circuit 130 , a shunt resistor 140 connected to the lower end of the main coil 120 to measure a DC current in the form of a voltage, and an auxiliary coil wound on the other side of the ferromagnetic core 110 . (150) and a first amplifier 160 for amplifying the induced electromotive force induced in the auxiliary coil 150 to change the oscillation period of the square plate of the square wave oscillation circuit 130 and outputting it to the square wave oscillation circuit 130 includes

_{With this configuration, the DC current in the form of a voltage (output voltage V out} ) output to the lower end of the main coil 120 is proportional to the current flowing through the measuring wire, which is a control board 170 of the high-sensitivity DC current transformer 100 to be described later. ) is provided to the arithmetic processing unit 171 to calculate the current value of the corresponding wire.

As an example, when there is no P, N-phase leakage and ground fault current that is a feeder wire passing through the ferromagnetic core 110 of the high-sensitivity DC current transformer 100 of the present invention, the current flowing in the wire is I = 0A, and the square wave oscillation circuit 130 of The oscillation waveform has a period as shown in FIG. 6A.

_{At this time, the DC current in the form of a voltage (V out} ) output to the lower end of the main coil 120 has the same waveform as (C).

On the other hand, if a very small ground fault or leakage current of several mA occurs in the P and N phases, the square wave oscillation circuit 130 with the induced electromotive force induced in the auxiliary coil 150 additionally wound as shown in FIG. 6(B). change the cycle of

As such, as the square wave whose period is changed by the square wave oscillation circuit 130 is input to the main coil 120, the output-side DC current of the main coil 120 is a waveform whose period is changed as shown in (D) and (E) of FIG. 6 . do. In this case, if a ground fault or leakage current occurs in the P phase, the upper T1 protrudes as shown in the waveform (D) of FIG. 6 and the T2 does not protrude. Conversely, when a ground fault or leakage current occurs in the N phase, it does not protrude from the upper part of T1 as shown in the waveform (E) of FIG. 6 but protrudes from T2.

On the other hand, the DC current is measured with the high-sensitivity DC current transformer 100 , and the measured waveform as shown in FIG. 7 is sampled by an analog-to-digital converter (ADC) 172 , and an area is calculated by the operation processing unit 171 . Existing flux gate DC current transformers change only the amplitude as shown in the waveforms (C) and (D) of FIG. 4, and there is no waveform change at several mA. Therefore, if the area is calculated, the same area is calculated, so it is difficult to measure low current, that is, several mA, As in the present invention, when there is no P, N phase ground fault or leakage current, that is, when I is '0', the waveform (A) of FIG. 7 is obtained.

Here, if a low ground fault or leakage current, that is, I = several mA, occurs during P and N phases, the area in which the amplitude and period are changed is calculated as shown in the waveforms (B) and (C) of FIG. 7 .

Therefore, even with a few mA, the change in the area is greatly changed, so that even a low direct current can be easily measured.

At this time, since the waveform (A) of FIG. 7 is vertically symmetric when I = 0, the top and bottom are the same when sampled by the ADC 172 and calculated by the area.

If, as shown in the waveform (B) of FIG. 7, when I = number + mA, the upper area is larger than the lower area, so it is diagnosed that a ground fault or leakage current has occurred in the P phase, and I = as shown in the waveform (C) of FIG. When the number - mA, the lower area is larger than the upper area, so it can be diagnosed that the N phase has a ground fault or leakage current.

On the other hand, according to FIGS. 8 to 10 , the high-sensitivity DC current transformer 100 of the present invention includes a ferromagnetic core 110 in which a main coil 120 and an auxiliary coil 150 are wound inside a case 101 as well as an operation processing unit 171 . ) may have a structure in which a printed circuit board (PCB) type control board 170 is assembled.

At this time, the RJ-45 connector 173 is assembled on the control board 170, and it is driven by supplying +12V, -12V power from the outside, and the detected current value is described later through RS-485 communication. It can be transmitted to the ultra-precise ground detection system 200 .

11, the ultra-precision grounding detection system 200 to which the high-sensitivity DC current transformer of the present invention is applied is Option #1 IEC61850, Option #2 Modbus AGFR, Option #3 RS-485, Ethernet TCP/IP, DGPS RS-485 consist of

The high-sensitivity DC current transformer 100 according to the present invention is connected to a DC Gound Processing System (DGPS) 210 to detect when a ground fault or leakage current occurs.

The DGPS 210 is connected to the high-sensitivity DC current transformer 100 to perform RS-485 serial communication. Accordingly, the high-sensitivity DC current transformer measures the ground fault and leakage current, which are the current values of the P and N phase conductors of the feeder, and transmits the measured values to the DGPS 210 through RS-485 serial communication.

Accordingly, the DGPS 210 sets alarm and trip reference values, receives the current value measured by the high-sensitivity DC current transformer 100, and determines an alarm and a trip compared to the ground fault and leakage current set values.

When an alarm or trip occurs, the DGPS 210 sends an output to the trip signal output unit (DO) 222 using RS-485 serial communication of Option #3 (220) to store the power or energy for the on-site switchboard, which will be described later. Disconnect the appropriate power to the device.

In addition, the IEC61850 of Option #1 (230) is transmitted to the upper system several times that the feeder has leakage and ground fault current, and is also sent to the HMI (Human Machine Interfaces) (242) several times through the Ethernet TCP/IP Port (240). It transmits that leakage and ground fault current have occurred in the feeder.

And, when AC ground fault and leakage current occur by connecting AGFR (AC Ground Fault Relay) 252 to Modbus of Option #2 (250), the corresponding feeder is sent to the port of Otipn #3 (220) in the same way as in DGPS (210). Turn off the power and transmit it to the host system 232 or HMI 242 through IEC 61850, Ethernet TCP/IP Port of Option #1 (230).

Meanwhile, FIG. 12 is a diagram illustrating an example in which the ultra-precision ground detection system 200 to which the high-sensitivity DC current transformer 100 of the present invention is applied is installed in the in-house switchboard 300 .

According to this, when a ground fault or leakage current occurs in the equipment of DC power, the current value is measured in the high-sensitivity DC current transformer 100 of the ultra-precision grounding detection system 200 as described above, and the corresponding feeder and equipment power is cut off with Option #3 as DO. to prevent fire and secondary accidents, and transmit to HMI 242 and upper system 232 with Option #1, #2, and Ethernet TCP/IP.

And, FIG. 13 is a diagram illustrating an example in which the ultra-precision ground detection system 200 to which the high-sensitivity DC current transformer 100 of the present invention is applied is applied to the renewable energy and the ESS 400 .

According to this, the high-precision DC current transformer 100 of the present invention is installed on the P and N phases connecting the DC power generated from the solar panel to the connection panel. That is, the high-precision DC current transformer 100 of the present invention is installed in all facilities using DC power such as solar panels, connection panels, PCS, and ESS to monitor ground faults and leakage currents.

In addition, AGFR (AC Ground Fault Relay) is installed on the line that converts PCS to AC power and supplies it to the smart grid to detect ground faults and leakage currents of AC power.

Therefore, if the equipment of DC or AC power has a ground fault or leakage current, as described above, cut off the feeder and equipment power with Option #3 to DO to prevent fire and secondary accidents, and Option #1, #2, Ethernet TCP It is sent to HMI 242 and upper system 232 by /IP.

The above description is merely illustrative of the technical idea of the present invention, and various modifications and variations are possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. The scope of protection should be interpreted by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100: high-sensitivity DC current transformer 110: ferromagnetic core
120: main coil 130: square wave oscillation circuit
140: shunt resistor 150: auxiliary coil
160: first amplifier 170: control board
171: arithmetic processing unit 172: ADC
173: RJ-45 connector 174: power supply
175: first filter 176: second filter
177: second amplifier 200: ultra-precision ground detection system

Claims (4)

In the ultra-precise grounding detection system for energy storage devices and on-site switchboards, Option #1 IEC61850 is connected to the upper system, Option #2 is Modbus connected to AGFR, and Option #3 RS-485 is DI, DO, CT/PT, AI It is configured to connect with the HMI through Ethernet TCP/IP, and to connect with the DC current transformer through DGPS (DC Ground Processing System) RS-485 so that it can be used selectively according to the installation environment,
The DC current transformer includes a ferromagnetic core through which the feeder P and N phase conductors pass, a main coil wound on one side of the ferromagnetic core, an auxiliary coil wound on the other side of the ferromagnetic core, and a voltage connected to the lower end of the main coil It consists of a shunt resistor for measuring current, and a square wave oscillation circuit that applies a square wave to one end of the main coil,
In the auxiliary coil, an induced electromotive force is induced by a ground fault or leakage current generated in any one of the P and N-phase conductors of the feeder, and the cycle of the square wave oscillation circuit is changed by the induced electromotive force. Ultra-precise ground detection system for storage devices and on-site switchboards.
delete The method of claim 1,
The DC current transformer includes a first amplifier that amplifies the induced electromotive force induced in the auxiliary coil to change the oscillation period of the spherical plate of the square wave oscillation circuit and outputs it to the square wave oscillation circuit, and a DC current in the form of a voltage output from the main coil Further comprising an ADC for converting , and an arithmetic processing unit for calculating a current value using a DC current input through the ADC,
The calculation processing unit calculates the area of the waveform sampled through the ADC,
If the upper area and lower area of the sampled waveform are the same, it is determined that there is no abnormality,
If the upper area is larger than the lower area, it is determined that a ground fault or leakage has occurred in the P phase,
If the lower area is larger than the upper area, it is characterized in that it is determined that a ground fault or leakage has occurred in the N phase.
4. The method of claim 3,
The arithmetic processing unit calculates the current value of the conducting wire and transmits it to the ultra-precision grounding detection system through RS-485 communication, wherein the ultra-precise grounding detection system determines whether the conducting wire has a ground fault or leakage current. Ultra-precise ground detection system for switchboards.

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