KR20130055046A - Measuring earth resistance method at the places of mixed neutral grounded and non grounded lv network - Google Patents
Measuring earth resistance method at the places of mixed neutral grounded and non grounded lv network Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16528—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values using digital techniques or performing arithmetic operations
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/30—Measuring the maximum or the minimum value of current or voltage reached in a time interval
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/08—Measuring resistance by measuring both voltage and current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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Abstract
Description
본 기술은 저압망에서 중성선 접지와 비접지 개소가 혼재된 개소에서 전원공급 변압기의 중성선까지의 대지접지 저항값을 측정하는 기술이다
This technique is to measure the earth ground resistance value from the mixed point of neutral ground and non-grounded point to the neutral line of power supply transformer in low voltage network.
우리나라에서 전력회사 보유 저압망은 중성선과 변압기 외함접지가 연결되어 대지로 접지된 반면, 전기사용자 빌딩 내부는 중성선과 외함접지가 분리되고 단지 외함접지만 피뢰침 접지에 연결되어 있는 구성이다. In Korea, a low-voltage network owned by a power company has a neutral ground and a transformer enclosure ground connected to the ground, while inside an electrical user building, the neutral ground and the enclosure ground are separated and only the enclosure ground is connected to the lightning rod ground.
최근 신재생 에너지원의 개발 증가 등으로 소형 분산전원을 전력회사 저압망에 연결하여 운전하고자 하는 수요가 증가하고 있고 이를 위해서는 지금까지의 전력공급 개념인 단방향 방사성 구조, 즉 전력회사에서 전기사용자로의 단방향 공급망,가 아닌 전기사용자가 역으로 전력회사 망을 통해 전기 공급자가 될 수 있는 양방향 구조의 지능형 전력망 개념의 저압망 구성변경이 필요하게 된다. Recently, due to the development of new and renewable energy sources, there is an increasing demand to operate small distributed power sources by connecting them to the low-voltage network of power companies. It is necessary to change the low-voltage network configuration of the intelligent power grid concept of the bidirectional structure in which electric users, not unidirectional supply chains, can reversely become electricity providers through the utility network.
우리나라는 계약용량에 따라 고압 또는 저압전력을 공급하고 있다. 계약용량 100kW 미만의 전력 수용장소에는 저압, 그 이상은 고압 송전한다. 배전용 변압기에서 저압변환 후 전기사업자 소유 저압망(220V 단상/380V 삼상)을 통해 전기사용자에게 전력을 공급하고 있다 (2010.11월부터는 500kW 미만으로 상향)Korea supplies high voltage or low voltage according to the contract capacity. Low-voltage and higher-voltage transmissions are made at power receiving sites with a contract capacity of less than 100 kW. After converting low voltage from power distribution transformer, it is supplying electric power to users through low voltage network (220V single phase / 380V three phase) owned by electricity companies (up to 500kW from November 2010).
기존 전력회사 소유의 저압망을 단방향이 아닌 양방향의 지능형 전력망으로 구성 변경하기 위해서 고려할 사항은 전원 공급방향이 바뀔 때 최대 허용전류, 고장전류 등에 대한 사항을 우선 검토하여야 한다. 즉 단방향 전력공급 방식에서는 전력회사의 변압기에서만 전기사용자에게 전력을 공급하기 위한 전선용량 및 저압망 고장에 대비한 보호설비를 구비하면 되지만 양방향으로 전력을 공급하는 지능형 전력망보호에서는 기존 저압망의 변압기 측에서의 보호뿐만 아니라 전기사용자 측에서 역으로 송전을 대비한 최대 고장전류, 지락전류, 고장시 전압 상승에 대비한 고려를 하여야 한다.In order to change the configuration of the low voltage network owned by the existing power company into an intelligent power grid of bidirectional rather than unidirectional, considerations should be first reviewed regarding the maximum allowable current and fault current when the power supply direction is changed. In other words, in the unidirectional power supply system, only the transformers of the power company need to have protection equipment for electric power capacity and low voltage network failure to supply electric users, but in the intelligent power network protection that supplies power in both directions, In addition to protection, consideration should also be given to the maximum fault current, ground fault current, and voltage rise in the event of an electrical transmission.
그러나 현재의 기술로는 활선 상태에서 즉 전력을 공급하고 있는 상태에서 전력선의 임피던스 값을 실측할 수 없어, 단지 전선 고유 임피던스 값에 거리를 곱하여 계산값으로 임피던스를 계산하여 고장전류, 지락전류, 고장시 상승전압 등을 계산하고 있어 현실성이 떨어진다. 특히 저압망은 전압이 낮아 관리가 잘 되지 않고 저압망 경로상에 많은 접속점 등이 있는데 이를 고려하지 못하고 있다. However, current technology cannot measure the impedance value of the power line in the live state, that is, while the power is being supplied, and simply calculates the impedance using the calculated value by multiplying the wire's intrinsic impedance value by the distance, and the fault current, ground current, and fault It is not realistic because the time rise voltage is calculated. In particular, low voltage networks are not well managed due to low voltage, and there are many connection points on the low voltage network path.
이를 해결하기 위해 활선 상태에서 기존 저압망의 구성을 파악하고 동시에 저압망 회선별 임피던스와 전원 공급 변압기의 중성선과의 임피던스를 측정하여 고장전류, 지락전류 및 고장시 상승전압을 측정하는 방법을 고안하고자 한다. In order to solve this problem, we have devised a method to measure the fault current, ground fault current and rising voltage in case of failure by grasping the composition of the existing low voltage network in the live state and measuring the impedance between the low voltage network line impedance and the neutral line of the power supply transformer. do.
전류 펄스 발생 기술을 이용한 기존 저압망 회선구성 및 설치경로를 탐사할때 동시에 저압망 상과 중성선 사이의 임피던스 및 외함과의 임피던스 값을 측정하여 고장전류, 지락전류, 누전시 외함전압 등을 계산하고 이의 보호대책을 강구할 수 있도록 하고자 한다Calculate fault current, ground fault current, enclosure voltage in case of short circuit by measuring the impedance between low voltage network and neutral wire and the enclosure at the same time when exploring the existing low voltage network configuration and installation path using current pulse generation technology. To take measures to protect this
지금까지 전기사용자 빌딩 내부의 저압망 고장에 의한 고장전류, 누전고장에 지락전류 및 외함에 인가되는 최대 전압등을 계산이 아닌 실측에 의한 측정을 가능하도록 하여 누전에 의한 감전 및 화재 고장을 미연에 방지하고자 한다.Until now, it is possible to measure the fault current caused by the low voltage network failure inside the electric user's building, the ground fault current in the ground fault, and the maximum voltage applied to the enclosure. To prevent it.
도1은1,
고안인은 중성선 다중접지 환경하에서 매설물 탐지기를 사용한 저압선 탐사 시 발생되는 오류를 요인을 방지하기 위한 전류성 펄스신호를 부하전류가 최소되는 제로크로싱점에 발생하여 이를 탐사하는 기술에 대해 출원을 한바 있다. The inventor has applied for a technique for detecting a current generated by generating a pulsed pulse signal at a zero crossing point where the load current is minimized in order to prevent an error caused when the low voltage line is detected using a buried material detector under a neutral wire grounding environment. .
기존 저압망의 부하측에서 전류성 펄스 신호를 발생하여 저압망 회선구성 및 설치경로를 탐사하면서 동시에 측정장소의 저압망 품질 측정을 할 수 있는 방안에 대해 고안을 하게 되었다. 즉 저압망에서 특히 우리나라와 같이 전력회사의 저압망은 중성선 다중접지되었지만 전기사용자 건물 내부는 중성선 비접지 구성망에서 누전발생시 이를 보호하기 위한 대책 등을 파악하여 이를 바로잡고자 한다. By developing a current pulse signal on the load side of the existing low voltage network, the low voltage network line configuration and installation path can be explored while devising a way to measure the low pressure network quality at the measurement site. In other words, in the low-voltage network, the low-voltage network of the electric power company, like Korea, is neutral grounded multi-ground, but inside the electrical user building, the neutral ground ungrounded network will identify and correct measures to protect against short circuits.
예를 들어 <그림1>과 같이 전기사용자 빌딩 내부 계량점에서 저압망 구성 탐사 후 전기사용자 빌딩에 전원을 공급하는 전력회사 소유의 변압기 와 저압망을 탐사완료한 후에 저압망 상선과 중성선 사이에 임피던스를 측정하는 모습이다. For example, as shown in <Figure 1>, the impedance between the low-voltage network and the neutral line after exploring the low voltage network and the transformer owned by the power company that supplies power to the user building after exploring the low voltage network configuration at the metering point inside the electric user building. It is a figure to measure.
<도7>과 같이 기존 저압회선 탐사를 위한 전류 펄스발생회로에 별도의 반파정류된 전류를 일정기간 연속하여(본 회로에서는 4싸이클) 전류를 R2를 통해 흐르도록 회로를 구성하여 전류 흐르기 이전의 전압값V1과 전류 흐르는 동안의 전압값V2의 차값(전압 강하값)의 비와 R2저항값을 곱해 미지의 임피던스를 측정한다.As shown in Fig. 7, the circuit is configured so that the current flows through R2 continuously for a certain period of time (four cycles in this circuit) in a separate half-wave rectified current in the current pulse generation circuit for the existing low voltage circuit detection. The unknown impedance is measured by multiplying the ratio of the difference (voltage drop) between the voltage value V1 and the voltage value V2 during the current flow and the resistance value of R2.
즉 <그림1>과 같이 저압망의 상선과 중성선을 연결하고 전압차를 이용한 임피던스를 측정하는 모습이다. 측정한 결과 전류를 흐르기 전에는 전압 V1은 229.44V이고 전류를 4싸이클 흘렸을 동안 전압 V2는 225.23V이다. 여기에 R2값 3.8옴을 곱하면 저압망 회선 및 변압기 내부임피던스 합한 값을 구할 수 있다. In other words, as shown in <Figure 1>, it connects phase wire and neutral wire of low voltage network and measures impedance using voltage difference. As a result of measurement, before the current flows, the voltage V1 is 229.44V and the voltage V2 is 225.23V while the current is cycled 4 cycles. Multiply that by the R2 value of 3.8 ohms to get the sum of the low-voltage network line and the internal impedance of the transformer.
즉 Zi는 전류가 측정점의 저압망 상선을 통해 변압 기 코일을 거쳐 중성선으로 귀환하여 Rs를 통과하여 흐를 때 발생되는 전압강하에 의한 임피던스의 합성값이다.In other words, Zi is the combined value of the impedance due to the voltage drop generated when the current flows through Rs through the transformer coil through the low-voltage network wire of the measuring point and passes through Rs.
<그림2>는 상선과 외함간 Loop Impednace를 측정한 결과이다. 즉 <그림1>은 전력선 상선과변압기 내부권선 및 중성선 임피던스를 합한 값이 0.07O이고 오른쪽은 전력선 상선과 변압기 내부권선 및 외함 접지 임피던스 값의 합이 7.36O이다 <Figure 2> shows the result of loop impedance measurement between merchant ship and enclosure. Figure 1 shows the sum of the power line upstream, transformer internal winding, and neutral line impedance, which is 0.07O. On the right, the sum of the power line upstream, transformer internal winding, and enclosure ground impedance is 7.36O.
상간 단락시 고장전류는 220V/0.07O=3,142A이고 지락시 고장전류 는 220V/7.36O=29A이다. 그러나 문제점은 <그림9>와 같이 외함접지와 변압기 중성선간 대지저항 과다로 지락 고장시 외함에 걸리는 전압은 217V로서 일반인 접촉시 감전사고가 발생할 수 있다. 또한 역방향으로 분산전 원이 전력을 공급할 때도 저압망의 접지점과 빌딩내 보호접지와는 저항값이 높아 적절한 보호협조가 불가능 하여 안전 또는 설비고장 위험이 있다는 점이다. 전원 전압이 인가된 상태에서 반파(DC)성분의 전류를 저압 망 상선과 중성선 사이에 4사이클 이상 의 전류를 흘러 이 때 발생되는 전압강하 값을 측정하여 미지의 저압 망 전력선과 변압기 내부 임피던스 Z1을 측정하고, 측정하고자 하는 접지 저항 측정점과 저압망 상선을 연결 하여 동일하게 4 사이클 이상의 전류를 흘려 발생되는 전압 강하값을 측정하여 접지저항 측정점과 변압기 중 성선의 대지접지점과 저압망 전력선 임피던스 값의 합 Z2를 측정하여 접지저항 측정점과 변압기 중성점까지 의 저항값을 구하는 방법 In case of short-circuit between phases, the fault current is 220V / 0.07O = 3,142A and in case of ground fault, the fault current is 220V / 7.36O = 29A. However, as shown in <Figure 9>, when the ground fault occurs due to excessive earth resistance between the ground of the enclosure and the transformer neutral wire, the voltage applied to the enclosure is 217V, which may result in electric shock. In addition, when distributed power supplies in the reverse direction, the resistance value is high between the grounding point of the low-voltage network and the protective ground in the building, so that proper protection coordination is not possible. Measure the voltage drop generated when a half-wave (DC) component flows more than 4 cycles of current between the low voltage network and the neutral line while the power supply voltage is applied, and then measure the unknown low voltage network power line and the internal impedance Z1 of the transformer. Connect the ground resistance measurement point to the low voltage network wire, and measure the voltage drop caused by passing 4 or more cycles of current in the same way, and then add the ground resistance measurement point to the earth ground point of the transformer neutral and the low voltage network power line impedance. How to measure the resistance between the ground resistance measurement point and the transformer neutral point by measuring Z2
Z2-Z1= 측정하고자 하는 점의 접지저항값(지락고장시 대 지전위 상승 최대치 계상값)
Z2-Z1 = Ground resistance at the point to be measured (Maximum value of ground potential rise in case of ground fault)
부호는The sign is
Claims (3)
전원에 연결된 전류소스;
접지 또는 대지에 연결된 전류싱크;
상기 전류소스와 전류싱크 사이 저항을 통과하는 전류를 단속하는 스위칭부;
상용전원 전압파형의 위치에 따라 상기 스위칭부의 단속 제어명령 신호를 발생하는 시간제어부;
상기 저항 양단에 걸리는 전압을 상기 스위칭부 단속 유지시간 동안 전압 측정하는 측정부;
상기 측정부로부터 받은 전압값과 연결된 저항값으로 임피던스 값을 계산하는 연산부를 포함하는 것을 특징으로 하는 중성선 비접지 저압망 점검방법resistance;
A current source connected to the power supply;
A current sink connected to ground or earth;
A switching unit which intercepts a current passing through a resistance between the current source and the current sink;
A time control unit generating an interruption control command signal of the switching unit according to a position of a commercial power supply voltage waveform;
A measurement unit measuring a voltage across the resistor during the switching unit interrupt duration;
Neutral wire ungrounded low voltage check method comprising a calculation unit for calculating the impedance value by the resistance value connected to the voltage value received from the measuring unit
두개의 다른 전류싱크와 전류소스간 임피던스 차값을 구하여 중성선 비접지 개소의 접지저항 값을 구하는 것을 특징으로 하는 중성선 비접지 저압망 점검방법 The method of claim 1,
Neutral ungrounded low voltage network checking method, characterized in that the ground resistance value of the non-grounded neutral point is obtained by calculating the impedance difference value between two different current sinks and the current source.
회선 및 경로를 파악하는 단계;
전력선 상선과 중성선간 임피던스를 구하는 단계;
전력선 상선과 대지접지 선간 임피던스를 구하는 단계;
이의 차값을 계산하여 대지저항 값을 파악하고 지락고장(누전)시 안전전압 30V를 초과되는 개소를 관리하는 것을 특징으로 하는 중성선 비접지 저압망 점검방법 In neutral ungrounded low voltage network,
Identifying circuits and paths;
Obtaining an impedance between the power line phase line and the neutral line;
Obtaining an impedance between the power line merchant line and the earth ground line;
Neutral wire ungrounded low voltage network checking method, which calculates the difference value and grasps earth resistance value and manages the place exceeding safety voltage 30V in case of ground fault
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105929245A (en) * | 2016-04-28 | 2016-09-07 | 吉林省泰华电子有限公司 | Ground resistance real-time monitoring device |
| CN109412178A (en) * | 2018-10-19 | 2019-03-01 | 湖南大学 | A kind of switching control method of high-voltage large-capacity impedance measurement equipment |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH09304453A (en) * | 1996-05-17 | 1997-11-28 | Mitsubishi Electric Corp | Simple measuring equipment and method for impedance of low voltage distribution line |
| KR100306569B1 (en) * | 2000-04-10 | 2001-11-07 | 정재기 | Apparatus for testing of ground resistance at activity state and therefor method |
| KR100584020B1 (en) * | 2003-06-26 | 2006-05-29 | 학교법인 인하학원 | A variable frequency inverter-type high power ground resistance measuring device and measuring method based on PC |
| KR100821705B1 (en) * | 2006-09-13 | 2008-04-14 | 전명수 | Earth resistance measurement method by clamp-on type current comparison |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105929245A (en) * | 2016-04-28 | 2016-09-07 | 吉林省泰华电子有限公司 | Ground resistance real-time monitoring device |
| CN109412178A (en) * | 2018-10-19 | 2019-03-01 | 湖南大学 | A kind of switching control method of high-voltage large-capacity impedance measurement equipment |
| CN109412178B (en) * | 2018-10-19 | 2021-04-30 | 湖南大学 | Switching control method of high-voltage high-capacity impedance measurement equipment |
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