KR20210023127A - System for identifying fault section of power distribution system - Google Patents

Abstract

The present invention relates to a power distribution system fault section identification system, which includes: a power distribution operating system for periodically receiving data measured from a plurality of remote control units (RTUs) and accumulatively storing the data in an internal operation DB; and a fault section determination controller receiving and processing data measured through a plurality of phase measurement units (PMUs) according to a specified period. The power distribution operating system and the fault section determination controller are connected to each other through a communication network. The RTU measurement data stored in the operation DB is transmitted to the fault section determination controller through the communication network. The fault section determination controller includes: a topology estimation unit receiving information on the switching state of a switchgear and a circuit breaker of the power distribution system from the operation DB, generating bus information, and processing straight path information between the PMUs; and a fault section determination unit including a fault type determination portion for determining the occurrence of faults in the distribution system and the type thereof, a main fault section determination portion primarily identifying fault sections on a main feeder by using PMU data, and a branch line fault section determining portion for determining a fault section inside the branch line by using a designated fault analysis method, when the primary identification fault section is a point where the branch line is connected.

Description

Distribution system fault section identification system {SYSTEM FOR IDENTIFYING FAULT SECTION OF POWER DISTRIBUTION SYSTEM}

The present invention relates to a distribution system failure section identification system, and more particularly, instantaneous events occurring in the distribution system using a PMU (Phasor Measurement Unit) capable of calculating and processing at least a hundred times sampling for one period waveform, and It relates to a distribution system failure section identification system, which detects a failure and enables the failure section of the distribution system to be identified.

Conventional technology 1 (10-2007-0041097, published, ground fault section detection and separation device and method in non-grounded distribution systems) is a selective ground overcurrent relay (SGR) that simply detects the ground fault of the line through the network. Detection of a faulty section in a non-grounded distribution system that enables transmission to the central control device and recovers the faulty section in a short time without experiencing a power outage as much as possible with the minimum number of switchgear operations using the intelligence of the central control device. And a separation device and method.

However, the conventional technique 1 is a method of finding a fault section through fault detection occurrence information of the connected line by moving the open point of the switch installed on the faulty line from the end (normally open point) to the power source in order to find the faulty section. It moves the point to the power side and detects the fault detection signal to determine the fault section, which puts a constant burden on the facility. In addition, in the case of a line with many switchgear installations, it is difficult to apply it in practice because it takes a long time to find a faulty section.

Conventional technology 2 (10-2009-0119058, published, intelligent FRTU-based fault section determination and autonomous separation method in the distribution system) is a voltage and current sensor by a FRTU (Feeder Remote Terminal Unit) installed in the switch of the overhead distribution line. 3-phase voltage through 1:1 communication with FRTU elements of Naver Zone under a ubiquitous-based distribution system environment after determining whether a fault/inrush/HIF (High Impedance Fault) exists from the 3-phase voltage and current waveform measured from By collecting current information, determining whether or not a fault has occurred in the self-protection section, and automatically separating the fault section before the circuit breaker (CB) or recloser is permanently opened, reducing the fault area and power outage time. It relates to an intelligent FRTU-based fault section determination and autonomous separation method in a distribution system that minimizes the ripple effect.

Conventional technology 3 (10-1514999, registration, autonomous failure section identification and separation method using a smart protection device in the distribution system, and its system) is a smart distribution grid system with a new distributed power supply. When detected, the protection device uses the two-way communication function of the smart distribution grid system to determine the failure section by itself, and to an autonomous failure section identification and separation method that can separate the fault section from the distribution system, and its system.

However, the conventional technology 2 and the conventional technology 3 determine a failure section by utilizing the two-way communication of the RTU and a failure detection signal. However, in the case of a method of performing fault detection through a communication method, it is difficult to determine fault detection in an actual system due to the problem of establishing a separate high-speed communication network and various exceptions (communication errors, etc.) according to the field situation.

According to an aspect of the present invention, the present invention was created to solve the above problems, and in a distribution system using a PMU (Phasor Measurement Unit) capable of calculating and processing at least a hundred times sampling for one period waveform. Its purpose is to provide a distribution system failure section identification system that enables the identification of the failure section of the distribution system by detecting instantaneous events and failures that occur.

A distribution system failure section identification system according to an aspect of the present invention includes: a distribution operating system that periodically receives data measured by a plurality of remote control station devices (RTUs) and accumulates and stores it in an internal operation DB; And a failure section determination controller for receiving and processing data measured through a plurality of PMUs (Phasor Measurement Units) according to a specified period, and wherein the distribution operation system and the failure section determination controller are connected to each other through a communication network. , The RTU measurement data stored in the operation DB is transmitted to the fault section determination controller through the communication network, and the fault section determination controller receives the opening/closing state information of the switchgear and circuit breaker of the distribution system from the operation DB and A topology estimation unit that generates and processes linear path information between PMUs; And a fault type determination unit that determines the occurrence and type of a failure in the distribution system, a main fault section determination unit that primarily identifies the fault section on the main feeder using PMU data, and the primary identification fault section is connected to a branch line. And a failure section determination unit including a branch line failure section determination unit for determining a failure section inside the branch line using a designated failure analysis method in the case of a branch.

In the present invention, it characterized in that it further comprises a front end processor (FEP) for interfacing the field data information transmitted from the plurality of remote control station (RTU) to the operation DB of the distribution operating system; .

In the present invention, the operation DB receives and stores topology information required for failure section determination information periodically from the front end processor (FEP) and the fault section determination controller, and is determined by the fault section determination unit. It is characterized by storing the result.

In the present invention, the information transmitted from the failure section determination controller includes system status information, including protection devices, switch status information, node connection relations, and information on loads and distributed power connected to each node; As the fault section determination information, the fault section location information of the distribution system identified by the fault section determination controller 24; And installation location information of the PMU and RTU installed to determine a failure section, as location information of the terminal device. It characterized in that it comprises at least one or more of.

In the present invention, the topology estimation unit searches and stores a straight path of the main feeder in which a PMU is installed to determine a fault section on the main feeder, and connects a node-equipment standard to perform a fault analysis for determining a branch line fault section. The relationship is changed to data based on the bus-equipment, and the topology data of the jurisdiction region is reconstructed when the distribution system is reconfigured and the system structure is changed according to the input and opening of the facility.

In the present invention, the fault type determination unit acquires the data of the PMU controlled by the fault section determination controller according to a set period, and through the voltage and current data of the PMU installed at the feeder starting point, the measured value of the voltage is When it becomes smaller than the set value and when the current becomes larger than the set current, a system failure is recognized, and a failure type is determined based on a voltage change amount before and after the failure.

In the present invention, the failure type determination unit is characterized in that to calculate the voltage and current change before and after the failure using Equation 1 and Equation 2 below in order to determine the type and section of the failure.

(Equation 1)

(Equation 2)

,

는 고장 후 PMU에서 계측된 전압, 전류의 크기 및 위상,

,

는 고장 전 PMU에서 계측된 전압, 전류의 크기 및 위상을 나타낸다. here,

,

Is the magnitude and phase of the voltage and current measured by the PMU after failure,

,

Represents the magnitude and phase of the voltage and current measured by the PMU before failure.

In the present invention, the failure type determination unit is characterized in that the balanced failure is classified using Equation 3 below, and the unbalanced failure is classified using Equation 4 below.

(Equation 3)

는 각 상의 고장발생 전후의 전압 변화이며,

는 평형 고장을 구분하기 위해 설정된 범위를 나타낸다. here,

Is the voltage change before and after the failure of each phase,

Denotes the range set to classify the equilibrium fault.

(Equation 4)

는 고장인지 단계에서 전압 범위를 벗어난 상들의 고장발생 후 전압 변화를 나타내며,

는 건전상,

는 불평형 고장을 구분하기 위해 건전상과 고장상간의 변화 범위를 나타낸다.here,

Represents the voltage change after failure of the phases out of the voltage range in the fault recognition phase,

Is healthy,

Represents the range of change between the sound phase and the fault phase to distinguish the unbalanced fault.

In the present invention, the main failure section determination unit, in order to determine the primary failure section within the PMU section installed at the starting point and the ending point on the main feeder, the voltage and current change amount and failure type before and after the failure obtained by the failure type determination unit. According to the PMU start point to the end direction (downstream), and from the end direction to the start point direction (upstream), the change in voltage and current of each bus is calculated, and all bus bars in the end direction (downstream) and the starting point direction (upstream) on the main feeder When the calculation of the voltage and current change amount for is completed, the voltage deviation between the two directions is calculated to detect the fault on the main feeder, and based on the Compensation Theorem of the circuit theory, the downstream direction and the starting point direction It is characterized in that the section with the smallest deviation of (upstream) is identified as the primary failure section.

In the present invention, when the result of the failure type determination unit is a balanced failure, the voltage and current change amounts of each section are calculated using Equations 5 and 6 below.

(Equation 5)

(Equation 6)

,

고장 전후 각 모선의 전압, 전류 변화량, n은 메인 피더의 각 모선 번호를 나타내며, 피더 시작점

,

과 피더 말단

,

는 해당지점 PMU에서 계측된 전압, 전류 변화량을 초기값으로 설정한다.

은 계산되는 모선과 직전 모선사이의 선로 임피던스를 나타내며,

는 구간 부하를 나타낸다. here,

,

Voltage and current change amount of each bus before and after failure, n represents each bus number of the main feeder, and the feeder starting point

,

And feeder end

,

Sets the voltage and current changes measured at the corresponding point PMU as initial values.

Represents the line impedance between the calculated bus and the immediately preceding bus,

Represents the section load.

In the present invention, when the result of the fault type determination unit is a one-line ground fault, the voltage and current change amounts for each bus on the fault are calculated using Equations 7 to 9 below.

(Equation 7)

(Equation 8)

(Equation 9)

는 각 상에 대한 모선 전류변화량,

는 고장 상에 대한 고장 전후 각 모선의 전압, 전류 변화량을 나타내며, 위의 평형해석과 동일하게 초기 값은 PMU의 계측값을 활용한다. 그리고 a =

,

,

,

고장 상에 대한 각 모선의 정상, 역상, 영상 전류 변화량,

,

,

는 n번째 모선과 그 직전 모선사이 선로의 정상, 영상, 역상분의 임피던스를 나타낸다. Here, n represents each bus number of the main feeder,

Is the amount of change in bus current for each phase,

Represents the amount of change in voltage and current of each bus before and after the failure for the fault phase, and the initial value is the measured value of the PMU, similar to the above balance analysis. And a =

,

,

,

The amount of change in normal, reverse, and image current of each bus for the fault phase,

,

,

Denotes the impedance of the normal, image, and reverse phase of the line between the nth bus and the immediately preceding bus.

In the present invention, when a failure occurs due to a distributed power supply connected to the system, a current change amount for the distributed power supply (PV) is calculated using Equations 10 and 11 below.

(Equation 10)

(Equation 11)

,

는 분기선 시작점 설치된 RTU에 취득된 고장 전후의 전류 크기이며,

,

는 고장 전후 피더시작점 PMU에서 계측된 전압위상,

,

는 고장 전후 RTU에서 취득된 전압-전류 위상차를 나타낸다.here,

,

Is the magnitude of the current before and after failure acquired in the RTU installed at the starting point of the branch line,

,

Is the voltage phase measured at the feeder starting point PMU before and after failure,

,

Represents the voltage-current phase difference acquired at the RTU before and after failure.

In the present invention, the branch line failure section determination unit receives the amount of insolation, maximum output, load condition, etc. of the distributed power supply (PV) in order to identify the fault section inside the branch line where the PMU is not installed, and When a failure is assumed, the magnitude of the current flowing at the feeder start point is calculated through failure analysis, and the section with the smallest deviation is determined as the failure section through comparison between the measured current value obtained from the PMU installed at the feeder start point after the failure and the failure analysis result value. It is characterized by that.

In the present invention, the branch line fault section determination unit defines a faulty bus among buses of the branch line for fault calculation, and calculates the admittance matrix of the distribution system by recognizing a fault in the fault type determination unit, and the type of bus line in the system. Classify and set the initial value, but the initial value is set as the bus voltage, the amount of insolation of the previously input PV, and the load condition, and the current calculation is performed until the voltage value at each bus is converged through the three-phase current calculation. , In order to consider the maximum output of the distributed power (PV) inverter after performing the current calculation, calculate the output current of the distributed power (PV) and check whether the specified maximum current output of the distributed power (PV) is exceeded, and check the above. As a result, when the current size of the distributed power supply (PV) is larger than the limit value, the size of the fault current of the distributed power supply (PV) is limited and the three-phase current is calculated again, and all distributed power sources (PV) are within the specified output range. In this case, the fault current is calculated based on the converged bus voltage and line impedance.

According to an aspect of the present invention, the present invention detects instantaneous events and failures occurring in the distribution system by using a PMU (Phasor Measurement Unit) capable of calculating and processing at least a hundred times sampling for one period waveform. To be able to identify the fault section of the device.

1 is an exemplary view showing a schematic configuration of a distribution system failure section identification system according to an embodiment of the present invention.
FIG. 2 is an exemplary diagram illustrating an operation of a topology estimation unit in FIG. 1.
3 is a flowchart for explaining an operation of a failure type determination unit of a failure section determination unit in FIG. 1.
4 is an exemplary view showing voltage change characteristics when a failure occurs in FIG. 3.
5 is a flow chart for explaining the operation of the main failure section determination unit in FIG. 1;
6 is an exemplary view illustrating a system including distributed power in order to explain a method of analyzing a system of a system in which distributed power is connected in FIG. 5.
7 is a flowchart illustrating an operation of a branch line failure section determination unit in FIG. 1.
8 is a flowchart for explaining in more detail a calculation process for failure analysis by a branch line failure section determination unit in step S83 of FIG. 7.
9 is an exemplary view showing a test system for verifying the effect of the fault section determination controller in FIG. 1.
10 and 11 are exemplary views for comparing the calculation and simulation results of voltage deviations on the main feeder according to the conventional method according to the present embodiment and the proposed method of the present embodiment.

Hereinafter, an embodiment of a system for identifying a failure section of a distribution system according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of users or operators. Therefore, definitions of these terms should be made based on the contents throughout the present specification.

1 is an exemplary view showing a schematic configuration of a distribution system failure section identification system according to an embodiment of the present invention.

As shown in Fig. 1, data measured by a plurality of remote terminal units (RTUs) are transmitted to an external distribution management system (DMS) 20, and are periodically operated DB ( 21) is accumulated and stored.

In addition, data measured through a plurality of PMUs (Phasor Measurement Units) are transmitted to a fault section determination controller (PDC: Phasor Data Concentrator) (24) that performs intermediate processing and a controller role according to a set period (10 to 60 times per second). do.

In addition, if necessary, the RTU measurement data on the operation DB 21 or the memory (not shown) of the DMS 20 can be connected to the communication network connected between the distribution operation system (DMS, 20) and the failure section determination controller (PDC, 24). The system topology and parameter data may also be transmitted from the operation DB 21 of the distribution operation system (DMS, 20) to the failure section determination controller (PDC, 24) as necessary.

At this time, the topology estimating unit 22 of the failure section determination controller (PDC, 24) receives information on the open/close state of the switchgear and breaker of the system from the operation DB 21 to generate bus information and process information on a straight path between PMUs. Carry out.

In addition, the fault section determination unit 23 of the fault section determination controller (PDC, 24) determines the fault section on the main feeder by using the fault type determination section 231 and PMU data to determine the occurrence and type of faults in the distribution system. The main fault section determination unit 232 that identifies the primary failure section, and the branch line fault section determination section 233 that determines the fault section inside the branch line using a fault analysis method when the primary fault section is a point where the branch line is connected. Consists of.

For reference, a front end processor (FEP), whose detailed description is omitted in FIG. 1, provides on-site data information (eg, status, control, measurement, etc.) coming up from the plurality of remote control station devices (RTUs) to the distribution operation. Interface to the operation DB (21) of the system (DMS, 20).

More specifically, the operation DB 21 stores data such as topology information (e.g., switch status information and connection relationship) necessary for failure section determination information, and the potential processor (FEP) and the failure section determination controller (PDC, 24). ) And stores it periodically. In addition, the operation DB 21 stores the result determined by the failure section determination unit 23 and is used to display the system recovery and system status.

For example, the necessary information (Data) from the failure section determination controller (PDC, 24) is (1) the status information of the system, such as the protection device, switch status information, the connection relationship of the nodes, and the load and distributed power connected to each node. Information, (2) as the fault section determination information, location information of the fault section of the distribution system identified by the fault section determination controller 24, and (3) the PMU installed to determine the fault section as the location information of the terminal device This is the RTU's installation location information.

2 is an exemplary diagram shown to explain the operation of the topology estimating unit in Fig. 1, and more specifically, the topology estimating unit 22 is a straight line of the main feeder in which a PMU is installed to determine a failure section on the main feeder. Browse and save the route.

In addition, the topology estimating unit 22 changes the connection relationship between the node-equipment standard to data based on the bus-equipment in order to perform a failure analysis for determining the branch line failure section, and reconfigures the distribution system and opens the facility (i.e., When the system structure changes according to the input and opening), the topology data of the jurisdiction region is reconstructed.

In addition, the topology estimating unit 22, as (1) an operation of busting the distribution system through the connection relationship between nodes, the current state data of the system from the operation DB 21, connection information between the nodes of the system, and each node. It collects data such as load and distributed power connected to, the state of the switch, the transformer, and the line between nodes and its impedance. In addition, the topology estimating unit 22 collects the nodes into which the switch is inserted into one bus through the open-open (ie, closed and closed) state of the relay and the connection relationship between the nodes, as shown in FIG. 2(a). Likewise, the node-equipment standard data is changed to the bus-equipment standard topology.

In addition, the topology estimating unit 22 is an operation of (2) identifying a straight path for a PMU installation section, and in order to perform PMU-based failure section determination (primary main feeder) in this embodiment, Fig. 2(b) ), the PMU location at the end of the line is tracked through information on the PMU installation location at the feeder start point, and the branch line where the PMU does not exist is identified by the main failure section determination unit 232 through a separate identification process. Do not perform an operation on the section.

3 is a flowchart illustrating the operation of the failure type determination unit 231 of the failure section determination unit 23 in FIG. 1.

More specifically, the fault type determination unit 231 acquires (or collects) data of the PMU controlled by the fault section determination controller (PDC, 24) according to a set period (S41), and at the feeder start point. Through the voltage and current data of the installed PMU, when the measured value of the voltage becomes smaller than the set value, and when the current becomes larger than the set current, a system failure is recognized. In addition, the fault type determination unit 231 determines the fault type based on the amount of voltage change before and after the fault.

4 is an exemplary view showing voltage change characteristics when a failure occurs in FIG. 3, in this embodiment, classification of the most frequently occurring unbalanced failures and balanced failures in the distribution system by utilizing voltage characteristics according to failure types. And the voltage change as shown in FIG. 4 can be seen in the type of failure.

At this time, in this embodiment, the voltage and current change amount (or change rate) before and after the failure is used to determine the type and section of the failure, and Equations 1 and 2 below are used to calculate this.

,

는 고장 후 PMU에서 계측된 전압, 전류의 크기 및 위상,

,

는 고장 전 PMU에서 계측된 전압, 전류의 크기 및 위상을 나타낸다. here,

,

Is the magnitude and phase of the voltage and current measured by the PMU after failure,

,

Represents the magnitude and phase of the voltage and current measured by the PMU before failure.

If the difference in the voltage change of the three phases after a fault is within the set range, the fault is classified as a balanced fault (or balanced short fault).

Equilibrium short circuit failure is classified using Equation 3 below (S43).

는 각 상의 고장발생 전후의 전압 변화이며,

는 평형 고장을 구분하기 위해 설정된 범위를 나타낸다. here,

Is the voltage change before and after the failure of each phase,

Denotes the range set to classify the equilibrium fault.

Meanwhile, if it is not the balanced failure, the unbalanced failure is classified using Equation 4 below (S44).

는 고장인지 단계에서 전압 범위를 벗어난 상들의 고장발생 후 전압 변화를 나타내며, 해당 상들을 고장상으로 판별한다(S45). here,

Denotes a voltage change after failure of the phases out of the voltage range in the fault recognition step, and determines the corresponding phases as faulty phases (S45).

는 고장발생 후 전압변화가 거의 일어나지 않는 건전상,

는 불평형 고장을 구분하기 위해 건전상과 고장상간의 변화 범위를 나타낸다.At this time

Is a sound condition that hardly changes the voltage after a failure occurs,

Represents the range of change between the sound phase and the fault phase to distinguish the unbalanced fault.

5 is a flowchart illustrating the operation of the main failure section determination unit 232 in FIG. 1.

As shown in Fig. 5, the main failure section determination unit 232 is before and after failure obtained by the failure type determination unit 231 in order to determine the primary failure section within the PMU section installed at the start and end points on the main feeder. Depending on the amount of voltage and current change and the type of fault, the change in voltage and current of each bus is calculated from the PMU start point to the end direction (downstream), and from the end direction to the start point direction (upstream) (S61).

At this time, when the voltage and current changes are calculated for all buses in the downstream and upstream directions of the main feeder, the voltage deviation between the two directions is calculated to detect a failure on the main feeder (S63).

In the above method, based on the compensation theory of the circuit theory, the section with the smallest deviation between the downstream and the starting point is identified (S64), and is identified (or identified) as the primary failure section ( S65). Thereafter, if the branch line is connected to the fault section of the main feeder (example in S66), the branch line fault section determination unit 233 is performed (S67), and if the fault section is, the branch line is not connected, and the main feeder is faulty. The section determination controller 24 ends.

On the other hand, when the result of the fault type determination unit 231 is a balanced fault, the voltage and current change amounts of each section are calculated as shown in Equation 5 and Equation 6 below.

,

고장 전후 각 모선의 전압, 전류 변화량, n은 메인 피더의 각 모선 번호를 나타내며, 피더 시작점

,

과 피더 말단

,

는 해당지점 PMU에서 계측된 전압, 전류 변화량을 초기값으로 설정한다.

은 계산되는 모선과 직전 모선사이의 선로 임피던스를 나타내며,

는 구간 부하를 나타낸다. here,

,

Voltage and current change amount of each bus before and after failure, n represents each bus number of the main feeder, and the feeder starting point

,

And feeder end

,

Sets the voltage and current changes measured at the corresponding point PMU as initial values.

Represents the line impedance between the calculated bus and the immediately preceding bus,

Represents the section load.

In this embodiment, it is assumed that the load amount of each section is known.

If the fault occurred is a one-line ground fault, the amount of change in voltage and current for each bus in the fault is calculated using Equations 7 to 9 below.

Here, n represents each bus number of the main feeder.

는 각 상에 대한 모선 전류변화량,

는 고장 상에 대한 고장 전후 각 모선의 전압, 전류 변화량을 나타내며, 위의 평형해석과 동일하게 초기 값은 PMU의 계측값을 활용한다. 그리고 a =

,

,

,

고장 상에 대한 각 모선의 정상, 역상, 영상 전류 변화량,

,

,

는 n번째 모선과 그 직전 모선사이 선로의 정상, 영상, 역상분의 임피던스를 나타낸다. And

Is the amount of change in bus current for each phase,

Represents the amount of change in voltage and current of each bus before and after the failure for the fault phase, and the initial value is the measured value of the PMU, similar to the above balance analysis. And a =

,

,

,

The amount of change in normal, reverse, and image current of each bus for the fault phase,

,

,

Denotes the impedance of the normal, image, and reverse phase of the line between the nth bus and the immediately preceding bus.

If a branch line is connected to the system, in order to consider the contribution to the failure of the distributed power supply (PV) in the event of a failure, the present embodiment uses Equation 10 and Equation 11 below, the voltage phase and the branch line of the PMU installed at the feeder starting point. The current magnitude of the RTU installed at the starting point and the phase difference between voltage and current were utilized (S62).

For reference, FIG. 6 is an exemplary diagram illustrating a system including distributed power in order to explain a method of analyzing a system of a system in which distributed power is connected in FIG. 5.

,

는 분기선 시작점 설치된 RTU에 취득된 고장 전후의 전류 크기이며,

,

는 고장 전후 피더시작점 PMU에서 계측된 전압위상,

,

는 고장 전후 RTU에서 취득된 전압-전류 위상차를 나타낸다. 상기 계측 정보를 통해

,

를 계산하여 분산전원에 대한 전류 변화량을 계산한다. here,

,

Is the magnitude of the current before and after failure acquired in the RTU installed at the starting point of the branch line,

,

Is the voltage phase measured at the feeder starting point PMU before and after failure,

,

Represents the voltage-current phase difference acquired at the RTU before and after failure. Through the above measurement information

,

Calculate the amount of change in the current for the distributed power source by calculating.

7 is a flowchart illustrating an operation of a branch line failure section determination unit in FIG. 1.

As shown in FIG. 7, the branch line failure section determination unit 233 receives PV insolation, maximum output, load conditions, etc. in order to identify a fault section inside the branch line in which the PMU is not installed (S81), and receives the PMU. Through the feeder start point fault current is acquired (S82).

In this embodiment, a failure of each bus (automatic and manual switch unit) inside the branch line is assumed (or set) through the failure analysis method, and the failure current at the feeder starting point is calculated through the failure analysis (S83).

For reference, when calculating the fault current, it was defined as a model that dynamically fluctuates PV (a PQ model or a constant current source model that varies depending on the situation) in order to take into account the output fluctuation according to the amount of PV insolation and the output limit by the inverter. The PV inverter outputs power proportional to the current insolation, and increases the current when the voltage drops to maintain the power output. However, by setting the maximum current (1.2 to 2 times), it has the characteristic of fixing the magnitude of the current when the increase of the current becomes larger than the corresponding value. In addition, the distribution system was converted to 3-phase in order to consider the system status in the event of an unbalanced failure. After that, the fault calculation is performed using the three-phase algae calculation.

8 is a flow chart for explaining in more detail the calculation process for the breakdown analysis by the branch line failure section determination unit in step S83. Referring to FIG. 8, a breakdown occurs among busbars of the branch line for failure calculation. The bus is defined, the fault type determination unit 231 recognizes the fault and calculates the admittance matrix of the distribution system (S91).

When calculating the admittance matrix, the elements (line, transformer, generator) of the system are converted into three-phase data in order to perform the three-phase current calculation, and the faulty bus is defined as being connected to the bus connected to the ground.

At this time, the faulty phase of the bus is treated as being grounded with the ground, and the sound phase is treated as being open. Classify the type of bus in the grid (e.g. Slack (substation), PQ (load, PV), PV (synchronous device), etc.) and set the initial value (S92).

At this time, the initial value is set to the bus voltage, the amount of insolation of the previously input PV, and the load condition, and the current is calculated until the voltage values at each bus are converged through the three-phase current calculation (S93).

For reference, when calculating the tidal current, Slack is set as a model using the magnitude and phase of the voltage as known values, and the load is processed as a PQ model by calculating active/reactive power consumption according to the load model. PV is treated as a PQ model that outputs a certain active/reactive power when it is below the limit output, and a model that outputs a fixed size current when it is above the limit output.

In addition, the synchronizer processes the PV (Active Power/Voltage) model that knows the magnitude and active power of the voltage. After performing the current calculation, in order to consider the maximum output of the PV inverter, calculate the output current of the PV and check whether the maximum current output (1.2 to 2 times) of the PV is exceeded (S94).

If the current size of the PV is larger than the limit value, the size of the fault current of the PV is limited (S95), and the three-phase current calculation is performed again (S93).

Accordingly, if all PVs are within the output range (No in S94), the fault current is calculated through the converged bus voltage and line impedance (S96).

Through the process as shown in FIG. 8, when a failure occurs in each bus, a failure analysis is executed to calculate the amount of current flowing to the feeder starting point (PMU installation point) (S83), and the PMU installed at the feeder starting point after the failure occurs. The section with the smallest deviation is determined as the fault section through the comparison (S84) between the measured current value acquired in (S82) and the fault analysis result value (S85).

For reference, in the case of the failure analysis method according to the present embodiment as described above, operation data such as load, solar radiation, and maximum output required for failure analysis are acquired through the operation DB 21.

As described above, the method applied to solve the conventional problem in this embodiment is summarized as follows.

(1) As a countermeasure for unbalanced faults, when a fault occurs, the type of fault (three-phase short circuit, one-line ground fault) is determined by utilizing the voltage change characteristics according to each fault. Perform the utilized equilibrium analysis. In the case of an unbalanced fault, the initial value (the value of the calculation starting point) of the symmetric component (normal, reversed phase, image) is calculated using the measured values of the voltage and current changes of each phase measured through the PMU installed at the power side and the end of the line. Failure section for both balanced and unbalanced faults through analysis of the downstream (power side → line end) and upstream (line end → power side) directions of each bus using calculated values, line impedance (image, normal, reverse phase) and load There is an effect of solving the problems of the prior art by performing the judgment.

(2) As a treatment plan for branch lines and distributed power, in the present invention, the start and end points on the main feeder are performed in order to determine the section when a branch line without a PMU is installed and the fault section reflecting the contribution of the fault to the distributed power supply. In addition to the measured values of the PMU installed in the branch line, a method for identifying the fault section using the existing RTU measured values and fault analysis methods installed at the starting point of the branch line was presented. The proposed method is largely divided into two stages. First, it is the step of calculating the current phase of the PV roughly and identifying the fault section on the main feeder using this. At this time, assuming that the voltage phase difference within the same feeder is not large, the current phase of the PV is calculated using the voltage-current phase difference at the point where the voltage phase data of the PMU installed on the power side and the distributed power supply (PV) are connected, and the voltage phase data of the PMU. do. In addition, when calculating the voltage and current variation of the bus on the main feeder, the calculated current phase of the PV was summed with the current flowing through the bus of the main line connected to the distributed power source to reflect the contribution of the distributed power source in case of failure. Second, after identifying the fault section on the main feeder in this way, if there is a branch line between the sections, the fault analysis method based on the current calculation considering PV insolation, maximum output, and load conditions is used to determine the fault point inside the branch line. Assuming a failure of each bus (automatic and manual switch unit) within the branch line, the difference between the calculated result and the measured value is the most by calculating the magnitude of the fault current flowing from the power side (PMU installation point) and comparing it with the PMU measurement value. There is an effect of identifying a small section as a fault section.

As described above, according to the present embodiment, it is possible to obtain at least three advantages over the existing technology. First, compared to the existing method, where the fault section can be identified only by installing PMUs at the start and end points of all sections, only two PMUs are installed at both ends of the main feeder, and the rest uses the RTU measurement value and fault analysis method. It has the advantage of being able to identify fault sections while maintaining the grid infrastructure. Second, there is an advantage that can be applied to the actual distribution system compared to the existing method by performing unbalanced failure handling. Third, through the above two advantages, the controller on the distribution feeder can determine the failure section of not only the existing automatic switch but also the manual switch unit, isolation and recovery, etc., so that the reduction of the failure section and the power failure time can be obtained. There is an advantage.

Meanwhile, in order to verify the effect on the failure section determination controller 24 according to the present embodiment, the test system (or test system) as shown in FIG. 9 was verified. 9 is an exemplary diagram showing a test system for verifying the effect of the fault section determination controller in FIG. 1.

로 구성하였으며, 분산전원이 연계된 분기선의 경우 0.5km, 메인피더분기선 및 Sub4 분기선의 경우 구간길이는 1km로 설정하였다. 또한, 각 태양광의 용량을 1MW로 설정하였으며 분산전원에 연계된 변압기는 분산전원과 동일 용량의 Y/△결선, Y/Y결선으로 설정하였다. 또한, PMU는 피더시작점(1번)과 말단(10번)에 설치하였으며, RTU는 분기선 시작점(Sub1_1, Sub2_1, Sub3_1, Sub4_1)에 설치하였다. The line impedance of the test system as shown in FIG. 9 is ACSR

In the case of a branch line connected with distributed power, the section length was set to 0.5 km, and in the case of the main feeder branch line and the Sub4 branch line, the section length was set to 1 km. In addition, the capacity of each solar power was set to 1MW, and the transformer connected to the distributed power supply was set to Y/△ connection and Y/Y connection of the same capacity as the distributed power supply. In addition, the PMU was installed at the feeder starting point (No. 1) and the end (No. 10), and the RTU was installed at the branch line starting points (Sub1_1, Sub2_1, Sub3_1, Sub4_1).

In addition, in order to identify the failure section according to the system analysis method, to compare and verify the analysis method according to the failure type determination of the existing failure analysis method and the failure analysis method according to this embodiment, a simulation is performed in MATLAB Simulink and each analysis method. A comparison was performed, and the ground fault of the first line was simulated between 6-7 buses and 4-5 in order to address the problems of the prior art.

10 and 11 are exemplary diagrams for comparing the voltage deviation calculation and simulation results of the main feeder according to the conventional method according to the present embodiment and the proposed method according to the present embodiment.

10 and 11 (a) are exemplary diagrams showing the voltage deviation and simulation voltage of the main feeder according to the conventional method, and FIGS. 10 and 11 (b) are the voltage of the main feeder according to the proposed method of the present embodiment. It is an exemplary diagram showing the deviation and simulated voltage.

In the case of the conventional method, when a 1-wire ground fault occurs, voltage deviation occurs in the downstream and upstream directions, so it can be confirmed that the fault section cannot be found. However, in the case of the method according to the present embodiment, it was confirmed that the calculation deviation between the downstream and upstream directions was widened after the actual failure period, and the failure period was accurately found.

Table 1 is a table showing the results of determining the main failure section according to the conventional method for failure section 1 and the proposed method of this embodiment.

Table 1 below shows values such as voltage change amount and deviation of all buses in the conventional method and the proposed method according to the present embodiment, and it can be seen that the simulation result and the deviation are severe in the case of the conventional method.

At this time, in Tables 1, 2, 3, 4, and 5 below, the gray shaded part shows the result of determining the failure section of each method.

Voltage deviation according to the fault section division

existing
system Downstream 0.2843 0.3583 0.4365 0.5158 0.5969 0.6798 0.7630 0.8465 0.9369 1.0276 Upstream 1.0028 0.9900 0.9772 0.9670 0.9572 0.9475 0.9396 0.9321 0.9315 0.9312 Deviation of change 0.7275 0.6366 0.5435 0.4527 0.3613 0.2687 0.1777 0.0870 0.0132 0.0968 suggestion
system Downstream 0.2843 0.3971 0.5191 0.6425 0.7686 0.8974 1.0267 1.1565 1.3058 1.4558 Upstream 1.1130 1.0807 1.0485 1.0234 0.9988 0.9744 0.9533 0.9328 0.9317 0.9312 Deviation of change 0.8359 0.6864 0.5305 0.3811 0.2304 0.0777 0.0740 0.2239 0.3743 0.5247 Matlab Simulink
Simulation results
Voltage deviation 0.2843 0.3970 0.5189 0.6418 0.7669 0.8999 0.9556 0.9338 0.9321 0.9312

Table 2 is a table showing the results of determining the main failure section according to the conventional method for failure section 2 and the proposed method of this embodiment.

Table 2 below shows the results of simulating the ground fault of line 1 in the fault section 2 (4-5). As with the result of fault section 1, it can be seen that it is difficult to accurately identify the fault section for the ground fault of the first line with the existing method.

Voltage deviation according to the fault section division

existing
system Downstream 0.3844 0.4847 0.5908 0.6984 0.8084 0.9222 1.0364 1.1511 1.2718 1.3930 Upstream 0.9610 0.9461 0.9313 0.9201 0.9093 0.8986 0.8916 0.8850 0.8844 0.8841 Deviation of change 0.5882 0.4678 0.3442 0.2239 0.1032 0.0328 0.1460 0.2665 0.3876 0.5090 suggestion
system Downstream 0.3844 0.5402 0.7089 0.8795 1.0538 1.2373 1.4215 1.6064 1.8088 2.0122 Upstream 1.0855 1.0468 1.0082 0.9792 0.9508 0.9226 0.9038 0.8856 0.8846 0.8841 Deviation of change 0.7111 0.5104 0.3006 0.1000 0.1030 0.3148 0.5177 0.7208 0.9243 1.1282 Matlab Simulink
Simulation results
Voltage deviation 0.3844 0.5410 0.7109 0.8829 0.9418 0.9242 0.9057 0.8871 0.8852 0.8841

On the other hand, regarding the identification of the failure section due to the occurrence of a branch line failure, in the proposed method of this embodiment, in order to determine the result of the branch line failure section determination unit when a failure occurs in a branch line without a PMU installed, Sub2_2-3, Sub3_1-2, Sub4_3- In 4, the ground fault of line 1 was simulated.

Table 3 is a table showing the branch line failure section determination results for failure section 1, Table 4 is a table showing the branch line failure section judgment results for failure section 2, and Table 5 shows the branch line failure section judgment results for failure section 3. This is Boin Yeable.

In other words, Tables 3, 4, and 5 show the results of the failure section judgment unit for failure sections 1, 2, and 3, and the results of the primary main failure section judgment section are sections connected to the branch line (5-6, 8-9, 4- 5) was confirmed to be identified. When comparing the PMU measurement values (1.09, 0.85, 0.863) after failure and the failure analysis results within each branch line to identify the failure section within the branch line, it can be seen that the location of the failure simulation is identified in the branch line failure determination section.

Voltage deviation according to the fault section Classification (1st)

Downstream 0.3087 0.4333 0.5682 0.7046 0.8420 1.1367 1.4322 1.7285 2.0409 2.3544 Upstream 1.7156 1.5327 1.3498 1.1746 1.0000 0.8255 0.8084 0.7917 0.7908 0.7904 Deviation of change 1.4168 1.1038 0.7835 0.4707 0.1581 0.3115 0.6241 0.9371 1.2504 1.5643 Voltage deviation (simulated) 0.3087 0.4337 0.5692 0.7064 0.8475 0.8287 0.8103 0.7925 0.7911 0.7904 Classification (2nd) Sub2_1 Sub2_2 Sub2_3 Failure analysis result 1.24 1.14 1.05 Final result Sub2_2>1.09>Sub2_3

Voltage deviation according to the fault section Classification (1st)

Downstream 0.2352 0.3260 0.4241 0.5233 0.6232 0.7233 0.8239 0.9250 1.0468 1.1691 Upstream 1.1123 1.0827 1.0532 1.0292 1.0058 0.9825 0.9600 0.9381 0.9370 0.9365 Deviation of change 0.8833 0.7591 0.6301 0.5062 0.3827 0.2592 0.1363 0.0164 0.1104 0.2331 Voltage deviation (simulated) 0.2352 0.3263 0.4248 0.5246 0.6271 0.7304 0.8342 0.9385 0.9372 0.9365 Classification (2nd) Sub3_1 Sub3_2 Failure analysis result 0.86 0.82 Final result Sub3_1>0.85>Sub3_2

Voltage deviation according to fault section 3 Classification (1st)

Downstream 0.2390 0.3356 0.4404 0.5465 0.6533 0.7604 0.8681 0.9762 1.0942 1.2127 Upstream 0.5913 0.5742 0.5572 0.5461 0.5353 0.5246 0.5142 0.5041 0.5035 0.5032 Deviation of change 0.3601 0.2420 0.1183 0.0044 0.1181 0.2361 0.3543 0.4727 0.5912 0.7101 Voltage deviation (simulated) 0.2390 0.3359 0.4412 0.5479 0.5363 0.5253 0.5146 0.5043 0.5036 0.5032 Classification (2nd) Sub1_1 Sub1_2 Sub1_3 Sub1_4 Sub1_5 Failure analysis result 1.2185 1.0418 0.9116 0.8118 0.7328 Final result Sub1_3>0.863>Sub1_4

As described above, the present invention has been described with reference to the embodiments shown in the drawings, but these are only exemplary, and those of ordinary skill in the field to which the technology pertains, various modifications and other equivalent embodiments are possible. I will understand the point. Therefore, the technical protection scope of the present invention should be determined by the following claims. Also, the implementation described herein may be implemented in, for example, a method or process, an apparatus, a software program, a data stream or a signal. Although discussed only in the context of a single form of implementation (eg, only as a method), the implementation of the discussed features may also be implemented in other forms (eg, an apparatus or program). The device may be implemented with appropriate hardware, software and firmware. The method may be implemented in an apparatus such as a processor, which generally refers to a processing device including, for example, a computer, a microprocessor, an integrated circuit or a programmable logic device, or the like. Processors also include communication devices such as computers, cell phones, personal digital assistants (“PDAs”) and other devices that facilitate communication of information between end-users.

20: distribution operation system 21: operation DB
22: topology estimation unit 23: failure section determination unit
231: fault type determination unit 232: main fault section determination unit
233: branch line fault section determination unit 24: fault section determination controller

Claims (14)

A distribution operating system that periodically receives data measured by a plurality of remote control station devices (RTUs) and stores them in an internal operation DB; And
Including; a fault section determination controller for receiving and processing data measured through a plurality of PMUs (Phasor Measurement Units) according to a specified period,
The distribution operation system and the failure section determination controller,
They are linked to each other through a communication network, and the RTU measurement data stored in the operation DB is transmitted to the fault section determination controller through the communication network,
The fault section determination controller,
A topology estimating unit for generating bus information and processing linear path information between PMUs by receiving information on open/close status of switchgear and breaker of the distribution system from the operation DB; And
A fault type determination unit that determines the occurrence and type of a fault in the distribution system, a main fault section determination unit that primarily identifies the fault section on the main feeder using PMU data, and the point where the branch line is connected to the primary identification fault section. In this case, a fault section determination unit including a branch line fault section determination unit that determines a fault section inside the branch line using a specified fault analysis method.
The method of claim 1,
Identification of a distribution system failure section, further comprising: a front end processor (FEP) that interfaces field data information transmitted from the plurality of remote control station units (RTUs) to an operation DB of the distribution operation system system.
The method of claim 1, wherein the operation DB,
The topology information required for the failure section determination information is periodically transmitted and stored from the potential processor (FEP) and the failure section determination controller, and
A distribution system failure section identification system, characterized in that storing a result determined by the failure section determination unit.
The method of claim 3, wherein the information received from the failure section determination controller comprises:
As system status information, protection device, switch status information, node connection relationship, and information on load and distributed power connected to each node;
As the fault section determination information, the fault section location information of the distribution system identified by the fault section determination controller 24; And
As location information of a terminal device, installation location information of a PMU and RTU installed to determine a fault section; Distribution system failure section identification system comprising at least one or more of.
The method of claim 1, wherein the topology estimation unit,
In order to determine the fault section of the main feeder, the straight path of the main feeder installed with the PMU is searched and saved, and the connection relationship between node and facility is changed to data based on bus-equipment in order to perform fault analysis to determine the branch line fault section. And, the distribution system failure section identification system, characterized in that the reconstruction of the distribution system and reconfiguration of the topology data of the jurisdiction when the system structure changes according to the input and opening of the facility.
The method of claim 1, wherein the failure type determination unit,
Acquires the data of the PMU under the jurisdiction of the failure section determination controller according to a set period,
Through the voltage and current data of the PMU installed at the starting point of the feeder, when the measured value of the voltage becomes smaller than the set value, and when the current becomes larger than the set current, it recognizes the failure of the system.
A distribution system failure section identification system, characterized in that the failure type is determined based on the amount of voltage change before and after failure.
The method of claim 6, wherein the failure type determination unit,
To determine the type and section of failure,
Distribution system failure section identification system, characterized in that calculating the amount of change in voltage and current before and after failure using Equation 1 and Equation 2 below.
(Equation 1)

(Equation 2)

here,

,

Is the magnitude and phase of the voltage and current measured by the PMU after failure,

,

Represents the magnitude and phase of the voltage and current measured by the PMU before failure.
The method of claim 7, wherein the failure type determination unit,
Classify the equilibrium failure using Equation 3 below,
Distribution system failure section identification system, characterized in that the unbalanced failure is classified using Equation 4 below.
(Equation 3)

here,

Is the voltage change before and after the failure of each phase,

Denotes the range set to classify the equilibrium fault.
(Equation 4)

here,

Represents the voltage change after failure of the phases out of the voltage range in the fault recognition phase,

Is healthy,

Represents the range of change between the sound phase and the fault phase to distinguish the unbalanced fault.
The method of claim 1, wherein the main failure section determination unit,
In order to determine the primary fault section within the PMU section installed at the start and end points on the main feeder, the voltage and current changes before and after the fault obtained from the fault type determination unit and the fault type, from the PMU start point to the end direction (downstream), and Calculate the change in voltage and current of each bus from the end direction to the starting point direction (upstream),
When the voltage and current variation for all buses in the downstream and upstream of the main feeder are calculated, the voltage deviation between the two directions is calculated to detect a fault on the main feeder.
Distribution system failure section identification characterized by identifying the section with the smallest deviation between the downstream direction and the starting point direction (upstream) based on the circuit theory's compensation theory and identifying it as the primary failure section. system.
The method of claim 9, wherein when the result of the failure type determination unit is a balanced failure,
Distribution system failure section identification system, characterized in that calculating the amount of change in voltage and current in each section using Equation 5 and Equation 6 below.
(Equation 5)

(Equation 6)

here,

,

Voltage and current change amount of each bus before and after failure, n represents each bus number of the main feeder, and the feeder starting point

,

And feeder end

,

Sets the voltage and current changes measured at the corresponding point PMU as initial values.

Represents the line impedance between the calculated bus and the immediately preceding bus,

Represents the section load.
The method of claim 9, wherein when the result of the fault type determination unit is a 1-line ground fault,
Distribution system fault section identification system, characterized in that calculating the voltage and current variation for each bus on the fault using Equations 7 to 9 below.
(Equation 7)

(Equation 8)

(Equation 9)

Here, n represents each bus number of the main feeder,

Is the amount of change in bus current for each phase,

Denotes the amount of change in voltage and current of each bus before and after the fault for the fault phase, and the initial value is the measured value of the PMU, similar to the above balance analysis. And a =

,

,

,

The amount of change in normal, reverse, and image current of each bus for fault phase

,

,

Denotes the impedance of the normal, image, and reverse phase of the line between the nth bus and the immediately preceding bus.
The method of claim 9, wherein when a failure occurs due to a distributed power supply connected to the system,
Distribution system failure section identification system, characterized in that calculating the amount of change in the current for the distributed power supply (PV) using Equation 10 and Equation 11 below.
(Equation 10)

(Equation 11)

here,

,

Is the magnitude of the current before and after failure acquired in the RTU installed at the starting point of the branch line,

,

Is the voltage phase measured at the feeder starting point PMU before and after failure,

,

Represents the voltage-current phase difference acquired at the RTU before and after failure.
The method of claim 1, wherein the branch line failure section determination unit,
In order to identify the fault section inside the branch line where the PMU is not installed, the amount of insolation, maximum output, and load conditions of the distributed power supply (PV) are input.
When assuming a failure in each bus line inside the branch line, the magnitude of the current flowing at the feeder starting point is calculated through failure analysis,
A distribution system fault section identification system, characterized in that the section with the smallest deviation is determined as the fault section through a comparison between the measured current value acquired from the PMU installed at the start point of the feeder after the fault and the fault analysis result value.
The method of claim 13, wherein the branch line failure section determination unit,
For fault calculation, the faulty bus is defined among the buses of the branch line, and the fault type determination unit recognizes the fault and calculates the admittance matrix of the distribution system.
Classify the type of bus in the system and set the initial value, but the initial value is set as the bus voltage, the amount of insolation of the previously input PV, and the load condition, and when the voltage values at each bus are converged through the three-phase current calculation. To perform algae calculation,
In order to consider the maximum output of the distributed power (PV) inverter after performing the current calculation, the output current of the distributed power (PV) is calculated to check whether the specified maximum current output of the distributed power (PV) is exceeded,
As a result of the above check, when the current magnitude of the distributed power supply (PV) is larger than the limit value, the magnitude of the fault current of the distributed power supply (PV) is limited and the three-phase current calculation is performed again.
Distribution system fault section identification system, characterized in that, when all distributed power sources (PVs) are within a specified output range, fault current is calculated through the converged bus voltage and line impedance.

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