KR101514999B1 - Method and system for self-checking and self-separating of fault section by using smart protection devices in a power distribution system - Google Patents

Abstract

The present invention relates to a method and system for self-checking and self-separating of a fault section by using smart protection devices in a power distribution system, and, in particular, to a method and system for self-checking and self-separating of a fault section by using smart protection devices in a power distribution system, by which, when an arbitrary breakdown occurs on a smart power distribution grid system having distributed resources, each smart protection device experiencing a fault current performs a high-speed information exchange with other smart devices on lines without any interference of a central controller, on the basis of a high-speed data communications ability; after collecting fault information such as a current direction as well as a voltage value and a current value, it is rapidly determined that a magnetic protection section is a fault section; and the fault section is accurately separated, so that the time of separating the fault section can be minimized.

Description

[0001] METHOD AND SYSTEM FOR SELF-CHECKING AND SELF-SEPARATING OF FAULT SECTION BY USING SMART PROTECTION DEVICES IN A POWER DISTRIBUTION SYSTEM [0002]

The present invention relates to a method and system for identifying and isolating an autonomic fault zone using a smart protection device in a power distribution system, and more particularly, to a smart distribution grid system having a new distributed power source, The present invention relates to a method and system for identifying and isolating an autonomic fault section that can determine a fault section by itself using a bi-directional communication function of a smart distribution grid system and isolate the fault section from the power distribution system.

In recent years, a great deal of attention has been focused on the smart distribution grid system, in which distributed power sources are introduced and two-way communication between facilities is enabled, in order to increase the proportion of energy generation and increase energy efficiency in order to overcome global warming. So far, centralized control-based distribution automation systems have contributed significantly to improving power supply reliability for dendritic distribution systems. However, in a dendritic line, since the protective device is designed to perform only the function of providing data or operating the switch according to the polling command of the central control device via the Feeder Remote Terminal Unit (FRTU), the smart distribution If applied directly to the grid system, there is a problem that the reliability of the power supply is significantly lowered due to the overload of the server implementing the control apparatus of the distribution automation system due to the batch execution of various complex distribution tasks and the time delay caused by the communication traffic have. Also, since the line automation solutions and protective devices have been developed for distribution systems with existing dendritic structures, there is a problem in applying them to smart distribution grid systems having a mixed form of loop lines due to dendritic lines and distributed power sources.

In order to effectively solve these problems, the protection device itself is applied to the loop and dendritic lines by utilizing the bi-directional communication function of the smart grid distribution system, completely different from the conventional centralized control method, New and innovative methodologies that can be

So far, several methodologies have been proposed to support distribution automation systems. Among them, line reconfiguration methodology to reduce line losses of power distribution system under normal conditions, methodology to obtain load equalization, methodology to identify fault locations under emergency conditions, methodology for fault recovery and HIF (High Impedance Fault) Methodologies have been proposed, but most of the above methods are about line reconfiguration suitable for a central control based distribution automation system based on unidirectional communication, and the technology of a distribution automation system based on bidirectional communication is rarely dealt with.

In order to solve the problem that the reliability of the power supply is significantly lowered due to the overload of the server implementing the control system of the distribution automation system and the time delay caused by the communication traffic, the autonomous separation method based on bidirectional communication and the HIF Although the autonomous partition methodology exists, these studies deal only with the distribution system with dendritic structure. Therefore, there is a problem that can not be directly applied to the smart distribution grid system of the composite structure of the dendritic structure and the loop structure due to the distributed power source there was.

In order to improve the operation efficiency and reliability of the smart distribution grid system according to the above-mentioned circumstances, when a failure occurs on the line of the smart distribution grid system including the dendritic structure and the loop structure at the same time, There is a demand for a new smart protection device capable of judging and separating a section by itself.

Thus, the present invention proposes a new fault segmentation method for a smart distributed grid system with a new distributed power source. In this method, when any smart protection device on the line senses a fault current, it exchanges malfunction information such as voltage and current with other protection devices by utilizing the bi-directional communication capability of smart distribution grid system by itself, It is possible to accurately and quickly judge whether or not the self-protection section is a failure section, and to identify and isolate the failure section.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above problems, and it is an object of the present invention to provide a smart protection device capable of performing self-loop and dendritic structures by using a bidirectional communication function of a smart distribution grid system, The present invention relates to a system and method for identifying and isolating an autonomous fault section of a smart protection device in a power distribution system.

The present invention also provides a method of detecting and isolating a fault section, such that when a smart protection device on a line senses a fault current, it uses the bi-directional communication capability of the smart distribution grid system to detect It is an object of the present invention to provide an autonomous fault section identification and separation system and method of a smart protection device of a power distribution system capable of identifying and separating a fault section by exchanging fault information.

Further, the present invention provides an autonomous fault section identification and separation system of a power distribution system smart protection device capable of accurately and promptly determining whether or not a self-protection section is a fault section based on heuristic rules in checking the fault section, and The purpose of the method is to provide.

   Further, it is an object of the present invention to provide a smart protection device capable of minimizing the failure section separation delay time by correctly determining whether or not the self-protection section is a failure section without interference by the central control apparatus, The present invention is directed to a system and method for identifying and isolating fault zones.

A smart distribution grid system according to an embodiment of the present invention includes at least one smart protection device; A distribution line connected between the at least one smart protection device; And a bidirectional communication line including wired, wireless, or a combination thereof connected between the at least one smart protection device, wherein the at least one smart protection device includes a current value, a voltage value, a current direction, or a combination thereof Directional communication with the smart protection devices on the self-protection interval to collect the failure information, check whether the self-protection interval is in the failure interval, and if the failure interval is determined based on the confirmation result, Way communication related to the open command of the protective device to the smart protection devices on the smart distribution device, and automatically separates the failure section from the smart distribution grid system. In the smart distribution grid system, the smart protection device is a protection device including a circuit breaker, a switch, or a recloser to which a feeder remote terminal unit (FRTU) is attached. The protection device is a three- And a sensor for measuring data on the output three-phase voltage. The FRTU receives the measured data to determine whether the distribution line is faulty, and transmits the determination result to the adjacent smart protection device Wherein the smart protection device comprises: an RMS calculation unit for calculating an effective value of an input voltage and a current; And a rule-based failure section determining unit that determines a low impedance failure (LIF) period based on the calculated RMS value. The Smart Protecting device includes a frequency transformation unit including a DWT or DFT for the input voltage value and the current value, A frequency converter for converting the frequency component into a frequency component; And a rule-based failure section determination unit for determining a high impedance failure (HIF) period through the frequency-converted input data, wherein the rule-based failure section determination unit determines that the distributed power source is a power- present as if one did not exist in the guard interval for, any smart protection device experiencing a fault current, the same as W _x is W _R in the smart protection device (where W _x is any smart protection device self Where W _R is the direction of the current flowing from the substation transformer, and if the protection interval of the smart protection device is a terminal interval, determining that the protection interval of the smart protection device is a failure interval; In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if one of the downstream protection devices of the smart protection device experiences a low voltage from the failure location f, then the smart Judges the protection zone of the protective device as the failure zone; In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if none of the downstream protection devices of the smart protection device from the fault location f experience a fault current, Determining the guard interval of the smart protection device as the fault interval; To the smart distribution grid system DG as when placed on the load side of the fault section, any smart protection device experiencing a fault current, the same as W _x is W _R in the smart protection device (where W _x is any W _R is the direction of the current flowing from the substation transformer), and W _x of one of its downstream protection devices from fault location f is not equal to W _R (the direction of the current measured at the self- Where W _x is the direction of the current measured at the magnetic location of any smart protection device, and W _R is the direction of the current flowing from the substation main transformer), and the guard interval of the smart protection device is determined as the fault zone .

In another aspect of the present invention, there is provided a method of autonomously determining and isolating a fault section in a smart distribution grid system, the smart protection device comprising a current value, a voltage value, a current direction, or a combination thereof Measuring a state including a current; Determining a low impedance fault (LIF) period based on the measured value of the state; And performing bidirectional communication with the smart protection devices on the low impedance fault section in relation to the open command of the protection device based on the determined result, and automatically separating the fault section from the smart distribution grid system do. In addition, in the smart distribution grid system, in the method of autonomously determining and distinguishing a fault interval, the step of determining the low impedance fault interval may include: measuring a measured value of each phase measured by the smart protection apparatus, Comparing the heuristic rule with the heuristic rule, and determining that the heuristic rule is satisfied if the rule is satisfied; And performing bi-directional communication with the smart protection devices on the self-protection period to collect failure information and checking whether the self-protection interval is in a failure interval if it is determined that the failure is a result of the determination, Is a case in which a distributed power source is present on the power side or end but does not exist in the corresponding protection period in a Smart Distribution Grid system in which any smart protection device experiences a fault current and W _x in the smart protection device is W _R Where W _x is the direction of the current measured at the magnetic location of any smart protection device and W _R is the direction of the current flowing from the substation transformer and if the protection interval of the smart protection device is a terminal interval, Judging the protection interval of the device as a failure interval; In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if one of the downstream protection devices of the smart protection device experiences a low voltage from the failure location f, then the smart Judges the protection zone of the protective device as the failure zone; In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if none of the downstream protection devices of the smart protection device from the fault location f experience a fault current, Determining the guard interval of the smart protection device as the fault interval; To the smart distribution grid system DG as when placed on the load side of the fault section, any smart protection device experiencing a fault current, the same as W _x is W _R in the smart protection device (where W _x is any W _R is the direction of the current flowing from the substation transformer), and W _x of one of its downstream protection devices from fault location f is not equal to W _R (the direction of the current measured at the self- Where W _x is the direction of the current measured at the magnetic location of any smart protection device, and W _R is the direction of the current flowing from the substation main transformer), and the guard interval of the smart protection device is determined as the fault zone .

Meanwhile, a smart distribution grid system to which a section modeling method for bidirectional communication is applied includes at least one smart protection device; A distribution line connected between the at least one smart protection device; And a bi-directional communication line including wired, wireless, or a combination thereof connected between the at least one smart protection device, wherein each of the intervals includes a set of smart protection devices and a bi- And a set of voltage directions required to indicate which side of the voltages are included in the section. In addition, in the smart distribution grid system applying the interval modeling method for bidirectional communication, the interval may include a current direction flowing from a source power source including a transformer to track upstream or downstream electrical connectivity to at least one smart protection device Determines one source interval and a sync interval based on the determined sync interval, and designates the determined sync interval as a guard interval; Wherein the at least one smart protection device exchanges malfunction information including voltage values, current values, current directions or a combination thereof with nearby smart protection devices on the line in the event of a failure, Characterized in that the protective device is designed to identify and isolate the fault zone before it is opened to the lockout state.

The present invention relates to a system and method for autonomous fault detection and isolation of a smart protection device of a power distribution system, and more particularly, to a smart protection grid The smart protection device performs high-speed information exchange with other smart protection devices on the line without intervention of the central control device based on the high-speed data communication capability, and collects fault information including the voltage value and the current value as well as the current direction , It is possible to quickly determine whether or not the self-protection section is a failure section, and to accurately divide the failure section, thereby minimizing the failure section detachment time period, thereby preventing the aftereffect of failure from propagating to the adjacent section.

Brief Description of the Drawings Fig. 1 is an exemplary view for explaining a configuration of a distribution automation system and a function of a protective device according to a conventional technique; Fig.
2 is an exemplary diagram illustrating a smart distribution grid system for applying the present invention;
3 is a diagram illustrating an example of a hardware configuration of a smart protection device according to an embodiment of the present invention.
FIG. 4 is an exemplary diagram illustrating a configuration of a smart protection device solution according to an embodiment of the present invention; FIG.
FIG. 5 is an exemplary diagram illustrating a heuristic rule according to an embodiment of the present invention; FIG.
FIG. 6 is a diagram for explaining section modeling for bidirectional communication according to an embodiment of the present invention; FIG.
7 is a flowchart illustrating a low impedance failure (LIF) reasoning procedure of a smart protection device solution according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a system and method for identifying and isolating an autonomic failure section of a smart card protective device of a power distribution system according to the present invention will be described with reference to the accompanying drawings.

1 is an exemplary diagram for explaining a configuration of a distribution automation system and a function of a protective device according to the prior art. As shown in FIG. 1, the conventional distribution automation system 10 performs all tasks of fault monitoring and management based on centralized, remote based, and polling-based unidirectional communication. The power distribution system is designed to have a multi-redundant structure to minimize the power outage in case of any failure or work interruption. That is, in order to remove and isolate an arbitrary fault on the line, a line protection circuit breaker CB, a circuit breaker, a recloser and a protective device 11 such as a switch, a FRTU A distribution automation system 10 including a feeder remote terminal unit 12 and a central control unit 13 is connected to a plurality of individual protective devices through a separate FRTU in a central control device via unidirectional communication The central controller collects the fault information by collecting the fault information, and determines whether the fault occurs in the central control unit, and separates the fault section by remotely controlling each protective device according to the determination result.

More specifically, the switches may be classified into a section switch for separating a fault section or a work section and an interrupter for switching a non-charge section to another line, and the power distribution automation system 10 may be classified into a unidirectional It monitors the protection devices on the line based on the communication, controls them when they are faulty, and separates the fault section and switches the normal power section to the nearby lines. The function of the FRTU measures the state of the line with respect to the three-phase voltage, the current, the phase, the state of the switch, or a combination thereof, and transmits the collected data to the central control device in accordance with the command of the central control device, The operator operates the switch in accordance with the command of FIG. Distribution Automation System The function of the central control unit 13 is to collect data from the FRTU in the form of a three-phase voltage, current, phase, switch, or combination thereof from the FRTU and collect data on the state of the line, It is possible to perform polling according to a predetermined time period for a predetermined period of time, and as the time period is shortened, it is possible to more frequently collect fault information (FI) from the FRTU, Do. In addition, based on the fault information from the collected individual FRTUs, a failure interval is determined, a load balancing strategy is established, and load switching is performed by sequentially transmitting an opening / closing operation command to the FRTU.

The power distribution reliability of the power distribution automation system 10 based on the central-based, remote-based, and polling-based unidirectional communication can be seriously degraded due to the delay of the fault isolation time. Accordingly, there is a demand for a smart protection device capable of minimizing the failure section separation delay time by determining whether or not the self-protection section is the failure section itself without interference from the central control device and accurately separating the failure section.

FIG. 2 is a diagram illustrating a smart distribution grid system to which the present invention is applied. As shown in FIG. 2, the smart distribution grid system 20 includes a tree structure line (feeder F2) 24 and a loop structure line (feeder F1) 23 due to a distributed power source. In Fig. 2, the symbols & cir & are the protective devices (switches) in the closed state, and the symbol O is the open protective devices (switches). Also, the protection device located on the vertical line of the distribution line is a section switch, and the protection device located on the horizontal line by the distribution line represents a link switch that connects the respective sections. The smart distribution grid system can effectively isolate a fault section on the distribution line of a tree structure and a loop structure through the section opening and closing switch.

Upstream protection devices experience fault currents from the fault zone, while downstream protection devices do not experience fault currents, in general, when any fault occurs on a distribution line with a dendritic structure. Here, the upstream protective device refers to the protection device between the power supply to the power line and the downstream protection device refers to the protection device located after the fault zone. The line automation solution of the distribution automation system 10 based on unidirectional communication as shown in Fig. 1 determines the fault interval based on this knowledge. However, this method can not be applied directly to the smart distribution grid system because the downstream protection devices from the fault section can experience fault currents due to the reverse fault current from the distributed power supply 21. For example, if one fault occurs between the protective device S1 and the protective device S2 on the F1 as a distribution line, then one downstream protection device S2 will not experience a fault current if the solar power distributed power source 21 is not present . On the other hand, as shown in FIG. 2, if there is a solar power dispersive power supply 21, one downstream protection device S2 will also experience a fault current. Unlike the conventional distribution automation system 10, the smart distribution grid system 20 can exchange high-speed information among protection devices on a line based on a high-speed digital communication network.

Therefore, when a failure occurs on a smart distribution grid system with a distributed power supply, each smart protection device experiencing a fault current will be able to communicate with other smart protection devices on the line Speed information exchange is performed to collect fault information such as the voltage value and the current value as well as the direction of the current and then quickly judge whether or not the magnetic protection section is a fault section and to accurately separate the fault section, A new method is needed to minimize the fault isolation time.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a system and method for identifying and isolating an autonomic failure section of a smart grid protection apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a diagram illustrating a hardware configuration of a smart protection device according to an exemplary embodiment of the present invention. The smart protection device 100 of the present invention may include a LIF (Low Impedance Fault) or HIF (High Impedance Fault) It is an intelligent protective device for intelligent distribution grid system that intelligence is able to identify and isolate a fault section by exchanging information with surrounding smart protective devices through high-speed two-way communication of smart distribution grid system at detection.

The smart protection device 100 is connected to a 22.9 kV three-phase power distribution line and includes a protector base unit 110 and a feeder remote terminal unit (FRTU) unit 120. The protector base 110 is connected to a voltage sensor (VS _A , VS _B ) for measuring the three-phase voltage (A phase voltage V _A , B phase voltage V _B , C phase voltage V _C ) , VS _C ) 111 are installed and voltage sensors (VS _R , VS _S , VS _T ) for measuring the three-phase load voltages (R phase voltage V _R , S phase voltage V _S , T phase voltage V _T ) ) 113 are provided. Current sensors (CT _A , CT _B , and CT _C ) 112 are provided on the power supply side to measure three-phase currents (A phase current, B phase current, and C phase current).

The FRTU unit 120 includes a surge protection circuit 121, a driver relay circuit 122, a measurement unit 123 for measuring DI system disposal state and AI current and voltage, a microprocessor 124, a real time Clock) chip 125, an RS232C 2 port (serial 2 port) 126, a power supply 127, a DC / DC converter 128, a RAM 129, an EPROM 130, an LCD display 131, A network card 132, a wired / wireless network communication port 133 for bidirectional communication, a bidirectional wireless communication antenna 134, and a battery 135. For reference, AI means analog input and DI means digital input.

The smart protection device 100 is located on the power distribution line, and the input three-phase power supply can be connected to or disconnected from the three-phase power output according to the command of the FRTU. That is, if the voltage value, the current value, the current direction, or a combination of them are measured and input to the FRTU from the input three-phase power source and the output three-phase power source, the FRTU determines whether or not the distribution line is faulty After that, the 3-phase power input to the protective device is commanded to be connected or disconnected from the output 3-phase power supply. The protector base 110 measures the voltage value, the current value. Current direction, or a combination thereof, receives the command according to a result determined by the FRTU, and disconnects or connects the power. The FRTU must be protected from overvoltage or overcurrent by the surge protection circuit 121. The FRTU receives the status of the smart protection device as a digital value and transmits a signal to the analog input for the voltage value, current value, current direction, . The measurement unit 123 can convert analog to digital (A / D conversion) or input measurement values selectively for each input measurement signal, and includes a meter transformer PT and a meter current transformer CT . Data on the state of the line with respect to the three-phase voltage, current, phase, state of the switch, or a combination thereof is input and stored in the microprocessor CPU / DSP 124, RAM 129, Based on the information, the fault zone is determined, the load balancing strategy is established, and the load switch is controlled by transmitting the switch operating command. It is also possible to communicate with a neighboring smart protection device via a wired / wireless network card 132, a bidirectional wired communication port 133 and a bidirectional wireless communication antenna 134. The RTC 125 is required for time synchronization between FRTUs, self-timer operation, etc., and it is possible for the user to directly access and control the microprocessor through the RD232C port 126, You can also control the FRTU by connecting it to the device. The FRTU can operate using its own battery, and can be supplied with power by using a charging facility if necessary. In addition, the FRTU can be connected to the input / output device through at least one of its own, a remote, a direct connection through a communication port, or a combination thereof. The input / output device may include a LCD and a key input, and may be connected using a keyboard and a virtual input / output device via a smart phone. The FRTU may set and store an initial value for operating the FRTU through the EPROM 130 or may store the parameters required at the initialization and restart of the smart protection device and upload it to the RAM 129 for use.

4 is an exemplary diagram illustrating a configuration of a smart protection device solution according to an embodiment of the present invention.

4, the smart protection device solution of the present invention basically includes a low impedance failure (LIF) determination unit 150, a high impedance failure (HIF) determination unit 160, And a communication unit 170. The LIF determination unit 150 includes an RMS calculation unit 151 and a rule-based LIF interval determination unit 152. The RMS calculation unit 151 calculates an effective value of each phase current, Based on the values, predefined Sink Zone information and heuristic rules, fault information is collected from the surrounding smart protection devices using the module of the communication unit, the LIF fault interval is determined, and fault isolation is performed. The communication unit 170 performs data communication between the smart protection devices and the smart protection device and the smart meter to collect the status of the adjacent smart protection devices and transmits them to the LIF determination unit 150 and the HIF determination unit 160, And receives status information on the smart protection device and transmits the status information to the outside. If the LIF determination unit 150 fails to confirm the failure, the HIF determination unit 160 is driven. The HIF determination unit 160 includes a Discrete Wavelet Transform (DWT) or Discrete Fourier Transform (DFT) transform unit 161, a HIF separator classifier 162, and a rule-based HIF interval determination unit 163. The HIF classifier 162 is designed as an artificial neural network (ANN) having a multilayered perceptron structure to determine the possibility of HIF failure. The rule-based HIF section determiner 163 classifies the HIF classifier 162 Collects malfunction information from the surrounding smart protection devices using the module of the communication unit 170 based on the output value of the communication unit 170, the predefined Sink Zone information and the heuristic rules, determines the HIF interval, .

More specifically, the RMS calculator 151 calculates an RMS value for a voltage value and a current value input to the smart protection device, and calculates a low impedance fault (LIF) based on the calculated RMS value And transmits it to the adjacent smart protection device through the communication unit. Meanwhile, DWT or DFT is performed on the input voltage value and the current value to separate the input value into a plurality of frequency components, and then the input values are classified through a high impedance failure (HIF) classifier 162, And transmits it to the adjacent smart protection device.

FIG. 5 is a diagram illustrating an example of a heuristic rule according to the present invention. The heuristic rule (HR) includes failures such as three-phase short circuit, phase-to-phase short circuit, Is obtained from the electrical and structural phenomena that are uniquely obtained according to the fault type, the fault location, and the disposition of the distributed power source 21, when occurring at various locations on the smart distribution grid system 20. [ 5, a transformer means a distribution transformer that supplies electric power to a distribution line of a smart distribution grid system, and a CB (Circuit Breaker) is a protection device (switch) located at a starting location by a distribution line. , And D (Distributed Generation) means distributed power.

HR 1: First, FIG. 5 (a) shows a case in which there is no distributed power source. B _{i , j} means the jth bus line to the i-th distribution line, and each bus line indicates the installation position of the protective device. If any smart protection device (B _{i , x} ) experiences a fault current and its W _x is equal to W _R and its guard interval is a terminal interval, its guard interval is the fault interval. Where W _x is the direction of the current measured at the magnetic location of any smart protection device and W _R is the direction of the current I _T flowing from the substation transformer 22 to the tree structure distribution line without the distributed power supply 21.

HR 2: Figure 5 (b) shows a case where the distributed power source is disposed on the power source side of the fault section. In this case, if any smart protection device experiences a fault current and its W _x is equal to W _R and one of its downstream protection devices from fault location f experiences a low voltage, . Where W _R is treated as equal to W _D. 5 (b), if the fault position f exists between the bus lines B _1,3 and B _1,4 , the current direction in the smart protection device S _p installed on bus lines B _1,3 is equal to the current direction from the distribution transformer, a smart protective device S _q, which is installed on the bus B _1,4 downstream protective devices in the field from point f will experience a lower voltage.

HR 3: Also, if any smart protection device experiences a fault current and its W _x is equal to W _R and none of its downstream protection devices from fault location f experience a fault current, This is the fault zone. 5 (b), if the fault position f exists between the bus lines B _1,3 and B _1,4 , the current direction in the smart protection device S _p installed on bus lines B _1,3 is It is equal to the current direction from the distribution transformer and experiences a fault current. But smart protection device S _q, which is installed on the bus B _1,4 downstream protective devices in the field from where f is not experiencing a fault current.

For reference, W _T and W _D indicate the directions of the fault current I _T flowing from the substation transformer and the fault current I _D flowing from the distributed power supply 21 when one fault occurs on the wiring line having the distributed power supply 21 In the direction of the arrow. And W _R is treated as being equal to W _T or W _D.

HD 4: Figure 5 (c) shows a case where the distributed power source is disposed on the load side of the fault section. In this case, any smart protection device experiences a fault current and its W _x is W _R (= W _T ), and from the fault location f W _x of one of its downstream protection devices is equal to W _R (= W _T ), its guard interval is the fault interval. 5 (c), if the fault location f exists between the bus lines B _1,2 and B _1,3 , the current direction in the smart protection device S _p installed on the bus lines B _1,2 is the same as the current direction from the distribution transformer, smart protection devices installed on the bus B _1,3 S _q is the current in the smart protection device S _q because receive power from distributed generation arranged on the load side via the grid-connected The direction is the current direction from the distribution transformer (W _R (= W _T )). Based on these results, the smart protection devices S _p and S _q It can be judged that the interval is the fault zone.

FIG. 6 is a diagram illustrating an example of section modeling for bidirectional communication according to the present invention. The smart protection device 100 of the present invention exchanges malfunction information including a voltage value, a current value, a current direction, or a combination thereof with neighboring smart protection devices on the line in the event of a failure, and then, based on the heuristic rules It is designed to identify and isolate the fault zone before it is opened to the lockout state. In order to apply the method to the smart distribution grid system 20, it is required that any smart protection devices verify the electrical connectivity with other smart protection devices on the distribution line. Therefore, one Zone Model 200 is defined which is surrounded by protective devices. Each section for bidirectional communication is represented by {SPDS (Smart Protection Device set), VDS (Voltage Direction Set)}, where SPDS represents a set of smart protection devices constituting an interval. On the other hand, the VDS is a set of voltage directions required to indicate which side of the bi-directional voltages of the respective protection devices included in the SPDS are included in the defined interval. This indication is required when processing the voltage information of the linkage switch.

6, each smart protection device 100 may be configured to detect one upstream or downstream electrical connection based on the current direction flowing from the substation transformer to track one electrical section A source zone 210 and a load zone or a sink zone 220. Here, the load zone 220 is a protection zone. For example, the smart protection device S ₆ may be divided into a power source zone and a zone, {{S ₁ , S ₂ , S ₃ , S ₆ }, {R, A, A, A} ) {{S ₆ , S ₇ }, {R, A}} as a protection zone (sink zone). Here, the upstream protection devices are {S ₁ , S ₂ , S ₃ }, the downstream protection devices are {S ₇ }, R is the RST phase voltage and A is the ABC phase voltage. Therefore, the smart protection device S ₃ is divided into a power source zone and a zone {{S ₁ , S ₂ , S ₃ , S ₆ }, {R, A, A, A} S ₃ , S ₄ , S ₈ }, {R, A, A}} as a protection zone (sink zone). Here, the upstream protection devices are {S ₁ , S ₂ , S ₆ } and the downstream protection devices are {S ₄ , S ₈ }. 6, DG (Distributed Generation) in FIG. 6 denotes a distributed power source of a smart distribution grid system, CB (Circuit Breaker) denotes a switch installed on a distribution line, S / S (SubStation) denotes a smart distribution grid system Power distribution transformer.

FIG. 7 is a flowchart for explaining an LIF inference procedure of the smart protection device solution according to the present invention. As shown in FIG. 7, the low impedance failure (LIF) .

Step 1: Each smart protection device measures the effective value (RMS value) of the currents I _A , I _B , and I _C of the self-protection period (S101). Where I _A , I _B , and I _C represent the a-phase current, b-phase current, and c-phase current measured at the point of installation of each protective device.

Step 2: A, B, and C phases are sequentially checked (S102) to determine whether the current of each phase measured and triggered at a predetermined sampling or cycle interval is larger than a predetermined set value I _SET . The triggering interval may be set by the user each time or by a program. If all of the phase currents are smaller than the preset current value, the normal current is determined and step 1 is repeated. On the other hand, if at least one phase current is larger than I _SET , it is determined as a fault current and step 3 (S103) is executed on the phase. Here, I _SET is a threshold value for determining whether or not the current measured at the self-installation position of each protective device is a fault current or not.

Step 3: Define the set of downstream protection devices DSPDS = {PD _k } from the Sink Zone information and confirm W _R (S103). Here, DSPDS refers to a downstream protection device set, and PD refers to a protection device.

Step 4: If the smart distribution system does not have distributed power for all downstream smart protection device sets, that is, if the heuristic rule 1 is met for all downstream smart protection device sets, (B _{i , x} ) experiences a fault current and its W _x is equal to W _R and its guard interval is a terminal interval, if it satisfies the rule of determining that its guard interval is a fault interval, go to step 10 , Otherwise k = 1 and step 5 is performed (S104).

Step 5: the PD _K through the communication with the ^{_{PD K I A k, I B}} k, I C k, W x (A) k, W x (B) k, W x (C) k, V A k, V _B ^k and V _C ^k Collect the data. Then go to step 6. ^{_{Here, I A k, I B k}} , I C k, W x (A) k, W x (B) k, W x (C) k, V A k, V B k and V _C ^k is the DSPDS k th element of a-phase current, B-phase current, C phase current, the a-phase current direction, B-phase current direction, C-phase current direction, and the a phase voltage, B phase voltage, C-phase voltage of the magnetic guard interval direction of the PD _K (S105).

Step 6: If DSPDS ^k is not {}, that is, if the data collection is not completed for all downstream protection devices, continue with step 5 with k = k + 1 and continue the data collection. Otherwise, since the collection of all the data is completed, the step 7 is performed (S106).

Step 7: If heuristic rule 2 (HR 2) is satisfied, step 10 is performed; otherwise, step 8 is performed (step 107). Where DSPDS ^k = DSPDS ^{k -1} -PD _k .

Step 8: If heuristic rule 3 (HR 3) is satisfied, step 10 is performed; otherwise, step 9 is performed (step S108).

Step 9: If heuristic rule 4 (HR 4) is satisfied, step 10 is performed; otherwise, step 1 is continuously performed (step S109).

Step 10: If the heuristic rules 1 to 4 are satisfied, since the failure is detected, the corresponding self-protection interval is determined as a failure interval, and an open command is issued to all the elements of the DSPDS so that the failure interval is autonomously separated S110).

In the present invention, heuristic rules 1 to 4 are merely illustrative, and such heuristic rules can be additionally defined as needed at any time and added to the present inference process. In addition, the heuristic rule, as the word implies, uses the user's heuristic method of determining the failure interval or the procedure in a regular fashion. By doing so, every time the smart distribution system is operated, If a heuristic rule is preliminarily determined during operation of the smart distribution system by including a heuristic rule in advance in the program instead of determining the fault section and determining the fault section according to a desired procedure, It is preferable to separate them.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, I will understand the point. Accordingly, the technical scope of the present invention should be defined by the following claims.

10: Existing distribution automation system 11: Protection device
12: FRTU 13: Central control device
20: Smart distribution grid system 21: Distributed power supply
22: distribution transformer 23: loop structure line
24: Tree structure line 100: Smart protection device
110: Protector base 111: Power supply 3-phase voltage sensor
112: Power side three-phase current sensor 113: Load side three-phase voltage sensor
120: FRTU part 121: Surge protection circuit
122: driving unit relay circuit 123:
124: Microprocessor 125: RTC
126: Serial 2 port 127: Power supply
128: DC / DC converter 129: RAM
130: EPROM 131: LCD indicator and key
132: wired / wireless network card 133: bidirectional wired communication port
134: Two-way radio communication antenna 135: Battery
150: LIF determination unit 151: RMS calculation unit
152: rule-based LIF section determination unit 160: HIF determination unit
161: DWT or DFT conversion unit 162: HIF separator (Classifier)
163: rule-based HIF section determination unit 170:
200: Zone Model 210: Source Zone
220: Load section or load section (Sink Zone) 230: Terminal zone

Claims (18)

At least one smart protection device;
A distribution line connected between the at least one smart protection device; And
And a bidirectional communication line including wired, wireless, or a combination thereof connected between the at least one smart protection device,
The smart protection device comprises:
An RMS calculation unit for performing measurement including a current value, a voltage value, a current direction, or a combination thereof, for each phase, and calculating an effective value for an inputted voltage and current, and a low impedance fault (LIF) A rule-based low impedance failure (LIF) period determining unit for determining a period; A frequency transform unit for transforming the voltage value and the current value into a frequency component using a frequency conversion technique including DWT or DFT, and a rule-based high impedance unit for determining a high impedance failure (HIF) A failure (HIF) section determination unit; Or a combination thereof,
The rule-based low impedance failure (LIF) interval determination unit or rule-based high impedance failure (HIF) interval determination unit compares the effective value or the frequency-converted input data with a predefined value to apply a heuristic rule to satisfy the corresponding rule Directional communication with the smart protection devices on the self-protection section to collect malfunction information, check whether the self-protection interval is in the fault zone, and if the failure is determined based on the confirmed result Way communication related to the open command of the protective device to the smart protection devices on the fault section, so that the fault section is automatically separated from the smart distribution grid system. The method according to claim 1,
The smart protection device comprises:
A protective device including a circuit breaker, a switch or a recloser to which a Feeder Remote Terminal Unit (FRTU) is attached,
Wherein the protective device includes a sensor for measuring data of an input three-phase voltage, a current, and an output three-phase voltage, respectively. The method of claim 2,
Wherein the FRTU receives the measured data to determine whether the distribution line is faulty, and exchanges the determined result with a neighboring smart protection device through bidirectional communication means. delete delete The method according to claim 1,
The rule-based low impedance failure (LIF)
In a smart distribution grid system, if the distributed power source is on the power side or at the end but is not present in the protection period, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R (Where Wx is the direction of the current measured at the magnetic location of any smart protection device and W _R is the direction of the current flowing from the substation transformer) and if the protection interval of the smart protection device is in the terminal section, And determining a section as a failure section. The method according to claim 1,
The rule-based low impedance failure (LIF)
In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if one of the downstream protection devices of the smart protection device experiences a low voltage from the failure location f, then the smart And the guard interval of the protective device is determined as a failure interval. The method according to claim 1,
The rule-based low impedance failure (LIF)
In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if none of the downstream protection devices of the smart protection device from the fault location f experience a fault current, Wherein the protection section of the smart protection device is determined as a failure section. The method according to claim 1,
The rule-based low impedance failure (LIF)
To the smart distribution grid system DG as when placed on the load side of the fault section, any smart protection device experiencing a fault current, the same as W _x is W _R in the smart protection device (where W _x is any W _R is the direction of the current flowing from the substation transformer), and W _x of one of its downstream protection devices from fault location f is not equal to W _R (the direction of the current measured at the self- Where W _x is the direction of the current measured at the magnetic location of any smart protection device and W _R is the direction of the current flowing from the substation main transformer), and determines the guard interval of the smart protection device as the fault zone Smart distribution grid system. A method for autonomously determining and isolating a fault section in a smart distribution grid system with at least one smart protection device,
Measuring the state of the smart protection device including a current value, a voltage value, a current direction, a voltage direction, or a combination thereof for each phase;
Determining a low impedance fault (LIF) period based on the measured value of the state; And
Performing bi-directional communication with the smart protection devices on the low impedance fault period in relation to the open command of the protection device based on the determined result, and automatically separating the fault interval in the smart distribution grid system,
The step of determining the low impedance failure period includes:
Comparing the measured value of each phase measured by the smart protection device with a predefined value, applying a heuristic rule, and determining the failure interval if the corresponding rule is satisfied; And
And if the failure is determined to be a failure, collecting failure information by performing bidirectional communication with the smart protection devices on the self protection period and checking whether the self protection period is in a failure interval. A method of autonomously determining and isolating a fault zone in a grid grid. delete The method of claim 10,
The heuristic rule includes:
In a smart distribution grid system, if the distributed power source is on the power side or at the end but is not present in the protection period, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R (Where W _x is the direction of the current measured at the magnetic location of any smart protection device and W _R is the direction of the current flowing from the substation transformer) and if the protection interval of the smart protection device is in the terminal section, And determining a guard interval as a failure interval. The method for autonomously determining and isolating a failure interval in a smart distribution grid system. The method of claim 10,
The heuristic rule includes:
In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if one of the downstream protection devices of the smart protection device experiences a low voltage from the failure location f, then the smart And the guard interval of the protective device is determined as a failure interval. The method for autonomously determining and isolating a failure interval in a smart distribution grid system. The method of claim 10,
The heuristic rule includes:
In a Smart Distribution Grid system, when distributed power is placed on the power side of a fault zone, any smart protection device experiences a fault current, and W _x in the smart protection device is equal to W _R , where W _x is arbitrary W _R is the direction of the current flowing from the substation transformer), and if none of the downstream protection devices of the smart protection device from the fault location f experience a fault current, Wherein the guard interval of the smart protection device is determined as a failure interval. The method of claim 10,
The heuristic rule includes:
To the smart distribution grid system DG as when placed on the load side of the fault section, any smart protection device experiencing a fault current, the same as W _x is W _R in the smart protection device (where W _x is any W _R is the direction of the current flowing from the substation transformer), and W _x of one of its downstream protection devices from fault location f is not equal to W _R (the direction of the current measured at the self- Where W _x is the direction of the current measured at the magnetic location of any smart protection device and W _R is the direction of the current flowing from the substation main transformer), and determines the guard interval of the smart protection device as the fault zone A method of autonomously identifying and isolating a fault zone in a smart distribution grid system. At least one smart protection device;
A distribution line connected between the at least one smart protection device; And
And a bi-directional communication line including wired, wireless, or a combination thereof connected between the at least one smart protection device, the Smart Distribution Grid system comprising:
Wherein the at least one smart protection device exchanges malfunction information including voltage values, current values, current direction or a combination thereof with nearby smart protection devices on the line in the event of a failure, It is designed to identify and isolate the fault zone before the device is opened to the lockout state,
Wherein at least one of the at least one respective interval is defined to include a collection of smart protection devices and a set of voltage directions required to indicate which of the bidirectional voltages of each smart protection devices are included in the interval. Smart distribution grid system applying modeling method. 18. The method of claim 16,
The above-
Determining one source interval and a sink interval based on a current direction flowing from a source power source including a transformer to track upstream or downstream electrical connectivity for at least one smart protection device, A smart distribution grid system to which an interval modeling method for bidirectional communication is applied. delete

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