KR102090761B1 - Methods and apparatuses for preventing separation of distributed generation - Google Patents

Abstract

The present invention relates to a relay correction method for preventing separation of a distributed power source and a device thereof. According to an embodiment of the present invention, the relay correction method for preventing separation of a distributed power source comprises the steps of: receiving grid analysis data which is calculated through power flow analysis and failure analysis of a grid; deriving a correction value of a relay based on the received grid analysis data so that a probability in which a distributed power source is separated in the event of disturbance in the grid is minimized; and adjusting the correction value in the relay in the grid as the derived correction value.

Description

METHODS AND APPARATUSES FOR PREVENTING SEPARATION OF DISTRIBUTED GENERATION}

The present invention relates to a relay correcting method and apparatus for preventing separation of distributed power.

Conventional relay correction methods include 1) a correction method in consideration of all failure conditions and abnormal conditions, and 2) a method using an optimization algorithm. In the first method, when correcting a relay in a mesh system, it is time consuming and complicated because complicated topology analysis must be performed. On the other hand, the optimization algorithm can calculate the correction value of the directional overcurrent relay relatively easily even in the mesh system.

The conventional directional overcurrent relay optimal correction method is largely the minimum time interval (Coordination Time Interval, CTI) for which the time difference between the main protection relay and the rear protection relay is allowed to minimize the operation time of the relay and ensure protection coordination between the relays. Consider this.

However, the conventional relay optimum correction method focuses on reducing the overall operation time of the relay rather than giving priority to preventing separation of distributed power. Therefore, the conventional relay optimum correction method does not consider the importance of supporting the distributed power system during the disturbances, which increases as the amount of system power in the distributed power supply increases. Therefore, a new correction method is required to more effectively prevent separation of disturbances in the distributed power supply.

As the penetration rate of distributed power gradually increases in the power system, the dependence on the distributed power of the system also increases. Fault Ride Through (FRT) regulations have been introduced in countries around the world to recognize the importance of distributed power and to maintain the support of distributed power during disturbances. In accordance with FRT regulations, distributed power during disturbance maintains linkage, supplies reactive power to the system, and supports system stability.

However, there is a limit to the FRT capability that distributed power can have. The system's protection system needs to isolate faults from the normal part of the system and from the distributed power source before the distributed power source is disconnected.

Accordingly, embodiments of the present invention are to provide a relay correction method and apparatus for preventing separation of distributed power, which can prevent separation of distributed power as much as possible by supplementing the conventional relay correction method and taking into account the FRT capability of distributed power. do.

According to an embodiment of the present invention, a method of correcting a relay performed by a relay correcting device, the method comprising: receiving grid analysis data calculated through a tide analysis and failure analysis of the system; Deriving a correction value of a relay based on the received grid analysis data, so that the probability that the distributed power is separated when the disturbance occurs in the grid is minimized; And adjusting the correction value of the relay in the system with the derived correction value.

In the receiving of the grid analysis data, a load current flowing through the grid, a fault current for a fault location, and a voltage of points of the Common Coupling (PCC) of distributed power during a fault may be acquired.

In the step of deriving the correction value, the operating current of the relay may be calculated using the load current flowing in the system.

In the step of deriving the correction value, the operating time of the main protection relay and the rear protection relay can be calculated using the fault current for the fault location.

In the step of deriving the correction value, a separation allowable time during which separation of distributed power is allowed is calculated using a voltage of a common connection point of the distributed power.

In the step of deriving the correction value, in order to minimize the probability that the distributed power is separated in the event of a disturbance in the system, the separation allowable time of the distributed power that is allowed to be separated in consideration of the system linkage regulation of the preset distributed power is determined. Can be minimized.

The separation allowable time of the distributed power may be defined as a time interval for a case in which the time allowed for separation of the distributed power is faster than the time at which the common connection point voltage of the distributed power recovers to a specified voltage.

In the step of deriving the corrected value of the relay, the corrected value of the relay is performed by performing at least one of a selection process of a set of corrected values of the relay, a crossing process, and a variation process according to a genetic algorithm that minimizes a predetermined target function value. Can be derived.

The predetermined objective function may include a cooperative violation time, a relay operation time, and a separation allowable time of distributed power.

In the step of deriving the correction value of the relay, the genetic algorithm may be repeatedly performed to alleviate the local convergence characteristic of the genetic algorithm.

On the other hand, according to another embodiment of the present invention, the transceiver for receiving the system analysis data calculated through the tide analysis and failure analysis of the system; A memory for storing the received system analysis data; And a processor connected to the transceiver and the memory, wherein the processor derives a correction value of the relay based on the received system analysis data, so that the probability that the distributed power is separated when the disturbance occurs in the system is minimized. A relay correction device for preventing separation of the distributed power supply that adjusts the correction value of the relay in the system with the derived correction value may be provided.

The transceiver may receive a load current flowing in the system, a fault current for a fault location, and a voltage of a point of the common coupling (PCC) of distributed power during a fault.

The processor may calculate the operating current of the relay using the load current flowing in the system.

The processor may calculate the operating time of the main protection relay and the rear protection relay by using the fault current for the fault location.

The processor may calculate a separation allowable time during which separation of the distributed power is allowed using the voltage of the common connection point of the distributed power.

The processor may minimize the separation allowable time of the distributed power that allows the separation of the distributed power in consideration of the system linkage rules of the preset distributed power, in order to minimize the probability that the distributed power is separated when the disturbance occurs in the system.

The separation allowable time of the distributed power may be defined as a time interval for a case in which the time allowed for separation of the distributed power is faster than the time at which the common connection point voltage of the distributed power recovers to a specified voltage.

The processor may derive a correction value of the relay by performing at least one of a selection process, a crossing process, and a variation process of a set of correction values of the relay according to a genetic algorithm that minimizes the value of a predetermined objective function.

The predetermined objective function may include a cooperative violation time, a relay operation time, and a separation allowable time of distributed power.

The processor may iteratively perform the genetic algorithm to alleviate the local convergence feature of the genetic algorithm.

On the other hand, according to another embodiment of the present invention, in a computer-readable recording medium recording a program for executing a relay correction method for preventing the separation of distributed power in a computer, calculated through the tide analysis and failure analysis of the system Receiving the systematic analysis data; Deriving a correction value of a relay based on the received grid analysis data, so that the probability that the distributed power is separated when the disturbance occurs in the grid is minimized; And a computer-readable recording medium recording a program for executing a step of adjusting the correction value of the relay in the system with the derived correction value.

Embodiments of the present invention can increase the probability of removing a fault before the distributed power is separated during the disturbance by calculating the relay correction value to prevent the separation of the distributed power during the disturbance as much as possible.

In terms of distributed power operation, embodiments of the present invention can eliminate the cost incurred in the process of shutting down and restarting the distributed power if the failure is eliminated before the distributed power is separated, and to prevent damages caused by power supply interruption You can.

In addition, in terms of system operation, the embodiments of the present invention can not only prevent loss due to a decrease in stability caused by separation of distributed power, but also lower the probability of a system collapse occurring when a large-scale power supply is disconnected. You can.

1 is a flow chart for explaining a relay correction method for preventing separation of distributed power according to an embodiment of the present invention.
2 is a flow chart for explaining the overall flow of a relay correction method for preventing separation of distributed power according to an embodiment of the present invention.
3 is a view for explaining a fault ride through rule used in an embodiment of the present invention.
4 and 5 are flowcharts for explaining the flow of the genetic algorithm and the iterative execution flow of the genetic algorithm used in an embodiment of the present invention.
6 is a diagram for explaining an IEEE 30 bus test system in which distributed power is connected to verify an embodiment of the present invention.
7 to 10 are diagrams for explaining the probability distribution of the separated distributed power capacity annually measured by Monte Carlo simulation according to an embodiment of the present invention and the prior art.
11 and 12 are diagrams for explaining the comparison of results by case according to an embodiment of the present invention and the prior art.
13 is a configuration diagram for explaining a configuration of a relay correction device for preventing separation of distributed power according to an embodiment of the present invention.

The present invention can be applied to various changes and may have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may be referred to as a first component. The term and / or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but other components may exist in the middle. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described herein, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms, such as those defined in a commonly used dictionary, should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the overall understanding in describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

1 is a flow chart for explaining a relay correction method for preventing separation of distributed power according to an embodiment of the present invention.

The relay correction method for preventing the separation of distributed power according to an embodiment of the present invention takes into account the Fault Ride Through (FRT) regulation introduced to prevent separation of distributed power during system disturbance and maintain grid support. Therefore, it is possible to optimally correct a directional overcurrent relay (DOCR). In the event of a disturbance, if the failure of the directional overcurrent relay is eliminated when the connection of the distributed power is maintained according to the FRT regulation, the voltage of the points of the Common Coupling (PCC) of the distributed power is restored to connect the grid of the distributed power Can keep. Therefore, in the relay correction method according to an embodiment of the present invention, when calculating the optimum value of the correction values of all directional overcurrent relays constituting a system using an optimization algorithm, the distributed power is separated during disturbance by considering the FRT of the distributed power. You can give priority to reducing the probability of becoming.

As an embodiment of the present invention, a relay correction method for preventing separation of distributed power is performed by a relay correction device.

In step S101, the relay correction device according to an embodiment of the present invention receives the grid analysis data calculated through the tide analysis and failure analysis of the system. Here, the relay correcting device may acquire a load current flowing in the system, a fault current for a fault location, and a voltage of points of the common coupling (PCC) of distributed power during a fault.

In step S102, the relay correcting device derives a correction value of the relay based on the received grid analysis data so that the probability that the distributed power is separated when the disturbance occurs in the system is minimized. In one example, the relay correction device may calculate the operating current of the relay using the load current flowing in the system. The relay correction device can calculate the operating time of the main protection relay and the rear protection relay by using the fault current for the fault location. The relay correcting device may calculate the separation allowable time allowed for separation of the distributed power using the voltage of the common connection point of the distributed power. The relay correcting device may minimize the separation allowable time of the distributed power, which allows the separation of the distributed power in consideration of the system linkage rules of the preset distributed power, in order to minimize the probability of the distributed power being separated in the event of a disturbance in the system. The separation allowable time of the distributed power may be defined as a time interval for a case in which the time allowed for the separation of the distributed power is faster than the time at which the common connection point voltage of the distributed power recovers to the specified voltage. The relay correction device may derive a correction value of the relay by performing at least one of a selection process, a crossing process, and a variation process of a set of correction values of the relay according to a genetic algorithm that minimizes the value of a predetermined objective function. The preset objective function may include a cooperative violation time, a relay operation time, and a separation allowable time of distributed power. The relay correction device may iteratively perform the genetic algorithm to alleviate the local convergence feature of the genetic algorithm.

In step S103, the relay correction device adjusts the correction value of the relay in the system with the derived correction value.

2 is a flow chart for explaining the overall flow of a relay correction method for preventing separation of distributed power according to an embodiment of the present invention.

One embodiment of the present invention relates to a method for calculating correction values of directional overcurrent relays installed in a grid in which distributed power is connected. According to an embodiment of the present invention, separation of the distributed power source during a failure can be minimized by considering the FRT capability of the distributed power source. One embodiment of the present invention begins by obtaining the load current flowing in each line of the grid through the system analysis program and the fault current data for all fault locations that may occur in the grid and the voltage data of the common connection point of the distributed power supply during the fault. . Load current data is used to calculate the operating current, which is one of the corrected values of the relay, taking into account the sensitivity of each relay. In addition, the fault current data at each fault position is used to calculate the operating time of the main protection relay and the back protection relay for each fault position, and the PCC voltage data of the distributed power supply is used to calculate the separation allowable time of the distributed power supply.

Each of the relays may be a main protection relay that should be operated first when a failure occurs depending on the location of the failure, or may be a post-protection relay that must be operated after a certain time delay if the main protection relay fails to operate. However, since the correction values of each relay are the same when operating as the main protection and when operating as the back protection, all relays cooperate when the system is complex (all the back protection relays are more constant than the operating time of the main protection relay). It is difficult to obtain a correction value (which works after time). Therefore, in one embodiment of the present invention, a relay's correction value can be more efficiently calculated using a genetic algorithm, which is one of the optimization algorithms, and is not limited to a specific algorithm. The genetic algorithm searches for generations of selection, crossover, and mutation processes of relays that minimize the value of a predetermined objective function. In one embodiment of the present invention, the objective function (Equation 5) may be composed of the degree of cooperation violation, the total operating time of all main protection relays, the sum of allowable separation time of distributed power, and the weight for each term. The load current, fault current and voltage data obtained above can be used to calculate the objective function in the genetic algorithm process. As a result, in an embodiment of the present invention, not only all relays cooperate through a genetic algorithm, but also quickly eliminate faults and calculate correction values of relays that minimize separation of distributed power.

The objective function used in the general optimal correction method can be generally expressed by [Equation 1] below.

와

는 각각 주보호계전기와 후비보호계전기의 동작시간을 의미,

는 계전기 사이의 협조위반의 정도를 나타내며 [수학식 2]로 정의된다. 최적화 알고리즘은 본 목적함수의 값을 최소화하는 정정치를 탐색한다.[Equation 1] is the simplest form of the objective function used when the relay is optimally corrected.

Wow

Is the operating time of the main protective relay and the rear protective relay, respectively,

Denotes the degree of coordination violation between relays and is defined by [Equation 2]. The optimization algorithm searches for correction values that minimize the value of the objective function.

[Equation 2] is an expression that indicates whether a minimum time interval between the back protection relay and the main protection relay is secured. When this value is less than 0, cooperation between the two relays may not be smoothly performed, for example, the back protection relay operates first or simultaneously with the main protection relay. The CTI value is usually between 0.2 and 0.5 [s] depending on the system situation.

가 계전기에 정정되고 고장전류

가 계전기에 감지될 경우 계전기는 동작시간 t에 동작을 수행한다.[Equation 3] is a relay characteristic equation for calculating the overcurrent relay operating time, and the relay characteristic curve constants (A, B) are determined according to the IEC 60255 standard. Existing relay correction value Time Dial Setting (TDS) and operating current

Is corrected to the relay and the fault current

When is detected by the relay, the relay performs an operation at the operation time t.

보다 분산전원의 분리가 가능한 시간

가 더 빠르다면 분산전원의 분리가 허용되며 그 시간 간격을

로 정의한다.[Equation 4] shows the separation allowable time of distributed power according to the FRT regulation. Time for the PCC voltage of the distributed power to recover to the specified voltage by removing the failure shown in FIG. 2

Time for more separation of distributed power

If is faster, separation of distributed power is allowed and the time interval is

Is defined as

[Equation 5] is an objective function including a term that minimizes the allowable separation time of distributed power. When calculating the correction value of the relay with this objective function, the correction value minimizes the probability that the distributed power is separated during the disturbance.

Figure 2 shows the overall flow of an embodiment of the present invention. One embodiment of the present invention starts with acquiring data that is essential for correcting the relay first.

In step S201, the relay correction device according to an embodiment of the present invention acquires the load current data through the tide analysis. The relay correction device acquires a load current value flowing at each relay position by performing an algae analysis on the target system.

In step S202, the relay correction device acquires fault current and voltage data through fault analysis. When a three-phase short circuit fault occurs in each line of the system through fault analysis, the relay correction device acquires a fault current flowing through each relay and acquires PCC voltage data of each distributed power supply. The acquired fault current data can be used to calculate the relay operating time, and the PCC voltage data can be used to calculate the time allowed for the separation of the distributed power supply.

In step S203, the relay correction device acquires cooperative relationship data of relays in the system. When a three-phase short circuit fault occurs in each line, the relay correction device can acquire data as to which relay should operate as the main protection relay or the rear protection relay. The pair of relays closest to each fault location can be the main protective relay, and the next closest relays can be the back protection relay.

As described above, the acquired data includes data indicating the load current, fault current, fault voltage, and relay cooperative relationship. Based on the acquired data, a genetic algorithm is performed to calculate the optimal relay correction value.

In step S204, the relay correction device repeats the genetic algorithm based on the acquired data. The relay correction device repeats the genetic algorithm with the acquired data to calculate the optimal correction values of the relays. The genetic algorithm searches for a corrected value of the relay that minimizes the set objective function value.

In step S205, the relay correction device derives a correction value that minimizes the objective function including the term for reducing the separation of the distributed power.

As described above, in an embodiment of the present invention, an objective function including a term for reducing the separation of distributed power is used in the process of optimizing the correction values of relays through a genetic algorithm. Therefore, according to an embodiment of the present invention, the relays corrected with the derived correction value reduce the probability that the distributed power is separated during the disturbance. The relay correction device may use a target function including a term for reducing the separation of distributed power, as well as terms for minimizing the total operating time of the relay and minimizing non-coordination between the relays.

In step S206, the relay correction device readjusts the relay correction value in the system with the derived correction value.

3 is a view for explaining a fault ride through rule used in an embodiment of the present invention.

According to the conventional distributed power supply linkage regulations, when a system failure occurs, the distributed power supply needs to be quickly separated to minimize the effect on the system protection system. However, as the system penetration rate of distributed power increased, the effect of distributed power on the system also increased. When distributed power is separated during disturbance according to the conventional regulations, it is possible to have a serious adverse effect on system stability. Therefore, FRT regulations in which the distributed power maintains linkage for more than a certain period of time during the disturbance have been introduced as a new system linkage rule.

FIG. 3 shows FRT regulations for all power sources except Germany's direct-link type power source.

의 값을 최소화시킬 필요가 있다.

가 작을수록 분산전원이 분리될 확률이 낮아질 것이다.As shown in FIG. 3, according to the German FRT regulation, the distributed power supply connected to the system should have a function of maintaining the connection at least during the time corresponding to the x-axis with respect to the voltage drop corresponding to the y-axis. That is, according to this regulation, in order for the distributed power to be connected to the system, when a voltage drop corresponding to the y-axis occurs, it must have a function to maintain the connection for a time corresponding to the x-axis. The regions A, B, C, and D of FIG. 3 are divided according to detailed rules for maintaining association. When the area C or D is reached, since the distributed power is allowed to be separated from the system, the maximum time to eliminate the failure is accelerated, and the allowable separation time of the distributed power shown in FIGS. 3 and 4

It is necessary to minimize the value of.

The smaller the value, the lower the probability that the distributed power source will be separated.

을 최소화하는 계전기 최적 정정값을 계산한다. 최적 정정치 계산을 위하여 우선적으로 계통의 조류해석 및 고장해석을 통하여 계통에서 발생할 수 있는 각 계전기가 감지하는 최대부하전류, 고장전류 값 그리고 고장 중 각 분산전원의 PCC 전압 값을 계산한다. 최대부하전류 데이터는 계전기의 과부하 상태 중의 오동작을 방지하기 위해서, 고장전류 데이터는 계전기 동작시간을 계산하기 위해서 사용된다. 고장 중 분산전원의 PCC 전압은 도 3을 통해 각 분산전원의 분리가 가능한 시간

를 구하는데 사용된다. 추가적으로 각 계전기의 협조여부 판별, 즉

의 계산을 위하여 각 계전기 사이의 협조관계 데이터 역시 필요하다. 각 계통 해석 데이터들을 이용하여 최적화 알고리즘 및 목적함수로 방향성 과전류 계전기의 최적 정정치를 계산한다. An exemplary embodiment of the present invention allows separation time of distributed power in consideration of FRT of distributed power

Calculate the optimum correction value for the relay that minimizes. In order to calculate the optimum correction value, the maximum load current, the fault current value, and the PCC voltage value of each distributed power source during a fault are calculated by first analyzing the current and fault analysis of the system. The maximum load current data is used to prevent malfunction during the relay overload condition, and the fault current data is used to calculate the relay operation time. The PCC voltage of the distributed power supply during the failure is the time at which each distributed power supply can be separated.

It is used to obtain In addition, it is determined whether each relay cooperates, that is,

Cooperative relationship data between each relay is also required for the calculation of. The optimum correction value of the directional overcurrent relay is calculated using the optimization algorithm and the objective function using each system analysis data.

4 and 5 are flowcharts for explaining the flow of the genetic algorithm and the iterative execution flow of the genetic algorithm used in an embodiment of the present invention.

In the optimization algorithm according to an embodiment of the present invention, a genetic algorithm may be used, and a schematic flow of the genetic algorithm is shown in FIGS. 4 and 5. The genetic algorithm is used to calculate relay correction values that minimize the value of the objective function. In one embodiment of the present invention, the genetic algorithm may be repeatedly performed to alleviate the local convergence feature of the genetic algorithm. The genetic algorithm can calculate the relay's correction to minimize the objective function.

Details of the genetic algorithm of FIGS. 4 and 5 are as follows. Assuming that a total of Y relays are installed in the system, a total of 2Y correction values are required to correct all the relays in the system. This is the case when the correction value that can be set by the relay is limited to TDS and two operating currents.

In step S301, the relay correction device generates N arbitrary sets of correction values.

In step S302, the relay correction device evaluates the set of correction values using the objective function.

In step S303, the relay correction device selects sets of correction values according to the fitness.

In step S304, the relay correcting device exchanges arbitrary correction values among the selected set of correction values to generate a new set of correction values.

In step S305, the relay correction device checks whether N new set of correction values has been generated.

In step S306, when N new set of correction values are generated, the relay correction apparatus replaces any correction values of the new set of correction values with an arbitrary value. On the other hand, if a set of N new correction values has not been generated, the relay correction apparatus starts from step S303.

In step S307, the relay correcting device checks whether the set maximum search number has been reached.

When the set maximum search number is reached, the relay correction device outputs a result and ends the genetic algorithm. On the other hand, if the set maximum search number has not been reached, the relay correction device starts from step S302.

4 will be described again. When these 2Y correction values are referred to as one correction value set, the genetic algorithm starts by generating a total of N correction value sets. After that, each set of correction values is evaluated through the set objective function. The objective function set in one embodiment of the present invention is represented by [Equation 5], and may be composed of the sum of the operating time of the main protective relay, the degree of cooperative violation between the cooperating relays, and the sum of the allowable separation time of each distributed power source. . The set of correction values for reducing the value of the objective function may be a set of correction values having better suitability. The genetic algorithm calculates a set of correction values that minimize the objective function value. The detailed description of the objective function will follow the description of the genetic algorithm. After evaluation of the fitness for each set of correction values, a pair of correction values are selected based on the fitness. The larger the goodness of fit, the higher the probability that the corresponding set of correction values is selected can be used. This is called the roulette wheel selection method in the genetic algorithm. When a pair of correction values are selected, arbitrary correction values are exchanged with each other. At this time, correction values corresponding to the same correction value of the same relay are exchanged with each other. For example, the operating current of relay m is exchanged with the operating current value of relay m of the remaining set of correction values. This is called crossover in genetic algorithms. After the roulette wheel selection method and the intersection are repeated, a new set of N correction values is generated, and then, arbitrary correction values of the newly generated N correction value sets are replaced with completely new arbitrary correction values. This is called mutation in genetic algorithms. By repeatedly performing this series of processes, a set of correction values that minimizes the objective function value is searched for, and when the preset number of searches is reached, one genetic algorithm is completed.

As shown in Fig. 5, in step S401, the relay correction device performs a genetic algorithm.

In step S402, the relay correction device stores a set of correction values with high suitability derived as a result of performing the genetic algorithm.

In step S403, the relay correction device checks whether the set genetic algorithm maximum repetition number has been reached.

In step S404, when the maximum number of repetitions of the set genetic algorithm is reached, the relay correction device performs genetic algorithm on the set of stored correction values as an initial value. Then, the relay correction device outputs the performance result and ends the genetic algorithm. On the other hand, if the maximum number of repetitions of the set genetic algorithm is not reached, the relay correction device starts from step S401.

5 will be described again. In one embodiment of the present invention, in order to compensate for the shortcomings of local convergence implied by a genetic algorithm, it is possible to use a genetic algorithm iterative method of performing a genetic algorithm once again with a set of high-adjustment correction values derived as a result of the genetic algorithm. have.

의 값이 음수일 경우 두 계전기 사이의 협조는 위반된 상태로서 목적함수에 음의

의 크기가 더해진다(정확하게는

가 더해진다). 마지막으로 분산전원의 분리허용시간은 도 3의

에 해당한다. 이 값은 PCC 전압 강하 정도에 따라 FRT 규정에 의하여 분산전원의 분리가 가능한 시간 (

)과 차단기에 의하여 고장이 제거되고 이에 따라 PCC 전압이 회복되는 시간 (

) 사이의 시간 간격으로서 이 값을 저감시킬수록 분산전원의 분리확률 역시 저감시킬 수 있다. 목적함수의 각 항은 중요도에 따라 협조위반 정도, 분산전원의 분리가 허용되는 시간, 주보호 계전기 동작시간 순으로 가중치를 부여한다. Meanwhile, the objective function used in the optimization algorithm is represented by [Equation 5]. As mentioned above, this objective function is a term that minimizes the sum of the operating time of the main protective relay for all fault locations considered in a given system, the degree of coordination violation between cooperative relays, and the sum of allowable separation time of each distributed power source at the same time. Can be configured. The sum of the operating times of the main protective relay corresponds to the sum of the operating times of the relays corresponding to the main protective relay when a 3-phase short circuit fault occurs in each line with one set of correction values input to the relays of the system. . The degree of coordination violation between cooperating relays is the minimum time interval between the main protective relay and the non-protective relay operating time when a 3-phase short circuit fault occurs in each line with one set of correction values input to the relays of the system. Means the degree of violation. [Equation 2]

If the value of is negative, cooperation between the two relays is in violation and the objective function is negative.

The size of

Is added). Finally, the allowable separation time of the distributed power is shown in FIG.

Corresponds to This value is the time during which the distributed power can be separated by the FRT regulation according to the PCC voltage drop.

) And the time when the fault is removed by the breaker and the PCC voltage is restored accordingly (

As the time interval between) decreases, the separation probability of the distributed power source can also decrease. Each term of the objective function is weighted in the order of the degree of cooperation violation, the time allowed for separation of distributed power, and the operation time of the main protection relay, depending on the importance.

는 과부하 상태 동안 오동작을 방지하기 위해서는 부하전류보다는 큰 값을 가져야 하기 때문에 [수학식 6]과 같이 부하전류의 k배로서 설정하였으며 직접적으로 최적화하는 대상은

값이 아닌 k가 된다. 또한, 각 계전기의 정정치는 계전기가 설정할 수 있는 범위 내로 제한되며 최적화 수행 동안 이는 제약조건이 되며 [수학식 7]로서 나타난다. 또한, 계전기의 최소동작시간 역시 최적화 수행 동안 제약조건으로 선정하였으며 이는 [수학식 8]로서 나타난다. [수학식 8]의 제약조건을 위반하는 정정치의 경우 큰 penalty 값이 목적함수에 더해져서 적합도가 떨어지게 되고 결과적으로 유전 알고리즘의 선택 과정에서 해당 정정치가 선택될 확률이 크게 감소한다.In addition, in one embodiment of the present invention, the digital directional overcurrent relay is utilized to further reduce the operating time of the relay by using the TDS and operating current as well as the relay characteristic curve constants (A, B) as correction values. However, since A and TDS are linearly proportional to the operation time, they were set as ATDS, which is a correction value, to reduce the calculation time. Also, operating current

Is set as k times the load current as shown in [Equation 6] because it must have a larger value than the load current to prevent malfunction during an overload condition.

This is k, not a value. In addition, the correction value of each relay is limited within a range that can be set by the relay, and during optimization, it becomes a constraint and is expressed as [Equation 7]. In addition, the minimum operating time of the relay was also selected as a constraint during optimization, which is shown as [Equation 8]. In the case of correction values that violate the constraints in [Equation 8], a large penalty value is added to the objective function, which decreases the suitability, and as a result, the probability that the corresponding correction value is selected in the selection process of the genetic algorithm is greatly reduced.

[Equation 6] corresponds to the operating current value of each relay. Since the operating current has to be set larger than the load current, it can be set by multiplying k greater than 1. The range of k was set in consideration of the sensitivity of the relay, and when the optimal k value is calculated through an optimization algorithm, an optimal operating current value is also determined accordingly.

[Equation 7] is a range of correction values that can be corrected by the relay, and during the execution of the optimization algorithm, the correction values can be set only to values within the range.

[Equation 8] is the minimum limit of the operating time due to the physical limit of the relay, which is a constraint during the optimization algorithm. In the case of correction values that violate the conditions, a penalty is imposed that adds a very large value to the objective function.

6 is a diagram for explaining an IEEE 30 bus test system in which distributed power is connected to verify an embodiment of the present invention.

6, seven distributed power sources were connected as a test system for verifying an embodiment of the present invention. In order to protect the system, a total of 31 directional overcurrent relays are connected, and a total of 18 three-phase ground faults (faults with an impedance of 0 Ω) are simulated in the center of each line.

In order to verify an embodiment of the present invention, the IEEE 30 test bus system shown in FIG. 6 was implemented using an Electro-Magnetic Transients Program (EMTP). According to the purpose, 2 MW-scale power converter-based distributed power is connected to 7 buses of this simulation system, and each distributed power complies with the FRT regulation of FIG. 3 according to the FRT capability of each distributed power during disturbance. It is assumed that the connection is maintained and the reactive power is supplied for a certain period of time. In addition, a total of 31 directional overcurrent relays are installed in this system to protect the equipment from fault conditions. In order to calculate the optimal correction value to be input to the relay, the load current sensed by each relay by tidal analysis, and the fault current and each distributed power PCC when a 3-phase complete short circuit fault occurs in the center of a total of 18 lines through failure analysis Voltage data was calculated.

7 to 10 are diagrams for explaining the probability distribution of the separated distributed power capacity annually measured by Monte Carlo simulation according to an embodiment of the present invention and the prior art.

Optimal correction values of 31 directional overcurrent relays were calculated based on the previously obtained data and the genetic algorithm of FIGS. 4 and 5. According to the objective function and relay type used to demonstrate the performance of an embodiment of the present invention, a total of four cases were classified.

For Case 1, the probability distribution of the annual distributed power capacity measured by Monte Carlo simulation is shown in FIG. 7. For Case 2, the probability distribution of the annual distributed power capacity measured by Monte Carlo simulation is shown in FIG. 8. In this way, the probability distribution of the distributed power capacity of each year, which can occur under the correction conditions of cases 1 and 2, obtained through Monte Carlo simulation, appears.

In the case of case 1 and case 2, it is a case that uses a relay having only a fixed relay characteristic curve (A = 0.14, B = 0.02) without a user set characteristic. In case 1 and case 2, the correction values were calculated using the objective function [Equation 5] according to an embodiment of the present invention considering the conventional objective function [Equation 1] and FRT, respectively. It appears that the annual distributed power capacity of Case 2 is reduced compared to Case 1.

On the other hand, for case 3 (Case 3), the probability distribution of the separated distributed power capacity annually measured by Monte Carlo simulation is shown in FIG. 9. For Case 4, the probability distribution of the annual distributed power capacity measured by Monte Carlo simulation is shown in FIG. 10. As described above, the probability distribution of the distributed power capacity of each year that can occur under the correction conditions of cases 3 and 4 obtained through the Monte Carlo simulation is shown.

Cases 3 and 4 show cases using a digital relay capable of correcting even the relay characteristic curve constants (A, B). In case 3 and case 4, the correction values were calculated using the objective function according to an embodiment of the present invention considering the conventional objective function and FRT, respectively. It appears that the annual distributed power capacity of Case 4 is reduced compared to Case 3.

11 and 12 are diagrams for explaining the comparison of results by case according to an embodiment of the present invention and the prior art.

As shown in FIG. 11, [Table 1] shows a comparison result of Case 1 and Case 2, and shows a case-by-case result when a relay having a fixed characteristic curve is used. In the case of the correction calculated by the objective function considering FRT, the sum of the relay operating times of cases 1 and 2 is similar to 19.5114 [s] and 19.6128 [s], respectively, when compared with the correction calculated by the conventional objective function. It is relatively high. However, the time allowed for the separation of the distributed power sources in cases 1 and 2 was reduced by 2.2492 [s] to 37.3987 [s] and 35.1495 [s], respectively. This is the same even when a digital relay capable of correcting the constant of the relay characteristic curve is used. FIG. 11 shows the results of correction values calculated by each objective function when the relay used has only a fixed characteristic curve (A = 0.14, B = 0.02).

As shown in Figure 12, [Table 2] shows the comparison results of Case 3 and Case 4. When the objective function considering FRT was used, the sum of the relay operating times of case 3 and case 4 was found to increase by about 0.0376 [s] from 15.9063 [s] to 15.9439 [s]. On the other hand, the sum of the time allowed for the separation of the distributed power supply of case 3 and case 4 decreased by 3.7847 [s] from 22.2068 [s] to 18.4221 [s]. In all four cases, the coordination violation time converges to zero, and all relays in the system perform cooperative operations with each other. 12 is a result of the correction values calculated by each objective function when the relay used is a digital relay capable of correcting up to a relay characteristic curve constant.

In order to increase the intuition for this result, Monte-Carlo Simulation was implemented using MATLAB, and the degree of separation of distributed power expected for one year per case was compared. In the simulation, the annual failure rate per line of the simulated system was assumed to be 0.058 frequency / year considering the average failure rate of the domestic distribution system, and each distributed power supply was not removed and the PCC voltage could not be recovered. According to the degree of the PCC voltage drop, it is assumed that after the boundary line 2 of FIG. 3, it is separated with the same probability up to 1.5 [s].

7 and 8 show probability distributions for distributed power separated for one year in a simulated system protected by directional overcurrent relays in which relay correction values obtained in cases 1 and 2 are input. 7 and 8, the x-axis represents the capacity of the distributed power source separated for one year in units of 100 kW, and it can be seen that the average decrease of 7.02% from 4486.36 kW to 4171.45 per year. This also applies to cases 3 and 4 shown in FIGS. 9 and 10. 9 and 10, when using the objective function considering FRT, it can be seen that, on average, the degree of separation of distributed power is reduced by 22.77% from 2338.45 kW to 1806.07 kW per year on average.

As a result, one embodiment of the present invention proved that it is possible to efficiently reduce the probability that the distributed power is separated during disturbance by reducing the allowable separation time of the distributed power without significant loss of the total operating time of the relay. Since it maintains performance irrespective of the type of relay used (a relay having a fixed relay characteristic curve or a digital relay capable of correcting a characteristic curve constant), additional equipment investment is not essential in the embodiment of the present invention. However, it can have a greater effect than when used with a commercially available digital relay.

13 is a configuration diagram for explaining a configuration of a relay correction device for preventing separation of distributed power according to an embodiment of the present invention.

As shown in FIG. 13, the relay correction device 100 for preventing separation of distributed power according to an embodiment of the present invention includes a transceiver 110, a memory 120, and a processor 130. However, not all of the illustrated components are essential components. The relay correcting apparatus 100 may be implemented by more components than the illustrated components, and the relay correcting apparatus 100 may be implemented by fewer components.

Hereinafter, a specific configuration and operation of each component of the relay correction device 100 of FIG. 13 will be described.

The transceiver 110 receives the system analysis data calculated through the analysis of the tide and the failure of the system. As an example, the transceiver 110 may receive a load current flowing in the system, a fault current for a fault location, and a voltage of a common connection point (Points of the Common Coupling, PCC) of distributed power during a fault.

The memory 120 stores the received system analysis data.

The processor 130 is connected to the transceiver 110 and the memory 120. The processor 130 derives a correction value of the relay based on the system analysis data received from the transceiver 110 so that the probability that the distributed power is separated when the disturbance occurs in the system is minimized, and the derived correction value of the relay in the system Adjust the correction value.

According to various embodiments of the present invention, the processor 130 may calculate the operating current of the relay using the load current flowing in the system. The processor 130 may calculate the operating time of the main protection relay and the rear protection relay by using the fault current for the fault location. The processor 130 may calculate a separation allowable time during which separation of the distributed power is allowed using the voltage of the common connection point of the distributed power. The processor 130 may minimize the separation allowable time of the distributed power that allows the separation of the distributed power in consideration of the system linkage rules of the preset distributed power in order to minimize the probability of the distributed power being separated in the event of a disturbance in the system. . The separation allowable time of the distributed power may be defined as a time interval for a case in which the time allowed for the separation of the distributed power is faster than the time at which the common connection point voltage of the distributed power recovers to the specified voltage. The processor 130 may derive a correction value of the relay by performing at least one of a selection process, a crossing process, and a variation process of a set of correction values of the relay according to a genetic algorithm that minimizes the value of a predetermined objective function. . The preset objective function may include a cooperative violation time, a relay operation time, and a separation allowable time of distributed power. The processor 130 may repeatedly perform the genetic algorithm to alleviate the local convergence characteristic of the genetic algorithm.

The relay correction method for preventing the separation of distributed power according to the above-described embodiments of the present invention can be implemented as a computer-readable code on a computer-readable recording medium. The relay correction method for preventing disconnection of distributed power according to embodiments of the present invention may be implemented in a form of program instructions that can be executed through various computer means and may be recorded in a computer-readable recording medium.

According to embodiments of the present invention, in a computer-readable recording medium recording a program for executing a relay correction method for preventing separation of distributed power in a computer, the system analysis calculated through the tide analysis and failure analysis of the system Receiving data, deriving a correction value of a relay based on the received grid analysis data so that a probability of separation of distributed power in the event of disturbance in the grid is minimized, and relaying in the grid with the derived correction value A computer-readable recording medium recording a program for executing the step of adjusting the correction value of may be provided.

The computer-readable recording medium includes any type of recording medium that stores data that can be read by a computer system. For example, there may be a read only memory (ROM), a random access memory (RAM), a magnetic tape, a magnetic disk, a flash memory, and an optical data storage device. In addition, the computer-readable recording medium may be distributed over computer systems connected by a computer communication network, and stored and executed as code readable in a distributed manner.

Although described above with reference to the drawings and examples, the protection scope of the present invention is not meant to be limited by the drawings or the examples, and those skilled in the art of the present invention described in the claims below It will be understood that various modifications and changes can be made to the present invention without departing from the spirit and scope.

Specifically, the described features can be implemented in digital electronic circuitry, or computer hardware, firmware, or combinations thereof. The features can be implemented in a computer program product implemented in storage in a machine-readable storage device, eg, for execution by a programmable processor. And the features can be performed by a programmable processor executing a program of instructions for performing the functions of the described embodiments by operating on input data and generating output. The described features include at least one programmable processor, at least one input device, and at least one output coupled to receive data and directives from the data storage system and to transmit data and directives to the data storage system. It can be executed in one or more computer programs that can be executed on a programmable system including a device. A computer program includes a set of directives that can be used directly or indirectly within a computer to perform a specific action on a given result. A computer program is written in any form of programming language, including compiled or interpreted languages, and is included as a module, element, subroutine, or other unit suitable for use in other computer environments, or as a standalone program. Can be used in any form.

Suitable processors for the execution of the program of directives include, for example, both general purpose and special purpose microprocessors, and either a single processor or multiple processors of other types of computers. Also suitable for implementing computer program instructions and data embodying the described features are storage devices suitable for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices, magnetic devices such as internal hard disks and removable disks. Devices, magneto-optical disks and all forms of non-volatile memory including CD-ROM and DVD-ROM disks. The processor and memory can be integrated within application-specific integrated circuits (ASICs) or added by ASICs.

The present invention described above is described based on a series of functional blocks, but is not limited by the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes without departing from the spirit of the present invention. It will be apparent to those skilled in the art that the present invention is possible.

Combinations of the above-described embodiments are not limited to the above-described embodiments, and various forms of combinations may be provided as well as the above-described embodiments according to implementation and / or needs.

In the above-described embodiments, the methods are described based on a flowchart as a series of steps or blocks, but the present invention is not limited to the order of steps, and some steps may occur in a different order than the steps described above or simultaneously. have. In addition, those skilled in the art may recognize that the steps shown in the flowchart are not exclusive, other steps are included, or one or more steps in the flowchart may be deleted without affecting the scope of the present invention. You will understand.

The foregoing embodiments include examples of various aspects. It is not possible to describe all possible combinations for representing various aspects, but a person skilled in the art will recognize that other combinations are possible. Accordingly, the present invention will be said to include all other replacements, modifications and changes that fall within the scope of the following claims.

100: relay correction device
110: transceiver
120: memory
130: processor

Claims (21)

In the relay correction method performed by the relay correction device,
Receiving the system analysis data calculated through the analysis of the current and the failure analysis of the system;
Deriving a correction value of a relay based on the received grid analysis data, so that the probability that the distributed power is separated when the disturbance occurs in the grid is minimized; And
And adjusting the correction value of the relay in the system with the derived correction value,
In the step of deriving the correction value, in order to minimize the probability that the distributed power is separated in the event of a disturbance in the system, the separation allowable time of the distributed power that is allowed to be separated in consideration of the system linkage regulation of the preset distributed power is determined. A relay correction method to minimize the separation of distributed power. According to claim 1,
The step of receiving the system analysis data,
A relay correction method for preventing separation of distributed power to obtain a voltage of a load current flowing in the system, a fault current for a fault location, and a point of the Common Coupling (PCC) of the distributed power during a fault. According to claim 2,
The step of deriving the correction value,
A relay correction method for preventing separation of distributed power sources that calculates an operating current of a relay using a load current flowing in the system. According to claim 2,
The step of deriving the correction value,
A relay correction method to prevent separation of distributed power sources that calculates the operating time of the main protection relay and the rear protection relay by using the fault current for the fault location. According to claim 2,
The step of deriving the correction value,
A method of correcting relays to prevent separation of distributed power, which calculates the allowable separation time allowed for separation of distributed power using the voltage at the common connection point of distributed power. delete According to claim 1,
The allowable separation time of the distributed power,
A method of correcting relays to prevent separation of distributed power, which is defined as a time interval when the time allowed for separation of distributed power is faster than the time at which the common connection point voltage of distributed power is restored to the specified voltage. According to claim 1,
The step of deriving the correction value of the relay,
A relay for preventing separation of distributed power that derives the corrected value of the relay by performing at least one of the process of selecting, crossing and mutating the set of corrected values of the relay according to a genetic algorithm that minimizes the value of a predetermined objective function. Correction method. The method of claim 8,
The preset objective function,
A method of correcting relays to prevent separation of distributed power sources including cooperative violation time, relay operating time and allowable time for separation of distributed power sources. The method of claim 8,
The step of deriving the correction value of the relay,
In order to alleviate the local convergence feature of the genetic algorithm, a relay correction method for preventing separation of distributed power sources repeatedly performing the genetic algorithm. Transceiver for receiving the system analysis data calculated through the analysis and fault analysis of the system;
A memory for storing the received system analysis data; And
And a processor connected to the transceiver and the memory,
The processor derives a correction value of a relay based on the received system analysis data so as to minimize the probability that the distributed power is separated when a disturbance occurs in the system, and adjusts the correction value of the relay in the system with the derived correction value and,
In order to minimize the probability that the distributed power is separated in the event of a disturbance in the system, the processor minimizes the allowable separation time of the distributed power that allows the separation of the distributed power in consideration of the system linkage rules of the preset distributed power. Correction device to prevent the separation of. The method of claim 11,
The transceiver,
A relay correcting device for preventing separation of distributed power receiving load current flowing in the system, fault current for a fault location, and voltages of distributed power points (Points of the Common Coupling, PCC). The method of claim 12,
The processor,
A relay correction device for preventing separation of distributed power sources that calculate a relay's operating current using a load current flowing in the system. The method of claim 12,
The processor,
A relay correction device for preventing separation of distributed power that calculates the operating time of the main protective relay and the rear protective relay using the fault current for the fault location. The method of claim 12,
The processor,
A relay correction device for preventing the separation of distributed power, which calculates the separation allowable time during which separation of distributed power is allowed using the voltage of the common connection point of distributed power. delete The method of claim 11,
The allowable separation time of the distributed power,
A relay correction device for preventing the separation of distributed power, which is defined as the time interval for when the time allowed for separation of distributed power is faster than the time at which the common connection point voltage of the distributed power is restored to the specified voltage. The method of claim 11,
The processor,
A relay for preventing separation of distributed power that derives the corrected value of the relay by performing at least one of the process of selecting, crossing and mutating the set of corrected values of the relay according to a genetic algorithm that minimizes the value of a predetermined objective function. Correction device. The method of claim 18,
The preset objective function,
Relay correction device to prevent separation of distributed power, including cooperative violation time, relay operating time, and allowable separation time of distributed power. The method of claim 18,
The processor,
In order to alleviate the local convergence feature of the genetic algorithm, a relay correction device for preventing separation of distributed power sources repeatedly performing the genetic algorithm. In the computer-readable recording medium recording a program for executing a relay correction method for preventing the separation of the distributed power source in the computer,
Receiving the system analysis data calculated through the analysis of the current and the failure analysis of the system;
Deriving a correction value of a relay based on the received grid analysis data, so that the probability that the distributed power is separated when the disturbance occurs in the grid is minimized; And
The step of adjusting the correction value of the relay in the system with the derived correction value is executed,
In the step of deriving the correction value, in order to minimize the probability that the distributed power is separated in the event of a disturbance in the system, the separation allowable time of the distributed power that is allowed to be separated in consideration of the system linkage regulation of the preset distributed power is determined. A computer-readable recording medium that records a program to run to minimize.

Images