KR102552773B1 - Distribution system voltage stabilization system and method - Google Patents

Abstract

According to an embodiment, an interconnection terminal device disposed at a point connected to a distribution system of distributed power, operating in a voltage constant range control mode at all times, and switching to a constant power factor control mode when receiving a cooperative control request from a main device; and a main device disposed at the back side of the trunk line of the extra-high voltage distribution system and operating in a heuristic-based cooperative control mode or a step-wise constant power factor control mode when a control limit situation of the associated terminal device occurs.

Description

Distribution system voltage stabilization system and method {Distribution system voltage stabilization system and method}

One embodiment of the present invention relates to a distribution system voltage stabilization system and method.

In general, the current shape and voltage characteristics of the existing distribution system are unidirectional currents flowing from substations to the load side, and the magnitude of the voltage drops unilaterally. Most of the voltage problems occurring in the existing distribution system are low voltage problems, and tap control using substation taps or SVR (Step Voltage Regulator) and reactive power compensation of capacitor banks and static VAR Compensator (SVC) solved through

Recently, in accordance with the new and renewable energy supply policy, a large number of large-capacity distributed power sources are being operated in connection with the distribution system, which is changing to a bidirectional current characteristic. Recently, the distribution system has a characteristic of causing an overvoltage problem due to reverse flow due to distributed power sources.

In Korea, applications for access by new and renewable energy providers to the distribution system are rapidly increasing, but connection delays occur due to voltage violation problems. It is not effective to solve the voltage problem through the existing voltage control equipment by predicting or measuring the output of the distributed power supply having intermittent output characteristics in real time. It is most effective to solve this problem through inverter control of distributed power supply with fast response speed, and power factor and reactive power control technology using this is needed.

A technical problem to be achieved by the present invention is to provide a distribution system voltage stabilization system and method for controlling a terminal device monitoring a distributed power side connection point to perform cooperative control according to the system situation.

According to an embodiment, an interconnection terminal device disposed at a point connected to a distribution system of distributed power, operating in a voltage constant range control mode at all times, and switching to a constant power factor control mode when receiving a cooperative control request from a main device; and a main device disposed at the back side of the trunk line of the extra-high voltage distribution system and operating in a heuristic-based cooperative control mode or a step-wise constant power factor control mode when a control limit situation of the associated terminal device occurs.

The voltage constant range control mode is a control mode that maintains the voltage size within a certain range through control when the power factor or voltage set by the main device is out of the specified range, and the constant power factor control mode is the power factor value set by the main device. It may be a control mode that keeps constant.

The dry pressure constant range control mode is a first mode for controlling the power factor so that the magnitude of the connection point voltage is maintained within the normal range when the magnitude of the voltage is out of a predetermined normal range, and the magnitude of the power factor when the magnitude of the voltage is in the normal range A second mode for reducing the reactive power control amount to converge to 1 may be included.

The associated terminal device applies the power factor setting value received from the main device after switching to the constant power factor control mode when the connected point voltage is in an abnormal range and the power factor control limit is in the power factor control limit situation while performing the voltage constant range control mode. can do.

The heuristic-based coordinated control mode is a control mode for deriving a command value of the associated terminal device to operate the voltage of an associated point according to a nominal voltage, and the stepwise constant power factor control mode is a set power factor of the associated terminal device when an abnormality occurs. It may be a mode in which step-by-step control is performed with respect to size.

According to an embodiment, the step of receiving, by the associated terminal device, the voltage, active power, reactive power, and voltage operating range of each phase of the distribution line; receiving, by the associated terminal device, a power factor set value and an operating mode from a main device; operating the associated terminal device in a voltage constant range control mode; and switching the connected terminal device to a constant power factor control mode when receiving a cooperative control request from the main device.

determining, by the connected terminal device, a controllable range using voltage, active power, reactive power, and a voltage operating range of each phase of the distribution line in the voltage constant range control mode; switching, by the connected terminal device, to the constant power factor control mode when the connection point voltage is in an abnormal range and is in a power factor control limit situation; and applying, by the associated terminal device, the power factor setting value received from the main device in the constant power factor control mode.

According to an embodiment, the step of receiving, by the main device, the voltage, active power, reactive power, voltage operating range, power factor setting value and operating mode of each phase from the associated terminal device; determining, by the main device, whether or not cooperative control is necessary according to whether a control limit situation occurs in the associated terminal device using information received from the associated terminal device; and operating, by the main device, in a heuristic-based cooperative control mode or a stepwise constant power factor control mode when a control limit situation of the associated terminal device occurs.

The main device may operate in the heuristic-based cooperative control mode operated according to a nominal voltage within a set voltage regulation range through cooperative control of distributed power sources linked to a plurality of linked terminal devices when a control limit situation of the linked terminal device occurs. there is.

The step-by-step constant power factor control mode in which the main device performs step-by-step constant power factor control within the reactive power control operating range of each distributed power source when a control limit situation of the associated terminal device occurs in a failure or inspection situation of a distribution line. can work as

According to an embodiment, a computer-readable recording medium in which a program for executing the above-described method is recorded on a computer is provided.

The distribution system voltage stabilization system and method according to the present invention can control a terminal device that monitors a distributed power side connection point to perform cooperative control according to the system situation.

1 is a block diagram of a distribution system voltage stabilization system according to an embodiment.
2 is a diagram for explaining an associated terminal device according to an embodiment.
Fig. 3 is a diagram for explaining a main device according to an embodiment.
4 is a flowchart of a method for stabilizing a distribution system voltage according to an embodiment.
5 is a diagram for explaining an operation of an associated terminal device according to an embodiment.
6 is a diagram for explaining a constant power factor control mode according to an embodiment.
7 is a diagram for explaining a voltage constant range control mode according to an embodiment.
8 and 9 are diagrams for explaining the operation of the main device according to the embodiment.
10 is a diagram for explaining a heuristic-based cooperative control mode according to an embodiment.
11 is a diagram for explaining a stepwise constant power factor control mode according to an embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

However, the technical idea of the present invention is not limited to some of the described embodiments, but may be implemented in a variety of different forms, and if it is within the scope of the technical idea of the present invention, one or more of the components among the embodiments can be selectively implemented. can be used by combining and substituting.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention, unless explicitly specifically defined and described, can be generally understood by those of ordinary skill in the art to which the present invention belongs. It can be interpreted as meaning, and commonly used terms, such as terms defined in a dictionary, can be interpreted in consideration of contextual meanings of related technologies.

Also, terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention.

In this specification, the singular form may also include the plural form unless otherwise specified in the phrase, and when described as "at least one (or more than one) of A and (and) B and C", A, B, and C are combined. may include one or more of all possible combinations.

Also, terms such as first, second, A, B, (a), and (b) may be used to describe components of an embodiment of the present invention.

These terms are only used to distinguish the component from other components, and the term is not limited to the nature, order, or order of the corresponding component.

In addition, when a component is described as being 'connected', 'coupled' or 'connected' to another component, the component is not only directly connected to, combined with, or connected to the other component, but also with the component. It may also include the case of being 'connected', 'combined', or 'connected' due to another component between the other components.

In addition, when it is described as being formed or disposed on the "top (above) or bottom (bottom)" of each component, the top (top) or bottom (bottom) is not only a case where two components are in direct contact with each other, but also one A case in which another component above is formed or disposed between two components is also included. In addition, when expressed as "up (up) or down (down)", it may include the meaning of not only an upward direction but also a downward direction based on one component.

Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings, but the same or corresponding components regardless of reference numerals are given the same reference numerals, and overlapping descriptions thereof will be omitted.

1 is a block diagram of a distribution system voltage stabilization system according to an embodiment. The distribution system voltage stabilization system 1 according to the embodiment may be a device applied to distributed power connected to the distribution system side. Referring to FIG. 1 , a power distribution system voltage stabilization system 1 according to an embodiment may include an associated terminal device 10 and a main device 20 .

The connection terminal device 10 is disposed at a point connected to the distribution system of distributed power, operates in a voltage constant range control mode at all times, and can switch to a constant power factor control mode when receiving a cooperative control request from the main device 20. there is. The connection terminal device 10 constituting the system may be installed at a connection point of extra-high voltage and low voltage where the distribution system and the distributed power source are connected. In an embodiment, the connected terminal device 10 may include a Remote Terminal Unit (RTU) installed in all power generation/substations of an EMS (Energy Management System) power system to acquire power system data. The RTU can acquire voltage size, current size, active power, reactive power, circuit breaker information, and the like.

In an embodiment, the voltage constant range control mode may be a control mode in which the voltage size is maintained within a certain range through control when the power factor or voltage set by the main device 20 is out of the specified range. In the dry pressure constant range control mode, the associated terminal device 10 controls the power factor so that the magnitude of the associated point voltage is maintained within the normal range when the magnitude of the voltage is out of the preset normal range, and the magnitude of the voltage is in the normal range In this case, it may operate in the second mode of reducing the reactive power control amount so that the magnitude of the power factor converges to 1. Unlike existing active voltage control algorithms, the voltage constant range control mode has a technical advantage in that power factor control can be performed regardless of line impedance, which is unclear information.

In an embodiment, the constant power factor control mode may be a control mode in which the power factor value set by the main device 20 is constantly maintained.

In addition, while the connected terminal device 10 is performing the voltage constant range control mode, when the connected point voltage is in an abnormal range and the power factor control limit situation is reached, after switching to the constant power factor control mode, the power factor received from the main device 20 Set values can be applied. In the embodiment, the main device and the management terminal device mean the same configuration.

2 is a diagram for explaining an associated terminal device according to an embodiment.

Referring to FIG. 2, the interconnection terminal device 10 can be divided into low voltage (a) and extra high voltage (b) interconnection terminal devices 10 of distributed power supply, and is installed on the low voltage side or extra high voltage side of a pole-type power transformer and is installed in a sub-zone. It is possible to collectively control the power factor of multiple distributed power sources linked to

The connected terminal device 10 may maintain the voltage of the connected point of the distributed power supply within an operating range through local-based active voltage control. Unlike conventional active voltage control algorithms, the connected terminal device 10 according to the embodiment can be maintained within a specified range through power factor control regardless of line impedance through a switching operation between a constant power factor control mode and a constant voltage range control mode. there is.

While the existing active voltage control algorithm maintains the voltage of the linkage point of the distributed power supply at the target voltage, the linked terminal device 10 according to the embodiment, when a voltage problem of the distributed power supply occurs regardless of the target voltage, steps It can be stabilized through the power factor control.

In addition, the existing active voltage control algorithm has a problem in that the target voltage cannot be kept constant in reality in a situation where it is difficult to know the exact impedance, while the line impedance must be accurately measured and input to the terminal device in the field. The connected terminal device 10 according to the embodiment can solve this problem through an active voltage control algorithm through power factor control of a step-by-step constant size.

Referring back to FIG. 1 , the main unit is disposed on the back side of the trunk line of the extra-high voltage distribution system, and can operate in a heuristic-based cooperative control mode or a stepwise constant power factor control mode when a control limit situation of the associated terminal device 10 occurs.

The main device 20 may be installed on the back side of the trunk line of the extra-high voltage distribution system so as to manage a plurality of associated terminal devices 10 . The main device 20 may replace the function performed through the change of loading algorithm.

In an embodiment, the heuristic-based coordinated control mode may be a control mode for deriving a command value of the associated terminal device 10 to operate the voltage of the associated point according to the nominal voltage. The heuristic-based coordinated control mode provides the most effective control by providing a solution to operate the voltage of each connection point close to the nominal voltage within the specified range.

In an embodiment, the stepwise constant power factor control mode may be a mode in which stepwise control is performed on the set power factor of the associated terminal device 10 when an abnormal state occurs. The step-by-step constant power factor control mode is a method of controlling each associated terminal device 10 step by step as much as the set constant power factor in a situation where the impedance is unknown, and the power factor gradual control of the constant voltage range control mode of the associated terminal device 10 similar to the way

Fig. 3 is a diagram for explaining a main device according to an embodiment.

Referring to FIG. 3 , the main device 20 of the distributed power source is installed at a special high voltage and can manage several connected terminal devices 10 of the distributed power source. In an embodiment, the main device 20 may mean a main device 20 for power distribution automation.

The main device 20 performs cooperative control between the associated terminal devices 10 installed below, and through this, it is possible to provide a solution for voltage stabilization. The main device 20 may perform voltage control when voltage control is no longer performed due to a limitation of reactive power or power factor control due to a voltage problem of an individual distributed power supply.

The main device 20 can solve the voltage problem by controlling the power factor or reactive power of the adjacent distributed power supply, and can provide an effective control solution by minimizing the voltage fluctuation caused by the distributed power source in addition to the purpose of resolving the voltage violation. there is.

4 is a flowchart of a method for stabilizing a distribution system voltage according to an embodiment. In FIG. 4, area No. 1 is a part for explaining the operation of the associated terminal device, and area No. 2 is a part for explaining the operation of the main device.

Referring to FIG. 4 , the associated terminal device receives setting data and measurement data. Setting data and measurement data may be input from an associated terminal device operator or a main device for distribution automation.

Next, the associated terminal device receives the data of the management terminal device as an input.

Next, the associated terminal device creates a common constraint range that satisfies the capacity and power factor constraint conditions, and determines the maximum voltage and minimum voltage. The associated terminal device may generate a common restriction range using setting data, measurement data, and management terminal device data. The common constraints of distributed power sources are inverter rated capacity, upper limit of voltage operating range, lower limit of voltage operating range, lagging power factor limit, step-leading power factor limit, lower limit of power factor limit, upper limit of power factor limit, lower limit of capacity limit, upper limit of capacity limit, lower limit of reactive power control , the upper limit of reactive power control, the lower limit of power factor control, the upper limit of power factor control, average active power, average reactive power, and three-phase average voltage. Common constraints can be summarized as shown in Table 1 below.

The connected terminal device calculates the current power factor using the active power output and the reactive power output of the distributed power source, distinguishes between lagging and leading phase power factors, and can determine the maximum voltage and minimum voltage using the voltages of each phase.

Next, the associated terminal device always operates in the voltage constant range control mode, but switches to the constant power factor control mode when receiving a cooperative control request from the main device.

Next, the associated terminal device determines the controllable range in the voltage constant range control mode.

Next, when the associated terminal device is out of the controllable range, it switches to a constant power factor control mode. The associated terminal device may determine the controllable range according to whether the power factor command value is out of the power factor upper limit value and the power factor lower limit value. That is, when the power factor command value is out of the power factor upper limit value and the power factor lower limit value, it is determined that it is out of the controllable range, and the constant power factor control mode is switched to operate.

After the connected terminal device performs an operation according to each mode, it transmits data to a power factor value, which is an inverter command, and a management terminal device.

Next, the main device receives voltage, active power, and reactive power data of each phase from each associated terminal device.

Next, the main device receives setting data and measurement data. The main unit can be composed of a main unit for distribution automation or a management terminal unit in the field. The subject of inputting the setting data and measurement data is the main device operator in the case of the main device for distribution automation, and the terminal device operator in the case of the management terminal device.

Next, the main device generates a maximum voltage matrix and a minimum voltage matrix. That is, the main device generates the input of setting data of the associated terminal device as a matrix. Table 2 below shows a maximum voltage matrix and a minimum voltage matrix generated according to input of setting data. In [Table 2], k means the k-th linked terminal device.

Next, the main device generates a common constraint matrix that satisfies the capacitance, power factor, and voltage constraints. The main device generates a common constraint matrix by utilizing the input value matrix of the setting data of the associated terminal device, and the common constraint matrix can be composed of 4 fields as shown in [Table 3] below. In [Table 3], k means the k-th linked terminal device.

Next, the main device determines whether a control limit situation has occurred in the associated terminal device.

Next, the main device operates in a heuristic-based cooperative control mode or a stepwise constant power factor control mode when a control limit situation of the associated terminal device occurs. At this time, the main device operates in the stepwise constant power factor control mode when a failure occurs in the distribution line or when the topology information of the distribution system cannot be grasped for other reasons, and operates in the heuristic-based coordinated control mode in other cases. .

Through this, the associated terminal device can perform local-based active voltage control, and the main device can perform cooperative control between each associated terminal device.

[Table 4] below is the setting data input to the connected terminal device and the main device, [Table 5] is the measurement data, and [Table 6] is the input data of the main device.

5 is a diagram for explaining an operation of an associated terminal device according to an embodiment.

Referring to FIG. 5, the associated terminal device receives input data including setting data and measurement data including voltage, active power, reactive power, and voltage operating range of each phase of the distribution line, and power factor setting value and operating mode from the main device. do.

Next, the associated terminal device creates a common constraint range that satisfies the capacity and power factor constraint conditions, and determines the maximum voltage and minimum voltage.

Next, the associated terminal device always operates in the voltage constant range control mode, but switches to the constant power factor control mode when receiving a cooperative control request from the main device.

Next, the associated terminal device determines the controllable range in the voltage constant range control mode. The associated terminal device determines the controllable range using the voltage, active power, reactive power, and voltage operating range of each phase of the distribution line in the voltage constant range control mode.

Next, when the associated terminal device is out of the controllable range, it switches to a constant power factor control mode. The associated terminal device switches to the constant power factor control mode when the associated point voltage is in an abnormal range and is in a power factor control limit situation. At this time, the associated terminal device applies the power factor setting value received from the main device in the constant power factor control mode.

After performing the operation according to each mode, the connected terminal device transmits data to the inverter command and management terminal device.

The associated terminal device is equipped with two control modes, and the control mode can be performed according to the selection of the operation mode by the operator or the upper system. The main device may transmit a command value regardless of a cooperative control request by performing a control algorithm in units of minutes in the same way as the associated terminal device. The common constraint range generation is the common constraint part of the capacity and power factor constraints, and unlike the existing active voltage control algorithms, the voltage constraints are not considered. That is, it does not require line impedance data.

The determination of the maximum voltage and the minimum voltage is performed by determining the largest voltage and the smallest voltage among the three-phase (R, S, T) voltages measured by the RTU of the associated terminal device.

The OP_MODE value, which means the operating mode, is initialized to 0, so that the voltage constant range control mode is performed in the constant mode, and when a cooperative control request (VM_MODE = 1) comes in from the main device, it switches to the constant power factor control mode. That is, when the cooperative control notification (VM_MODE) of the distributed power supply is 0 or does not exist, it operates in the constant voltage range control mode. In the process of performing the voltage constant range control mode, if the voltage is in the abnormal range and control is no longer possible due to the power factor control limit, the distributed power supply changes the operating mode to the constant power factor control mode and receives the power factor set value from the main device. apply

6 is a diagram for explaining a constant power factor control mode according to an embodiment.

Referring to FIG. 6, the constant power factor control mode is a control mode in which the power factor value set in the main device is constantly maintained. In this case, an operation to keep the set power factor constant is performed.

In the constant power factor control mode, the controllable range of the set power factor value is determined and the power factor is maintained constant in the controllable range, but the limit value of the constraint condition is controlled when it is out of the controllable range.

The constant power factor control mode is divided into a lagging power factor control part and a step power factor control part, and the parameters applied to it are defined as shown in [Table 7].

In FIG. 6, the upper region No. 1 is the lagging power factor part, and if it is greater than the lagging power factor limit value, the power factor value has the size of the limit value. . In other cases, the set power factor is maintained.

In FIG. 6, the lower region No. 2 is a forward power factor part, and if it is smaller than the forward power factor limit value, the power factor value has the size of the forward power factor limit value, and if it is greater than 1, it is judged to be an error and has a set value of 1. In other cases, the set power factor is maintained.

7 is a diagram for explaining a voltage constant range control mode according to an embodiment.

Referring to FIG. 7 , the voltage constant range control mode performs an operation to maintain the voltage within a certain range through control by the size of a certain power factor when the voltage is out of the set or specified voltage range.

When out of a certain range, the algorithm of the corresponding mode is performed to prevent frequent control, and in the case of a normal range, the reactive power control amount of the distributed power supply can be reduced by controlling the power factor to gradually converge to 1. Since the impedance of the line is not used to control the voltage, there is no dependence on the line impedance for voltage control.

The voltage constant range control mode can operate in the first mode and the second mode, which are lower operating modes, and a mode for controlling a constant power factor to maintain the voltage within a certain range and a mode for controlling the power factor when the voltage is in the normal range. It can be divided into a mode in which the amount of reactive power control is reduced by gradually converging the magnitude to 1.

Parameters applied to the voltage constant range control mode are defined as in [Table 8].

In FIG. 7, areas No. 1 and No. 3 indicate the first mode, and area No. 2 indicates the second mode.

In the case of overvoltage in area 1, the main device compensates for the voltage through lagging power factor control, and in the case of low voltage, it compensates for the voltage through phase-advancing power factor control. In area 2, the main device can set a stable range with a narrower range than the specified range through DB2 within the stable voltage operating range. gradually converges to a power factor of 1.

Area 3 indicates a case where control is no longer possible due to limitations in power factor and capacity constraints in case of overvoltage or undervoltage, and the main device operates the connected terminal device in a constant power factor control mode through a cooperative control request. .

The review of the constraint condition range in FIG. 7 means a review process for the main device to transmit the power factor command value within the range of leading and lagging power factor constraints before the power factor control size is calculated and a command is issued to the inverter. . When the main device deviates from the constraint conditions, the power factor command value is calculated as the limit value of the constraint condition that satisfies the power factor and capacity constraints.

8 and 9 are diagrams for explaining the operation of the main device according to the embodiment.

Referring to FIG. 8, the main device receives setting data and measurement data including voltage, active power, and reactive power of each phase from the connected terminal device, and includes voltage operating range, power factor setting value, operating mode, and cooperative control notification. data is received from the linked terminal device.

Next, the main device generates a common constraint matrix that satisfies the maximum voltage matrix and minimum voltage matrix, capacitance, power factor, and voltage constraint conditions.

Next, the main device determines whether a control limit situation has occurred in the associated terminal device.

Next, the main device operates in a heuristic-based cooperative control mode or a stepwise constant power factor control mode when a control limit situation of the associated terminal device occurs. At this time, the main device operates in the stepwise constant power factor control mode when a failure occurs in the distribution line or when the topology information of the distribution system cannot be grasped for other reasons, and operates in the heuristic-based coordinated control mode in other cases. .

The main device derives the power factor command value of each linked terminal device, and mainly performs cooperative control so that the adjacent distributed type power source can compensate when the linked terminal device can no longer control due to the limit of control. In FIG. 8, area 1 is a part for determining when cooperative control is required in an associated terminal device, and at the same time, overvoltage and undervoltage are determined. Region 2 is a process of performing step-by-step power factor control mode, and region 3 represents a process of performing heuristic-based cooperative control mode.

In performing cooperative control in the main device, the first method to be performed is to generate a reactive power sensitivity matrix of the distributed power supply, which is used in a heuristic-based cooperative control algorithm.

Referring to FIG. 9 , reactive power sensitivity, that is, reactance, of a distributed power supply can be calculated using impedance from a substation to a main device and line impedance information between the main device and an associated terminal device. For example, the main device calculates the reactive power sensitivity of the distributed power supply by summing the reactance component of the line between the substation and the management terminal device, the reactance component of the line between the main device and the adjacent linked terminal device, and the reactance component between the adjacent linked terminal devices. . That is, the reactive power sensitivity of the distributed power supply can be calculated as the sum of the reactance components between the substation and the distributed power supply.

10 is a diagram for explaining a heuristic-based cooperative control mode according to an embodiment.

Referring to FIG. 10 , in the heuristic-based cooperative control mode, the main device independently controls the associated terminal device to control the voltage of each associated point, and determines the control command value for each associated terminal device. The purpose of the heuristic-based coordinated control mode is to operate close to a nominal voltage within a set voltage regulation range through cooperative control of distributed power sources linked to a plurality of connected terminal devices.

Cooperative control performs an algorithm when a voltage problem occurs in a connected terminal device of distributed power supply or when control is no longer possible due to the limit of the control range of distributed power supply, and through power factor control of adjacent distributed power supplies that can be controlled. voltage problem can be solved. The objective function of the heuristic-based coordinated control mode can be expressed by Equation 1 below, and the constraints can be expressed by Equation 2 below.

번째,

번째 모선이고, Q_DG,min,k는

번째 분산형 전원의 무효전력 제어 하한값이고, Q_DG,max,k는

번째 분산형 전원의 무효전력 제어 상한값이고, Q⁰ _DG,k는

번째 분산형 전원의 현재 무효전력 제어 크기이고, △QD_G,k는

번째 분산형 전원의 무효전력 제어량이다.In Equations 1 and 2, N _bus is the number of buses in the management terminal device area of the distributed power supply (= management terminal device bus + number of connected terminal device buses), and V _i , V _j are the distributed power supply

th,

th busbar, and Q _DG,min,k is

It is the lower limit of the reactive power control of the th distributed power supply, and Q _DG,max,k is

It is the upper limit of the reactive power control of the th distributed power supply, and Q ⁰ _DG,k is

is the current reactive power control size of the th distributed power supply, and △QD _G,k is

It is the reactive power control amount of the th distributed power supply.

The main device derives a solution of the objective function of Equation 1 through a voltage flattening process by applying a heuristic technique. The main device calculates the average voltage according to Equation 3 below for voltage flattening, and through this, it is possible to calculate the reactive power control amount of the terminal distributed power supply as Equations 4 to 7.

The main device can check whether the reactive power control command value of the terminal distributed power supply violates the constraint condition as shown in Equation 6, and can estimate the voltage after control through the terminal reactive power control as shown in Equation 7.

는 각 분산형 전원의 관리 및 연계 단말 장치간의 평균 전압(

)이고,

는 공칭전압(

)이고,

는 분산형 전원의 무효전력 전압 민감도(변전소로부터 분산형 전원사이의 리액턴스)이고,

,

는 분산형 전원의 제어 가능한 무효 전력의 하한값 및 상한값이다.In Equations 3 to 7,

Is the average voltage between the management and associated terminal devices of each distributed power supply (

)ego,

is the nominal voltage (

)ego,

is the reactive power voltage sensitivity of the distributed power supply (reactance between the substation and the distributed power supply),

,

is the lower limit and upper limit of the controllable reactive power of the distributed power supply.

The main device estimates the voltage after reactive power control of the distributed power supply at the end, calculates the average voltage again, and sequentially repeatedly calculates the reactive power control calculation process of the distributed power supply at the front stage, thereby finalizing each connection as shown in FIG. 10. A control value of the terminal device may be derived.

In area 1 in FIG. 10, the main device calculates the average voltage using the voltage measured in the first associated terminal device, and then calculates the voltage deviation of the nominal voltage and calculates the reactive power control value of the distributed power supply at the end. In area 2, the main device calculates the average value again by estimating after the reactive power control of the distributed power supply at the end, and then calculates the voltage deviation from the nominal voltage, until the voltage fluctuation amount is close to zero. The process of calculating the reactive power control value of is repeated to derive the final reactive power control value of each distributed power source.

11 is a diagram for explaining a stepwise constant power factor control mode according to an embodiment.

Referring to FIG. 11 , the stepwise constant power factor control mode, like the heuristic-based cooperative control mode, can be applied when a voltage problem occurs from an associated terminal device and control is no longer possible due to control limitations.

However, the phased constant power factor control mode can be preferentially applied when the topology information of the distribution system is unknown, and the problem is solved through phased constant power factor control within the operating range of each distributed power supply's reactive power control. .

The step-by-step constant power factor control mode is an algorithm that can effectively stabilize the voltage of distribution lines when the topology is changed due to failure or inspection of distribution lines, or when accurate topology information cannot be confirmed.

In FIG. 11, area 1 shows a process of solving the voltage problem by gradually controlling the power factor by the set power factor when an overvoltage occurs, and area 2 shows a process of solving the voltage problem by gradually controlling the power factor by the set power factor when an undervoltage occurs represents the process of In cases other than overvoltage and undervoltage, it operates to maintain the current power factor value.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable recording medium. In this case, the medium may continuously store a program executable by a computer or temporarily store the program for execution or download. In addition, the medium may be various recording means or storage means in the form of a single or combined hardware, but is not limited to a medium directly connected to a certain computer system, and may be distributed on a network. Examples of the medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical recording media such as CD-ROMs and DVDs, and magneto-optical media such as floptical disks. , and ROM, RAM, flash memory, etc. configured to store program instructions. In addition, examples of other media include “recording media” or storage media managed by an app store that distributes applications, a site that supplies or distributes other various software, and a server.

The term '~unit' used in this embodiment means software or a hardware component such as a field-programmable gate array (FPGA) or ASIC, and '~unit' performs certain roles. However, '~ part' is not limited to software or hardware. '~bu' may be configured to be in an addressable storage medium and may be configured to reproduce one or more processors. Therefore, as an example, '~unit' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Functions provided within components and '~units' may be combined into smaller numbers of components and '~units' or further separated into additional components and '~units'. In addition, components and '~units' may be implemented to play one or more CPUs in a device or a secure multimedia card.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the claims below. You will understand that it can be done.

1: Distribution system voltage stabilization system
10: associated terminal device
20: main device

Claims (11)

An interconnection terminal device disposed at a point connected to a distribution system of distributed power, operating in a voltage constant range control mode at all times, and switching to a constant power factor control mode when receiving a cooperative control request from a main device; and
A main device disposed on the back side of the trunk line of the extra-high voltage distribution system and operating in a heuristic-based coordinated control mode or a step-by-step constant power factor control mode when a control limit situation of the linked terminal device occurs,
The associated terminal device applies the power factor setting value received from the main device after switching to the constant power factor control mode when the connected point voltage is in an abnormal range and the power factor control limit is in the power factor control limit situation while performing the voltage constant range control mode. distribution system voltage stabilization system.
According to claim 1,
The voltage constant range control mode is a control mode in which the voltage level is maintained within a certain range through control when the power factor or voltage set in the main device is out of the specified range,
The constant power factor control mode is a control mode in which the power factor value set by the main device is constantly maintained.
According to claim 2,
The voltage constant range control mode is a first mode for controlling the power factor so that the magnitude of the connection point voltage is maintained within the normal range when the magnitude of the voltage is out of a predetermined normal range, and the magnitude of the power factor is reduced when the magnitude of the voltage is in the normal range. A power distribution system voltage stabilization system including a second mode for reducing the reactive power control amount to converge to 1.
delete According to claim 1,
The heuristic-based coordinated control mode is a control mode for deriving a command value of the associated terminal device to operate the voltage of an associated point according to a nominal voltage;
The step-by-step constant power factor control mode is a mode for performing step-by-step control on the set power factor of the associated terminal device when an abnormality occurs.
receiving, by an associated terminal device, voltage, active power, reactive power, and a voltage operating range of each phase of a distribution line;
receiving, by the associated terminal device, a power factor set value and an operating mode from a main device;
operating the associated terminal device in a voltage constant range control mode; and
Switching the connected terminal device to a constant power factor control mode when receiving a cooperative control request from the main device;
determining, by the connected terminal device, a controllable range using voltage, active power, reactive power, and a voltage operating range of each phase of the distribution line in the voltage constant range control mode; switching, by the connected terminal device, to the constant power factor control mode when the connection point voltage is in an abnormal range and is in a power factor control limit situation; and applying, by the associated terminal device, the power factor setting value received from the main device in the constant power factor control mode.
delete receiving, by the main device, the voltage, active power, reactive power, voltage operating range, power factor setting value and operating mode of each phase from the associated terminal device;
determining, by the main device, whether or not cooperative control is necessary according to whether a control limit situation occurs in the associated terminal device using information received from the associated terminal device; and
operating, by the main device, in a heuristic-based cooperative control mode or a stepwise constant power factor control mode when a control limit situation of the associated terminal device occurs;
The power distribution operating in the heuristic-based cooperative control mode in which the main device operates according to the nominal voltage within the voltage regulation range set through cooperative control of distributed power sources linked to a plurality of linked terminal devices when a control limit situation of the linked terminal device occurs. Grid voltage stabilization method.
delete According to claim 8,
The main device is in the step-by-step constant power factor control mode to perform step-by-step constant power factor control within the reactive power control operating range of each distributed power source when a control limit situation of the associated terminal device occurs in a failure or inspection situation of a distribution line. A method for stabilizing the operating distribution system voltage.
A computer-readable 　recording medium on which a program for executing the method of any one of claims 6, 8, and 10 is recorded on a computer.

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