Method for operating of connection distributed generation in automatic voltage regulator and automatic voltage regulator therefor

Abstract

The present invention relates to a distributed power source connection method in an automatic voltage control device and an automatic voltage control device for the same. A distributed power source connection method in an automatic voltage control device according to one embodiment of the present invention comprises: a step of determining whether a phase reverse error occurs in which the direction of the current is recognized as reverse due to reverse current generation caused by the distributed power source connection; a step of measuring the secondary bus voltage of a power transformer when a phase reverse error is detected as a result of the determination; and a step of transmitting a driving control signal of an on-load tap changer (OLTC) by comparing the bus voltage with a preset reference voltage.

Description

Technology Field

[0001] The present invention relates to a method for connecting distributed power sources in an automatic voltage control device and an automatic voltage control device for the same. More specifically, it relates to a method for operating a distributed power source connection in an automatic voltage control device and an automatic voltage control device for the same, which enables stable normal operation of the distributed power source connection by performing voltage control based on the bus voltage when a phase reverse error occurs due to reverse current generation during the connection of distributed power sources. Background Technology

[0002] Recently, there has been growing interest in new and renewable energy sources, such as solar and wind power, which replace fossil fuels. These sources are utilized as distributed power sources, deployed on a small scale near consumers who require electricity, rather than using the existing large-scale, centralized power grid. In other words, distributed power sources refer to small-scale power generation facilities that use new and renewable energy to simplify and improve the efficiency of transmission network distribution facilities.

[0003] However, while distributed power sources utilizing new and renewable energy are on the rise, appropriate measures have not been established to address the issues arising from the connection between grid power and distributed power sources.

[0004] For example, solar power generation facilities are constructed in a concentrated manner across specific regions because site conditions are determined by factors such as sunlight intensity and investment costs. This regional concentration can cause grid-connected solar power facilities to exceed the maximum rated output voltage of their inverters. In such cases, as a problem arising from the interconnection between grid power and distributed power sources, reverse power may occur in power transformers within the distribution system connected to the distributed power.

[0005] Then, the Automatic Voltage Regulator (AVR) of the power transformer may recognize the direction of the current in reverse, causing a phase reverse error. Figure 1 is a diagram showing a substation open circuit where reverse current occurs. As shown in Figure 1, reverse current can occur when the amount of power generated by distributed sources increases.

[0006] However, if a reverse phase error occurs, the automatic voltage control function of the AVR stops, making it impossible to automatically control the voltage of the power transformer.

[0007] Accordingly, a measure must be provided for the AVR so that the automatic voltage control function for the power transformer voltage can operate normally even if reverse current occurs. Prior art literature

[0008] Korean Published Patent Application No. 10-2019-0004177 (Published Jan. 11, 2019) The problem to be solved

[0009] The objective of the present invention is to provide a method for operating a distributed power source connection in an automatic voltage control device and an automatic voltage control device for the same, which enables stable normal operation of the distributed power source connection by performing voltage control based on the bus voltage when a phase reverse error occurs due to reverse current generation during the connection of distributed power sources. means of solving the problem

[0010] A distributed power source connection operation method in an automatic voltage control device according to an embodiment of the present invention may include: a step of determining whether a phase reverse error occurs in which the direction of the current is recognized as reverse due to reverse current caused by the distributed power source connection; a step of measuring the secondary bus voltage of a power transformer when a phase reverse error is detected as a result of the determination; and a step of transmitting a driving control signal of an on-load tap changer (OLTC) by comparing the bus voltage with a preset reference voltage.

[0011] The above drive control signal may be a signal that indicates the rise of the load-time tap changer when the bus voltage is lower than the reference voltage, and a signal that indicates the fall of the load-time tap changer when the bus voltage is higher than the reference voltage.

[0012] The above busbar voltage may be the voltage measured at the 23 kV secondary busbar of the power transformer.

[0013] The above busbar voltage may be maintained within a voltage maintenance range of 22.9±2.5%.

[0014] The above busbar voltage may be measured using an instrument transformer.

[0015] In addition, a distributed power source linkage operation method in an automatic voltage control device according to an embodiment of the present invention may further include, after the determining step, a step of measuring the load center point voltage when no reverse phase error is detected as a result of the determination; and a step of transmitting a driving control signal of an on-load tap changer (OLTC) by comparing the load center point voltage with a preset reference voltage.

[0016] The above drive control signal may be a signal that indicates the rise of the load-time tap changer when the load center point voltage is lower than the reference voltage, and a signal that indicates the fall of the load-time tap changer when the load center point voltage is higher than the reference voltage.

[0017] Additionally, an automatic voltage regulator according to an embodiment of the present invention comprises at least one processor and a memory for storing computer-readable instructions. When the instructions are executed by the at least one processor, the automatic voltage regulator determines whether a phase reverse error occurs, in which the direction of the current is recognized as reverse due to reverse current caused by the connection of distributed power sources. When a phase reverse error is detected as a result of the determination, the regulator measures the secondary bus voltage of a power transformer and transmits a driving control signal for an on-load tap changer (OLTC) by comparing the bus voltage with a preset reference voltage.

[0018] When the above commands are executed by the at least one processor, the automatic voltage control device may measure the load center point voltage when no reverse phase error is detected as a result of the judgment, and transmit a drive control signal for the on-load tap changer (OLTC) by comparing the load center point voltage with a preset reference voltage.

[0019] In addition, a voltage control system for distributed power source linkage operation according to one embodiment of the present invention may include: an instrument transformer for measuring the secondary busbar voltage of a power transformer; and an automatic voltage control device for determining whether a phase reverse error occurs due to reverse current generation caused by distributed power source linkage, thereby recognizing the direction of the current in reverse, and for transmitting a driving control signal for an on-load tap changer (OLTC) by comparing the busbar voltage with a preset reference voltage when a phase reverse error is detected as a result of the determination. Effects of the invention

[0020] The present invention enables stable normal operation of distributed power source interconnection by performing voltage control based on the bus voltage in the event that a phase reverse error occurs due to reverse current generation during the interconnection of distributed power sources. Brief explanation of the drawing

[0021] Figure 1 is a diagram showing a substation open circuit where reverse current occurs. FIG. 2 is a drawing showing a substation disconnection according to an embodiment of the present invention, FIG. 3 is a diagram illustrating a load center point voltage control method. FIG. 4 is a diagram showing a distributed power source linkage operation method in an automatic voltage control device according to an embodiment of the present invention. Specific details for implementing the invention

[0022] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, detailed descriptions of known functions or configurations that may obscure the essence of the present invention in the following description and the accompanying drawings are omitted. Additionally, it should be noted that identical components throughout the drawings are indicated by the same reference numerals whenever possible.

[0023] The terms and words used in the specification and claims described below should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define terms to best describe his invention.

[0024] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0025] In the attached drawings, some components are exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect its actual size. The present invention is not limited by the relative sizes or spacing depicted in the attached drawings.

[0026] Throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, when a part is described as "connected" to another part, this includes not only cases where they are "directly connected" but also cases where they are "electrically connected" with other elements interposed between them.

[0027] A singular expression includes a plural expression unless the context clearly indicates otherwise. Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0028] Additionally, the term “part” as used in the specification refers to a hardware component, such as software, FPGA, or ASIC, and the “part” performs certain roles. However, the meaning of “part” is not limited to software or hardware. The “part” may be configured to reside in an addressable storage medium or configured to run on one or more processors. Thus, by example, the “part” includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and “parts” may be combined into a smaller number of components and “parts” or further separated into additional components and “parts.”

[0029] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0030] Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings.

[0031] FIG. 2 is a diagram showing a substation open circuit according to an embodiment of the present invention, and FIG. 3 is a diagram explaining a load center point voltage control method.

[0032] As illustrated in FIG. 2, in a substation single line according to one embodiment of the present invention, a power transformer (10) is located between a 154 kV bus and a 23 kV bus, and a plurality of distributed power sources (20) are connected to the distribution system. In the line, a voltage drop occurs due to resistance (30) and inductive reactance (40). A 154 kV bus is positioned on the primary side of the power transformer (10), and a 23 kV bus is positioned on the secondary side of the power transformer (10).

[0033] In particular, the AVR (Automatic Voltage Regulator) (110) can operate stably and normally because it performs voltage control based on the 23 kV bus voltage even when a reverse phase error occurs, which recognizes the direction of the load current in reverse as reverse current occurs in the power transformer (10) when there are many distributed power sources (20).

[0034] This AVR (110) transmits a tap adjustment signal to an On Load Tap Changer (hereinafter 'OLTC') (120) to perform voltage control.

[0035] Specifically, when the AVR (110) detects a reverse sequence error in which the direction of the load current is reversed, it measures the bus voltage using a bus voltage measuring unit (130) installed on the 23 kV bus on the secondary side of the power transformer (10). Here, the bus voltage measuring unit (130) may be a metering outfit.

[0036] Then, the AVR (110) compares the measured bus voltage with a preset reference voltage and transmits a signal to the OLTC driver indicating whether to raise or lower the OLTC (120), thereby causing the OLTC (120) to operate and maintain an appropriate voltage. At this time, when the bus voltage is lower than the reference voltage (i.e., bus voltage < reference voltage), the AVR (110) transmits a signal to the OLTC driver indicating whether to raise the OLTC (120), and when the bus voltage is higher than the reference voltage (i.e., bus voltage > reference voltage), it transmits a signal to the OLTC driver indicating whether to lower the OLTC (120). Accordingly, the AVR (110) stably maintains the bus voltage within the voltage maintenance range (22.9 ± 2.5%).

[0037] Additionally, the AVR (110) and the instrument transformer (130) can be integrated to provide a voltage control system for distributed power connection operation.

[0038] Meanwhile, the AVR (110) can operate in a load center voltage control manner as shown in FIG. 3 when no reverse phase error occurs. That is, the AVR (110) controls the voltage based on the load center by compensating for the voltage drop caused by line resistance and inductive reactance according to line voltage compensation (LVC).

[0039] Specifically, the AVR (110) measures the load center point voltage and, considering the voltage drop of the line, compares it with a preset reference voltage and transmits a signal to the OLTC driver indicating the rise and fall of the OLTC (120).

[0040] At this time, the AVR (110) transmits a signal to the OLTC driver indicating that the OLTC (120) should rise when the load center point voltage is lower than the reference voltage (i.e., load center point voltage < reference voltage), and transmits a signal to the OLTC driver indicating that the OLTC (120) should fall when the load center point voltage is higher than the reference voltage (i.e., bus voltage > reference voltage). Accordingly, the AVR (110) stably maintains the load center point voltage within the voltage maintenance range (22.9 ± 2.5%).

[0041] As described above, the AVR (110) can perform a 'bus voltage-based voltage control function' of a 23 kV bus placed on the secondary side of the power transformer (10) when it detects a reverse phase error, and a 'load center point-based voltage control function' in the general case where it does not detect a reverse phase error.

[0042] FIG. 4 is a diagram showing a distributed power source linkage operation method in an automatic voltage control device according to an embodiment of the present invention.

[0043] As shown in FIG. 4, the AVR (110) determines whether there is a reverse phase error in which the direction of the current is recognized in reverse due to reverse current caused by the connection of distributed power sources, and if a reverse phase error is detected, measures the bus voltage of the 23 kV bus placed on the secondary side of the power transformer (10) to perform a voltage control function based on the bus voltage (S201, S202).

[0044] Then, the AVR (110) compares the measured bus voltage with a preset reference voltage and transmits a drive control signal to control the operation of the OLTC (120) (S203). At this time, when the bus voltage is lower than the reference voltage, the AVR (110) transmits a signal to the OLTC drive device instructing the OLTC (120) to rise and controls the voltage to maintain an appropriate voltage (S204), and when the bus voltage is higher than the reference voltage, transmits a signal to the OLTC drive device instructing the OLTC (120) to lower and controls the voltage to maintain an appropriate voltage (S205). That is, the drive control signal is a signal instructing the OLTC (120) to rise when the bus voltage is lower than the reference voltage, and a signal instructing the OLTC (120) to lower when the bus voltage is higher than the reference voltage.

[0045] Meanwhile, the AVR (110) includes at least one processor and a memory for storing computer-readable instructions, and can perform a distributed power linkage operation method according to an embodiment of the present invention when computer-readable instructions stored in the memory are executed by at least one processor.

[0046] A method according to some embodiments may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either alone or in combination. The program instructions recorded on the medium may be those specifically designed and configured for the present invention, or they may be those known and available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc.

[0047] Although the foregoing description has focused on the novel features of the invention applicable to various embodiments, those skilled in the art will understand that various deletions, substitutions, and modifications are possible in the forms and details of the apparatus and method described above without departing from the scope of the invention. Accordingly, the scope of the invention is defined by the appended claims rather than by the foregoing description. All variations within the equivalent scope of the claims are encompassed within the scope of the invention. Explanation of the symbols

[0048] 10 ; Power transformer 20 ; Distributed power source 30 ; resistor 40 ; Inductive reactance 110 ; Automatic Voltage Regulator (AVR) 120 ; On Load Tap Charger (OLTC) 130 ; Busbar voltage measuring unit

Claims

Claim 1 A step of determining whether a phase reverse error occurs due to reverse current caused by the connection of distributed power sources, thereby recognizing the direction of the current in reverse; and a step of measuring the secondary busbar voltage of a power transformer when a phase reverse error is detected as a result of the above determination. The method includes the step of transmitting a drive control signal for an on-load tap changer (OLTC) by comparing the bus voltage with a preset reference voltage to operate the distributed power connection normally; wherein the drive control signal is a signal indicating the rise of the on-load tap changer when the bus voltage is lower than the reference voltage, and a signal indicating the fall of the on-load tap changer when the bus voltage is higher than the reference voltage; wherein the bus voltage is a voltage measured at the secondary side 23 kV bus of the power transformer, and the measurement of the bus voltage is performed using one bus voltage measuring unit (130) installed on the secondary side 23 kV bus of the power transformer, and the bus voltage is maintained within a voltage maintenance range of 22.9 ± 2.5%; and, after the judgment step, the method includes the step of measuring the load center point voltage when no reverse phase error is detected as a result of the judgment. A method for operating a distributed power source in an automatic voltage control device, further comprising the step of transmitting a driving control signal of an on-load tap changer (OLTC) by comparing the load center point voltage with a preset reference voltage. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A distributed power connection operation method in an automatic voltage control device, wherein, in claim 1, the busbar voltage is measured using an instrument transformer. Claim 6 delete Claim 7 delete Claim 8 As an Automatic Voltage Regulator, at least one processor; and memory for storing computer-readable instructions; wherein, when the instructions are executed by the at least one processor, the automatic voltage control device determines whether a phase reverse error occurs where the direction of the current is recognized in reverse due to reverse current caused by the distributed power connection, and if a phase reverse error is detected as a result of the determination, the secondary bus voltage of the power transformer is measured, and a drive control signal for an on-load tap changer (OLTC) is transmitted by comparing the bus voltage with a preset reference voltage to operate the distributed power connection normally, the drive control signal is a signal indicating the rise of the on-load tap changer when the bus voltage is lower than the reference voltage, and a signal indicating the fall of the on-load tap changer when the bus voltage is higher than the reference voltage, the bus voltage is a voltage measured at the secondary 23 kV bus of the power transformer, and the measurement of the bus voltage is performed by a device installed on the secondary 23 kV bus of the power transformer An automatic voltage control device that is formed using one bus voltage measuring unit (130), wherein the bus voltage is maintained within a voltage maintenance range of 22.9 ± 2.5%, and wherein, when the commands are executed by the at least one processor, the automatic voltage control device is made to measure the load center point voltage when no reverse phase error is detected as a result of the judgment, and transmits a driving control signal of an on-load tap changer (OLTC) by comparing the load center point voltage with a preset reference voltage. Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 In claim 8, the above busbar voltage is an automatic voltage control device that is measured using an instrument transformer. Claim 13 delete Claim 14 delete Claim 15 delete

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