Line Simulation Apparatus and Control Method Thereof

Abstract

The present invention relates to a manual R·L-based line simulation device and a technology for reproducing system strength (SCR) through virtual impedance injection. More specifically, the invention relates to a variable SCR line simulation device and a control method thereof that improves the stability and reproducibility of inverter and distributed power source interconnection tests by combining multiple R·L step lines to implement various system capacities of 50 to 250 kVA and SCR 2, 3, and 5 conditions, performing PLC-MC-based automatic switching control, system short-circuit capacity calculation, R·L step division, PSCAD-based current verification, bus configuration, and communication interconnection control, and reproducing the X / R ratio and dynamic characteristics of an actual system by including Rvirt and Lvirt-based virtual impedance adjustment functions. According to the concept of the present invention, an R·L step module composed of a plurality of R·L lines having different resistance (R) and inductance (L) values, wherein each line is designed in a fixed step form to form a target system impedance solely by selecting or combining series and parallel lines; an R·L step configuration unit configured to determine necessary R and L values ​​corresponding to the system rated capacity and target SCR conditions, and to distribute the determined values ​​into multiple R·L steps to implement all SCR 2, SCR 3, and SCR 5 conditions; a PLC-based MC control unit that controls a motor contactor (MC) corresponding to each R·L line to perform line switching or disconnection, and automatically selects a line based on a predefined switching combination table according to capacity and SCR conditions; a user interface unit that displays line-specific setting and operation information; a control system that controls the switching of R·L lines based on BUS settings, SCR settings, a switching combination table, and virtual impedance settings transmitted from the user interface unit, and performs protection operations and interlock functions to detect abnormalities; and physical R·L The present invention provides a line simulation device and a control method thereof, characterized by including a virtual impedance injection unit that variably forms the X / R ratio and system strength by adjusting equivalent resistance components and inductive components without changing the line.

Description

Technology Field

[0001] The present invention relates to a manual R·L-based line simulation device and a technology for reproducing system strength (SCR) through virtual impedance injection. More specifically, the invention relates to a variable SCR line simulation device and a control method thereof that improves the stability and reproducibility of inverter and distributed power source interconnection tests by combining multiple R·L step lines to implement various system capacities of 50 to 250 kVA and SCR 2, 3, and 5 conditions, performing PLC-MC-based automatic switching control, system short-circuit capacity calculation, R·L step division, PSCAD-based current verification, bus configuration, and communication interconnection control, and reproducing the X / R ratio and dynamic characteristics of an actual system by including Rvirt and Lvirt-based virtual impedance adjustment functions. Background Technology

[0002] Recently, with the integration of new and renewable energy, the expansion of distributed power sources, and the advancement of power electronics-based grid control technology, the importance of line emulation technology for verifying whether inverter devices operate stably under conditions similar to the actual grid has been significantly highlighted. In particular, since the Short Circuit Ratio (SCR) directly affects inverter control stability, PLL operation, protection coordination characteristics, and transient response, it is essential to reproduce various SCR conditions in a test environment. However, conventional technology utilized a single type of simulation circuit capable of implementing only specific capacities or fixed impedance conditions, and there were limitations in precisely adjusting the R and L values ​​required for the target SCR or covering multiple capacities with a single device. Furthermore, existing manual simulation devices required physical circuit replacement or wiring changes, resulting in significant time and manpower consumption when modifying test configurations and limited reproducibility during repetitive testing.

[0003] Furthermore, verifying inverter control in a weak grid environment requires implementing various grid impedances with varying X / R ratios; however, conventional devices provided only fixed reactances or limited resistance adjustment functions, making it difficult to faithfully simulate the dynamic characteristics of the actual grid. While some systems introduced methods combining variable reactances or standalone R·L modules, the module-based exchange method is unsuitable for high-capacity grids or complex tests involving multiple SCR conditions. Additionally, controller-based virtual impedance injection functions were limited to separate, independent devices, posing a problem that made integrated operation with line simulators difficult.

[0004] Furthermore, when the circuit configuration, bus mapping, switching control, protection functions, and virtual impedance settings of the line simulation device are operated in a separated structure, the tester must configure the device individually, making changes to operating conditions complex. Additionally, the lack of seamless automation for integration with higher-level control systems such as EMS, SCADA, and HILS results in inefficiency for large-scale repetitive testing or real-time scenario-based evaluation. Moreover, while there is an increasing need for simulation automation functions to verify whether the current flowing through the circuit exceeds allowable limits for various combinations of multiple capacities (50–250 kVA) and multiple SCR conditions (2, 3, 5), conventional devices often lack such systematic verification functions.

[0005] Therefore, there is a need for an integrated line simulator capable of variably configuring impedances of multiple capacitance ranges by hierarchically combining various R and L steps, immediately implementing SCR conditions without module replacement through PLC-based MC switching control, and dynamically adjusting the X / R ratio by utilizing virtual resistance / virtual inductance. The problem to be solved

[0006] Accordingly, the technical problem of the present invention is conceived from this point, and the objective of the present invention is to provide a line simulation device and a control method thereof that can variably implement SCR 2, SCR 3, and SCR 5 conditions for various system capacities from 50 kVA to 250 kVA in a single device by combining a plurality of R·L step lines, and precisely form a system impedance (R, L) corresponding to a target SCR.

[0007] In addition, the present invention provides a line simulation device and a control method thereof that can automatically configure line combinations through PLC-MC-based switching without physical wiring changes by inversely calculating the required inductance and resistance values ​​using a system short-circuit capacity calculation formula and a target SCR value, and dividing and arranging them into multiple R·L steps.

[0008] Furthermore, the invention provides a line simulation device and a control method thereof that can guarantee stability in various test scenarios by verifying whether the current per circuit in each capacity / SCR combination exceeds the allowable limit through PSCAD-based EMT (Time-Domain) simulation and securing safe operating conditions through a predefined MC input table.

[0009] In addition, the invention provides a line simulation device and a control method thereof that flexibly configures BUS1, BUS2, and BUS3 configurations and system branching scenarios through PLC automatic control functions including bus selection rules and line mapping rules, and supports remote control and automatic test configuration by linking with EMS / SCADA / HILS systems.

[0010] In addition, the present invention provides a line simulation device and a control method thereof that can precisely test control stability and protection logic response under weak grid conditions by including a virtual impedance function capable of injecting virtual resistance (Rvirt) and virtual inductance (Lvirt) into a power converter separately from physical R·L lines, thereby dynamically reproducing actual X / R ratio changes and dynamic characteristics.

[0011] In addition, the invention provides a line simulation device and a control method thereof that can ensure safe operation of the line unit and the entire system by integrating multi-stage protection functions such as overvoltage, overcurrent, short circuit, leakage current, insulation abnormality, door interlock, and E-Stop, and can improve test reproducibility and problem analysis by automatically recording protection operations and switching events.

[0012] In addition, by providing test automation routines including line energization, operation verification, and log uploading, the invention provides a line simulator and a control method thereof that can perform complex test conditions, such as capacity change, SCR switching, and X / R ratio adjustment, in large quantities and repeatedly.

[0013] Furthermore, the above components are organically interconnected to integrate the entire process leading from grid impedance design → R·L step combination → PLC-MC switching → simulation verification → virtual impedance adjustment → protection and event management → remote test automation, thereby enabling interconnection testing of inverters and distributed power devices under conditions identical to the actual grid and providing a line simulation device and a control method thereof that innovatively improve the accuracy, reproducibility, and efficiency of the test. means of solving the problem

[0014] According to the concept of the present invention, an R·L step module composed of a plurality of R·L lines having different resistance (R) and inductance (L) values, wherein each line is designed in a fixed step form to form a target system impedance solely by selecting or combining series and parallel lines; an R·L step configuration unit configured to determine necessary R and L values ​​corresponding to the system rated capacity and target SCR conditions, and to distribute the determined values ​​into multiple R·L steps to implement all SCR 2, SCR 3, and SCR 5 conditions; a PLC-based MC control unit that controls a motor contactor (MC) corresponding to each R·L line to perform line switching or disconnection, and automatically selects a line based on a predefined switching combination table according to capacity and SCR conditions; a user interface unit that displays line-specific setting and operation information; and a control system that controls the switching of R·L lines based on BUS settings, SCR settings, a switching combination table, and virtual impedance settings transmitted from the user interface unit, and performs protection operations and interlock functions to detect abnormalities. The present invention provides a line simulation device and a control method thereof, characterized by including a virtual impedance injection unit that variably forms the X / R ratio and system strength by adjusting equivalent resistance components and inductive components without changing the physical R·L line. Effects of the invention

[0015] According to one aspect of the present invention, a passive line simulation structure combining multiple R·L step lines is configured to reproduce SCR 2, SCR 3, and SCR 5 conditions for various system capacities from 50 kVA to 250 kVA in a single device, so that the control stability, protection coordination, and PLL operation characteristics of the inverter and distributed power generation device can be verified under conditions identical to those of the actual system.

[0016] In addition, by dividing the inductance / resistance values ​​calculated based on the system short-circuit capacity and target SCR into multi-stage R·L steps and applying PLC-MC-based automatic switching control, various impedance combinations can be rapidly configured without physical wiring replacement, thereby significantly improving the efficiency of the test configuration and operational convenience.

[0017] In addition, by using PSCAD-based EMT simulation, it is possible to verify in advance whether the line current for each capacity / SCR combination exceeds the allowable limit, thereby preventing the risk of overcurrent during actual operation and ensuring the operational safety of the line simulation device.

[0018] In addition, it includes a control function that automatically applies BUS1 / BUS2 / BUS3-based multi-circuit bus configurations and circuit mapping rules, allowing for flexible setting of various grid branching scenarios and parallel operation conditions, and enables remote test automation through integration with EMS / SCADA / HILS systems.

[0019] In addition, by providing a virtual impedance function that allows for dynamic adjustment of the equivalent X / R ratio by injecting virtual resistance (Rvirt) and virtual inductance (Lvirt) into the power converter, weak grid conditions, dynamic characteristic change conditions, and grid strength switching scenarios can be precisely reproduced without the need for physical R·L line input.

[0020] In addition, since multi-stage protection logic including overvoltage, overcurrent, short circuit, insulation abnormality, leakage current, door interlock, E-Stop, etc. operates automatically, damage to the device / line / EUT can be prevented and safety can be ensured during testing.

[0021] In addition, since test procedures such as line energization, operation verification, log recording, and event analysis are automated, SCR change tests, capacity change tests, and protection response tests can be performed repeatedly and in large quantities, improving test reproducibility and operational efficiency.

[0022] In addition, since the physical R·L step-based line simulation function and the virtual impedance-based SCR simulation function can be integrated and operated, variations in the X / R ratio, damping ratio changes, and dynamic characteristic changes that may occur in actual power systems can be implemented economically and flexibly, and the reliability of controller verification and protection logic testing under various system conditions can be enhanced.

[0023] In addition, since the entire system performs impedance design, step combination, switching control, simulation verification, virtual SCR adjustment, protection, and event logging in conjunction, it provides a high-reliability line simulation environment capable of precisely evaluating the interconnection performance of inverters and distributed power devices at the real-system level.

[0024] However, the effects of the present invention are not limited to the above effects and may be extended in various ways within the scope and spirit of the present invention. Brief explanation of the drawing

[0025] FIG. 1 is a drawing showing a track simulation device according to one embodiment of the present invention. FIG. 2 is a diagram showing a circuit diagram of a line simulation device according to one embodiment of the present invention. FIG. 3 is a block diagram showing each component of a track simulation device according to one embodiment of the present invention. FIG. 4 is a drawing showing a line number selection and optimization table of a line simulation device according to one embodiment of the present invention. FIG. 5 is a diagram exemplarily showing the modeling and simulation results of a track simulation device according to one embodiment of the present invention. FIG. 6 is a diagram exemplarily showing the simulation results (250kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to one embodiment of the present invention. FIG. 7 is a diagram exemplarily showing the simulation results (200kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to one embodiment of the present invention. FIG. 8 is a diagram exemplarily showing the simulation results (150kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to one embodiment of the present invention. FIG. 9 is a diagram exemplarily showing the simulation results (100kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to one embodiment of the present invention. FIG. 10 is a diagram exemplarily showing the simulation results (50kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to one embodiment of the present invention. FIG. 11 is a drawing that exemplarily shows a user interface of a track simulation device according to one embodiment of the present invention. Specific details for implementing the invention

[0026] The embodiments described in this specification and the configurations illustrated in the drawings are merely preferred examples of the disclosed invention, and various modifications that may replace the embodiments and drawings of this specification may exist at the time of filing this application.

[0027] Additionally, the same reference numerals or symbols presented in each drawing of this specification represent parts or components that perform substantially the same function.

[0028] Furthermore, the terms used in this specification are for describing embodiments and are not intended to limit or / or restrict the disclosed invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0029] Additionally, terms including ordinal numbers, such as “first,” “second,” etc., as used herein may be used to describe various components, but said components are not limited by said terms, and said terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the 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.

[0030] In addition, terms such as "~part," "~unit," "~block," "~part," and "~module" may refer to a unit that processes at least one function or operation. For example, the above terms may refer to at least one piece of hardware such as an FPGA (field-programmable gate array) or an ASIC (application specific integrated circuit), at least one piece of software stored in memory, or at least one process processed by a processor.

[0031] FIG. 1 is a drawing showing a line simulation device according to an embodiment of the present invention, FIG. 2 is a drawing showing a circuit diagram of a line simulation device according to an embodiment of the present invention, FIG. 3 is a block diagram showing each component of a line simulation device according to an embodiment of the present invention, and FIG. 4 is a drawing showing a line number selection and optimization table of a line simulation device according to an embodiment of the present invention.

[0032] Referring to FIGS. 1, 2, 3 and 4, the present invention relates to a manual R·L-based line simulation device (100) capable of variably implementing a short circuit ratio (SCR) condition to verify the performance of a power grid-connected power converter in the same way as in a real environment. More specifically, the invention relates to a line simulation device (100) configured to demonstrate SCR 2, SCR 3, and SCR 5 conditions for various capacity ranges (50 kVA to 250 kVA) by combining an R·L step module composed of a plurality of lines.

[0033] The line simulation device (100) according to the present invention comprises an R·L step module (110), an R·L step component (120), a PLC-based MC control unit (130), a user interface unit (140), a control system (150), and a virtual impedance injection unit (160). The R·L step module (110) is composed of multiple R·L lines having different resistance values ​​(R) and inductance values ​​(L), and each line is designed in a fixed step form to form a target system impedance by selecting the line or combining series and parallel lines. The R·L step configuration unit (120) determines the necessary R and L values ​​corresponding to the system rated capacity and target SCR conditions, and distributes the determined values ​​into multiple R·L steps to enable the implementation of SCR 2, SCR 3, and SCR 5 conditions. The PLC-based MC control unit (130) controls the motor contactor (MC) corresponding to each R·L line to perform line switching or blocking, and automatically selects the line based on a predefined switching combination table according to the capacity and SCR conditions. The user interface unit (140) displays line-specific setting and operation information, and the control system (150) based on the BUS setting, SCR setting, switching combination table, and virtual impedance setting transmitted from the user interface unit. It controls the insertion of the R·L line and performs protection operations and interlock functions to detect abnormalities, and the virtual impedance injection unit (160) performs the role of variably forming the X / R ratio and system strength by adjusting the equivalent resistance component and inductive component without changing the physical R·L line.

[0034] The line simulation device (100) according to the present invention includes a plurality of R·L lines having different resistance values ​​(R) and inductance values ​​(L), and each line is designed in a fixed step form, so that the user can obtain a target system impedance by selecting a line or a parallel / series combination. It is possible to implement this. The step structure consisting of 9 lines is designed to have different impedance scales for each line, thereby enabling the target SCR conditions to be formed using the same device regardless of changes in the system rated capacity (50, 100, 150, 200, 250 kVA).

[0035] In the present invention, in order to satisfy a specific SCR value, first, the system short-circuit capacity Calculate according to the following mathematical formula 1.

[0036] Mathematical formula 1:

[0037]

[0038] If the target SCR (e.g., 2, 3, 5) is given through the above Equation 1, the system rated voltage (V) and the rated capacity of the equipment under test The inductance required in response to The value is inversely calculated, and design criteria for the circuit component are established based on the inductance value. In addition, to correct the attenuation and transient response characteristics of the system, a resistance value (R) corresponding to the inductance is additionally set, and these R and L values ​​are divided and distributed across multiple circuit steps. That is, for a target SCR value (e.g., 2, 3, or 5), the required inductance value using the above Equation 1 First, calculate the resistance value so that the system's damping ratio and transient response characteristics can be corrected for the above-calculated inductance. After setting it, determined in this way and The value is divided into multiple R·L steps to realize the final line impedance through each R·L step combination defined in the table.

[0039] The R·L steps calculated as above are hierarchically distributed across nine lines, and the operator can reproduce the conditions of SCR 2, SCR 3, and SCR 5 without replacing a separate module by selecting the connection and disconnection of the lines through PLC-based switching. Accordingly, the same line simulation device (100) can cover the entire rated range from 250 kVA to 50 kVA, and can verify the control response and protection logic of the inverter or distributed power device while changing the system strength during operation.

[0040] In addition, the line simulation device (100) according to the present invention can be utilized for voltage stability testing of an inverter, dynamic linkage testing of a distributed power source, control stability testing under weak grid conditions, and verification of protection operation based on a grid strength change scenario. In particular, by forming various grid impedances using only the step configuration of the R·L module, it has the advantage of being able to economically and repeatedly reproduce changes in the X / R ratio (ratio of inductive reactance (X) to resistive component (R), damping ratio, and dynamic characteristics that may occur in an actual grid.

[0041] FIG. 5 is a diagram exemplarily showing the modeling and simulation results of a line simulation device according to an embodiment of the present invention; FIG. 6 is a diagram exemplarily showing the simulation results (250kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to an embodiment of the present invention; FIG. 7 is a diagram exemplarily showing the simulation results (200kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to an embodiment of the present invention; FIG. 8 is a diagram exemplarily showing the simulation results (150kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to an embodiment of the present invention; FIG. 9 is a diagram exemplarily showing the simulation results (100kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to an embodiment of the present invention; and FIG. 10 is a diagram exemplarily showing the simulation results (50kVA, SCR 5 / SCR3 / SCR2) of a line simulation device according to an embodiment of the present invention.

[0042] Referring to FIGS. 4, 5, 6, 7, 8, 9, and 10, the simulation method of the line simulation device (100) according to the present invention is intended to verify whether there exists a case where the current flowing through each line exceeds the maximum current capacity of the line based on an MC switching table defined according to capacity and SCR combination (a switching combination table defined by pre-mapping the switching or disconnection state of a motor contactor (MC: Magnetic Contactor) that determines whether each line is connected for a plurality of R·L lines constituting the line simulation device according to rated capacity and short-circuit ratio (SCR) conditions). To this end, the present invention constructs a system model consisting of a transmission end, a line model, and a receiving end using PSCAD (PSC Aided Design, specialized simulation software for precisely analyzing electromagnetic transients (EMT) occurring in a power system in the time domain), and implements a voltage source similar to an actual three-phase system by applying a Three Phase Voltage Source Model to the transmission end and the receiving end.

[0043] More specifically, the rated capacity of the system is set to satisfy Equation 2.

[0044] Mathematical formula 2:

[0045]

[0046] Here, the Power Factor is fixed at 1, and the phase angle optimized to satisfy the above Equation 2 The target operating point is formed by applying it to the transmission end voltage source. Multimeters are installed on each line to measure the current flowing through each circuit, and the current distribution for each MC switching combination is verified by organizing and analyzing the measured current values. At this time, the rated capacity By setting the values ​​to 50, 100, 150, 200, and 250 kVA and the SCR values ​​to 2, 3, and 5, and performing simulations for a total of 15 combinations (cases), it is possible to systematically verify whether the line-specific current operates within the allowable current capacity under all capacity and SCR conditions.

[0047] Meanwhile, based on the MC input table defined according to the combination of rated capacity and short-circuit ratio (SCR), a simulation is performed to verify whether the current flowing through each R·L line constituting the line simulation device (100) exceeds the allowable current capacity of the corresponding line. This verification is intended to confirm whether the equivalent impedance formed by the switching combination for each line is within a safe operating range under each operating condition, and current values ​​are calculated for all combinations of rated capacity (50, 100, 150, 200, 250 kVA) and SCR (2, 3, 5).

[0048] Upon examining the simulation results, it was confirmed that for all 15 operating cases, the current flowing through each R·L line did not exceed the maximum allowable current of the corresponding line. Accordingly, the MC input table according to the present invention demonstrated that it is possible to configure a stable line simulation device (100) without the risk of overcurrent under all rated and SCR conditions. Consequently, it was confirmed that the line simulation device (100) of the present invention can be safely utilized for inverter and distributed power source connection tests, system strength change tests, and protection logic verification.

[0049] FIG. 11 is a drawing that exemplarily shows a user interface of a track simulation device according to one embodiment of the present invention.

[0050] Referring to FIG. 11, the user interface of a line simulation device (100) according to one embodiment of the present invention is configured to include a multi-line based bus selection function, a communication linkage function with an upper control system, a system summary information display function, and a line-by-line impedance information display function.

[0051] First, the user interface is configured to support a multi-line bus structure so that Bus 1, Bus 2, and Bus 3 can be activated simultaneously, while other lines are implemented to operate by selecting a single bus. Through this, the user can flexibly set various system branching configurations and parallel operation scenarios according to the test purpose.

[0052] In addition, the user interface provides communication linkage functions with PLC (Programmable Logic Controller), HILS (Hardware-In-the-Loop Simulation), EMS (Energy Management System), and SCADA (Supervisory Control And Data Acquisition) systems, thereby enabling remote execution of test operation scenarios, transmission of device control commands, and real-time status monitoring. The communication is performed using industrial standard protocols according to system requirements.

[0053] In addition, the user interface includes an area for displaying bus summary information, which displays information summarizing the operating status of the line simulator, such as the currently set SCR value, the total impedance value of the input R and L, and the number of active lines. Through this, the user can immediately verify whether the set conditions match the actual configured system model.

[0054] In addition, the user interface includes a circuit-specific information table and displays the resistance value (in R, Ω) and inductance value (in L, mH) corresponding to each circuit, as well as the ON / OFF status and other operating status of the circuit in real time, thereby allowing the step impedance setting and switching status of the circuit unit to be clearly checked.

[0055] Finally, the user interface includes an area displaying the Rvirt (Virtual Resistance) value, Lvirt (Virtual Inductance) value, and Enable status (virtual SCR mode active state) for the virtual SCR simulation function, allowing the user to intuitively verify whether virtual grid strength adjustment is being performed without the need for physical R·L line engagement. This virtual SCR simulation function enables hybrid SCR control combined with physical step configuration, thereby allowing for the efficient reproduction of a wider range of grid conditions.

[0056] In addition, the control system (150) of the line simulation device (100) according to one embodiment of the present invention includes a PLC-MC-based step control function, thereby controlling the ON / OFF status of each R·L line in real time and automatically setting the bus configuration structure of the line simulation device (100) by applying a bus mapping rule for each line (e.g., lines 1, 2, 8, and 9 can be selected from buses 1 / 2 / 3, and other lines are dedicated to a single bus). This step control performs a key function for forming various system impedance conditions without changing the physical wiring.

[0057] Furthermore, the present invention includes a virtual impedance injection function, which is implemented by setting and receiving Rvirt and Lvirt values ​​from a controller to adjust the equivalent X / R ratio. Through this, the user can virtually reproduce SCR conditions or system strength change conditions without the need for physical R·L line insertion, and a hybrid impedance simulation environment combined with a physical step configuration is provided.

[0058] In addition, the control system (150) according to the present invention includes protection and safety measures and performs E-Stop operation, interlock control between MCCB / MC, and automatic shutdown function based on detection of overcurrent / overtemperature / leakage current. The protection function is intended to prevent damage to the device in the event of an abnormal condition and to ensure safety during testing, and is configured to allow for a reset after the protection operation based on user approval or satisfaction of system conditions.

[0059] Finally, the present invention includes an event recording function that automatically records logs containing timestamps and user information for events such as line trips, protection operations, setting changes, and user operations, and enables rollback to a previous normal state or restoration to a user-specified preset configuration when necessary. This recording function provides foundational information for ensuring test reproducibility and analyzing the root cause of problems.

[0060] In addition, the control system (150) of the line simulation device (100) according to one embodiment of the present invention is configured to include a PLC-based MC switching control function, an automatic line connection function based on capacity and SCR conditions, a protection function, and an operational safety function.

[0061] First, the control system (150) includes a PLC control unit, and the PLC control unit is configured to generate an MC control signal to selectively connect or disconnect each R / L step line. In addition, the PLC controls the selection of at least one of bus 1, bus 2, and bus 3 according to a bus selection rule per line, and incorporates protection logic and interlock functions for each bus and line to prevent abnormal line combinations or duplicate connections.

[0062] In addition, the present invention includes a PLC-based automatic MC control function, wherein the function is implemented so that the PLC automatically switches on or off the MC of each line by referring to a predefined capacity / SCR-based MC switching table in response to BUS settings and SCR conditions selected in the line simulation device UI. Accordingly, the user can immediately configure various line impedance conditions without changing physical wiring or manually operating switches.

[0063] Meanwhile, the control system (150) includes a protection function and is linked with sensors and relays that detect abnormal conditions such as overvoltage, overcurrent, short circuit, and leakage current, and immediately disconnects the corresponding line through a circuit breaker and an interlock mechanism. It also includes an insulation protection function that detects whether there is an abnormality in the insulation state and automatically protects the system.

[0064] In addition, the present invention includes an operational safety function. When an emergency stop (E-Stop) switch is operated, the device door is opened, or a communication error or system abnormality is detected, the PLC immediately switches to a fail-safe mode to cut off the connection of the entire line or a specific line, and restricts reconnection until operating conditions are restored to normal. This safety function is intended to prevent device damage caused by malfunction or unexpected system fluctuations during testing.

[0065] In addition, a line simulation device (100) according to one embodiment of the present invention includes a virtual impedance injection function, and the function is configured to variably adjust the X / R ratio of the equivalent impedance using Rvirt values ​​(in Ω units) and Lvirt values ​​(in mH units) set through a user interface (UI). Through this, the user can reproduce various system strength conditions and dynamic characteristics without changing the physical R·L lines.

[0066] The virtual impedance injection function of the present invention is implemented to change the Rvirt and Lvirt values ​​in real time, and said changes are reflected in the current control loop of the power converter to immediately modify the resistive and inductive components of the equivalent impedance. Accordingly, the X / R ratio is dynamically adjusted, and when the X / R ratio changes, the equivalent impedance of the line simulator changes, which has a direct effect on the SCR value.

[0067] In addition, the virtual SCR control function of the present invention includes a protection function to prepare for abnormal conditions such as overvoltage, overcurrent, short circuit, and leakage current, and is configured to immediately cut off the virtual impedance injection function and related circuits when abnormal conditions occur by linking with a protection relay, a circuit breaker, and an interlock mechanism. Furthermore, it includes an insulation protection function that detects abnormalities in the insulation state and a fail-safe cutoff function, thereby ensuring the safe operation of the system.

[0068] Through the virtual SCR adjustment function of the present invention, the user can precisely verify the performance of the Equipment Under Test (EUT), such as control algorithms, PLL stability, weak system responsiveness, and protection response, under various system conditions with X / R ratio adjustment applied. This provides the effect of reproducing various operating situations that may occur in an actual system environment in a laboratory setting.

[0069] Meanwhile, a line simulation device (100) according to one embodiment of the present invention is configured to automatically set and control the operating conditions of the line simulation device (100) from a remote location through linkage with a customer's Energy Management System (EMS). Specifically, the EMS remotely transmits control commands including BUS selection, SCR setting, MC input table selection, and virtual impedance (Rvirt, Lvirt) adjustment commands, and the PLC automatically performs MC switching control and virtual impedance injection control according to the commands. Through this, the user can dynamically configure various system conditions from a remote location without physical operation.

[0070] Communication between the EMS and the line simulation device (100) is performed using an industrial communication protocol based on Modbus TCP / IP, which ensures high reliability, low latency, and stable data exchange in an industrial environment. The EMS transmits control commands to the line simulation device UI and PLC through the above protocol, and conversely, the line simulation device (100) transmits current operating status, system impedance, protection operation, and log information to the EMS, enabling real-time monitoring in the upper control system.

[0071] In addition, a line simulation device (100) according to one embodiment of the present invention includes a test automation function, and the EMS is configured to automatically execute a test scenario through communication linkage with the UI of the line simulation device (100). Accordingly, the UI transmits a line control command based on the scenario and MC input table transmitted from the EMS to the PLC, and the PLC automatically performs pre-check, line input, operation verification, and test log upload. Through this automation procedure, complex SCR change tests, EUT reaction tests, and system strength change scenarios can be performed repeatedly and in large quantities, and the reproducibility and efficiency of the test are greatly improved.

[0072] Specific embodiments have been illustrated and described above. However, the invention is not limited to the embodiments described above, and those skilled in the art may make various modifications without departing from the essence of the technical concept of the invention as described in the following claims. Explanation of the symbols

[0073] 100: Track Simulator 110: R·L Step Module 120: R·L Step Configuration Unit 130: PLC-based MC Control Unit 140: User Interface Section 150: Control System 160: Virtual Impedance Injection Section

Claims

Claim 1 An R·L step module composed of multiple R·L lines having different resistance (R) and inductance (L) values, wherein each line is designed in a fixed step form to form a target system impedance solely through line selection or series-parallel combination; an R·L step configuration unit configured to determine necessary R and L values ​​corresponding to the system rated capacity and target SCR conditions, and to distribute the determined values ​​into multiple R·L steps to implement SCR 2, SCR 3, and SCR 5 conditions; a PLC-based MC control unit that controls a motor contactor (MC) corresponding to each R·L line to perform line switching or disconnection, and automatically combines multiple R·L lines based on a predefined switching combination table according to capacity and SCR conditions; a user interface unit that displays line-specific setting and operation information; and a control system that controls the switching of R·L lines based on BUS settings, SCR settings, a switching combination table, and virtual impedance settings transmitted from the user interface unit, and performs protection operations and interlock functions to detect abnormalities. A line simulation device characterized by including a virtual impedance injection unit that dynamically varies the X / R ratio and system strength of a system by adjusting equivalent resistance components and inductive components by injecting virtual resistance (Rvirt) and virtual inductance (Lvirt) into a power converter without changing the physical R·L lines. Claim 2 A line simulation device according to claim 1, characterized in that the R·L step component is configured to calculate the system short-circuit capacity when a target SCR value is input, and to determine the necessary inductance and resistance values ​​by inversely calculating the target system impedance based thereon. Claim 3 A line simulation device according to claim 2, characterized in that the R·L step component is configured to hierarchically distribute the determined inductance and resistance values ​​to nine or more R·L step lines to reproduce target SCR conditions through a single line or a series and parallel combination of multiple lines. Claim 4 A line simulation device according to claim 2, characterized in that the R·L step component is configured to pre-define an R·L step combination table to satisfy all conditions of SCR 2, SCR 3, and SCR 5 for each of the rated capacities of 50 kVA, 100 kVA, 150 kVA, 200 kVA, and 250 kVA. Claim 5 A line simulation device according to claim 1, characterized in that the control system is configured to selectively activate at least one of BUS 1, BUS 2, and BUS 3, and is configured to automatically map a plurality of lines to a selected bus. Claim 6 A line simulation device according to claim 5, characterized in that the PLC-based MC control unit is configured to automatically switch on or off the motor contactor of each line by referring to a predefined switching combination table according to BUS settings and SCR settings transmitted from a user interface unit or a higher-level control system. Claim 7 A line simulation device according to claim 6, characterized in that the control system is configured to automatically disconnect the entire line or the relevant line by switching it to Fail-safe mode when an overvoltage, overcurrent, short circuit, leakage current, insulation abnormality, door opening, or emergency stop (E-Stop) signal is detected, and to record the protection operation history along with a timestamp. Claim 8 An R·L step module composed of multiple R·L lines having different resistance (R) and inductance (L) values, wherein each line is designed in a fixed step form to form a target system impedance solely through line selection or series-parallel combination; an R·L step configuration unit configured to determine necessary R and L values ​​corresponding to the system rated capacity and target SCR conditions, and to distribute the determined values ​​into multiple R·L steps to implement SCR 2, SCR 3, and SCR 5 conditions; a PLC-based MC control unit that controls a motor contactor (MC) corresponding to each R·L line to perform line switching or disconnection, and automatically combines multiple R·L lines based on a predefined switching combination table according to capacity and SCR conditions; a user interface unit that displays line-specific setting and operation information; and a control system that controls the switching of R·L lines based on BUS settings, SCR settings, a switching combination table, and virtual impedance settings transmitted from the user interface unit, and performs protection operations and interlock functions to detect abnormalities. A system comprising a line simulation device characterized by including a virtual impedance injection unit that dynamically varies the X / R ratio and system strength of a system by adjusting equivalent resistive and inductive components by injecting virtual resistance (Rvirt) and virtual inductance (Lvirt) into a power converter without changing the physical R·L lines. Claim 9 A system including a line simulation device according to claim 8, wherein the R·L step component is configured to calculate the system short-circuit capacity when a target SCR value is input, and to determine the necessary inductance and resistance values ​​by inversely calculating the target system impedance based thereon. Claim 10 A system including a line simulation device according to claim 9, wherein the R·L step component is configured to hierarchically distribute the determined inductance and resistance values ​​to nine or more R·L step lines to reproduce target SCR conditions through a single line or a series and parallel combination of multiple lines. Claim 11 A system including a line simulation device according to claim 9, characterized in that the R·L step component is configured to pre-define an R·L step combination table to satisfy all conditions of SCR 2, SCR 3, and SCR 5 for each of the rated capacities of 50 kVA, 100 kVA, 150 kVA, 200 kVA, and 250 kVA. Claim 12 A system comprising a line simulation device according to claim 8, wherein the control system is configured to selectively activate at least one of BUS 1, BUS 2, and BUS 3, and is configured to automatically map a plurality of lines to a selected bus. Claim 13 A system including a line simulation device, characterized in that, in claim 12, the PLC-based MC control unit is configured to automatically switch on or off the motor contactor of each line by referring to a predefined switching combination table according to BUS settings and SCR settings transmitted from a user interface unit or a higher-level control system. Claim 14 A system including a line simulation device according to claim 13, characterized in that the control system is configured to automatically disconnect the entire line or the relevant line by switching it to Fail-safe mode when an overvoltage, overcurrent, short circuit, leakage current, insulation abnormality, door open, or emergency stop (E-Stop) signal is detected, and to record the protection operation history along with a timestamp. Claim 15 A method for controlling a line simulation device, characterized by comprising: receiving a system rated capacity and target SCR conditions; determining a resistance value and an inductance value necessary to form a target system impedance corresponding to the target SCR conditions; selecting a plurality of R·L lines or combining them in series or in parallel based on the determined resistance value and inductance value; controlling a motor contactor (MC) corresponding to each R·L line to perform switching on or off of the line, and automatically combining a plurality of R·L lines based on a predefined switching combination table according to the system capacity and target SCR conditions; displaying line-specific setting and operation information through a user interface; dynamically varying the system X / R ratio and system strength by adjusting equivalent resistive and inductive components by injecting a virtual resistance (Rvirt) and a virtual inductance (Lvirt) into a power converter without changing the physical R·L lines; and detecting an abnormal state and performing protection operations and interlock functions. Claim 16 A line simulation device control method according to claim 15, wherein the step of determining the required resistance and inductance values ​​includes the step of calculating the system short-circuit capacity when a target SCR value is input, and determining the required inductance and resistance values ​​by inversely calculating the target system impedance based on the calculated short-circuit capacity. Claim 17 A line simulation device control method according to claim 16, characterized by including the step of hierarchically distributing the determined inductance and resistance values ​​to nine or more R·L step lines and reproducing target SCR conditions through a single line or a series and parallel combination of multiple lines. Claim 18 A line simulation device control method according to claim 16, characterized by including the step of pre-defining an R·L step combination table to satisfy SCR 2, SCR 3, and SCR 5 conditions for each of the rated capacities of 50 kVA, 100 kVA, 150 kVA, 200 kVA, and 250 kVA, and automatically selecting a line based on the combination table. Claim 19 A method for controlling a line simulation device according to claim 15, characterized by including the step of selectively activating at least one of BUS 1, BUS 2, and BUS 3, and automatically mapping a plurality of R·L lines to the selected bus. Claim 20 A line simulation device control method according to claim 19, characterized by including the step of automatically closing or closing the motor contactor of each line by referring to a predefined switching combination table according to BUS settings and SCR settings transmitted from a user interface unit or an upper control system. Claim 21 A method for controlling a line simulation device according to claim 20, characterized by including the step of automatically disconnecting the entire line or the relevant line by switching it to Fail-safe mode when an overvoltage, overcurrent, short circuit, leakage current, insulation abnormality, door opening, or emergency stop (E-Stop) signal is detected, and recording the protection operation history along with a timestamp.

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