Apparatus and method for verifying heterogeneous inverter on basis of virtual renewable energy grid simulation

Abstract

The present invention relates to an apparatus and a method for verifying performance and interoperability of heterogeneous inverters on the basis of virtual renewable energy power grid simulation, wherein the apparatus may comprise: a real-time simulator which generates a plurality of virtual renewable energy grids; and a power amplifier which generates virtual renewable energy power corresponding to one of the grids and provides the virtual renewable energy power to an inverter to be verified. Through this, interoperability and system stability of grid-forming inverters are effectively verified under various renewable energy sources and system conditions by using real-time simulation technology such as PHILS simulation, thus making it possible to contribute to stable power system operation.

Description

Device and method for verifying heterogeneous inverters based on virtual renewable energy power grid simulation

[0001] The present invention relates to a simulation-based heterogeneous inverter verification apparatus and method, and more specifically, to an apparatus and method for verifying the performance and interoperability of heterogeneous inverters based on a virtual renewable energy power grid simulation.

[0002] Power systems are rapidly shifting away from conventional fossil fuel-based generation methods and centering on renewable energy sources. Renewable energy sources such as solar, wind, and energy storage devices are garnering attention as eco-friendly and sustainable sources, and their adoption rates are surging globally. These renewable energy sources must be reliably integrated into the power grid, and grid-forming inverters play an essential role in this process. Grid-forming inverters can independently control the grid's voltage and frequency, enabling stable power supply even amidst the intermittent output characteristics of renewable energy sources. As the proportion of renewable energy increases, the importance of grid-forming inverters is growing, making the development of high-performance grid-forming inverter technology essential for the stable operation of power systems.

[0003] However, when heterogeneous grid-forming inverters produced by various manufacturers are connected to the power grid, interoperability issues emerge as a critical factor threatening the stability of the power system. Since each manufacturer uses different control algorithms, communication protocols, and hardware specifications, unexpected interactions and collisions can occur when heterogeneous inverters are connected together. These problems lead to grid instability and, in severe cases, can result in large-scale power outages. In particular, large-scale renewable energy complexes with multiple connected inverters face a higher likelihood of low-frequency oscillation problems, such as Sub-Synchronous Oscillation (SSO), which can have a serious impact on grid stability. SSO is a resonance phenomenon caused by the interaction between the inverter and the grid; it is a dangerous phenomenon that can impair the dynamic stability of the grid and cause equipment damage.

[0004] Existing inverter verification methods primarily focus on testing the performance of a single inverter. Consequently, it is difficult to adequately verify interoperability issues between heterogeneous inverters or grid stability problems, such as SSO, that may occur in actual grid environments. Furthermore, existing testing methods face limitations in accurately evaluating the actual performance of inverters because they struggle to simulate dynamic interactions similar to those in a real grid. To overcome these limitations, it is necessary to establish simulation-based verification systems and methods that mimic real grid environments, as well as a comprehensive testing environment that considers various renewable energy sources and grid conditions.

[0005] The present invention provides a simulation-based verification system and method that simulates an actual grid environment, and aims to establish a comprehensive test environment that considers various renewable energy sources and grid conditions.

[0006] According to one embodiment of the present invention, an inverter verification device is disclosed comprising: a real-time simulator for generating a plurality of virtual renewable energy networks; and a power amplifier for generating a first virtual renewable energy power corresponding to a first virtual renewable energy network among the plurality of virtual renewable energy networks and providing it to an inverter to be verified.

[0007] According to an embodiment, the real-time simulator may further generate a virtual power system, and the power amplifier may generate virtual system power corresponding to the virtual power system and provide it to the output terminal of the inverter to be verified.

[0008] According to an embodiment, the power amplifier can generate the first virtual renewable energy power and provide it to the input terminal of the inverter to be verified.

[0009] According to an embodiment, the real-time simulator may generate a plurality of virtual inverters corresponding to virtual renewable energy networks other than the first virtual renewable energy network, and the inverter to be verified and the plurality of virtual inverters may be configured to interact in conjunction with each other in the virtual power grid.

[0010] According to an embodiment, the inverter to be verified may be a grid forming inverter of a different type from the virtual inverter.

[0011] According to an embodiment, a line impedance simulation device may be formed between the power amplifier and the inverter to be verified.

[0012] According to an embodiment, a monitoring device may be further included to determine the operating status of the inverter to be verified by analyzing operation information received from the inverter to be verified.

[0013] According to an embodiment, the monitoring device feeds back the operation information to the real-time simulator, and the real-time simulator can control the output of the power amplifier based on the feedback information.

[0014] According to the present invention, the interoperability and grid stability of heterogeneous grid-forming inverters can be effectively verified under various renewable energy sources and grid conditions through real-time simulations such as PHILS simulations, thereby contributing to the stable operation of the power system.

[0015] A brief description of each drawing is provided to help to better understand the drawings cited in the detailed description of the invention.

[0016] FIG. 1 is a block diagram of a heterogeneous inverter verification system according to one embodiment of the present invention.

[0017] FIG. 2 is a block diagram illustrating a case where an actual power grid is connected to a heterogeneous inverter verification system according to one embodiment of the present invention.

[0018] FIG. 3 is a block diagram illustrating a case where a plurality of inverters to be verified are connected to a heterogeneous inverter verification system according to one embodiment of the present invention.

[0019] FIG. 4 is a table illustrating heterogeneous inverter verification items according to one embodiment of the present invention.

[0020] FIG. 5 is a flowchart illustrating a heterogeneous inverter verification method according to another embodiment of the present invention.

[0021] The technical concept of the present disclosure is subject to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the technical concept of the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the scope of the technical concept of the present disclosure.

[0022] In describing the technical concept of the present disclosure, detailed descriptions of related prior art are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the technical concept of the present disclosure. Furthermore, numbers used in the description of the present invention (e.g., First, Second, etc.) are merely identification symbols to distinguish one component from another.

[0023] In addition, when a component is described in this document as being "connected" or "joined" with another component, it should be understood that the component may be directly connected or joined to the other component, but unless otherwise specifically stated, it may also be connected or joined through another component in between.

[0024] Additionally, terms such as “~part,” “~device,” and “~part” described herein refer to a unit that processes at least one function or operation, and this may be implemented as hardware such as a processor, microprocessor, microcontroller, CPU (Central Processing Unit), GPU (Graphics Processing Unit), APU (Accelerate Processor Unit), DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), software, or a combination of hardware and software.

[0025] Furthermore, it is intended to clarify that the classification of the components in this document is merely based on the primary function each component is responsible for. That is, two or more components described below may be combined into a single component, or a single component may be divided into two or more components based on more subdivided functions. Additionally, each component described below may additionally perform some or all of the functions of other components in addition to its own primary function, and it goes without saying that some of the primary functions of each component may be exclusively performed by other components.

[0026] Hereinafter, various embodiments according to the technical concept of the present disclosure will be described in detail in turn.

[0027]

[0028] FIG. 1 is a block diagram of a heterogeneous inverter verification system according to one embodiment of the present invention.

[0029] A heterogeneous inverter verification system (100) according to one embodiment of the present invention may include a real-time simulator (110), a power amplifier (120), an inverter to be verified (130), and a monitoring device (140). The function and operation of each component will be described in detail.

[0030] The real-time simulator (110) is a component that simulates a virtual power grid and renewable energy sources. For example, the real-time simulator (110) can implement a virtual environment that simulates the characteristics of various renewable energy sources (solar, wind, energy storage devices, etc.) and create multiple virtual inverter models to generate conditions similar to the actual grid. Additionally, the real-time simulator (110) can simulate various grid conditions by adjusting parameters such as grid voltage, frequency, and impedance according to test scenarios. The real-time simulator (110) can perform a key role in PHILS simulation by exchanging data with the power amplifier (120) and the monitoring device (140).

[0031] For reference, Power Hardware-In-the-Loop Simulation (PHILS) is an extended concept of the existing Hardware-In-the-Loop Simulation (HILS), referring to a system capable of power exchange between actual hardware and a simulation environment. Since it transmits and receives high-voltage and high-current signals through power amplifiers and allows for real-time verification of interactions with the Device Under Test (DUT), it is utilized in various fields such as smart grids, microgrids, electric vehicles, and aerospace, contributing to improved system stability, efficiency, and safety.

[0032] The power amplifier (120) amplifies voltage and current data generated in the real-time simulator (110) into actual power signals and supplies them to the inverter under verification (130). Through this, the inverter under verification (130) can recognize and operate the power generated in the virtual environment as if it were actual power. The power amplifier (120) can be classified into a renewable energy simulation and a grid simulation, and can generate power that simulates the characteristics of a virtual renewable energy source and a virtual power grid, respectively, and supply it to the inverter under verification (130).

[0033] The inverter to be verified (130) is an actual inverter whose performance and interoperability are to be verified through a heterogeneous inverter verification system (100) according to one embodiment of the present invention. It operates by receiving power supplied from a power amplifier (120), and its output data can be measured in real time through a monitoring device (140). In the heterogeneous inverter verification system (100), various types of grid-forming inverters can be used as the inverter to be verified (130).

[0034] The monitoring device (140) may be a device that measures and analyzes output data (voltage, current, frequency, etc.) of the inverter (130) under verification in real time. The measured data may be fed back to the real-time simulator (110) to update the virtual environment, thereby enabling the implementation of a closed-loop test environment. Additionally, the results analyzed by the monitoring device (140) may be used to evaluate the performance, stability, and interoperability of the inverter (130) under verification.

[0035] The components illustrated in FIG. 1 can be organically connected to each other to form a PHILS simulation-based heterogeneous inverter verification system (100). A real-time simulator (110) creates a virtual environment, a power amplifier (120) converts the power of the virtual environment into actual power, an inverter to be verified (130) operates using actual power, and a monitoring device (140) measures the output data of the inverter and feeds it back to the real-time simulator (110). Through this closed-loop test environment, the interoperability and grid stability of heterogeneous inverters can be effectively verified under various renewable energy sources and grid conditions.

[0036] Hereinafter, an embodiment of the present invention will be described in detail assuming that the inverter (130) to be verified is a single unit.

[0037]

[0038] FIG. 2 is a block diagram illustrating a case where an actual power grid is connected to a heterogeneous inverter verification system according to one embodiment of the present invention.

[0039] A heterogeneous inverter verification system (200) according to one embodiment of the present invention may be designed to evaluate the performance of an inverter (130) to be verified through interaction with an actual power system (220). The main components may include a real-time simulator (110), power amplifiers (first power amplifier (120-1), second power amplifier (120-2)), a grid-forming inverter (130) to be verified, a monitoring device (140), a line impedance simulation device (210), and an actual power system (220). These components may be organically interconnected to implement a closed-loop test environment based on Power Hardware-in-the-Loop Simulation (PHILS). That is, the real-time simulator (110) constitutes the simulation environment (230), and the remaining components are composed of actual hardware (240) to implement a closed-loop test environment based on PHILS.

[0040] The real-time simulator (110) is the core of the system (200) and can perform the role of simulating a virtual power grid and a renewable energy environment. The real-time simulator (110) can generate a plurality of virtual renewable energy networks, including a first virtual renewable energy network and a second virtual renewable energy network. Each virtual renewable energy network can simulate the characteristics of various renewable energy sources, such as solar power, wind power, and energy storage devices, and can simulate various phenomena that may occur in actual renewable energy sources, such as output fluctuations and harmonic generation.

[0041] The first virtual renewable energy network can be connected to the inverter (130) under verification, and the second virtual renewable energy network can be connected to a virtual inverter generated within the real-time simulator (110). The virtual inverter is an inverter model implemented in software, which can increase the flexibility of the test by simulating the characteristics of various types of grid-forming inverters. On the other hand, the inverter (130) under verification is an actual hardware inverter, and its performance and interoperability can be evaluated through the verification system of the present invention.

[0042] The output of the first virtual renewable energy network can be transmitted to the first power amplifier (120-1). The first power amplifier (120-1) can generate a real power signal corresponding to the output value of the real-time simulator (110) using power supplied from the real power grid (220). The real power thus generated is supplied as an input to the inverter under verification (130), thereby creating an environment in which the inverter under verification (130) interacts with the virtual renewable energy source. That is, the inverter under verification (130) can perceive itself as operating in a virtual environment created by the real-time simulator (110).

[0043] The output of the second virtual renewable energy network can be transmitted to the second power amplifier (120-2). The second power amplifier (120-2) can generate power according to the output value of the virtual inverter and can be connected to the inverter under verification (130) through the line impedance simulation device (210). Through this configuration, the interaction between the virtual inverter and the inverter under verification (130) can be simulated, and the operating characteristics of the system can be analyzed under various scenarios.

[0044] The line impedance simulation device (210) is positioned between the second power amplifier (120-2) and the inverter under verification (130) to simulate the line impedance of an actual power system. Since line impedance is an important factor affecting power loss, voltage drop, and system stability, accurately simulating it is essential for establishing a realistic test environment. The line impedance simulation device (210) of the present invention can set various impedance values, thereby enabling the evaluation of the performance of the inverter under verification (130) under various system conditions.

[0045] The monitoring device (140) can measure output data (voltage, current, frequency, phase, etc.) of the inverter (130) under verification in real time and feed it back to the real-time simulator (110). The real-time simulator (110) can update the virtual environment based on the feedback data and control the outputs of the first power amplifier (120-1) and the second power amplifier (120-2) to implement a closed-loop test environment. This allows the inverter (130) under verification to experience dynamic interactions similar to when it is connected to an actual grid, thereby enabling more accurate performance verification.

[0046] Meanwhile, in FIG. 2, the dotted arrow may represent a data line, and the solid arrow may represent a power line. A heterogeneous inverter verification system (200) according to one embodiment of the present invention can provide an environment in which the interoperability and grid stability of heterogeneous grid-forming inverters can be effectively verified under various renewable energy sources and grid conditions through such a configuration.

[0047]

[0048] FIG. 3 is a block diagram illustrating a case where a plurality of inverters to be verified are connected to a heterogeneous inverter verification system according to one embodiment of the present invention.

[0049] A heterogeneous inverter verification system (300) according to one embodiment of the present invention may be designed to simultaneously test two inverters to be verified and to evaluate interoperability between the inverters. The main components may include a real-time simulator (110), a second power amplifier (120-2), a first line impedance simulation device (210-1), a second line impedance simulation device (210-2), a first grid-forming inverter to be verified (130-1), a second grid-forming inverter to be verified (130-2), a first-1 power amplifier (120-1-1), a first-2 power amplifier (120-1-2), and a real power system (220).

[0050] The real-time simulator (110) can generate two virtual renewable energy networks, a first virtual renewable energy network and a second virtual renewable energy network. The output of each virtual renewable energy network can be transmitted to the first-1 power amplifier (120-1-1) and the first-2 power amplifier (120-1-2), respectively. That is, the output of the first virtual renewable energy network can be transmitted to the first-1 power amplifier (120-1-1), and the output of the second virtual renewable energy network can be transmitted to the first-2 power amplifier (120-1-2).

[0051] Additionally, the first-1 power amplifier (120-1-1) can use power from the actual power grid (220) to generate power corresponding to the output of the first virtual renewable energy network and output it to the first inverter to be verified (130-1). Through this configuration, the first inverter to be verified (130-1) can receive the effect of being actually connected to the first virtual renewable energy network. Likewise, the first-2 power amplifier (120-1-2) can use power from the actual power grid (220) to generate power corresponding to the output of the second virtual renewable energy network and output it to the second inverter to be verified (130-2). Through this configuration, the second inverter to be verified (130-2) can receive the effect of being actually connected to the second virtual renewable energy network.

[0052] The two inverters to be verified (130-1, 130-2) are actual hardware inverters, and their outputs can be connected to the second power amplifier (120-2), and changes in output values ​​can affect the output of the second power amplifier (120-2).

[0053] The first line impedance simulation device (210-1) is positioned between the second power amplifier (120-2) and the first inverter to be verified (130-1), so as to provide the effect that the first inverter to be verified (130-1) is actually connected to the actual power grid (220). Similarly, the second line impedance simulation device (210-2) is positioned between the second power amplifier (120-2) and the second inverter to be verified (130-2), so as to provide the effect that the second inverter to be verified (130-2) is actually connected to the actual power grid (220).

[0054] Through this configuration, the heterogeneous inverter verification system (300) of the present invention can simultaneously test a plurality of inverters to be verified and evaluate interoperability between the inverters. Each inverter to be verified can be connected to an independent virtual renewable energy network and can be configured to operate in an environment similar to the actual power grid (220) at the same time. Through this, interoperability for various combinations of heterogeneous inverters can be effectively verified.

[0055]

[0056] FIG. 4 is a table illustrating heterogeneous inverter verification items according to one embodiment of the present invention.

[0057] Referring to Figure 4, various test items and specific details for each item are presented to comprehensively evaluate the performance, stability, and interoperability of grid-forming inverters upon grid connection. Each test item can be performed through Power Hardware-in-the-Loop Simulation (PHILS) that simulates an actual grid environment, enabling not only single inverter testing but also testing in complex grid environments where multiple heterogeneous inverters are connected.

[0058] Each test item exemplified in Fig. 4 will be explained in detail below.

[0059]

[0060] System voltage phase sudden change:

[0061] This test is intended to verify whether the inverter operates stably in situations where the phase of the grid voltage fluctuates rapidly. The phase of the grid voltage may change suddenly due to grid faults, circuit breaker malfunctions, large-scale load drops, etc., and in such situations, the inverter (130) under verification must maintain synchronization with the grid and continue to supply stable power. This test can be designed to analyze the operating characteristics of the inverter (130) under verification and evaluate the impact on grid stability by setting various conditions such as the magnitude of the sudden phase change, the rate of change, and the duration.

[0062] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0063] The real-time simulator (110) can simulate a situation of sudden phase change in the grid voltage and transmit it to the power amplifier (120). The power amplifier (120) can amplify the sudden phase change signal generated by the real-time simulator (110) into an actual power signal and supply it to the inverter under verification (130). The inverter under verification (130) can transmit output data to the monitoring device (140) to verify the maintenance of output stability, grid synchronization, and normal operation of protection functions during the sudden phase change situation. The monitoring device (140) can measure and analyze the output data (voltage, current, frequency, phase, etc.) of the inverter under verification (130) and feed it back to the real-time simulator (110).

[0064]

[0065] Sudden change in system voltage:

[0066] The system voltage sudden change test is a test to evaluate the performance of an inverter in a situation where the magnitude of the system voltage changes suddenly. Voltage sudden changes can occur due to various causes such as system faults, load fluctuations, or changes in generator output, and the inverter (130) under verification must operate stably in response to such voltage fluctuations and maintain system stability. In this test, the magnitude of the voltage fluctuation, the rate of change, and the duration can be set in various ways to measure changes in the output voltage, current, frequency, etc. of the inverter (130) under verification, and to verify whether problems such as overvoltage, undervoltage, or harmonic generation occur.

[0067] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0068] The real-time simulator (110) can simulate a sudden change in grid voltage (overvoltage, undervoltage, etc.) and transmit it to the power amplifier (120). The power amplifier (120) can amplify the sudden change in voltage signal and supply it to the inverter under verification (130). The inverter under verification (130) can transmit output data to the monitoring device (140) to verify output voltage and current control performance, whether protection functions are activated, and whether stable operation is maintained in the event of a sudden change in voltage. The monitoring device (140) can measure and analyze the output data of the inverter under verification (130) and information regarding grid voltage and current, and feed back to the real-time simulator (110).

[0069]

[0070] Frequency-Active Power Control:

[0071] This test evaluates the active power control performance of the inverter (130) under verification regarding grid frequency fluctuations that occur when the power balance between the generator and the load is disrupted. Grid frequency is an indicator representing the balance between power demand and supply, and frequency fluctuations have a direct impact on grid stability. In this test, grid frequency fluctuations are generated by simulating various situations such as load fluctuations and generator failures, and the ability of the inverter (130) under verification to stabilize the grid frequency by adjusting the active power output according to the frequency fluctuations can be verified. The magnitude of the frequency fluctuation, the rate of change, and the response speed and accuracy of the inverter (130) under verification can be used as evaluation criteria.

[0072] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0073] A real-time simulator (110) can simulate frequency fluctuations resulting from changes in the power grid state between generator loads. A power amplifier (120) can supply a power signal reflecting the frequency fluctuations generated by the real-time simulator (110) to a verification target inverter (130). The verification target inverter (130) can transmit output data to a monitoring device (140) to verify the ability to regulate active power output according to frequency fluctuations and whether it contributes to grid frequency stabilization. The monitoring device (140) can measure and analyze the change in active power between the grid frequency and the output of the verification target inverter (130).

[0074]

[0075] Voltage-Reactive Power Control:

[0076] The voltage-reactive power control test evaluates the reactive power control performance of the inverter (130) under verification against grid voltage fluctuations. Reactive power plays an important role in maintaining voltage stability in the power grid, and the inverter (130) under verification must maintain voltage stability by adjusting the reactive power output according to grid voltage fluctuations. In this test, various grid voltage fluctuation situations are simulated, and the ability of the inverter (130) under verification to appropriately supply reactive power to mitigate voltage fluctuations and maintain a stable voltage is verified. The magnitude of the voltage fluctuation, the rate of change, and the response speed and accuracy of the inverter can be used as evaluation criteria, and the performance of the inverter (130) under verification can be accurately evaluated by simulating various control methods, such as changing the voltage stabilization target value or limiting the response time.

[0077] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0078] The real-time simulator (110) can simulate voltage fluctuation conditions resulting from changes in reactive power supply and control capacity. The power amplifier (120) can supply a power signal reflecting the voltage fluctuation conditions to the inverter (130) under verification.

[0079] The inverter (130) under verification can transmit output data to a monitoring device (140) to verify the reactive power control performance according to voltage fluctuations, the voltage stabilization effect, and the performance regarding various control methods (change in voltage stabilization target value, response time limit, etc.). The monitoring device (140) can measure grid voltage fluctuations and changes in reactive power of the output of the inverter (130) under verification.

[0080]

[0081] Voltage Ride-through Function:

[0082] The voltage ride-through function test is a test to verify the ability of the inverter (130) under verification to maintain operation without being disconnected from the grid in situations where the grid voltage temporarily fluctuates to an abnormal value. The grid voltage may fluctuate significantly instantaneously due to grid faults or sudden load changes, and in such situations, the inverter (130) under verification must operate stably without being disconnected from the grid. In this test, it is verified whether the inverter (130) under verification maintains a state of being connected to the grid and performs normal functions under various voltage fluctuation conditions (magnitude, duration, rate of change), and if it is disconnected from the grid without satisfying the conditions, the conditions are recorded and can be used to seek improvement measures in the future.

[0083] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0084] A real-time simulator (110) can simulate abnormal grid voltage fluctuation situations (voltage drop, voltage rise). A power amplifier (120) can supply a voltage signal including the voltage fluctuation output from the real-time simulator (110) to a verification target inverter (130). The verification target inverter (130) can transmit output data to a monitoring device (140) to verify whether it maintains its function without being disconnected from the grid during grid voltage fluctuations, and whether its operating characteristics and protection functions operate in low voltage or overvoltage situations. The monitoring device (140) can monitor the output status of the verification target inverter (130) and the grid connection status during voltage fluctuations.

[0085]

[0086] Frequency ride-through function:

[0087] The frequency ride-through function test is a test to verify the ability of the inverter (130) under verification to maintain operation without being disconnected from the grid in situations where the grid frequency fluctuates abnormally. The grid frequency may deviate from the normal range due to power imbalance between the generator and the load, grid accidents, etc., and in such situations, the inverter (130) under verification must operate stably without being disconnected from the grid. In this test, it is verified whether the inverter (130) under verification maintains a state of being connected to the grid and performs normal functions under various frequency fluctuation conditions (magnitude, duration, rate of change), and if it fails to satisfy the conditions and is disconnected from the grid, the conditions are recorded and can be used to seek improvement measures in the future.

[0088] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0089] The real-time simulator (110) can simulate abnormal grid frequency fluctuation situations (frequency drop, frequency rise). The power amplifier (120) can supply a voltage signal containing the frequency fluctuation input from the real-time simulator (110) to the inverter under verification (130). The inverter under verification (130) can transmit output data to a monitoring device (140) to verify whether it maintains its function without being disconnected from the grid during grid frequency fluctuations, and to verify its operating characteristics and protection function operation in low-frequency or high-frequency situations. The monitoring device (140) can analyze the output data to monitor the output status of the inverter under verification (130) and the grid connection status during frequency fluctuations.

[0090]

[0091] Inertia response function:

[0092] The inertia response function test is a test to verify the ability of the inverter (130) under verification to mitigate grid frequency fluctuations by simulating inertia like a synchronous generator when the grid frequency fluctuates. Traditional synchronous generators play a role in mitigating frequency fluctuations by reacting immediately to grid frequency fluctuations due to inertia caused by rotating mass. In this test, it is possible to verify whether the inverter (130) under verification responds quickly and accurately to grid frequency fluctuations through this inertia response function, thereby minimizing frequency fluctuations and maintaining grid stability.

[0093] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0094] A real-time simulator (110) can simulate grid frequency fluctuation conditions. A power amplifier (120) can supply power signals corresponding to frequency fluctuations input from the real-time simulator (110) to an inverter under verification (130). The inverter under verification (130) can transmit output data to a monitoring device (140) to verify the inertia response output (instantaneous power supply or frequency fluctuation mitigation) function, response speed, and accuracy regarding frequency fluctuations. The monitoring device (140) can analyze the output data to measure and analyze the inertia response output of the inverter under verification (130) and changes in grid frequency during frequency fluctuations.

[0095]

[0096] Frequency change rate response function:

[0097] The frequency change rate response function test is a test to evaluate the response characteristics of the inverter (130) under verification in a situation where the grid frequency change rate fluctuates rapidly. The grid frequency may change rapidly due to grid faults, sudden load changes, etc., and in such situations, the inverter (130) under verification must respond appropriately according to the frequency change rate to maintain grid stability. In this test, changes in output voltage, current, frequency, etc. of the inverter (130) under verification under various frequency change rate conditions can be measured, and it can be verified whether the inverter (130) under verification responds excessively and has an adverse effect on the grid, or whether the response is delayed and impedes grid stability.

[0098] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0099] A real-time simulator (110) can generate a change in the grid frequency change rate by simulating various accident or delayed accident situations. A power amplifier (120) can supply a voltage signal reflecting the change in the frequency change rate input from the real-time simulator (110) to an inverter (130) under verification. The inverter (130) under verification can transmit output data to a monitoring device (140) to verify the response characteristics (output voltage, current, frequency change) of the inverter (130) according to the change in the frequency change rate, whether a transient response occurs, and whether a response delay occurs. The monitoring device (140) can analyze the output data to measure the change in the output of the inverter (130) when the change in the frequency change rate occurs.

[0100]

[0101] Fault current supply function:

[0102] The fault current supply function test is a test to verify the ability of the inverter (130) under verification to supply a fault current to quickly isolate the fault section and protect other parts of the system when a fault occurs in the system. System faults can occur in various forms, such as short circuits and ground faults, and the fault current is the current required for the operation of the protection relay that isolates the fault section. In this test, the ability of the inverter (130) under verification to quickly supply a fault current of sufficient magnitude when a fault occurs and to return to a normal state after isolating the fault section is verified.

[0103] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0104] A real-time simulator (110) can simulate system fault situations (short-circuit, ground fault, etc.). A power amplifier (120) can supply a power signal reflecting the fault situation to a verification target inverter (130). The verification target inverter (130) can transmit output data to a monitoring device (140) to verify whether it rapidly supplies a fault current of sufficient magnitude when a fault occurs, and whether it returns to a normal state after isolating the fault section. The monitoring device (140) can analyze the output data to measure the output current of the verification target inverter (130), system voltage, and current data when the fault current is supplied.

[0105]

[0106] SSO Evaluation Feature:

[0107] The SSO (Sub Synchronous Oscillation) evaluation function test is a test to detect the SSO phenomenon that may occur when multiple inverters, including the inverter (130) under verification, are connected to the grid, and to analyze the operating characteristics of the inverter (130) under verification and the impact on grid stability when SSO occurs. SSO is a low-frequency vibration phenomenon caused by the interaction between the inverter (130) under verification and the grid, and is a dangerous phenomenon that can impair grid stability and cause equipment damage. In this test, the possibility of SSO occurring under various grid conditions and inverter operating conditions is evaluated, and when SSO occurs, changes in the output characteristics of the inverter (130) under verification, grid voltage and frequency fluctuations, and the impact on grid stability are analyzed to find a solution to the SSO problem.

[0108] In this test, each component of the heterogeneous inverter verification system (300) according to one embodiment of the present invention may operate as follows.

[0109] A real-time simulator (110) can simulate a situation where multiple inverters are connected to the grid to evaluate the possibility of SSO occurrence and perform an SSO occurrence simulation. A power amplifier (120) can supply a power signal reflecting the SSO occurrence situation to an inverter (130) under verification. The inverter (130) under verification can transmit output data to a monitoring device (140) to verify changes in output characteristics, whether grid stability is impaired, and the possibility of equipment damage when SSO occurs. The monitoring device (140) can analyze the output data to measure and analyze the inverter (130) output, grid voltage, and frequency fluctuation data when SSO occurs.

[0110]

[0111] FIG. 5 is a flowchart illustrating a heterogeneous inverter verification method according to another embodiment of the present invention.

[0112] The verification method according to an embodiment of the present invention is based on Power Hardware-in-the-Loop Simulation (PHILS) and may include a process of verifying the performance and interoperability of heterogeneous inverters using a real-time simulator, a power amplifier, an inverter to be verified, and a monitoring device. Each step may be configured as follows.

[0113] In step S410, a real-time simulator, power amplifier, sensor, monitoring device, test scenario, etc., can be configured and connected to the inverter system under verification. In this step, a virtual grid, a renewable energy source model, a virtual inverter model, grid parameters (impedance, voltage, frequency), a data measurement method, a control algorithm, a test scenario, etc., can be predefined (Test Setup step).

[0114] In step S420, a real-time simulation is started based on the set values, and the power amplifier output is controlled according to the real-time simulator output to supply power to the inverter under verification. In addition, a power environment similar to reality, such as fluctuations in renewable energy source output, grid voltage, and frequency, can be provided (Simulation Start step).

[0115] In step S430, output data (voltage, current, frequency, phase, etc.) of the inverter under verification is measured in real time through a monitoring device, and the measured data is fed back to a real-time simulator so that the virtual environment can be updated. Through this, a closed-loop test environment can be implemented (Data Measurement and Feedback step).

[0116] In step S440, the real-time simulator updates the virtual grid state based on the feedback data, and the power amplifier adjusts its output according to the update, thereby changing the characteristics of the power supplied to the inverter under verification. In this way, a grid environment that changes in real time according to the feedback data can be simulated (Power Amplifier Output Adjustment step).

[0117] In step S450, operation information of the inverter under verification is collected and analyzed through a monitoring device, and the performance of the inverter under verification (voltage control, frequency control, interoperability, stability, etc.) can be evaluated. Additionally, if necessary, simulation results can be output and analyzed in the form of graphs or tables (Monitoring and Analysis step).

[0118] In step S460, when the test termination condition is satisfied, the simulation is terminated, and result data and analysis results can be saved. Additionally, a result report including test configuration information, simulation results, performance analysis results, conclusions, etc., can be generated (Simulation End & Report Generation step).

[0119]

[0120] As described above, according to embodiments of the present invention, the interoperability and grid stability of heterogeneous grid-forming inverters can be effectively verified through PHILS simulation under various renewable energy sources and grid conditions, thereby contributing to the stable operation of the power system.

[0121]

[0122] Meanwhile, the embodiments described above may be implemented as hardware components, software components, and / or combinations of hardware and software components. For example, the devices, methods, and components described in the embodiments may be implemented using a general-purpose computer or a special-purpose computer, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing unit may execute an operating system (OS) and software applications executed on said operating system. Additionally, the processing unit may access, store, manipulate, process, and generate data in response to the execution of the software. For ease of understanding, the processing unit may be described as being used as a single unit, but those skilled in the art will understand that the processing unit may include multiple processing elements and / or multiple types of processing elements. For example, the processing unit may include multiple processors or one processor and one controller. In addition, other processing configurations, such as parallel processors, are also possible.

[0123] Software may include computer programs, code, instructions, or a combination of one or more of these, and may configure a processing unit to operate as desired or command the processing unit independently or collectively. Software and / or data may be permanently or temporarily embodied in any type of machine, component, physical device, virtual equipment, computer storage medium, or device so as to be interpreted by the processing unit or to provide instructions or data to the processing unit. Software may be distributed over networked computer systems and may be stored or executed in a distributed manner. Software and data may be stored on computer-readable recording media.

[0124] 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 medium. The computer-readable medium may store program instructions, data files, data structures, etc., either individually or in combination, and the program instructions recorded on the medium may be those specifically designed and configured for the embodiment or 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.

[0125] The hardware device described above may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa.

[0126]

[0127] The description of the above-described embodiments is merely an example provided with reference to the drawings for a more thorough understanding of the present disclosure, and should not be interpreted as limiting the technical scope of the present disclosure.

Claims

1. A real-time simulator for generating multiple virtual renewable energy networks; and A power amplifier that generates a first virtual renewable energy power corresponding to a first virtual renewable energy network among a plurality of the above-mentioned virtual renewable energy networks and provides it to an inverter to be verified; An inverter verification device including 2. In Paragraph 1, The above real-time simulator further generates a virtual power system, and An inverter verification device in which the power amplifier generates virtual grid power corresponding to the virtual power grid and provides it to the output terminal of the inverter to be verified.

3. In Paragraph 2, An inverter verification device in which the above power amplifier generates the first virtual renewable energy power and provides it to the input terminal of the inverter to be verified.

4. In Paragraph 3, An inverter verification device configured such that the real-time simulator generates a plurality of virtual inverters corresponding to virtual renewable energy networks other than the first virtual renewable energy network, and the inverter to be verified and the plurality of virtual inverters interact in conjunction in the virtual power grid.

5. In Paragraph 4, An inverter verification device in which the inverter to be verified is a grid forming inverter of a different type from the virtual inverter.

6. In Paragraph 1, An inverter verification device further comprising: a line impedance simulation device formed between the power amplifier and the inverter to be verified.

7. In Paragraph 1, A monitoring device that analyzes operation information received from the inverter to be verified and determines the operation status of the inverter to be verified; An inverter verification device further comprising 8. In Paragraph 7, The above monitoring device feeds back the operation information to the real-time simulator, and The above real-time simulator is an inverter verification device that controls the output of the power amplifier based on the above feedback information.

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