System for analyzing real time effective ground by distributed generation and load characteristics

Abstract

An effective grounding image analysis system for distributed power sources and load characteristics capable of reflecting real-time changing system conditions is disclosed. The image analysis system is characterized by comprising: a collection unit for acquiring system condition data; a grounding analysis unit for generating grounding information for loads and distributed power sources using the system condition data; a circuit application unit for applying a symmetrical component circuit considering the characteristics of each type of distributed power source; and an analysis unit for calculating the final fault current and final fault voltage of the power system by applying the principle of superposition to the symmetrical component circuit.

Description

Technology Field

[0001] The present invention relates to an effective grounding image analysis technology, and more specifically, to a system that reflects real-time changing system conditions by applying simulation.

[0002] Furthermore, the present invention relates to a system and method that facilitates real-time analysis by directly applying an impedance matrix, rather than an admittance matrix, during system analysis. Background Technology

[0003] When receiving power from a 3-phase 4-wire system at a transmitting end and distributing the transformed voltage to the receiving end by branching off one phase and the neutral line, the transmitting end current and the return current returning from the receiving end to the transmitting end are measured. This can be expressed by the following mathematical formula.

[0004]

[0005] Here, R g : Effective grounding resistance of the transmitting and receiving ends, I g [pu]: Current flowing through the ground resistance, R l : It is the resistance of the neutral wire.

[0006] After calculating the neutral line impedance, the effective grounding resistance of the transmitting and receiving ends is calculated using the return current and the neutral line impedance, as shown in the following mathematical formula.

[0007]

[0008] As explained above, the existing effective grounding resistance calculation relies on a formula to determine the effective ground. Consequently, this method has the disadvantage of being unable to reflect real-time changes in system conditions. Furthermore, the system topology changes moment by moment and must be taken into account.

[0009] In addition, existing effective grounding standards for fault analysis lack effective grounding effect analysis technology that considers inverter-based distributed power sources. Accordingly, standards requiring effective grounding coordination must specify that the primary side of the distributed power source connection transformer must be grounded, while considering only synchronous-based distributed power sources.

[0010] Furthermore, existing methods for calculating effective grounding do not consider the grounding or non-grounding status of loads directly connected to the system, nor do they account for the grounding or non-grounding status of load transformers; instead, they consider only the grounding of distributed power sources. Consequently, this approach has the disadvantage of being unable to accurately evaluate effective grounding because it fails to account for the impact of varying load grounding conditions. Prior art literature

[0011] 1. Republic of Korea Registered Patent No. 10-1471341 (Registration Date: December 03, 2014) The problem to be solved

[0012] The present invention is proposed to resolve the problems according to the above background technology, and aims to provide an effective grounding image analysis system and method for distributed power sources and load characteristics that can reflect the conditions of a system changing in real time.

[0013] In addition, another objective of the present invention is to provide a system and method that enable a technology for analyzing the influence of effective grounding considering inverter-based distributed power sources.

[0014] In addition, another objective of the present invention is to provide a system and method capable of accurately evaluating effective grounding by considering the effect of effective grounding that varies depending on the grounding condition of the load. means of solving the problem

[0015] To achieve the above-mentioned objectives, the present invention provides an effective grounding image analysis system for distributed power sources and load characteristics that can reflect real-time changing system conditions.

[0016] The above image analysis system is,

[0017] A collection unit that acquires system status data;

[0018] A grounding analysis unit that generates grounding information for loads and distributed power sources using the above system condition data;

[0019] A circuit application unit that applies a symmetric component circuit considering the characteristics of each type of distributed power source; and

[0020] It is characterized by including an analysis unit that calculates the final fault current and final fault voltage of a power system by applying the principle of superposition to the above-mentioned symmetric component circuit.

[0021] In addition, if the type of the distributed power source is a synchronous machine-based distributed power source, the symmetric component circuit is interpreted identically to the synchronous generator of the main system, and if it is an inverter-based distributed power source, a current source ( ) and Norton impedance (Z Nort It is characterized by being interpreted through Norton impedance equivalent in the negative sequence and zero sequence circuit networks.

[0022] In addition, the circuit application unit applies the symmetrical component circuit to the ground information to calculate the symmetrical component circuit impedance value, and uses the symmetrical component circuit impedance value to apply a first applied voltage ( ) and second pressurized voltage ( It is characterized by producing ).

[0023] In addition, the first pressure voltage ( ) is a mathematical expression (Here, is the zero-sequence, positive-sequence, and negative-sequence bus impedance matrix constructed based on the Thevenin equivalent circuit, and It is characterized by being calculated using (which refers to the zero-sequence current, positive-sequence current, and negative-sequence current of the Thevenin equivalent circuit).

[0024] In addition, the second pressure voltage ( ) is a mathematical expression (Here, is the bus impedance matrix before the fault, is a column vector consisting of the 2 columns of the bus impedance matrix before the fault, is a row vector consisting of the second row of the busbar impedance matrix before the fault, and T is the transpose symbol. ) and ( Here, is a bus impedance matrix of zero sequence (0), positive sequence (1), and negative sequence (2) configured based on a Norton equivalent circuit, is the symmetric component fault current of the Norton equivalent circuit. Calculate using It is characterized by becoming.

[0025] In addition, the symmetric component fault current of the above Norton equivalent circuit ( ) is normal current( ), negative sequence current( ) and image current( It is calculated using ), and the above normal current ( ) is the negative sequence component, zero sequence component, driving point impedance, and fault impedance for busbar ②( ) is calculated by equivalenting it to the positive component network, and the above negative sequence current ( ) and the above image current ( ) is the above normal current ( It is characterized by being produced identically to ).

[0026] In addition, the above normal current ( ) is a mathematical expression (Here, is the sum of the negative sequence and zero sequence driving point impedances and the fault impedance for busbar ②, and It is characterized by being defined as the voltage of bus ② in a normal circuit network.

[0027] In addition, the above system, the final fault current ( ), final pressure voltage ( ), and system current values ​​flowing in the power system ( It is characterized by including an evaluation unit that calculates a healthy phase potential value based on ) and evaluates whether the healthy phase potential value deviates from a predetermined temporary overvoltage standard range.

[0028] In addition, it is determined using the above healthy phase potential value, and the above healthy phase potential value is a mathematical formula (Here, f is a subscript indicating the fault voltage, and b and c indicate the phase, is the zero-sequence fault voltage, and is the normal component fault voltage, and is the negative sequence fault voltage, and a is It is characterized by being produced using ).

[0029] In addition, the above-mentioned symmetrical component circuit impedance value is characterized by being calculated by dividing the phase voltage by the power value of one phase in the case of a grounded load.

[0030] In addition, the above symmetric component circuit impedance value is calculated by converting the ungrounded load into a grounded load in the case of an ungrounded load, and is characterized by being interpreted as an open state as a zero-sequence equivalent circuit considering the absence of a neutral line.

[0031] On the other hand, another embodiment of the present invention provides a method for analyzing effective grounding images according to distributed power source and load characteristics, characterized by comprising: (a) a collection unit acquiring system condition data; (b) a grounding analysis unit generating grounding information of a load and a distributed power source using the system condition data; (c) a circuit application unit applying a symmetrical component circuit considering the characteristics of each type of distributed power source; and (d) an analysis unit applying the principle of superposition to the symmetrical component circuit to calculate the final fault current and final fault voltage of the power system.

[0032] In addition, the above method, after step (d), the evaluation unit, the final fault current ( ), final pressure voltage ( ), and system current values ​​flowing in the power system ( It is characterized by including the step of calculating a healthy phase potential value based on ), and evaluating whether the healthy phase potential value deviates from a predetermined temporary overvoltage reference range. Effects of the invention

[0033] According to the present invention, a technique is provided to accurately analyze the influence of grounding and non-grounding of a load on effective grounding, and furthermore, it is possible to accurately analyze the influence on effective grounding of inverter-based distributed power sources and synchronous machine-based distributed power sources.

[0034] In addition, another advantage of the present invention is that the protection coordination method of the system can be reconfigured based on the analysis results, thereby enabling the connection of renewable energy sources to the distribution system to be smooth, economical, and efficient.

[0035] In addition, another advantage of the present invention is that it calculates system impedance at regular time intervals and updates the potential of healthy phases, which is possible due to the fast speed of fault analysis.

[0036] In addition, another advantage of the present invention is that it allows for the continuous analysis of the impact of loads and distributed power sources on effective grounding, thereby enabling the calculation of effective grounding values ​​based on system conditions in real time and ultimately allowing for the response to unpredictable fault situations.

[0037] In addition, another advantage of the present invention is that by using the admittance matrix of the symmetric component circuit, there is no need to apply the inverse matrix of the impedance matrix during fault current and bus voltage, so the calculation processing speed is fast and efficient. Brief explanation of the drawing

[0038] FIG. 1 is a block diagram of an effective grounding image analysis system according to distributed power source and load characteristics according to an embodiment of the present invention. FIG. 2 is the symmetric component impedance in the case of grounding of a load according to an embodiment of the present invention. Figure 3 shows the symmetric component impedance in the case of an ungrounded load according to an embodiment of the present invention. FIG. 4 is a symmetric component circuit diagram of a grid connected with an inverter-based distributed power source according to an embodiment of the present invention. FIG. 5 is a flowchart showing the process of analyzing the real-time effective grounding effect according to distributed power source and load characteristics in accordance with an embodiment of the present invention. Specific details for implementing the invention

[0039] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0040] When describing each drawing, similar reference numerals are used for similar components.

[0041] Terms such as first, second, etc., may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another.

[0042] 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 of a plurality of related described items.

[0043] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains.

[0044] Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0045] A system and method for analyzing effective grounding images according to distributed power sources and load characteristics according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0047] FIG. 1 is a block diagram of an effective ground image analysis system (100) according to distributed power source and load characteristics according to an embodiment of the present invention. Referring to FIG. 1, the effective ground image analysis system (100) may be configured to include a collection unit (110), a ground analysis unit (120), a circuit application unit (130), an analysis unit (140), an evaluation unit (150), a display unit (160), etc.

[0048] The collection unit (110) performs the function of acquiring system status data. The data acquisition unit (110) acquires data generated through the power system. The power system may include power generation facilities, transmission facilities, distribution facilities, and consumers.

[0049] Of course, the collection unit (110) may acquire data by connecting to sensors and measuring instruments through a communication network (not shown), or it may be directly connected to sensors. To this end, the collection unit 1L10) may be configured to include a communication modem, a microprocessor, memory, etc. System condition data may be loads, distributed power sources, etc.

[0050] System condition data includes basic system information (line impedance, transformer impedance, bus voltage), data affecting the effective grounding system (including characteristics of loads and distributed power sources), and fault analysis data (fault currents injected by synchronous-based power sources and inverter-based distributed power sources).

[0051] A communication network refers to a connection structure that enables information exchange between individual nodes, such as multiple terminals and servers, and can be a Public Switched Telephone Network (PSTN), Public Switched Data Network (PSDN), Integrated Services Digital Networks (ISDN), Broadband Integrated Services Digital Network (BISDN), Local Area Network (LAN), Metropolitan Area Network (MAN), or Wide Area Network (WLAN).

[0052] However, the present invention is not limited thereto and may be wireless communication networks such as CDMA (Code Division Multiple Access), WCDMA (Wideband Code Division Multiple Access), Wibro (Wireless Broadband), WiFi (Wireless Fidelity), HSDPA (High Speed ​​Downlink Packet Access) networks, Bluetooth, NFC (Near Field Communication) networks, satellite broadcasting networks, analog broadcasting networks, DMB (Digital Multimedia Broadcasting) networks, etc. Alternatively, it may be a combination of these wired communication networks and wireless communication networks.

[0053] The grounding analysis unit (120) generates grounding information by analyzing the grounding / ungrounding of loads and distributed power sources using system condition information.

[0054] The circuit application unit (120) calculates the symmetrical component circuit impedance value by applying the symmetrical component circuit of the transformer, line, generator, and load impedance, and uses this to calculate the applied voltage applied to each busbar of the equivalent circuit.

[0055] The analysis unit (140) calculates the final fault current and final fault voltage of the power system by applying the principle of superposition.

[0056] The evaluation unit (150) performs an analysis of the effective grounding effect based on the final fault current, the final fault voltage, and the current value flowing through the power system.

[0057] The display unit (160) performs the function of outputting the results of the effective grounding effect analysis. The output may be a combination of graphics, text, and voice. To this end, the display unit (160) may be configured to include a display, a sound system, etc.

[0058] Displays can include LCD (Liquid Crystal Display), LED (Light Emitting Diode) display, PDP (Plasma Display Panel), OLED (Organic LED) display, touch screen, CRT (Cathode Ray Tube), flexible display, Micro LED, Mini LED, etc. In the case of touch screens, they can be used not only as an output means but also as an input means.

[0059] FIG. 2 shows the symmetrical component impedance in the case of grounding a load according to an embodiment of the present invention. Referring to FIG. 2, in the case of a grounded load, the impedance value is calculated by dividing the phase voltage by the power value of one phase.

[0060]

[0061] Here, Z load (y) is the symmetric component impedance value, and V LN is the phase voltage, and P 1φ is the power value of one phase.

[0062] FIG. 3 shows the symmetric component impedance in the case of an ungrounded load according to an embodiment of the present invention. Referring to FIG. 3, for convenience of analysis, the ungrounded load is converted into a grounded load and the analysis is performed. This is the process of converting Equation 4 into Equation 5.

[0063]

[0064]

[0065] Here, Z load (D) is the symmetric component impedance value, and V LL is the phase voltage, and P 1φ is the power value of one phase.

[0066] In the case of an ungrounded load, the power consumed is the same as that of a grounded load. Therefore, when converting an ungrounded load to a grounded load, the impedance value is the same as that of the existing grounded load. However, in the case of an ungrounded load, it is interpreted as an open state in the zero-sequence equivalent circuit, taking into account the absence of a neutral line.

[0067] FIG. 4 is a circuit diagram of the symmetrical component of a grid connected to an inverter-based distributed power source according to an embodiment of the present invention. Referring to FIG. 4, the symmetrical component of the synchronous machine-based distributed power source is interpreted as being identical to the synchronous generator of the main grid.

[0068] For fault analysis, distributed power sources are classified into synchronous (rotary) based and static (inverter) based types. Since synchronous-based distributed power sources maintain voltage even after a fault, it is advantageous to model them as voltage-based distributed power sources. On the other hand, inverter-based distributed power sources are modeled as current-based distributed power sources because the generated power is connected via a current injection method through the inverter.

[0069] Meanwhile, inverter-based distributed power sources are current sources ( ) and Norton impedance (Z Nort ) and analyze the Norton impedance in the negative sequence and zero sequence circuit networks by equivalent.

[0070] In the case of inverter-based distributed power sources, they are connected to the grid through a current-controlled voltage source inverter to improve power quality and efficiency, thereby supplying a constant current to the grid in the event of a fault. In addition, inverter-based distributed power sources are designed as three-phase balanced power sources to stably operate the connected grid.

[0071] Figure 4 will be explained in more detail with reference to Figure 5.

[0072] FIG. 5 is a flowchart illustrating the process of analyzing the real-time effective grounding effect according to distributed power source and load characteristics in accordance with an embodiment of the present invention. Referring to FIG. 5, the grounding / ungrounding of the load and the grounding / ungrounding of the distributed power source are analyzed using system condition data (step S510).

[0073] To elaborate, in the case of a grounded load, the impedance value is calculated by dividing the phase voltage by the power value of one phase. Additionally, for the convenience of analysis, the ungrounded load is converted into a grounded load to perform the analysis.

[0074] Subsequently, a symmetric component circuit is applied considering the characteristics of each type of distributed power source (step S520). To elaborate, the symmetric component circuit of a synchronous machine-based distributed power source is analyzed in the same way as a synchronous generator in the main system, and an inverter-based distributed power source is a current source ( ) and Norton impedance (Z Nort ) is analyzed through Norton impedance equivalent in the negative sequence and zero sequence circuit networks.

[0075] Subsequently, the symmetric component fault current and bus voltage contributed by the synchronous machine-based distributed power source are calculated (step S530). To elaborate, the normal current ( ), negative sequence current( ), image current( Using ) symmetric component fault current( Calculate ). This can be expressed as a mathematical formula as follows.

[0076]

[0077] Here, V2(0) is the voltage before the fault at bus ②, is the positive, negative, and zero sequence driving point impedance for busbar ②, is the fault impedance. Also, 012 means that it covers the zero sequence, positive sequence, and negative sequence components, f,vs are subscripts indicating the symmetrical component fault current, 22 indicates the direction from bus 2 to bus 2, i.e., bus 2 itself, and the superscript "0" indicates the zero sequence, the superscript "1" indicates the positive sequence, and the superscript "2" indicates the negative sequence.

[0078] - Normal component: A voltage or current component whose phase sequence is a, b, c (or R, S, T).

[0079] - Negative sequence component: A voltage or current component with a phase sequence of a, c, b (or R, T, S).

[0080] - Zero-sequence component: A voltage or current component without phase sequence.

[0081] Based on the above equation, the applied voltage (applied to each busbar of the Thevenin equivalent circuit) Calculate ). This can be expressed as a mathematical formula as follows.

[0082]

[0083] Here, is the zero-sequence, positive-sequence, and negative-sequence bus impedance matrix constructed based on the Thevenin equivalent circuit. And, represents the zero sequence current, positive sequence current, and negative sequence current of the Thevenin equivalent circuit.

[0084] Negative sequence, zero sequence driving point impedance, and fault impedance for busbar ② ( Equivalent ) to the positive component network to obtain the positive current ( Calculate ). Negative sequence current ( ) and image current( ) is calculated the same as the normal current.

[0085]

[0086] Here, is the sum of the negative sequence and zero sequence driving point impedances and the fault impedance for busbar ②, and is the voltage of bus ② in the normal circuit network.

[0087]

[0088]

[0089] Here, V3(0) is the voltage before the fault at bus 3, P + jQ is the apparent power of the distributed power source connected to bus 5 in FIG. 2, and T is the transpose matrix. At the time of the fault, the impedance matrix ( ) is in Fig. 2 Busbar impedance matrix in the case where this is not considered ( Calculate as follows using ).

[0090]

[0091] Here, is the bus impedance matrix before the fault, is a column vector consisting of two columns of the bus impedance matrix, is a row vector consisting of the second row of the bus impedance matrix, and T is the transpose symbol.

[0092] Based on the above equation, calculate the applied voltage applied to each busbar of the Norton equivalent circuit.

[0093]

[0094] Here, is a bus impedance matrix of zero sequence (0), positive sequence (1), and negative sequence (2) configured based on a Norton equivalent circuit, is the symmetric component fault current of the Norton equivalent circuit.

[0095] and is the same relationship, and is the current supplied by the inverter-based distributed power source.

[0096] Subsequently, the fault current is analyzed based on the principle of superposition (step S540). To elaborate, the final fault current of a power system in which synchronous machine-based distributed power sources and inverter-based distributed power sources are connected ( ), final pressure voltage ( ), system current value flowing in the power system( Produces ).

[0097]

[0098] Here, is the first fault current of the Thevenin equivalent circuit, and is the second fault current of the Norton equivalent circuit, and is the first applied voltage applied to each busbar of the Thevenin equivalent circuit, and is the second applied voltage applied to each busbar of the Norton equivalent circuit. Also, f is a subscript representing the fault current, and i and j indicate the direction from node i to node j.

[0099] In the previous step, the final fault current, final applied voltage, and system current flowing through the power system were calculated through fault analysis.

[0100] Subsequently, based on these values, the rise in the healthy phase potential value is derived to perform an effective grounding effect analysis (step S550). After calculating the symmetrical component voltage value of the fault bus, the healthy phase potential value of the fault bus can be calculated based on this. A formula was derived assuming a single-line ground fault in phase a.

[0101]

[0102] Here, f is a subscript indicating the fault voltage, and b and c indicate the phase, is the zero-sequence fault voltage, and is the normal component fault voltage, and is the negative sequence fault voltage, and a is am.

[0103] To elaborate, impedances for distributed power sources and loads are set considering real-time changing system conditions, and the system impedance is updated by detecting real-time changes.

[0104] In consideration of this, the potential value of the healthy phase is updated in the event of a fault. The potential of the healthy phase is monitored to see if it exceeds the set temporary overvoltage standard range, and the system is reinforced if a violation occurs.

[0106] Additionally, the steps of the method or algorithm described in connection with the embodiments disclosed herein may be implemented in the form of program instructions that can be executed through various computer means, such as a microprocessor, a processor, a CPU (Central Processing Unit), etc., and recorded on a computer-readable medium. The computer-readable medium may include program (instruction) code, data files, data structures, etc., either alone or in combination.

[0107] The program (instruction) code recorded on the above medium may be those specifically designed and configured for the present invention, or those known and available to those skilled in the art of computer software. Examples of computer-readable recording media may include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs, DVDs, and Blu-rays; and semiconductor memory devices specifically configured to store and execute program (instruction) code, such as ROM (Read Only Memory), RAM (Random Access Memory), and flash memory.

[0108] Here, examples of program (instruction) code include not only machine code, such as that generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter, etc. The aforementioned hardware device may be configured to operate as one or more software modules to perform the operation of the present invention, and vice versa. Explanation of the symbols

[0109] 100: Effective Grounding Image Analysis System 110: Collection Department 120: Grounding Analysis Unit 130: Circuit application section 140: Interpretation section 150: Evaluation Department 160: Display unit

Claims

Claim 1 A collection unit (110) that acquires system condition data from power generation facilities, transmission facilities, distribution facilities, and consumers by connecting to sensors and measuring instruments through a communication network; a grounding analysis unit (120) that generates grounding information for loads and distributed power sources using the system condition data; and a circuit application unit (120) that applies a symmetric component circuit by considering the characteristics of each type of distributed power source. The distributed power source and load characteristic-specific effective grounding image analysis system comprises: an analysis unit (140) that calculates the final fault current and final fault voltage of a power system by applying the principle of superposition to the symmetrical component circuit; and a display unit (160) that outputs the results of the effective grounding effect analysis from the analysis unit (140) through a display or sound system. The impedance value of the symmetrical component circuit is calculated by dividing the phase voltage by the power value of one phase in the case of a grounded load, and the impedance value of the symmetrical component circuit is calculated by converting the non-grounded load into a grounded load in the case of an ungrounded load, and is analyzed as an open state as a zero-sequence equivalent circuit considering the absence of a neutral line, and in the case of an ungrounded load, is equal to the amount of power consumed by the grounded load, and when the ungrounded load is converted into a grounded load, the impedance value is equal to the impedance of the existing grounded load. Claim 2 In claim 1, if the type of distributed power source is a synchronous machine-based distributed power source, the symmetric component circuit is interpreted identically to the synchronous generator of the main system, and if it is an inverter-based distributed power source, a current source ( ) and Norton impedance (Z Nort A distributed power source and load-specific effective grounding image analysis system characterized by being analyzed through Norton impedance equivalent in negative sequence and zero sequence circuit networks. Claim 3 In claim 1, the circuit application unit (120) applies the symmetrical component circuit to the ground information to calculate the symmetrical component circuit impedance value, and uses the symmetrical component circuit impedance value to apply a first applied voltage ( ) and second pressurized voltage ( A distributed power source and load-specific effective grounding image analysis system characterized by calculating ). Claim 4 In claim 3, the first pressure voltage ( ) is a mathematical expression (Here, is the zero-sequence, positive-sequence, and negative-sequence bus impedance matrix constructed based on the Thevenin equivalent circuit, and A distributed power source and load-specific effective grounding image analysis system characterized by being calculated using (meaning zero-sequence current, positive-sequence current, and negative-sequence current of the Thevenin equivalent circuit). Claim 5 In claim 4, the second pressurized voltage ( ) is a mathematical expression Here, is the bus impedance matrix before the fault, is a column vector consisting of the 2 columns of the bus impedance matrix before the fault, is a row vector consisting of the second row of the busbar impedance matrix, and T is the transpose symbol. ) and ( Here, is a bus impedance matrix of zero sequence (0), positive sequence (1), and negative sequence (2) configured based on a Norton equivalent circuit, A distributed power source and load-specific effective grounding image analysis system characterized by being calculated using (which is the symmetric component fault current of the Norton equivalent circuit). Claim 6 In claim 5, the symmetric component fault current of the Norton equivalent circuit ( ) is normal current( ), negative sequence current( ) and image current( It is calculated using ), and the above normal current ( ) is the negative sequence component, zero sequence component, driving point impedance, and fault impedance for busbar ②( ) is calculated by equivalenting it to the positive component network, and the above negative sequence current ( ) and the above image current ( ) is the above normal current ( A distributed power source and load-specific effective grounding image analysis system characterized by being calculated identically to ). Claim 7 In claim 5, the above normal current ( ) is a mathematical expression (Here, is the sum of the negative sequence and zero sequence driving point impedances and the fault impedance for busbar ②, and A distributed power source and load-specific effective grounding image analysis system characterized by being defined as (the voltage of busbar ② in the normal circuit network). Claim 8 In claim 1, the final fault current ( ), final pressure voltage ( ), and system current values ​​flowing in the power system ( A distributed power source and load-specific effective grounding image analysis system characterized by including an evaluation unit (150) that calculates a healthy phase potential value based on ) and evaluates whether the healthy phase potential value deviates from a predetermined temporary overvoltage reference range. Claim 9 In claim 8, it is determined using the sound phase potential value, and the sound phase potential value is a mathematical formula (Here, f is a subscript indicating the fault voltage, and b and c indicate the phase, is the zero-sequence fault voltage, and is the normal component fault voltage, and is the negative sequence fault voltage, and a is A distributed power source and load-specific effective grounding image analysis system characterized by being calculated using ).

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