Fault positive sequence component network and fault sequence component current calculation method

Abstract

The invention relates to the technical field of power systems, and discloses a fault positive-sequence component network and a fault sequence component current calculation method, comprising: calculating equivalent positive-sequence power supply potential and equivalent positive-sequence power supply impedance of a new energy side in a new energy grid-connected system and equivalent positive-sequence line impedance between a protection installation position and a fault point; the fault positive-sequence component network comprises equivalent positive-sequence power potential, equivalent positive-sequence power impedance, equivalent positive-sequence line impedance between a protection installation position and a fault point, equivalent positive-sequence voltage at the fault point, and a voltage-controlled voltage source at the fault point, namely, the voltage-controlled voltage source is introduced into the fault positive-sequence component network; the fault positive-sequence component network suitable for the new energy grid-connected system is constructed, a brand-new effective way is provided for protection design and fault analysis of the new energy grid-connected system, the fault analysis precision is remarkably improved, safe and stable operation of the new energy grid-connected system is powerfully guaranteed, and the fault positive-sequence component network is suitable for the new energy grid-connected system. And a solid foundation is laid for reliable power supply and efficient management of a power system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and in particular to a fault positive sequence component network and a fault sequence component current calculation method. BACKGROUND

[0002] Under the background of energy transformation, new energy power generation technologies such as wind energy and solar energy are developing rapidly. Large-scale new energy systems are connected to the power grid through AC transmission lines, which has become a typical operating scenario of modern power systems. However, there are fundamental differences between new energy generation units and traditional synchronous generators in terms of fault characteristics, which are mainly due to the complex control mechanism of the converter. The fault positive sequence component network model widely used in fault analysis of traditional power systems is based on the characteristics of synchronous generators, but in new energy grid-connected systems, especially when the positive and negative sequence impedances are significantly different, this model is no longer applicable. Because the existing fault positive sequence component network does not fully consider the unique characteristics of new energy grid-connected systems, it is difficult to accurately describe their dynamic behavior in fault operating state, which severely limits the accuracy of fault analysis and cannot meet the needs of safe and stable operation and accurate fault analysis of power systems. SUMMARY

[0003] Therefore, it is necessary to propose a fault positive sequence component network and a fault sequence component current calculation method to address the above problems. By introducing a voltage-controlled voltage source into the fault positive sequence component network, a fault positive sequence component network suitable for new energy grid-connected systems is constructed, providing a new and effective approach for protection design and fault analysis of new energy grid-connected systems, significantly improving the accuracy of fault analysis, and effectively ensuring the safe and stable operation of new energy grid-connected systems, laying a solid foundation for reliable power supply and efficient management of power systems.

[0004] To achieve the above purpose, in a first aspect, the present application provides a fault positive sequence component network, which includes an equivalent positive sequence source potential, an equivalent positive sequence source impedance and an equivalent positive sequence line impedance between a protection installation and a fault point on a new energy side of a new energy grid-connected system, and an equivalent positive sequence source potential, an equivalent positive sequence source impedance and an equivalent positive sequence line impedance between a protection installation and a fault point on a grid side of the new energy grid-connected system, and an equivalent positive sequence voltage at the fault point, and a voltage-controlled voltage source. The equivalent positive sequence power supply potential, the equivalent positive sequence power supply impedance and the equivalent positive sequence line impedance of the new energy side, the equivalent positive sequence line impedance of the grid side, the equivalent positive sequence power supply impedance and the equivalent positive sequence power supply potential of the grid side, the voltage-controlled voltage source, the equivalent positive sequence power supply potential of the new energy side are connected in series, and the connection points between the equivalent positive sequence line impedance of the new energy side and the equivalent positive sequence line impedance of the grid side and between the voltage-controlled voltage source and the equivalent positive sequence power supply potential of the grid side are connected to the equivalent positive sequence voltage.

[0005] Optionally, in the case of using the fault positive sequence component network for fault analysis of single-phase ground short circuit, the expression of the voltage-controlled voltage source is: ; Wherein, , , , , , ; In the above formula, is the voltage value of the voltage-controlled voltage source, is the voltage before the fault at the fault point, is the equivalent positive sequence impedance of the new energy grid-connected system, is the equivalent negative sequence impedance of the new energy grid-connected system, is the equivalent zero sequence impedance of the new energy grid-connected system, is the equivalent positive sequence power supply impedance of the new energy side, is the equivalent positive sequence line impedance of the new energy grid-connected system, is the equivalent positive sequence power supply impedance of the grid side, is the equivalent positive sequence line impedance of the new energy side, is the equivalent positive sequence line impedance of the grid side, is the equivalent negative sequence power supply impedance of the new energy side, is the equivalent negative sequence line impedance of the new energy grid-connected system, is the equivalent negative sequence power supply impedance of the grid side, is the equivalent negative sequence line impedance of the new energy side, is the equivalent negative sequence line impedance of the grid side, is the equivalent zero sequence power supply impedance of the new energy side, is the equivalent zero sequence line impedance of the new energy grid-connected system, is the equivalent zero sequence power supply impedance of the grid side, is the equivalent zero sequence line impedance of the new energy side, is the equivalent zero sequence line impedance of the grid side.

[0006] Optionally, when the fault positive sequence component network is used for fault analysis of two-phase phase-to-phase short circuits, the expression for the voltage-controlled voltage source is: ; in, , , , ; In the above formula, The voltage value of the voltage-controlled voltage source. The voltage before the fault at the fault point is... Let be the equivalent positive sequence impedance of the new energy grid-connected system. Let be the equivalent negative sequence impedance of the new energy grid-connected system. Let be the equivalent positive-sequence power supply impedance on the new energy side. Let be the equivalent positive sequence line impedance of the new energy grid-connected system. The equivalent positive-sequence power supply impedance on the grid side is given. The equivalent positive-sequence line impedance on the new energy side is given. This is the equivalent positive-sequence line impedance on the power grid side. The equivalent negative sequence power supply impedance on the new energy side is given. Let be the equivalent negative sequence line impedance of the new energy grid-connected system. The equivalent negative sequence power supply impedance on the grid side is given. This represents the equivalent negative sequence line impedance on the new energy side. The equivalent negative sequence line impedance on the power grid side.

[0007] Optionally, when the fault positive sequence component network is used for fault analysis of a two-phase-to-ground short circuit, the expression for the voltage-controlled voltage source is: ; in, , , , , , ; In the above formula, The voltage value of the voltage-controlled voltage source. The voltage before the fault at the fault point is... Let be the equivalent positive sequence impedance of the new energy grid-connected system. Let be the equivalent negative sequence impedance of the new energy grid-connected system. The equivalent zero-sequence impedance of the new energy grid-connected system is given. Let be the equivalent positive-sequence power supply impedance on the new energy side. an equivalent positive sequence line impedance of the new energy grid-connected system, an equivalent positive sequence source impedance of the grid side, an equivalent positive sequence line impedance of the new energy side, an equivalent positive sequence line impedance of the grid side, an equivalent negative sequence source impedance of the new energy side, an equivalent negative sequence line impedance of the new energy grid-connected system, an equivalent negative sequence source impedance of the grid side, an equivalent negative sequence line impedance of the new energy side, an equivalent negative sequence line impedance of the grid side, an equivalent zero sequence source impedance of the new energy side, an equivalent zero sequence line impedance of the new energy grid-connected system, an equivalent zero sequence source impedance of the grid side, an equivalent zero sequence line impedance of the new energy side, an equivalent zero sequence line impedance of the grid side.

[0008] Optionally, in the case that the fault positive sequence component network is used for fault analysis of three-phase short circuit, the expression of the voltage-controlled voltage source is: ; In the above formula, is the voltage value of the voltage-controlled voltage source.

[0009] To achieve the above object, the present application provides in a second aspect a fault sequence component current calculation method, which comprises: equivalent analysis is performed on the new energy grid-connected system from a fault point of the new energy grid-connected system to construct a fault negative sequence component network and a fault zero sequence component network; a fault positive sequence component current expression, a fault negative sequence component current expression and a fault zero sequence component current expression of the new energy grid-connected system are respectively established according to the fault positive sequence component network, and the fault negative sequence component network and the fault zero sequence component network as in any one of the first aspect; fault sequence current calculation data of the new energy grid-connected system are obtained according to the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression; the fault positive sequence component current, the fault negative sequence component current and the fault zero sequence component current of the new energy grid-connected system are respectively calculated according to the fault sequence current calculation data by using the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression.

[0010] Optionally, the fault positive-sequence component current expression is: ; wherein, is a fault positive-sequence component current of the new energy grid-connected system, is a fault positive-sequence component current of the new energy side, is a fault positive-sequence component current of the grid side, is a pre-fault voltage at the fault point, is a voltage value of the voltage-controlled voltage source, is an equivalent positive-sequence source impedance of the new energy side, is an equivalent positive-sequence line impedance of the new energy grid-connected system, is an equivalent positive-sequence source impedance of the grid side.

[0011] Optionally, the fault negative-sequence component current expression is: ; wherein, is a fault negative-sequence component current of the new energy grid-connected system, is a fault negative-sequence component current of the new energy side, is a fault negative-sequence component current of the grid side, is a pre-fault voltage at the fault point, is an equivalent negative-sequence line impedance of the new energy grid-connected system, is an equivalent negative-sequence source impedance of the grid side.

[0012] Optionally, the fault zero-sequence component current expression is: ; wherein, is a fault zero-sequence component current of the new energy grid-connected system, is a fault zero-sequence component current of the new energy side, is a fault zero-sequence component current of the grid side, is a pre-fault voltage at the fault point, is an equivalent zero-sequence source impedance of the new energy side, is an equivalent zero-sequence line impedance of the new energy grid-connected system, is an equivalent zero-sequence source impedance of the grid side.

[0013] Optionally, the fault negative sequence component network comprises equivalent negative sequence source impedance of the new energy side, equivalent negative sequence line impedance between the protection installation and the fault point, equivalent negative sequence source impedance of the grid side, equivalent negative sequence line impedance between the protection installation and the fault point, and equivalent negative sequence voltage at the fault point. The equivalent negative sequence source impedance of the new energy side and the equivalent negative sequence line impedance, the equivalent negative sequence line impedance of the grid side and the equivalent negative sequence source impedance, and the equivalent negative sequence source impedance of the new energy side are connected in series, and the connection points between the equivalent negative sequence line impedance of the new energy side and the equivalent negative sequence line impedance of the grid side and between the equivalent negative sequence source impedance of the new energy side and the equivalent negative sequence source impedance of the grid side are connected with the equivalent negative sequence voltage. The fault zero sequence component network comprises equivalent zero sequence source impedance of the new energy side, equivalent zero sequence line impedance between the protection installation and the fault point, equivalent zero sequence source impedance of the grid side, equivalent zero sequence line impedance between the protection installation and the fault point, and equivalent zero sequence voltage at the fault point. The equivalent zero sequence source impedance of the new energy side and the equivalent zero sequence line impedance, the equivalent zero sequence line impedance of the grid side and the equivalent zero sequence source impedance, and the equivalent zero sequence source impedance of the new energy side are connected in series, and the connection points between the equivalent zero sequence line impedance of the new energy side and the equivalent zero sequence line impedance of the grid side and between the equivalent zero sequence source impedance of the new energy side and the equivalent zero sequence source impedance of the grid side are connected with the equivalent zero sequence voltage.

[0014] To achieve the above object, the third aspect of the present application provides a fault sequence component current calculation device, which comprises: A network construction module is configured to perform equivalent analysis on the new energy grid-connected system from the fault point of the new energy grid-connected system to construct a fault negative sequence component network and a fault zero sequence component network. An expression establishment module is configured to establish a fault positive sequence component current expression, a fault negative sequence component current expression and a fault zero sequence component current expression of the new energy grid-connected system according to the fault positive sequence component network, the fault negative sequence component network and the fault zero sequence component network. A data acquisition module is configured to acquire fault sequence current calculation data of the new energy grid-connected system according to the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression. The current calculation module is configured to calculate the fault positive sequence component current, the fault negative sequence component current and the fault zero sequence component current of the new energy grid-connected system according to the fault sequence current calculation data by using the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression.

[0015] To achieve the above object, the present application provides a computer readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the fault sequence component current calculation method according to any one of the second aspect.

[0016] To achieve the above object, the present application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, which, when executed by the processor, causes the processor to perform the fault sequence component current calculation method according to any one of the first aspect.

[0017] The present application has the following advantages: the fault positive sequence component network includes equivalent positive sequence power potential, equivalent positive sequence power impedance and equivalent positive sequence line impedance between the protection installation and the fault point on the new energy side of the new energy grid-connected system, equivalent positive sequence power potential, equivalent positive sequence power impedance and equivalent positive sequence line impedance between the protection installation and the fault point on the grid side of the new energy grid-connected system, equivalent positive sequence voltage at the fault point, and a voltage-controlled voltage source; the equivalent positive sequence power potential, the equivalent positive sequence power impedance and the equivalent positive sequence line impedance on the new energy side, the equivalent positive sequence line impedance on the grid side, the equivalent positive sequence power impedance and the equivalent positive sequence power potential on the grid side, the voltage-controlled voltage source, and the equivalent positive sequence power potential on the new energy side are connected in series; the connection points between the equivalent positive sequence line impedance on the new energy side and the equivalent positive sequence line impedance on the grid side and between the voltage-controlled voltage source and the equivalent positive sequence power potential on the grid side are connected with the equivalent positive sequence voltage; that is, by introducing the voltage-controlled voltage source into the fault positive sequence component network, a fault positive sequence component network suitable for the new energy grid-connected system is constructed, which provides a new and effective way for protection design and fault analysis of the new energy grid-connected system, significantly improves the accuracy of fault analysis, effectively ensures the safe and stable operation of the new energy grid-connected system, and lays a solid foundation for reliable power supply and efficient management of the power system. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0019] wherein: Figure 1 is a schematic diagram of a new energy grid-connected system in an embodiment of the present application; Figure 2 is a schematic diagram of a fault positive sequence component network in an embodiment of the present application; Figure 3 is a schematic diagram of a fault sequence component current calculation method in an embodiment of the present application; Figure 4 is a schematic diagram of a fault negative sequence component network in an embodiment of the present application; Figure 5 is a schematic diagram of a fault zero sequence component network in an embodiment of the present application; Figure 6 is a schematic diagram of a fault sequence component current calculation device in an embodiment of the present application; Figure 7 is an internal structure diagram of a computer device in some embodiments. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0021] Under the background of energy transformation today, new energy power generation technologies such as wind energy and solar energy are developing rapidly. Large-scale new energy systems are connected to the power grid through AC transmission lines, which has become a typical operating scenario of modern power systems. However, there are fundamental differences between new energy power generation units and traditional synchronous generators in terms of fault characteristics, which mainly stem from the complex control mechanism of the converter. The fault positive sequence component network model widely used in fault analysis of traditional power systems is based on the characteristics of synchronous generators, but in new energy grid-connected systems, especially when the positive and negative sequence impedances differ significantly, this model is no longer applicable. That is, the existing fault positive sequence component network fails to fully consider the unique characteristics of new energy grid-connected systems, making it difficult to accurately describe their dynamic behavior in fault operating states, and thus severely limiting the accuracy of fault analysis, which cannot meet the needs of safe and stable operation of power systems and accurate fault analysis.

[0022] To solve the above problems, the application provides a fault positive sequence component network and a fault sequence component current calculation method. By introducing a voltage-controlled voltage source into the fault positive sequence component network, a fault positive sequence component network suitable for a new energy grid-connected system is constructed, which provides a new and effective way for protection design and fault analysis of the new energy grid-connected system, significantly improves the accuracy of fault analysis, effectively ensures the safe and stable operation of the new energy grid-connected system, and lays a solid foundation for reliable power supply and efficient management of the power system. The specific implementation principle will be described in detail in the following embodiments.

[0023] Referring to Figure 1 , a schematic diagram of a new energy grid-connected system in an embodiment of the application is shown, which includes a new energy side and a grid side; wherein, is an equivalent source impedance of the new energy side, is an equivalent line impedance between a protection installation position and a fault point of the new energy side, is an equivalent line impedance between the protection installation position and the fault point of the grid side, is an equivalent source impedance of the grid side, is an equivalent line impedance of the new energy grid-connected system, , , are A phase, B phase and C phase respectively, and the schematic diagram shows that a single-phase ground fault occurs in the A phase of the new energy grid-connected system.

[0024] In a first aspect, the application provides a fault positive sequence component network.

[0025] Referring to Figure 2 , a schematic diagram of a fault positive sequence component network in an embodiment of the application is shown, which includes an equivalent positive sequence source potential , an equivalent positive sequence source impedance and an equivalent positive sequence line impedance between a protection installation position and a fault point of a new energy side in a new energy grid-connected system, and an equivalent positive sequence source potential , an equivalent positive sequence source impedance and an equivalent positive sequence line impedance between the protection installation position and the fault point of a grid side in the new energy grid-connected system, and an equivalent positive sequence voltage at the fault point, and a voltage-controlled voltage source .

[0026] In a feasible implementation manner, the equivalent positive sequence source potential , the equivalent positive sequence source impedance and the equivalent positive sequence line impedance of the new energy side, the equivalent positive sequence line impedance , equivalent positive sequence source impedance and equivalent positive sequence source potential , voltage-controlled voltage source , equivalent positive sequence source potential on the new energy side , equivalent positive sequence line impedance on the new energy side in series connection and equivalent positive sequence line impedance on the grid side , connection point between voltage-controlled voltage source and equivalent positive sequence source potential on the grid side are connected with equivalent positive sequence voltage .

[0027] For the construction mode of the fault positive sequence component network, in some embodiments, the new energy grid-connected system can be equivalently analyzed from the fault point of the new energy grid-connected system to construct the fault positive sequence component network.

[0028] In the embodiments of the present application, by introducing the voltage-controlled voltage source into the fault positive sequence component network, a fault positive sequence component network suitable for the new energy grid-connected system is constructed, which provides a new and effective way for protection design and fault analysis of the new energy grid-connected system, significantly improves the accuracy of fault analysis, effectively guarantees the safe and stable operation of the new energy grid-connected system, and lays a solid foundation for reliable power supply and efficient management of the power system.

[0029] In addition, in addition to the above-mentioned beneficial effects, the fault positive sequence component network also has the following advantages: enhancing system adaptability: better adapt to the development trend of power system with increasing proportion of new energy power generation, with large-scale access of wind energy, solar energy and other new energy to the power grid, the problem of fault analysis caused by the difference between its characteristics and traditional synchronous generator becomes more prominent, this application provides an effective means to solve this problem, so that the power system can more calmly accept new energy, and promote the smooth progress of energy transformation; optimizing protection strategy: accurate fault analysis helps to optimize the protection strategy of new energy grid-connected system, based on more accurate fault positive sequence component network, more sensitive and reliable protection devices can be designed, reducing the occurrence of misoperation and refusal to act, improving the correct action rate of protection, thereby further ensuring the safe and stable operation of the power system; reducing operation and maintenance cost: improving fault analysis accuracy can more accurately locate fault location and judge fault type, which helps to quickly repair faults, shorten power outage time, reduce equipment damage and power loss caused by faults, which not only improves the power supply reliability of the power system, but also reduces the operation and maintenance cost of the power enterprise and improves the economic benefit; promote new energy consumption: reliable safe and stable operation guarantee and accurate fault analysis can help improve the grid's acceptance capacity of new energy generation, reduce the power cut of new energy generation caused by inaccurate fault analysis, thereby promoting the full consumption of new energy, improving energy utilization efficiency, and promoting the widespread application of clean energy; support the construction of smart grid: provide technical support for the development of smart grid, which requires high automation, informatization and interactivity, accurate fault analysis and reliable system operation are the basis for achieving these goals, this application helps to improve the intelligent level of the power system and promote the construction and development of smart grid; improve the industry technology level: this innovation provides a new idea for the research and practice of new energy grid-connected field, which helps to promote the technical progress of the entire industry in fault analysis, protection design and other aspects, and improves China's international competitiveness in the field of new energy power.

[0030] In a feasible implementation manner, in the case that the fault positive sequence component network is used for fault analysis of single-phase ground fault, the expression of the voltage-controlled voltage source is: ; wherein, , , , , , ; In the above formula, is the voltage value of the voltage-controlled voltage source, is the pre-fault voltage at the fault point, is the equivalent positive sequence impedance of the new energy grid-connected system, An equivalent negative sequence impedance for a new energy grid-connected system, An equivalent zero sequence impedance for a new energy grid-connected system, An equivalent positive sequence source impedance on the new energy side, An equivalent positive sequence line impedance for a new energy grid-connected system, An equivalent positive sequence source impedance on the grid side, An equivalent positive sequence line impedance on the new energy side, An equivalent positive sequence line impedance on the grid side, An equivalent negative sequence source impedance on the new energy side, An equivalent negative sequence line impedance for a new energy grid-connected system, An equivalent negative sequence source impedance on the grid side, An equivalent negative sequence line impedance on the new energy side, An equivalent negative sequence line impedance on the grid side, An equivalent zero sequence source impedance on the new energy side, An equivalent zero sequence line impedance for a new energy grid-connected system, An equivalent zero sequence source impedance on the grid side, An equivalent zero sequence line impedance on the new energy side, An equivalent zero sequence line impedance on the grid side.

[0031] In the embodiments of the present application, an accurate voltage-controlled voltage source expression is provided for single-phase ground fault analysis of a new energy grid-connected system, and the accuracy and reliability of fault analysis are significantly improved.

[0032] Understandably, this model offers several advantages: First, it accurately reflects fault characteristics. The expression comprehensively considers numerous parameters in the renewable energy grid-connected system, including positive-sequence, negative-sequence, and zero-sequence power supply impedances and line impedances on both the renewable energy side and the grid side. In single-phase ground fault analysis, it accurately reflects the impact of the differences in characteristics between renewable energy generation and traditional synchronous generators on the fault, overcoming the limitations of traditional models in renewable energy grid-connected systems. Second, it improves fault analysis accuracy. By incorporating key factors such as the pre-fault voltage and the equivalent impedances of each sequence in the system into the expression, the calculated voltage-controlled voltage source voltage value can be used for fault positive-sequence component network analysis, enabling more accurate determination of the fault location and type, significantly improving the accuracy of fault analysis. Third, it ensures safe and stable system operation. Accurate fault analysis results help power system protection devices operate more promptly and accurately. In the event of a single-phase ground fault, it can quickly disconnect the faulty portion, preventing the fault from escalating. This approach reduces the impact on renewable energy grid-connected systems and the entire power system, effectively ensuring the safe and stable operation of renewable energy grid-connected systems and providing a solid guarantee for reliable power supply. It also optimizes protection design: this expression provides important theoretical basis for the protection design of renewable energy grid-connected systems. Based on accurate fault analysis results, protection strategies and device parameters that better meet the actual needs of renewable energy grid-connected systems can be designed, improving the sensitivity and selectivity of protection devices, reducing false trips and failures to operate, and further enhancing the operational reliability of the power system. Furthermore, it promotes renewable energy consumption: reliable fault analysis and protection design can enhance the grid's capacity to accept renewable energy generation, reducing power curtailment caused by inaccurate fault analysis, enabling renewable energy generation to be more fully integrated into the grid and consumed, improving energy utilization efficiency, promoting the widespread application of clean energy, and facilitating the smooth progress of energy transformation.

[0033] In one feasible implementation, when the fault positive sequence component network is used for fault analysis of two-phase phase-to-phase short circuits, the expression for the voltage-controlled voltage source is: ; in, , , , ; In the above formula, This refers to the voltage value of the voltage-controlled voltage source. This represents the pre-fault voltage at the fault point. The equivalent positive sequence impedance of the new energy grid-connected system. The equivalent negative sequence impedance of the new energy grid-connected system. This represents the equivalent positive-sequence power supply impedance on the new energy side. This refers to the equivalent positive-sequence line impedance of a new energy grid-connected system. This represents the equivalent positive-sequence source impedance on the grid side. equivalent positive sequence line impedance on the new energy side, equivalent positive sequence line impedance on the grid side, equivalent negative sequence source impedance on the new energy side, equivalent negative sequence line impedance of the new energy grid-connected system, equivalent negative sequence source impedance on the grid side, equivalent negative sequence line impedance on the new energy side, equivalent negative sequence line impedance on the grid side.

[0034] In the embodiments of the present application, a precise voltage-controlled voltage source expression is provided for two-phase interphase short-circuit fault analysis of the new energy grid-connected system, greatly improving the accuracy and reliability of fault analysis.

[0035] It can be understood that the fault characteristics are accurately reflected: the expression comprehensively covers the key parameters such as positive sequence and negative sequence source impedance and line impedance on the new energy side and the grid side in the new energy grid-connected system, and can accurately present the influence of the difference between new energy generation and traditional synchronous generator characteristics on the fault during two-phase interphase short-circuit fault analysis, effectively overcoming the limitations of traditional models in the new energy grid-connected system, providing a more practical basis for fault analysis; improve the accuracy of fault analysis: important factors such as pre-fault voltage and system positive sequence and negative sequence equivalent impedance are included in the expression, so that the voltage value of the voltage-controlled voltage source calculated by the expression can carry out fault positive sequence component network analysis, which can more accurately determine the fault location and fault type, significantly improve the accuracy of fault analysis, and meet the demand of power system for accurate fault analysis; ensure safe and stable operation of the system: accurate fault analysis results help the protection device of the power system to act in time and accurately, and when two-phase interphase short-circuit occurs, the protection device can quickly cut off the fault part to prevent the fault from expanding, reduce the impact on the new energy grid-connected system and the entire power system, and effectively ensure the safe and stable operation of the new energy grid-connected system, laying a solid foundation for reliable power supply of the power system; optimize protection design: the expression provides important theoretical support for the protection design of the new energy grid-connected system, based on the accurate fault analysis results, the protection strategy and device parameters that meet the actual needs of the new energy grid-connected system can be designed, the sensitivity and selectivity of the protection device are improved, the probability of misoperation and refusal to act is reduced, and the operation reliability of the power system is further improved; promote new energy consumption: reliable fault analysis and protection design can improve the accommodation capacity of the power grid for new energy generation, reduce the power cut of new energy generation due to inaccurate fault analysis, make new energy generation more fully connected to the power grid and consumed, improve energy utilization efficiency, promote the widespread application of clean energy, and promote the smooth progress of energy transformation.

[0036] In a feasible implementation, in the case of using the fault positive sequence component network for fault analysis of two-phase ground fault, the expression of the voltage-controlled voltage source is: ; wherein, , , , , , ; In the above formula, is the voltage value of the voltage-controlled voltage source, is the pre-fault voltage at the fault point, is the equivalent positive sequence impedance of the new energy grid-connected system, is the equivalent negative sequence impedance of the new energy grid-connected system, is the equivalent zero sequence impedance of the new energy grid-connected system, is the equivalent positive sequence source impedance on the new energy side, is the equivalent positive sequence line impedance of the new energy grid-connected system, is the equivalent positive sequence source impedance on the grid side, is the equivalent positive sequence line impedance on the new energy side, is the equivalent positive sequence line impedance on the grid side, is the equivalent negative sequence source impedance on the new energy side, is the equivalent negative sequence line impedance of the new energy grid-connected system, is the equivalent negative sequence source impedance on the grid side, is the equivalent negative sequence line impedance on the new energy side, is the equivalent negative sequence line impedance on the grid side, is the equivalent zero sequence source impedance on the new energy side, is the equivalent zero sequence line impedance of the new energy grid-connected system, is the equivalent zero sequence source impedance on the grid side, is the equivalent zero sequence line impedance on the new energy side, is the equivalent zero sequence line impedance on the grid side.

[0037] In the embodiments of the present application, a precise voltage-controlled voltage source expression is provided for two-phase ground fault analysis of the new energy grid-connected system, greatly improving the accuracy and reliability of fault analysis, effectively ensuring the safe and stable operation of the new energy grid-connected system, and promoting energy transformation and smart grid construction.

[0038] It can be understood that the fault characteristics are accurately reflected: the expression comprehensively considers many parameters such as positive sequence, negative sequence and zero sequence power source impedance and line impedance on the new energy side and the grid side in the new energy grid-connected system, can accurately present the influence of the difference between the new energy generation and the traditional synchronous generator characteristics on the fault in the two-phase ground fault analysis, effectively overcomes the limitations of the traditional model in the new energy grid-connected system, and provides a more practical basis for fault analysis; improve the accuracy of fault analysis: important factors such as pre-fault voltage and system positive sequence, negative sequence and zero sequence equivalent impedance are included in the expression, so that the voltage value of the voltage-controlled voltage source calculated by the voltage-controlled voltage source can more accurately determine the fault location and fault type, significantly improve the accuracy of fault analysis, and meet the demand of power system for accurate fault analysis; ensure the safe and stable operation of the system: accurate fault analysis results help the protection device of the power system to act in time and accurately, and when two-phase ground fault occurs, the protection device can quickly cut off the fault part to prevent the fault from expanding, reduce the impact on the new energy grid-connected system and the entire power system, and effectively ensure the safe and stable operation of the new energy grid-connected system, laying a solid foundation for reliable power supply of the power system; optimize protection design: the expression provides important theoretical support for the protection design of the new energy grid-connected system, based on the accurate fault analysis results, the protection strategy and device parameters that meet the actual needs of the new energy grid-connected system can be designed, the sensitivity and selectivity of the protection device are improved, the probability of misoperation and refusal to act is reduced, and the operation reliability of the power system is further improved; promote new energy consumption and energy transformation: reliable fault analysis and protection design can improve the accommodation capacity of the power grid to new energy generation, reduce the power cut of new energy generation caused by inaccurate fault analysis, make new energy generation more fully connected to the power grid and consumed, improve energy utilization efficiency, promote the widespread application of clean energy, and promote the smooth progress of energy transformation; support the construction of smart grid: provide technical support for the development of smart grid, smart grid requires high automation, informatization and interactivity level, accurate fault analysis and reliable system operation are the basis for achieving these goals, and the present application helps to improve the intelligent level of the power system and promote the construction and development of smart grid.

[0039] In a feasible implementation manner, in the case that the fault positive sequence component network is used for fault analysis of three-phase short circuit, the expression of the voltage-controlled voltage source is: ; In the above formula, is the voltage value of the voltage-controlled voltage source.

[0040] In the embodiments of the present application, reasonable basis is provided for three-phase short circuit fault analysis, the stable operation of the system is ensured, and the related development is promoted.

[0041] It can be understood that the analysis rationality is guaranteed: since there is no negative sequence component during the three-phase short-circuit fault, there is no need to add the voltage-controlled voltage source introduced by the difference between the positive and negative sequence impedances, at this time the voltage value of the voltage-controlled voltage source is 0, which meets the characteristics of the three-phase short-circuit fault, provides a reasonable model basis for fault analysis, and makes the analysis result more accurately reflect the actual situation; the safe and stable operation of the system is guaranteed: based on the reasonable fault analysis, the protection device of the power system can more accurately judge the fault condition, act in time and accurately when the three-phase short-circuit occurs, quickly cut off the fault part, prevent the fault from expanding, reduce the impact on the new energy grid-connected system and the entire power system, and effectively guarantee the safe and stable operation of the new energy grid-connected system, laying a solid foundation for the reliable power supply of the power system; the protection design is optimized: this case provides an important reference for the protection design of the new energy grid-connected system, based on accurate fault analysis, the protection strategy and device parameters that meet the actual needs of the new energy grid-connected system can be designed, the sensitivity and selectivity of the protection device are improved, the probability of misoperation and refusal to act is reduced, and the operation reliability of the power system is further improved; promote new energy consumption and energy transformation: reliable fault analysis and protection design can improve the accommodation capacity of the power grid for new energy generation, reduce the power cut of new energy generation caused by inaccurate fault analysis, make new energy generation more fully connected to the power grid and consumed, improve energy utilization efficiency, promote the widespread application of clean energy, and promote the smooth progress of energy transformation; support the construction of smart grid: provide technical support for the development of smart grid, accurate fault analysis and reliable system operation are the basis for realizing the high automation, informatization and interactivity level of smart grid, this case helps to improve the intelligent level of the power system and promote the construction and development of smart grid.

[0042] The application provides a fault sequence component current calculation method in a second aspect.

[0043] Please refer to Figure 3 , which is a schematic diagram of a fault sequence component current calculation method in an embodiment of the application. The method comprises the following steps. Step 310: performing equivalent analysis on the new energy grid-connected system from the fault point of the new energy grid-connected system to construct a fault negative sequence component network and a fault zero sequence component network.

[0044] It should be noted that no voltage-controlled voltage source is introduced for the fault negative sequence component network and the fault zero sequence component network, therefore, the specific construction method of the fault negative sequence component network and the fault zero sequence component network can use the existing fault negative sequence component network and fault zero sequence component network construction method in some embodiments, which is not limited here.

[0045] Step 320: according to the fault positive sequence component network, and the fault negative sequence component network and the fault zero sequence component network as any one of the first aspect, respectively, the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression of the new energy grid-connected system are established.

[0046] It should be noted that the fault X sequence component network is equivalent to a circuit, and therefore, for the establishment method of the fault X sequence component current expression, in some embodiments, in the case where the fault X sequence component network is known, the fault X sequence component network can be directly written according to the circuit analysis basic law (such as Kirchhoff's voltage law, Kirchhoff's current law) according to the fault X sequence component network, and the equation corresponding to the fault X sequence component network is written, which is the required fault X sequence component current expression; wherein X takes positive, negative, zero in turn.

[0047] Step 330: according to the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression, the fault sequence current calculation data of the new energy grid-connected system is obtained.

[0048] It should be noted that according to the fault X sequence component current expression, it can be determined which parameters are required for calculating the fault X sequence component current, and therefore, in some embodiments, all parameters in the fault X sequence component current expression except the fault X sequence component current can be used as the fault sequence current calculation data; wherein X takes positive, negative, zero in turn.

[0049] Step 340: according to the fault sequence current calculation data, the fault positive sequence component current, the fault negative sequence component current and the fault zero sequence component current of the new energy grid-connected system are calculated respectively by using the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression.

[0050] For the calculation method of the fault X sequence component current, in some embodiments, according to the fault X sequence component current expression, a plurality of corresponding parameters can be obtained from the fault X sequence current calculation data, and then the plurality of corresponding parameters are substituted into the fault X sequence component current expression to calculate the fault X sequence component current; wherein X takes positive, negative, zero in turn.

[0051] In the embodiments of the present application, the calculation accuracy of the fault sequence component current of the new energy grid-connected system is improved, which provides reliable support for the safe and stable operation of the system.

[0052] It can be understood that the calculation accuracy is improved: the fault positive sequence component network of the application fully considers the different characteristics of the new energy side and the grid side under the fault state by introducing the voltage-controlled voltage source, overcomes the problem of ignoring the unique positive and negative sequence impedance difference of the new energy grid-connected system in the traditional method, can more accurately calculate the fault sequence component current, and makes the calculation result closer to the actual situation; guarantee the safe and stable operation of the system: the accurate fault sequence component current calculation result provides more reliable theoretical basis and calculation support for relay protection optimization, fault diagnosis and power grid stability analysis, based on these accurate data, the protection device of the power system can act more timely and accurately, quickly cut off the fault part, prevent the fault from expanding, reduce the impact on the new energy grid-connected system and the whole power system, and effectively guarantee the safe and stable operation of the new energy grid-connected system, and lay a solid foundation for the reliable power supply of the power system; optimize the protection design: based on the accurate fault sequence component current calculation result, the protection strategy and device parameter that can meet the actual demand of the new energy grid-connected system can be designed, the sensitivity and selectivity of the protection device are improved, the probability of misoperation and refusal to act is reduced, and the operation reliability of the power system is further improved; promote new energy consumption and energy transformation: reliable fault analysis and protection design can improve the accommodation capacity of the power grid to new energy generation, reduce the power cut of new energy generation caused by inaccurate fault analysis, make new energy generation more fully connected to the power grid and consumed, improve energy utilization efficiency, promote the widespread application of clean energy, and promote the smooth progress of energy transformation; support the construction of smart grid: provide technical support for the development of smart grid, smart grid requires high automation, informatization and interactivity level, accurate fault analysis and reliable system operation are the basis for achieving these goals, the application helps to improve the intelligent level of the power system and promote the construction and development of smart grid.

[0053] In a feasible implementation manner, the fault positive sequence component current expression in the above embodiment is: ; Among them, is the fault positive sequence component current of the new energy grid-connected system, is the fault positive sequence component current of the new energy side, is the fault positive sequence component current of the grid side, is the pre-fault voltage at the fault point, is the voltage value of the voltage-controlled voltage source, is the equivalent positive sequence source impedance of the new energy side, is the equivalent positive sequence line impedance of the new energy grid-connected system, is the equivalent positive sequence source impedance of the grid side.

[0054] It should be noted that for the value of the voltage value of the voltage-controlled voltage source, the above expression of the voltage-controlled voltage source can be used for calculation according to different fault types, which will not be described here.

[0055] In the embodiments of the present application, the consideration of the voltage-controlled voltage source makes the fault positive sequence component current calculation more accurate, fully reflects the fault characteristics of the new energy grid-connected system, and provides reliable support for the safe and stable operation of the system.

[0056] It can be understood that the fault characteristics are accurately reflected: the expression fully considers the positive sequence source impedance, line impedance and pre-fault voltage of the new energy side and the grid side by introducing the voltage-controlled voltage source, can accurately present the influence of the difference between new energy power generation and traditional synchronous generator characteristics on the fault positive sequence component current, and overcomes the limitations of traditional models in new energy grid-connected systems, providing a more practical basis for fault analysis; improve the calculation accuracy: important factors such as pre-fault voltage, voltage value of voltage-controlled voltage source and system positive sequence equivalent impedance are included in the expression, so that the calculated fault positive sequence component current is closer to the real fault condition, significantly improving the calculation accuracy of the fault positive sequence component current, meeting the demand of power system for accurate fault analysis; guarantee the safe and stable operation of the system: accurate fault positive sequence component current calculation results provide reliable theoretical basis and calculation support for relay protection optimization, fault diagnosis and power grid stability analysis, based on these accurate data, the protection device of the power system can act more timely and accurately, quickly cut off the fault part, prevent the fault from expanding, reduce the impact on the new energy grid-connected system and the entire power system, and effectively guarantee the safe and stable operation of the new energy grid-connected system, laying a solid foundation for reliable power supply of the power system; optimize protection design: based on the accurate fault positive sequence component current calculation results, more suitable protection strategies and device parameters for the actual needs of the new energy grid-connected system can be designed, the sensitivity and selectivity of the protection device are improved, the probability of misoperation and refusal to act is reduced, and the operation reliability of the power system is further improved; promote new energy consumption and energy transformation: reliable fault analysis and protection design can improve the accommodation capacity of the power grid for new energy power generation, reduce the power cut of new energy power generation due to inaccurate fault analysis, make new energy power generation more fully connected to the grid and consumed, improve energy utilization efficiency, promote the widespread application of clean energy, and promote the smooth progress of energy transformation; support the construction of smart grid: provide technical support for the development of smart grid, smart grid requires high automation, informatization and interactivity, accurate fault analysis and reliable system operation are the basis for achieving these goals, the present application helps to improve the intelligent level of the power system and promote the construction and development of smart grid.

[0057] In a feasible implementation manner, the fault negative sequence component current expression in the above embodiment is: ; wherein, is the fault negative sequence component current of the new energy grid-connected system, is the fault negative sequence component current of the new energy side, is the fault negative sequence component current of the grid side, is the pre-fault voltage at the fault point, is the equivalent negative sequence line impedance of the new energy grid-connected system, is the equivalent negative sequence source impedance of the grid side.

[0058] In the embodiments of the present application, by accurately calculating the fault negative sequence component current, the fault characteristics of the new energy grid-connected system are comprehensively reflected, and the fault diagnosis accuracy is significantly improved.

[0059] It can be understood that accurately reflecting the fault characteristics: the expression comprehensively considers the negative sequence source impedance and line impedance of the new energy side and the grid side, accurately presents the suppression effect of new energy generation on the fault negative sequence component current and the actual influence of the grid side fault negative sequence component current, and overcomes the limitation of traditional methods that ignore the grid side fault negative sequence component current (i.e. the grid side fault negative sequence component current is actually not 0), providing a more realistic basis for fault analysis; improving the accuracy of fault diagnosis: by including the pre-fault voltage and the system negative sequence equivalent impedance in the calculation, the calculation result of the fault negative sequence component current is closer to the true value, especially under complex fault types, significantly improving the accuracy of fault diagnosis, meeting the demand of power system for accurate fault analysis; ensuring safe and stable operation of the system: accurate calculation of the fault negative sequence component current provides reliable data support for the relay protection device, enabling it to act more timely and accurately, quickly cutting off the fault part, preventing the expansion of the fault, reducing the impact on the new energy grid-connected system and the entire power system, and effectively ensuring the safe and stable operation of the system; optimizing protection design: based on the accurate calculation result of the fault negative sequence component current, more suitable protection strategies and device parameters for the actual needs of the new energy grid-connected system can be designed, improving the sensitivity and selectivity of the protection device, reducing the probability of misoperation and refusal to act, and further improving the operation reliability of the power system; promoting new energy consumption and energy transformation: reliable fault analysis and protection design improve the grid's acceptance of new energy generation, reduce the power limit caused by inaccurate fault analysis, enable new energy generation to be more fully connected to the grid and consumed, improve energy utilization efficiency, and promote the widespread application of clean energy and the smooth progress of energy transformation; supporting the construction of smart grid: providing technical support for the development of smart grid, which requires a high level of automation, informatization and interactivity, accurate fault analysis and reliable system operation are the basis for achieving these goals, and the present application helps to improve the intelligent level of the power system and promote the construction and development of smart grid.

[0060] In a feasible implementation, the fault zero-sequence component current expression in the above embodiment is: ; wherein, is a fault zero-sequence component current of the new energy grid-connected system, is a fault zero-sequence component current of the new energy side, is a fault zero-sequence component current of the grid side, is a pre-fault voltage at the fault point, is an equivalent zero-sequence source impedance of the new energy side, is an equivalent zero-sequence line impedance of the new energy grid-connected system, is an equivalent zero-sequence source impedance of the grid side.

[0061] In the embodiments of the present application, the fault zero-sequence component current is accurately calculated, the fault characteristics of the new energy grid-connected system are comprehensively reflected, and the fault analysis reliability is significantly improved.

[0062] It can be understood that the fault characteristics are accurately reflected: the expression comprehensively considers the zero sequence source impedance and line impedance of the new energy side and the grid side, accurately presents the inhibition of new energy generation on the zero sequence current and the actual influence of the grid side zero sequence current, overcomes the limitation of traditional methods ignoring the grid side zero sequence current, and provides a more realistic basis for ground fault analysis; improve the reliability of fault analysis: by including the pre-fault voltage and system zero sequence equivalent impedance in the calculation, the calculation result of the fault zero sequence component current is closer to the true value, especially in complex ground fault types, which significantly improves the reliability of fault analysis and meets the demand of power system for accurate fault analysis; ensure the safe and stable operation of the system: accurate fault zero sequence component current calculation provides reliable data support for relay protection devices, enabling them to act more timely and accurately, quickly cut off the fault part, prevent the fault from expanding, reduce the impact on the new energy grid-connected system and the entire power system, and effectively ensure the safe and stable operation of the system; optimize protection design: based on the accurate fault zero sequence component current calculation result, more accurate protection strategies and device parameters that meet the actual needs of the new energy grid-connected system can be designed, the sensitivity and selectivity of the protection device are improved, the probability of misoperation and refusal to act is reduced, and the operation reliability of the power system is further improved; promote new energy consumption and energy transformation: reliable fault analysis and protection design improve the grid's acceptance of new energy generation, reduce the power limit caused by inaccurate fault analysis, enable new energy generation to be more fully connected to the grid and consumed, improve energy utilization efficiency, and promote the widespread application of clean energy and the smooth progress of energy transformation; support the construction of smart grid: provide technical support for the development of smart grid, which requires a high level of automation, informatization and interactivity. Accurate fault analysis and reliable system operation are the basis for achieving these goals. The present application helps to improve the intelligent level of the power system and promote the construction and development of the smart grid.

[0063] Please refer to Figure 4 , which is a schematic diagram of the fault negative sequence component network in the embodiment of the present application. The fault negative sequence component network includes the equivalent negative sequence source impedance of the new energy side and the equivalent negative sequence line impedance between the protection installation and the fault point , the equivalent negative sequence source impedance of the grid side and the equivalent negative sequence line impedance between the protection installation and the fault point , and the equivalent negative sequence voltage at the fault point .

[0064] In a feasible implementation manner, the equivalent negative sequence source impedance of the new energy side and the equivalent negative sequence line impedance , the equivalent negative sequence line impedance of the grid side and the equivalent negative sequence source impedance Equivalent negative sequence power supply impedance on the new energy side The equivalent negative sequence line impedance on the new energy side is connected in series. Equivalent negative sequence line impedance to the grid side Connection points between them, equivalent negative sequence power supply impedance on the new energy side Equivalent negative sequence power supply impedance to the grid side The connection points between them are all connected to the equivalent negative sequence voltage. Connection, where the equivalent negative sequence power supply impedance on the new energy side It is in an open circuit state.

[0065] In this embodiment, by accurately constructing a fault negative-order component network, the fault characteristics of the new energy grid-connected system are comprehensively reflected, significantly improving the reliability of fault analysis.

[0066] Understandably, this network structure accurately reflects fault characteristics: it comprehensively considers the negative-sequence power supply impedance and line impedance on both the renewable energy side and the grid side, and explicitly states that the equivalent negative-sequence power supply impedance on the renewable energy side is in an open-circuit state. This accurately presents the suppression effect of renewable energy generation on the fault negative-sequence component current and the actual impact of the grid-side fault negative-sequence component current, overcoming the limitations of traditional methods that ignore the grid-side fault negative-sequence component current, thus providing a more realistic basis for fault analysis. It also improves the reliability of fault analysis: by constructing a complete fault negative-sequence component network and combining it with the actual characteristics of the renewable energy grid-connected system, the calculated results of the fault negative-sequence component current are closer to the true value. Especially under complex fault types, it significantly improves the reliability of fault analysis, meeting the power system's need for accurate fault analysis. Furthermore, it ensures the safe and stable operation of the system: accurate fault negative-sequence component current analysis provides reliable data support for relay protection devices, enabling them to act more promptly and accurately, quickly disconnecting the faulty part, preventing the fault from escalating, and reducing the impact on the renewable energy grid-connected system and the entire system. The impact on the power system effectively ensured the safe and stable operation of the system; optimized protection design: based on the accurate fault negative sequence component network, protection strategies and device parameters that better meet the actual needs of the renewable energy grid-connected system can be designed, improving the sensitivity and selectivity of protection devices, reducing the probability of false operation and failure to operate, and further enhancing the operational reliability of the power system; promoted renewable energy consumption and energy transition: reliable fault analysis and protection design improved the grid's ability to accept renewable energy generation, reduced power curtailment caused by inaccurate fault analysis, enabled renewable energy generation to be more fully connected to the grid and consumed, improved energy utilization efficiency, and promoted the widespread application of clean energy and the smooth progress of energy transition; supported the construction of smart grids: provided technical support for the development of smart grids. Smart grids require a high level of automation, informatization, and interactivity. Accurate fault analysis and reliable system operation are the foundation for achieving these goals. This application helps to improve the intelligence level of the power system and promote the construction and development of smart grids.

[0067] Please see Figure 5 This is a schematic diagram of the fault zero-sequence component network in an embodiment of this application. The fault zero-sequence component network includes the equivalent zero-sequence power supply impedance on the new energy side. The equivalent zero-sequence line impedance between the protection installation point and the fault point and the equivalent zero-sequence power supply impedance on the grid side The equivalent zero-sequence line impedance between the protection installation point and the fault point and the equivalent zero-sequence voltage at the fault point .

[0068] In one feasible implementation, the equivalent zero-sequence power supply impedance on the new energy side... and equivalent zero-sequence line impedance Equivalent zero-sequence line impedance on the power grid side and equivalent zero-sequence source impedance Equivalent zero-sequence power supply impedance on the new energy side The equivalent zero-sequence line impedance on the new energy side is connected in series. Equivalent zero-sequence line impedance to the grid side Connection points between them, equivalent zero-sequence power supply impedance on the new energy side Equivalent zero-sequence power supply impedance to the grid side The connection points between them are all connected to the equivalent zero-sequence voltage. connect.

[0069] In this embodiment, by accurately constructing a fault zero-sequence component network, the characteristics of grounding faults in the new energy grid-connected system are fully reflected, significantly improving the reliability of fault analysis.

[0070] Understandably, this network structure accurately reflects fault characteristics: it comprehensively considers the zero-sequence power supply impedance and line impedance on both the renewable energy side and the grid side, accurately presenting the suppression effect of renewable energy generation on zero-sequence current and the actual impact of grid-side zero-sequence current. This overcomes the limitations of traditional methods that ignore grid-side zero-sequence current, providing a more realistic basis for ground fault analysis. It also improves the reliability of fault analysis: by constructing a complete fault zero-sequence component network and combining it with the actual characteristics of the renewable energy grid-connected system, the calculated results of the fault zero-sequence component current are closer to the true value. Especially under complex ground fault types, it significantly improves the reliability of fault analysis, meeting the power system's need for accurate fault analysis. Furthermore, it ensures the safe and stable operation of the system: accurate fault zero-sequence current analysis provides reliable data support for relay protection devices, enabling them to act more promptly and accurately, quickly disconnecting the faulty part, preventing fault expansion, reducing the impact on the renewable energy grid-connected system and the entire power system, and effectively protecting the system. The application provides the following benefits: Safe and stable operation; optimized protection design: Based on accurate fault zero-sequence component networks, protection strategies and device parameters that better meet the actual needs of new energy grid-connected systems can be designed, improving the sensitivity and selectivity of protection devices, reducing the probability of maloperation and failure to operate, and further enhancing the operational reliability of the power system; Promotes new energy consumption and energy transition: Reliable fault analysis and protection design enhance the grid's capacity to accept new energy generation, reducing power curtailment caused by inaccurate fault analysis, enabling new energy generation to be more fully integrated into the grid and consumed, improving energy utilization efficiency, and promoting the widespread application of clean energy and the smooth progress of energy transition; Supports smart grid construction: Provides technical support for the development of smart grids. Smart grids require a high level of automation, informatization, and interactivity. Accurate fault analysis and reliable system operation are the foundation for achieving these goals. This application helps to improve the intelligence level of the power system and promote the construction and development of smart grids.

[0071] This application provides a fault sequence component current calculation device in a third aspect.

[0072] Please see Figure 6 This is a schematic diagram of a fault sequence component current calculation device according to an embodiment of this application. The device 610 includes: The network construction module 611 is used to perform equivalent analysis on the new energy grid-connected system from the fault point of the new energy grid-connected system, so as to construct the fault negative sequence component network and the fault zero sequence component network. The expression establishment module 612 is used to establish the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression of the new energy grid-connected system according to the fault positive sequence component network, the fault negative sequence component network and the fault zero sequence component network as in any of the first aspects. The data acquisition module 613 is used to acquire fault sequence current calculation data of the new energy grid-connected system based on the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression. The current calculation module 614 is used to calculate the fault positive-sequence current, fault negative-sequence current, and fault zero-sequence current of the new energy grid-connected system based on the fault sequence current calculation data, using the fault positive-sequence current expression, fault negative-sequence current expression, and fault zero-sequence current expression.

[0073] In this embodiment of the application, the relevant contents of the network construction module 611, expression establishment module 612, data acquisition module 613 and current calculation module 614 can be found in the following references. Figure 3 The contents of the illustrated embodiments will not be repeated here.

[0074] It should be noted that the device 610 of this application also includes other modules. It is understood that the method of this application and the device 610 have a one-to-one correspondence. Therefore, the other modules of the device 610 of this application are the contents corresponding to the method of this application in the above embodiments.

[0075] In this embodiment of the application, by improving the accuracy of fault sequence component current calculation in the new energy grid-connected system, reliable support is provided for the safe and stable operation of the system.

[0076] Understandably, this application improves calculation accuracy by introducing a voltage-controlled voltage source to fully consider the different characteristics of the renewable energy side and the grid side under fault conditions. This overcomes the problem of traditional devices neglecting the unique positive and negative sequence impedance differences of renewable energy grid-connected systems, enabling more accurate calculation of fault sequence currents and making the calculation results closer to reality. It also ensures safe and stable system operation by providing more reliable theoretical basis and computational support for relay protection optimization, fault diagnosis, and grid stability analysis. Based on this accurate data, power system protection devices can operate more promptly and accurately, quickly disconnecting faulty parts, preventing fault expansion, reducing the impact on renewable energy grid-connected systems and the entire power system, effectively ensuring the safe and stable operation of renewable energy grid-connected systems, and laying a solid foundation for reliable power supply. Furthermore, it optimizes protection design based on accurate fault sequence current calculations. As a result, it is possible to design protection strategies and device parameters that better meet the actual needs of new energy grid-connected systems, improve the sensitivity and selectivity of protection devices, reduce the probability of malfunctions and failures to operate, and further enhance the operational reliability of the power system; promote the consumption of new energy and energy transition: reliable fault analysis and protection design can enhance the grid's capacity to accept new energy generation, reduce power curtailment caused by inaccurate fault analysis, enable new energy generation to be more fully connected to the grid and consumed, improve energy utilization efficiency, promote the widespread application of clean energy, and facilitate the smooth progress of energy transition; support the construction of smart grids: provide technical support for the development of smart grids. Smart grids require a high level of automation, informatization, and interactivity. Accurate fault analysis and reliable system operation are the foundation for achieving these goals. This application helps to improve the intelligence level of the power system and promote the construction and development of smart grids.

[0077] In a fourth aspect, this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform a fault sequence component current calculation method as described in any of the first aspects.

[0078] This application provides a computer device in a fifth aspect, including a memory and a processor, the memory storing a computer program, which, when executed by the processor, causes the processor to perform a fault sequence component current calculation method as described in any of the first aspects.

[0079] Figure 7 The diagram illustrates the internal structure of a computer device in some embodiments. This computer device may specifically be a terminal, a server, or a gateway. Figure 7 As shown, the computer device includes a processor, memory, and network interface connected via a system bus.

[0080] The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When executed by a processor, this computer program causes the processor to perform the steps in the above method embodiments. The internal memory may also store a computer program, which, when executed by a processor, causes the processor to perform the steps in the above method embodiments. Those skilled in the art will understand that... Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0081] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods.

[0082] Any references to memory, storage, database, or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0083] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0084] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A faulty positive-sequence component network, characterized in that, The fault positive sequence component network includes the equivalent positive sequence power supply potential, equivalent positive sequence power supply impedance, and equivalent positive sequence line impedance between the protection installation point and the fault point on the new energy grid-connected system, as well as the equivalent positive sequence power supply potential, equivalent positive sequence power supply impedance, and equivalent positive sequence line impedance between the protection installation point and the fault point on the grid side of the new energy grid-connected system, the equivalent positive sequence voltage at the fault point, and a voltage-controlled voltage source; The equivalent positive sequence power supply potential, equivalent positive sequence power supply impedance, and equivalent positive sequence line impedance on the new energy side, the equivalent positive sequence line impedance, equivalent positive sequence power supply impedance, and equivalent positive sequence power supply potential on the grid side, the voltage-controlled voltage source, and the equivalent positive sequence power supply potential on the new energy side are connected in series. The connection point between the equivalent positive sequence line impedance on the new energy side and the equivalent positive sequence line impedance on the grid side, and the connection point between the voltage-controlled voltage source and the equivalent positive sequence power supply potential on the grid side are all connected to the equivalent positive sequence voltage.

2. The fault-positive component network according to claim 1, characterized in that, When the fault positive sequence component network is used for fault analysis of a single-phase ground fault, the expression for the voltage-controlled voltage source is: ； in, , , , , , ; In the above formula, The voltage value of the voltage-controlled voltage source. The voltage before the fault at the fault point is... Let be the equivalent positive sequence impedance of the new energy grid-connected system. Let be the equivalent negative sequence impedance of the new energy grid-connected system. The equivalent zero-sequence impedance of the new energy grid-connected system is given. Let be the equivalent positive-sequence power supply impedance on the new energy side. Let be the equivalent positive sequence line impedance of the new energy grid-connected system. The equivalent positive-sequence power supply impedance on the grid side is given. The equivalent positive-sequence line impedance on the new energy side is given. This is the equivalent positive-sequence line impedance on the power grid side. The equivalent negative sequence power supply impedance on the new energy side is given. Let be the equivalent negative sequence line impedance of the new energy grid-connected system. The equivalent negative sequence power supply impedance on the grid side is given. This represents the equivalent negative sequence line impedance on the new energy side. This represents the equivalent negative sequence line impedance on the power grid side. Let be the equivalent zero-sequence power supply impedance on the new energy side. Let be the equivalent zero-sequence line impedance of the aforementioned new energy grid-connected system. Let be the equivalent zero-sequence power supply impedance on the grid side. Let be the equivalent zero-sequence line impedance on the new energy side. The equivalent zero-sequence line impedance on the power grid side is given.

3. The fault-positive component network according to claim 1, characterized in that, When the fault positive sequence component network is used for fault analysis of two-phase short circuits, the expression for the voltage-controlled voltage source is: ； in, , , , ; In the above formula, The voltage value of the voltage-controlled voltage source. The voltage before the fault at the fault point is... Let be the equivalent positive sequence impedance of the new energy grid-connected system. Let be the equivalent negative sequence impedance of the new energy grid-connected system. Let be the equivalent positive-sequence power supply impedance on the new energy side. Let be the equivalent positive sequence line impedance of the new energy grid-connected system. The equivalent positive-sequence power supply impedance on the grid side is given. The equivalent positive-sequence line impedance on the new energy side is given. This is the equivalent positive-sequence line impedance on the power grid side. The equivalent negative sequence power supply impedance on the new energy side is given. Let be the equivalent negative sequence line impedance of the new energy grid-connected system. The equivalent negative sequence power supply impedance on the grid side is given. This represents the equivalent negative sequence line impedance on the new energy side. The equivalent negative sequence line impedance on the power grid side.

4. The fault-order component network according to claim 1, characterized in that, When the fault positive sequence component network is used for fault analysis of a two-phase-to-ground short circuit, the expression for the voltage-controlled voltage source is: ； in, , , , , , ; In the above formula, The voltage value of the voltage-controlled voltage source. The voltage before the fault at the fault point is... Let be the equivalent positive sequence impedance of the new energy grid-connected system. Let be the equivalent negative sequence impedance of the new energy grid-connected system. The equivalent zero-sequence impedance of the new energy grid-connected system is given. Let be the equivalent positive-sequence power supply impedance on the new energy side. Let be the equivalent positive sequence line impedance of the new energy grid-connected system. The equivalent positive-sequence power supply impedance on the grid side is given. The equivalent positive-sequence line impedance on the new energy side is given. This is the equivalent positive-sequence line impedance on the power grid side. The equivalent negative sequence power supply impedance on the new energy side is given. Let be the equivalent negative sequence line impedance of the new energy grid-connected system. The equivalent negative sequence power supply impedance on the grid side is given. This represents the equivalent negative sequence line impedance on the new energy side. This represents the equivalent negative sequence line impedance on the power grid side. Let be the equivalent zero-sequence power supply impedance on the new energy side. Let be the equivalent zero-sequence line impedance of the aforementioned new energy grid-connected system. Let be the equivalent zero-sequence power supply impedance on the grid side. Let be the equivalent zero-sequence line impedance on the new energy side. The equivalent zero-sequence line impedance on the power grid side is given.

5. The fault-positive component network according to claim 1, characterized in that, When the fault positive sequence component network is used for fault analysis in a three-phase short circuit, the expression for the voltage-controlled voltage source is: ； In the above formula, The voltage value of the voltage-controlled voltage source.

6. A method for calculating fault sequence component current, characterized in that, The method includes: From the fault point of the new energy grid-connected system, an equivalent analysis is performed on the new energy grid-connected system to construct a fault negative-sequence component network and a fault zero-sequence component network. Based on the fault positive sequence component network as described in any one of claims 1 to 5, and the fault negative sequence component network and the fault zero sequence component network, the fault positive sequence component current expression, the fault negative sequence component current expression and the fault zero sequence component current expression of the new energy grid-connected system are respectively established. Based on the fault positive sequence current expression, the fault negative sequence current expression, and the fault zero sequence current expression, obtain the fault sequence current calculation data of the new energy grid-connected system; Using the expressions for the positive-sequence fault current, the negative-sequence fault current, and the zero-sequence fault current, and based on the fault sequence current calculation data, the positive-sequence fault current, the negative-sequence fault current, and the zero-sequence fault current of the new energy grid-connected system are calculated respectively.

7. The fault sequence component current calculation method according to claim 6, characterized in that, The expression for the fault positive-sequence component current is: ； in, The fault positive sequence component current of the aforementioned new energy grid-connected system. This refers to the fault positive-sequence component current on the new energy side. This refers to the fault positive-sequence component current on the grid side. The voltage before the fault at the fault point is... The voltage value of the voltage-controlled voltage source. Let be the equivalent positive-sequence power supply impedance on the new energy side. Let be the equivalent positive sequence line impedance of the new energy grid-connected system. The equivalent positive-sequence power supply impedance on the grid side is given.

8. The fault sequence component current calculation method according to claim 6, characterized in that, The expression for the fault negative sequence component current is: ； in, The fault negative sequence current of the aforementioned new energy grid-connected system. This refers to the fault negative sequence component current on the new energy side. This refers to the fault negative sequence component current on the grid side. The voltage before the fault at the fault point is... Let be the equivalent negative sequence line impedance of the new energy grid-connected system. The equivalent negative sequence power supply impedance on the grid side is given.

9. The fault sequence component current calculation method according to claim 6, characterized in that, The expression for the zero-sequence component current of the fault is: ； in, The fault zero-sequence component current of the aforementioned new energy grid-connected system. This refers to the fault zero-sequence component current on the new energy side. This refers to the zero-sequence fault component current on the grid side. The voltage before the fault at the fault point is... Let be the equivalent zero-sequence power supply impedance on the new energy side. Let be the equivalent zero-sequence line impedance of the aforementioned new energy grid-connected system. The equivalent zero-sequence power supply impedance on the grid side is given.

10. The fault sequence component current calculation method according to claim 6, characterized in that, The fault negative sequence component network includes the equivalent negative sequence power supply impedance and the equivalent negative sequence line impedance between the protection installation point and the fault point on the new energy side, the equivalent negative sequence power supply impedance and the equivalent negative sequence line impedance between the protection installation point and the fault point on the grid side, and the equivalent negative sequence voltage at the fault point. The equivalent negative sequence power supply impedance and equivalent negative sequence line impedance on the new energy side, the equivalent negative sequence line impedance and equivalent negative sequence power supply impedance on the grid side, and the equivalent negative sequence power supply impedance on the new energy side are connected in series. The connection point between the equivalent negative sequence line impedance on the new energy side and the equivalent negative sequence line impedance on the grid side, and the connection point between the equivalent negative sequence power supply impedance on the new energy side and the equivalent negative sequence power supply impedance on the grid side are all connected to the equivalent negative sequence voltage. The equivalent negative sequence power supply impedance on the new energy side is in an open circuit state. The fault zero-sequence component network includes the equivalent zero-sequence power supply impedance and the equivalent zero-sequence line impedance between the protection installation point and the fault point on the new energy side, the equivalent zero-sequence power supply impedance and the equivalent zero-sequence line impedance between the protection installation point and the fault point on the grid side, and the equivalent zero-sequence voltage at the fault point. The equivalent zero-sequence power supply impedance and equivalent zero-sequence line impedance on the new energy side, the equivalent zero-sequence line impedance and equivalent zero-sequence power supply impedance on the grid side, and the equivalent zero-sequence power supply impedance on the new energy side are connected in series. The connection point between the equivalent zero-sequence line impedance on the new energy side and the equivalent zero-sequence line impedance on the grid side, and the connection point between the equivalent zero-sequence power supply impedance on the new energy side and the equivalent zero-sequence power supply impedance on the grid side are all connected to the equivalent zero-sequence voltage.

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