CN116914701A - Distribution network current protection applicability analysis method and device containing distributed photovoltaic - Google Patents

Abstract

The invention discloses a distribution network current protection applicability analysis method and device containing distributed photovoltaics, and relates to the technical field of current protection applicability analysis. The method includes: establishing a distribution network equivalent circuit according to the actual conditions of the distribution network lines. model; determine the short-circuit current at the beginning of the distribution network line based on the distribution network equivalent circuit model; determine the short-circuit current at the end of the distribution network line based on the distribution network equivalent circuit model; determine the short-circuit current at the beginning end of the distribution network line, distribution network The short-circuit current, setting current value and sensitivity threshold at the end of the distribution network line generate sensitivity analysis results; based on the current value, setting current value and distribution network line at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line The total length and the protection range threshold generate the protection range analysis results. The present invention can realize the applicability analysis of the current protection of the distributed photovoltaic distribution network by calculating the sensitivity and protection range of the current protection.

Description

Applicability analysis method and device for current protection of distribution network including distributed photovoltaics

Technical field

The present invention relates to the technical field of current protection applicability analysis, and in particular to a current protection applicability analysis method and device for a distribution network containing distributed photovoltaics.

Background technique

This section is intended to provide background or context for the embodiments of the invention set forth in the claims. The description herein is not admitted to be prior art by inclusion in this section.

During the construction process of the new power system, it will gradually present the characteristics of high proportion of new energy and high degree of power electronics, which will bring new challenges to the reliable power supply, safety, stability and economic operation of the power grid. Photovoltaic power will be more connected to the distribution network in a distributed, multi-point, decentralized and dense form, which will have a greater impact on traditional relay protection and automation systems. A high proportion of distributed photovoltaics is connected to the distribution network, resulting in great changes in the structure and characteristics of the distribution network. The network changes from a single-terminal network to a multi-terminal power supply network. When a fault occurs, the fault current characteristics of the distribution network will also change. , traditional fault calculation methods and relay protection settings may no longer be applicable, which may lead to problems such as current protection refusal or malfunction, affecting the safe operation of the distribution network. At present, there is no complete analysis and evaluation method for the applicability of current protection in distribution networks with a high proportion of distributed photovoltaic access.

Contents of the invention

Embodiments of the present invention provide a method for analyzing the applicability of current protection of distribution networks containing distributed photovoltaics, which is used to analyze the applicability of current protection of distribution networks containing distributed photovoltaics by calculating the sensitivity and protection range of current protection. The applicability analysis methods for current protection of distribution networks containing distributed photovoltaics include:

Establish a distribution network equivalent circuit model based on the actual conditions of the distribution network lines; the distribution network lines include distributed photovoltaics and three-stage current protection devices;

Determine the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line based on the equivalent circuit model of the distribution network;

Determine the short-circuit current at the end of the distribution network line when a metallic two-phase short circuit occurs at the end of the distribution network line based on the equivalent circuit model of the distribution network;

Generate current protection sensitivity analysis results based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value and the preset current protection sensitivity threshold;

The protection range of the current protection is generated based on the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and the preset protection range threshold of the current protection. Analyze the results.

Embodiments of the present invention also provide a current protection applicability analysis device for a distribution network containing distributed photovoltaics, which is used to analyze the applicability of current protection for a distribution network containing distributed photovoltaics by calculating the sensitivity and protection range of the current protection. , the distribution network current protection suitability analysis device including distributed photovoltaics includes:

A model building module is used to establish an equivalent circuit model of the distribution network based on the actual conditions of the distribution network; the distribution network includes distributed photovoltaics and a three-stage current protection device;

The first short-circuit current determination module is used to determine the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line based on the distribution network equivalent circuit model;

The second short-circuit current determination module is used to determine the short-circuit current at the end of the distribution network line when a metallic two-phase short circuit occurs at the end of the distribution network line based on the distribution network equivalent circuit model;

The sensitivity analysis module is used to generate the sensitivity analysis results of the current protection based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value and the preset sensitivity threshold of the current protection;

The protection range analysis module is used to calculate the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and the preset protection range of the current protection. The threshold generates the protection range analysis results of the current protection.

An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned distributed photovoltaic-containing distribution system is implemented. Grid current protection suitability analysis method.

Embodiments of the present invention also provide a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the above-mentioned distribution network current protection applicability analysis including distributed photovoltaics is implemented. method.

Embodiments of the present invention also provide a computer program product. The computer program product includes a computer program. When the computer program is executed by a processor, the above-mentioned method for analyzing the suitability of distribution network current protection with distributed photovoltaics is implemented.

Compared with the existing technology, embodiments of the present invention establish a distribution network equivalent circuit model based on the actual conditions of the distribution network lines; the distribution network lines include distributed photovoltaics and three-stage current protection devices; according to the distribution network The equivalent circuit model determines the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line; according to the distribution network equivalent circuit model, it determines the distribution network when a metallic two-phase short circuit occurs at the end of the distribution network line. The short-circuit current at the end of the line; the sensitivity analysis result of the current protection is generated based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value and the preset sensitivity threshold of the current protection; based on the distribution network line When a metallic two-phase short circuit occurs at the end, the current value at the three-stage current protection device, the set current value, the total length of the distribution network line and the preset protection range threshold of the current protection generate the protection range analysis results of the current protection, which can be achieved Applicability analysis of current protection for distribution networks containing distributed photovoltaics.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts. In the attached picture:

Figure 1 is a flow chart of a distribution network current protection applicability analysis method containing distributed photovoltaics in an embodiment of the present invention;

Figure 2 is an equivalent circuit diagram of distributed photovoltaic in the embodiment of the present invention;

Figure 3 is a node diagram of the equivalent circuit model of the distribution network in the embodiment of the present invention;

Figure 4 is a flow chart for determining the minimum protection range of the current protection section I in the embodiment of the present invention;

Figure 5 is a structural block diagram of a distribution network current protection suitability analysis device containing distributed photovoltaics in an embodiment of the present invention;

Figure 6 is a structural block diagram of a specific example of a distribution network current protection suitability analysis device containing distributed photovoltaics in the embodiment of the present invention.

Detailed ways

Embodiments of the present invention provide a distribution network current protection applicability analysis method, device, computing device, computer-readable storage medium and computer program product including distributed photovoltaics.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not used to limit the present invention.

The terminology involved in the present invention is first introduced below.

Set current (set value, set value, set current value): Set current is an important term in relay protection. It means that the standard value compared with the actual current when the relay protection is judged to trip. The setting value is artificially prescribed and calculated based on the endurance capacity of the circuit and power grid.

Three-stage current protection device: refers to a current protection device that operates in response to the increase in current in the form of three-stage current protection (staged current protection) when a short circuit occurs on the line and the current flows through a certain predetermined value.

Three-stage current protection: a type of staged current protection. The contents of the three-stage current protection refer to current quick-break protection (current protection stage I), time-limited current quick-break protection (current protection stage II), and definite time overcurrent. protection (current protection section III) that cooperates with each other to form a set of protection. Among them, current protection section I: The setting current value of current protection section I (instantaneous current quick-break protection) is set according to the principle of being greater than the maximum short-circuit current at the end of the protected line. The protection scope is greatly affected by the system operation mode and fault type.

Protection scope: Generally refers to the protection scope of relay protection. The range expected to be covered by the protection, beyond which non-unit protection will not operate. The protection range of section I of current protection is usually relatively small, ranging from 15 to 50% of the full length of the line. Current protection section II: Current protection section II (time-limited current quick-break protection) is set up to make up for the defects of section I protection. Current protection section III: Current protection section III (definite time overcurrent protection) has a larger protection range and is usually used as near backup protection for the line and as far backup protection for the adjacent line.

Sensitivity (sensitivity): refers to the ability of the current protection device to respond to fault conditions within the specified protection range. Usually sensitivity is expressed by the sensitivity coefficient.

Current protection applicability: The embodiment of the present invention uses the sensitivity and protection range of current protection to characterize the applicability of current protection, and uses a combination of sensitivity and protection range to evaluate the applicability of current protection.

In view of the shortcomings of the existing technology, embodiments of the present invention realize the applicability analysis of current protection for distribution networks containing distributed photovoltaics by calculating the sensitivity and protection range of current protection. The embodiments of the present invention provide a distribution network containing distributed photovoltaics. Grid current protection applicability analysis method. Figure 1 is a flow chart of a distribution network current protection applicability analysis method containing distributed photovoltaics in an embodiment of the present invention. As shown in Figure 1, the method provided by the embodiment of the present invention contains Distributed photovoltaic distribution network current protection applicability analysis methods include:

Step 101: Establish a distribution network equivalent circuit model based on the actual conditions of the distribution network lines; the distribution network lines include distributed photovoltaics and three-stage current protection devices;

Step 102: Determine the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line based on the distribution network equivalent circuit model;

Step 103: Determine the short-circuit current at the end of the distribution network line when a metallic two-phase short circuit occurs at the end of the distribution network line based on the distribution network equivalent circuit model;

Step 104: Generate sensitivity analysis results of the current protection based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value, and the preset sensitivity threshold of the current protection;

Step 105: Generate current protection based on the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line, and the preset protection range threshold of the current protection. The results of the protection scope analysis.

In one embodiment, the set current value includes: the set current value of current protection section I, the set current value of current protection section II, and the set current value of current protection section III.

In one embodiment, the distribution network lines are analyzed according to the actual line conditions and various distribution network parameters based on the distribution network lines are determined. The distribution network lines include distributed photovoltaic and three-stage current protection devices. .

In one embodiment, a distribution network equivalent circuit model is established based on the actual conditions of the distribution network lines and distribution network parameters. For distributed photovoltaic, that is, the power supply side upstream of the transformer, an ideal voltage source can be set, and its voltage is based on the actual Rated voltage setting, frequency can be set to 50Hz. For transformers and distribution lines, their equivalent circuits are established based on their resistance and reactance, which include a series total impedance Z=R+jX; for loads, they are represented by given active power and reactive power. Figure 2 is an equivalent circuit diagram of distributed photovoltaic in the embodiment of the present invention. As shown in Figure 2, since the positive and negative sequence currents output by the photovoltaic power supply are controlled by the voltage of the grid connection point, it can be equivalent to a voltage controlled by the voltage of the grid connection point. A controlled current source forms an equivalent circuit containing distributed photovoltaic distribution network. is the photovoltaic positive sequence current,/> is the photovoltaic negative sequence current,/> is the voltage of the photovoltaic grid connection point; the photovoltaic positive sequence current and the photovoltaic negative sequence current are both functions of the photovoltaic grid connection point voltage. The functional relationship is shown in the formula in Figure 2. The photovoltaic positive sequence current and the photovoltaic negative sequence current are both controlled by the photovoltaic grid connection point voltage. .

In one embodiment, the sensitivity analysis results of the current protection are generated based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value, and the preset sensitivity threshold of the current protection, including:

Determine the sensitivity coefficient of current protection section I based on the short-circuit current at the beginning of the distribution network line and the set current value of current protection section I;

Determine the sensitivity coefficient of the current protection section II according to the short-circuit current at the end of the distribution network line and the setting current value of the current protection section II;

Determine the sensitivity coefficient of current protection section III based on the short-circuit current at the end of the distribution network line and the setting current value of current protection section III;

The sensitivity analysis result of the current protection is generated based on the sensitivity coefficient of the current protection section I, the sensitivity coefficient of the current protection section II, the sensitivity coefficient of the current protection section III and the preset current protection sensitivity threshold.

In this embodiment, the power flow calculation method can be used to calculate the values required for sensitivity verification, for example: calculate the short-circuit current at the fault point when a metallic three-phase short circuit occurs at the outlet (beginning) of the distribution line; calculate the short-circuit current at the end of the distribution line When a metallic two-phase short circuit occurs, the short-circuit current at the fault point.

In this embodiment, the sensitivity of current protection is measured by the sensitivity coefficient K _sen :

Among them, I _k is the short-circuit current. When judging the setting current value of section I of the current protection, the three-phase short-circuit current at the outlet of the protected line is used. When judging the setting current value of sections II and III of the current protection, the two-phase short-circuit current at the end of the protected line is used; I _set is the set current value, including the set current value of current protection section I, the set current value of current protection section II, and the set current value of current protection section III.

In this embodiment, the preset current protection stage I sensitivity threshold may be 1, the stage II sensitivity threshold may be 1.3, and the stage III sensitivity threshold may be 1.5. When the calculated sensitivities of sections I, II, and III of the current protection are all greater than the preset sensitivity threshold of the current protection, the sensitivity is deemed to have passed the check.

In one embodiment, according to the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line, and the preset protection range threshold of the current protection Generate protection range analysis results for current protection, including:

Determine the location where a metallic two-phase short circuit occurs on the distribution network line when the current value at the three-stage current protection device is equal to the set current value of the current protection section I;

According to the impedance value between the said position and the beginning of the distribution network line, the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and The preset protection range threshold of the current protection generates the protection range analysis result of the current protection.

In this embodiment, it is also necessary to calculate the value required for protection range verification. The following is the calculation of the values required for the current protection section I calibration analysis:

Figure 3 is a node schematic diagram of the equivalent circuit model of the distribution network in the embodiment of the present invention. As shown in Figure 3, assume that the head end (starting end) node of the line is node 1, the end node is node z, and any node in the line is node i, the next node of node i is node j, and the impedance between the two nodes is a fixed value Z _ij . In order to facilitate the calculation of the protection range, a mobile node s is added between node i and node j; let Z _is =kZ _ij , k takes a value from 0 to 1, and increases by t (step size) each time.

Calculate the current at the protection installation site when a metallic two-phase short circuit occurs at node s of the distribution line. Suppose that when a metallic two-phase short circuit occurs at the distribution line node s ₀ , the current I ₁ at the protection installation is equal to the current protection I section fixed value I _Iset . The following process is used to determine the position of s _0. Figure 4 shows the embodiment of the present invention. The flow chart for determining the minimum protection range of section I of current protection is shown in Figure 4. Based on the generated equivalent circuit model of the distribution network, a distribution network equation with z+1 nodes is established; the initial setting is i=1, k=0 ;We can use the power flow calculation method to solve the current at the protection installation point, that is, the current value at the three-stage current protection device, and determine whether the current value at the three-stage current protection device is equal to the set current value of the current protection section I. If not, are equal and k is not 1, k increases by t, i increases by 1; continue to use the power flow calculation method to solve the current at the protection installation, and determine whether the current value at the three-stage current protection device is equal to the set current value of the current protection section I. Until it is judged that the current value at the three-stage current protection device is equal to the set current value of the I stage of the current protection, the values of i and k are determined, and then the position of s ₀ is determined.

In one embodiment, according to the impedance value between the position of s ₀ and the beginning of the distribution network line, the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, The total length of the distribution network line and the preset protection range threshold of the current protection generate the protection range analysis results of the current protection, including:

Determine the minimum protection range of section I of the current protection based on the impedance value between the position of s ₀ and the beginning of the distribution network line and the total length of the distribution network line;

According to the minimum protection range of current protection section I, the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the set current value of current protection section II, and the set current value of current protection section III and the preset protection range threshold of the current protection to generate the protection range analysis result of the current protection.

In this embodiment, after determining the position of node s ₀ , the impedance value Z _1s0 between node 1 and node s ₀ can be determined. Then the minimum protection range is:

Among them, z _p is the line impedance per unit length, and L is the total length of the line.

In this embodiment, the calculation of the values required for the protection range analysis and verification of the current protection sections II and III is as follows: Calculate the current at the protection installation point when a metallic two-phase short circuit occurs at the end of the distribution line, that is, three sections The current value at the type current protection device.

In this embodiment, the I-section protection range threshold can be set to 15% of the full length of the line. When the minimum protection range R _min of the current protection I-section is greater than the threshold specified by the verification, the protection range is considered to have passed the verification. Set the protection range threshold of sections II and III to 100% of the full length of the line. When the calculated metallic two-phase short circuit occurs at the end of the distribution line, the current at the protection installation is greater than the set current value of sections II and III, then sections II and III can protect the entire length of the line, that is, the protection range of sections II and III of the current protection The analysis result is that it passed the verification.

In summary, when the sensitivity and protection range both pass the check, it is considered that the current protection setting current value has passed the applicability evaluation.

It should be noted that although the operations of the methods of the present invention are depicted in a particular order in the drawings, this does not require or imply that the operations must be performed in that particular order, or that all of the illustrated operations must be performed to achieve desired results. . Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step for execution, and/or one step may be broken down into multiple steps for execution.

Embodiments of the present invention also provide a distribution network current protection applicability analysis device containing distributed photovoltaics, as described in the following embodiments. Since the problem-solving principle of this device is similar to the applicability analysis method of current protection of distribution network with distributed photovoltaic, the implementation of this device can be referred to the implementation of the applicability analysis method of current protection of distribution network with distributed photovoltaic, repeat. No further details will be given.

Figure 5 is a structural block diagram of a distribution network current protection suitability analysis device containing distributed photovoltaics in an embodiment of the present invention. As shown in Figure 5, a distribution network current protection suitability analysis device 500 containing distributed photovoltaics provided by the present invention includes:

The model building module 501 is used to establish a distribution network equivalent circuit model based on the actual conditions of the distribution network lines; the distribution network lines include distributed photovoltaics and three-stage current protection devices;

The first short-circuit current determination module 502 is used to determine the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line based on the distribution network equivalent circuit model;

The second short-circuit current determination module 503 is used to determine the short-circuit current at the end of the distribution network line when a metallic two-phase short circuit occurs at the end of the distribution network line based on the distribution network equivalent circuit model;

The sensitivity analysis module 504 is used to generate sensitivity analysis results of current protection based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value, and the preset sensitivity threshold of current protection;

The protection scope analysis module 505 is used for protection based on the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and the preset current protection The range threshold generates the protection range analysis results of the current protection.

In one embodiment, the set current value includes: the set current value of current protection section I, the set current value of current protection section II, and the set current value of current protection section III.

In one embodiment, the sensitivity analysis module 504 is specifically used to:

Determine the sensitivity coefficient of current protection section I based on the short-circuit current at the beginning of the distribution network line and the set current value of current protection section I;

Determine the sensitivity coefficient of the current protection section II according to the short-circuit current at the end of the distribution network line and the setting current value of the current protection section II;

Determine the sensitivity coefficient of current protection section III based on the short-circuit current at the end of the distribution network line and the setting current value of current protection section III;

The sensitivity analysis result of the current protection is generated based on the sensitivity coefficient of the current protection section I, the sensitivity coefficient of the current protection section II, the sensitivity coefficient of the current protection section III and the preset current protection sensitivity threshold.

In one embodiment, the protection scope analysis module 505 is specifically used to:

Determine the location where a metallic two-phase short circuit occurs on the distribution network line when the current value at the three-stage current protection device is equal to the set current value of the current protection section I;

According to the impedance value between the said position and the beginning of the distribution network line, the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and The preset protection range threshold of the current protection generates the protection range analysis result of the current protection.

In one embodiment, the protection scope analysis module 505 is specifically used to:

Determine the minimum protection range of section I of the current protection based on the impedance value between the location and the beginning of the distribution network line and the total length of the distribution network line;

According to the minimum protection range of current protection section I, the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the set current value of current protection section II, and the set current value of current protection section III and the preset protection range threshold of the current protection to generate the protection range analysis result of the current protection.

Figure 6 is a structural block diagram of a specific example of a distribution network current protection suitability analysis device containing distributed photovoltaics in the embodiment of the present invention. As shown in Figure 6, the model establishment module 501 and the first short-circuit current determination module can be 502. The second short-circuit current determination module 503 serves as a calculation module, which is further divided into an instruction input unit, a model generation unit and a calculation unit. The sensitivity analysis module 504 and the protection range analysis module 505 serve as the protection analysis and evaluation module.

In this embodiment, the instruction input unit determines the types of values in the distribution network that need to be calculated. The model generation unit determines to generate a distribution network model with z nodes or z+1 nodes according to its instructions. The calculation unit will determine according to the calculation instructions And the generated model is iteratively calculated to obtain the values required by the protection analysis and evaluation module.

The values required by the protection analysis and evaluation module are summarized as follows: (1) When a metallic three-phase short circuit occurs at the outlet of the distribution line, the short-circuit current at the fault point; (2) When a metallic two-phase short circuit occurs at the end of the distribution line, the fault point The short-circuit current at the point; (3) When a metallic two-phase short circuit occurs at the end of the distribution line, the current at the protection installation location; (4) The minimum protection range of segment I.

Compared with the existing technology, the embodiment of the present invention determines the equivalent circuit model of the distribution network according to the actual situation of the distribution network; the distribution network includes distributed photovoltaics and a three-stage current protection device; according to the distribution network The equivalent circuit model determines the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line; according to the distribution network equivalent circuit model, it determines the distribution network when a metallic two-phase short circuit occurs at the end of the distribution network line. The short-circuit current at the end of the line; the sensitivity analysis result of the current protection is generated based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value and the preset sensitivity threshold of the current protection; based on the distribution network line When a metallic two-phase short circuit occurs at the end, the current value at the three-stage current protection device, the set current value, the total length of the distribution network line and the preset protection range threshold of the current protection generate the protection range analysis results of the current protection, which can be achieved Analyze the sensitivity and protection range of current protection in distribution networks containing distributed photovoltaics, and then analyze and evaluate the applicability of current protection.

An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the above-mentioned distributed photovoltaic-containing distribution system is implemented. Grid current protection suitability analysis method.

Embodiments of the present invention also provide a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the above-mentioned distribution network current protection applicability analysis including distributed photovoltaics is implemented. method.

Embodiments of the present invention also provide a computer program product. The computer program product includes a computer program. When the computer program is executed by a processor, the above-mentioned method for analyzing the suitability of distribution network current protection with distributed photovoltaics is implemented.

Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce a use A device for realizing the functions specified in one process or multiple processes of the flowchart and/or one block or multiple blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. A method for analyzing the applicability of current protection in distribution networks containing distributed photovoltaics, which is characterized by including: Establish a distribution network equivalent circuit model based on the actual conditions of the distribution network lines; the distribution network lines include distributed photovoltaics and three-stage current protection devices; Determine the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line based on the equivalent circuit model of the distribution network; Determine the short-circuit current at the end of the distribution network line when a metallic two-phase short circuit occurs at the end of the distribution network line based on the equivalent circuit model of the distribution network; Generate current protection sensitivity analysis results based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value and the preset current protection sensitivity threshold; The protection range of the current protection is generated based on the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and the preset protection range threshold of the current protection. Analyze the results. 2. The method of claim 1, wherein the set current value includes: a set current value of current protection section I, a set current value of current protection section II, and a set current value of current protection section III. 3. The method according to claim 2, characterized in that the current protection value is generated according to the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value and the preset sensitivity threshold of the current protection. Sensitivity analysis results, including: Determine the sensitivity coefficient of current protection section I based on the short-circuit current at the beginning of the distribution network line and the set current value of current protection section I; Determine the sensitivity coefficient of the current protection section II according to the short-circuit current at the end of the distribution network line and the setting current value of the current protection section II; Determine the sensitivity coefficient of current protection section III based on the short-circuit current at the end of the distribution network line and the setting current value of current protection section III; The sensitivity analysis result of the current protection is generated based on the sensitivity coefficient of the current protection section I, the sensitivity coefficient of the current protection section II, the sensitivity coefficient of the current protection section III and the preset current protection sensitivity threshold. 4. The method according to claim 2, characterized in that, according to the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and The preset protection range threshold of current protection generates the protection range analysis results of current protection, including: Determine the location where a metallic two-phase short circuit occurs on the distribution network line when the current value at the three-stage current protection device is equal to the set current value of the current protection section I; According to the impedance value between the said position and the beginning of the distribution network line, the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and The preset protection range threshold of the current protection generates the protection range analysis result of the current protection. 5. The method according to claim 4, characterized in that, according to the impedance value between the position and the beginning of the distribution network line, when a metallic two-phase short circuit occurs at the end of the distribution network line, the three-stage current protection device is The current value, the set current value, the total length of the distribution network line and the preset protection range threshold of the current protection generate the protection range analysis results of the current protection, including: Determine the minimum protection range of section I of the current protection based on the impedance value between the location and the beginning of the distribution network line and the total length of the distribution network line; According to the minimum protection range of current protection section I, the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the set current value of current protection section II, and the set current value of current protection section III and the preset protection range threshold of the current protection to generate the protection range analysis result of the current protection. 6. A distribution network current protection applicability analysis device containing distributed photovoltaics, which is characterized by including: A model building module is used to establish an equivalent circuit model of the distribution network based on the actual conditions of the distribution network; the distribution network includes distributed photovoltaics and a three-stage current protection device; The first short-circuit current determination module is used to determine the short-circuit current at the beginning of the distribution network line when a metallic three-phase short circuit occurs at the beginning of the distribution network line based on the distribution network equivalent circuit model; The second short-circuit current determination module is used to determine the short-circuit current at the end of the distribution network line when a metallic two-phase short circuit occurs at the end of the distribution network line based on the distribution network equivalent circuit model; The sensitivity analysis module is used to generate the sensitivity analysis results of the current protection based on the short-circuit current at the beginning of the distribution network line, the short-circuit current at the end of the distribution network line, the set current value and the preset sensitivity threshold of the current protection; The protection range analysis module is used to calculate the current value at the three-stage current protection device when a metallic two-phase short circuit occurs at the end of the distribution network line, the setting current value, the total length of the distribution network line and the preset protection range of the current protection. The threshold generates the protection range analysis results of the current protection. 7. The device according to claim 6, wherein the set current value includes: a set current value of current protection section I, a set current value of current protection section II, and a set current value of current protection section III. 8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that when the processor executes the computer program, any one of claims 1 to 5 is realized. described method. 9. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method of any one of claims 1 to 5 is implemented. 10. A computer program product, characterized in that the computer program product includes a computer program, and when the computer program is executed by a processor, the method of any one of claims 1 to 5 is implemented.