A distributed power distribution integrated protection method and system in power system

Abstract

The present invention relates to a new type of distributed distribution fusion protection method and system in a power system, characterized in that the method comprises the following steps: taking the grid connection point of each centralized new energy source as the coupling point of a distributed distribution coupling unit, and calculating the short-circuit ratio of the coupling point; when a fault is detected in the distributed distribution coupling unit, selecting the protection mode of the coupling unit based on the short-circuit ratio of the coupling point. The present invention ensures that new energy sources participate in the control strategy, and provides more effective support for grid-side faults and abnormal operations.

Description

Technical Field

[0001] The present invention relates to the field of power systems, and more specifically, to a distributed distribution integrated protection method and system in a power system. Background Art

[0002] In order to prevent major power outages and cascading events caused by a single event, the power system has proposed the concept of a defense system. The essence of this concept is to provide a wide-area, intelligent, adaptive protection and control system that provides critical and wide-area information in real time, quickly assesses system vulnerability, and performs timely self-healing and adaptive reconstruction of network structure and power distribution based on system-wide vulnerability analysis, providing support for the safe and stable operation of the power grid.

[0003] In recent years, with the support of new technologies, wind and solar power generation and other renewable energy sources have gradually replaced traditional energy generation, power generation units have gradually become smaller and more decentralized, power storage technology has developed and matured, and the controllability and observability of the power grid have been greatly improved. Due to the large-scale addition of flexible resources such as distributed generation, energy storage, and electric vehicles, the distribution network has gradually become active and proactive, which has put forward new requirements for its protection fault diagnosis and reconstruction, and also provided more options and optimization paths for the selection of defense system strategies.

[0004] As the role of new energy sources has changed, the original passive grid energy absorption object of the new power system has been transformed into an effective supporting subject that actively participates in grid control adjustment and abnormal operation of the system side, and there are obvious differences in its protection strategy selection and corresponding system vulnerability evaluation. Because the active distribution network control strategy involving new energy sources can provide more effective support to the grid side when faults occur and abnormal operation occurs.

[0005] However, up to now, there has not been an active distribution network control strategy involving new energy in power grid control, which can provide more effective support for the power grid side when faults occur or abnormal operations occur. At the same time, the power grid control process has not provided adaptive and intelligent protection through the active participation of the active distribution network, and realized autonomous and adaptive remedial control measures for power grid faults or risks, as well as reconstruction solutions for vulnerable areas.

[0006] In view of the above problems, there is an urgent need for a distributed distribution integrated protection method and system in a power system. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a distributed distribution integrated protection method and system in an electric power system, which creates a coupling unit, obtains the coupling point and calculates the short-circuit ratio, so as to implement reasonable hierarchical protection in the reconstructed fault area when a fault is detected.

[0008] The present invention adopts the following technical solution.

[0009] The first aspect of the present invention relates to a distributed distribution integrated protection method in an electric power system, the method comprising the following steps: taking the grid connection point of each centralized new energy source as the coupling point of a distributed distribution coupling unit, and calculating the short-circuit ratio of the coupling point; when a fault is detected in the distributed distribution coupling unit, selecting the protection mode of the coupling unit based on the short-circuit ratio of the coupling point.

[0010] Preferably, the grid connection point of each centralized new energy source is used as the coupling point of the distributed distribution coupling unit, including: centralized new energy sources include centralized wind farms and centralized photovoltaic stations; the coupling unit includes distributed power sources, energy storage devices and loads that realize energy coupling within the unit; wherein, centralized wind farms above a preset scale belong to distributed power sources; centralized photovoltaic stations above a preset scale belong to distributed power sources, and centralized photovoltaics below a preset scale belong to loads.

[0011] Preferably, based on the short-circuit ratio of the coupling point, a protection mode of the coupling unit is selected, including: if the short-circuit ratio of the coupling point is greater than a preset threshold, the coupling point is judged to be a strong coupling point, and the system current regulation mode is selected to protect the coupling unit; if the short-circuit ratio of the coupling point is less than the preset threshold, the coupling point is judged to be a weak coupling point, and a longitudinal differential protection mode or an overcurrent protection mode is selected to protect the coupling unit.

[0012] Preferably, a longitudinal differential protection method or an overcurrent protection method is selected to protect the coupling unit, including: adopting a longitudinal differential protection method for the centralized wind farm, and adopting line zero-sequence current protection if the centralized wind farm does not deploy differential protection equipment; adopting an overcurrent protection method for the centralized photovoltaic station.

[0013] Preferably, a longitudinal differential protection method or an overcurrent protection method is selected to protect the coupling unit, including: when a fault is detected in the distributed power distribution coupling unit, the fault area is divided according to the outgoing line switch of the distributed power source and the corresponding connecting switch; according to the outgoing line switch, section switch, branch switch and boundary switch of the distributed power source in the fault area, a three-level fault removal and multi-level grounding coordination are constructed to protect and set the fault area.

[0014] Preferably, the three-level fault excision is as follows: the first-level fault excision, the second-level fault excision and the third-level fault excision are sequentially constructed on the outgoing line switches, section switches and boundary switches within the fault area; wherein the third-level fault excision adopts a zero-sequence current transient criterion, and the second-level fault excision adopts a time-limited quick-break criterion.

[0015] Preferably, the multi-level grounding coordination is: constructing multiple levels of the multi-level grounding coordination in sequence on the outgoing line switches, section switches, branch switches and boundary switches in the fault area; based on the number of section switches in the fault area and the connection order with the outgoing line switches, the section switches are deployed in multiple levels respectively.

[0016] Preferably, the method also includes: performing online calibration of fixed values ​​on transformer substations at different voltage levels of the power system and obtaining calibration results; dividing the vulnerability levels of the substations according to the calibration results; and reconstructing the substations with high vulnerability levels, wherein the reconstruction is to increase the number of section switches between the outgoing line switch and the connecting switch.

[0017] Preferably, the vulnerability level of the substation area is divided according to the verification result, including: dividing the vulnerability level based on the number of faults, fault types, and adaptability of protection settings of relay protection devices in the area.

[0018] The second aspect of the present invention relates to a distributed distribution integrated protection system in an electric power system using the method of the first aspect of the present invention, the system comprising a coupling module and a protection module; wherein the coupling module is used to use the grid connection point of each centralized new energy source as a coupling point of a distributed distribution coupling unit and calculate the short-circuit ratio of the coupling point; the protection module is used to select the protection mode of the coupling unit based on the short-circuit ratio of the coupling point when a fault is detected in the distributed distribution coupling unit.

[0019] The beneficial effect of the present invention is that, compared with the prior art, the distributed distribution integrated protection method and system in the power system of the present invention creates a coupling unit, obtains the coupling point and calculates the short-circuit ratio, so as to implement reasonable hierarchical protection in the reconstructed fault area when a fault is detected. The present invention ensures that new energy participates in the control strategy and provides more effective support for the occurrence of faults and abnormal operation on the grid side.

[0020] The beneficial effects of the present invention also include:

[0021] 1. Methods Through the active participation of active distribution networks, adaptive and intelligent protection is provided to achieve autonomous, adaptive, preventive and corrective remedial control measures, and local fault separation and reconstruction are combined with wide-area protection and information to form a hierarchical decision-making and globally optimized system reconstruction plan.

[0022] 2. The method adopts active distribution network system vulnerability analysis. In view of the changes in the system regulation mode of new energy participating in the system, a new power defense system vulnerability assessment method based on active distribution network under the background of new power system is proposed. Through the three-level protection method and the coordination of the refined protection action area, the regional vulnerability level is effectively reduced.

[0023] 3. At the medium-voltage power grid level, the present invention proposes a systemic protection safety hierarchical rating system based on the integration of regional protection scheme wide-area protection setting sheets in response to the global assessment requirements of the safety of power grid protection strategies, combined with the idea of ​​system stability hierarchical safety operation margin. This protection safety verification system targets the changes in the system network topology and the distribution characteristics of transient quantities after the access of new power sources. By integrating the information strategies of relevant setting sheets and mapping the corresponding network topology nodes, it can timely verify and discover the over-dense points and insufficient sensitivity points of the protection coordination level in the region, thereby improving the safety margin of the regional power grid and reducing the level of vulnerability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a coupling unit in a distributed power distribution integrated protection method in a power system according to the present invention;

[0025] Figure 2 A schematic diagram of the connection relationship between the coupling unit protection device and the system in a distributed distribution integrated protection method in an electric power system of the present invention;

[0026] Figure 3 A schematic diagram of three-level protection of a fault area in a distributed power distribution integrated protection method in a power system of the present invention;

[0027] Figure 4 A schematic diagram of risk information reporting in a distributed power distribution integrated protection method in a power system according to the present invention;

[0028] Figure 5 It is a schematic diagram of a protection safety verification system in a distributed power distribution integrated protection system in a power system of the present invention;

[0029] Figure 6 It is a schematic diagram of a method for obtaining protection setting values ​​in a distributed distribution integrated protection system in an electric power system of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in the present invention are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments not recorded in the present invention obtained by ordinary technicians in this field according to the embodiments recorded in the present invention without making creative work should belong to the protection scope of the present invention.

[0031] Figure 1 FIG. 1 is a schematic diagram of a coupling unit in a distributed power distribution integrated protection method in a power system of the present invention. Figure 1 As shown, the first aspect of the present invention relates to a distributed distribution integrated protection method in an electric power system, and the method includes step 1 and step 2.

[0032] Step 1: Take each grid-connected point of centralized renewable energy as a coupling point of a distributed power distribution coupling unit, and calculate the short-circuit ratio of the coupling point.

[0033] The initial defense system was proposed mainly for catastrophic power outages in large power grids. With the continuous access of new energy sources and the continuous improvement of the reliable operation and management level of distribution networks, this application has been extended to the distribution network level. In particular, the introduction of the spot market mechanism in the power market has raised the power supply reliability index to a new level. Because this index will generate fines due to major distribution network power supply accidents. To this end, this high voltage level provides a healthy grid structure to support the absorption capacity of new energy; and the distribution network, as the direct port for the access of new energy, is more defensive in its ability to actively respond to abnormal and faulty conditions in coordination with new energy sites.

[0034] In this invention, an attempt is made to analyze and obtain an analysis method based on the vulnerability of the active distribution network system by studying the protection strategy and automatic device action strategy of the active distribution network after the access of new energy. To this end, the method weakens the anti-islanding protection and strengthens the precise removal of faults.

[0035] In the present invention, the distributed power source, energy storage device and load constitute a decentralized coupling unit that can be effectively coupled with the power system. Since it is regarded as an active unit, from the system perspective, more emphasis is placed on its effective integration and support with the system, rather than its anti-islanding characteristics. The previous passive island state was transformed into an active fusion unit due to the strong support of the energy storage unit. It is precisely because of this that the current power system control emphasizes the timely isolation of faults within the unit to enhance the active and healthy operation state of the coupling unit.

[0036] To this end, the method implements centralized renewable energy as one of the important bases for dividing distributed distribution coupling units.

[0037] Preferably, the grid connection point of each centralized new energy source is used as the coupling point of the distributed distribution coupling unit, including: centralized new energy sources include centralized wind farms and centralized photovoltaic stations; the coupling unit includes distributed power sources, energy storage devices and loads that realize energy coupling within the unit; wherein, centralized wind farms above a preset scale are classified as distributed power sources; centralized photovoltaic stations above a preset scale are classified as distributed power sources, and centralized photovoltaics below a preset scale are classified as loads; for the coupling units that respectively belong to distributed power sources, energy storage devices and loads, energy coupling is implemented based on the charging and discharging restrictions of distributed power sources, energy storage devices and loads during the grid connection process.

[0038] The charging and discharging restrictions mentioned here are that distributed energy can only discharge to the grid, energy storage devices can charge and discharge, and loads can only obtain electricity from the grid. For example, centralized photovoltaics below the preset scale are calculated together with other loads in the area for the total power consumption. Since small-scale photovoltaics are only responsible for the self-sufficiency of electricity within the coupling unit, the total power consumption will not be calculated as a negative number.

[0039] It is easy to imagine that the coupling unit can be determined according to the scale and number of multiple centralized wind farms and photovoltaic power plants. The number of centralized new energy stations and their grid connection points into the system can correspond to the number of coupling units and coupling points. The energy interaction points between coupling units can also serve as another type of coupling point.

[0040] Within the coupling unit, the distributed power source, energy storage device and load can achieve efficient energy exchange to a certain extent, and maintain a certain degree of independence under isolated conditions or weak coupling with the power grid. On this basis, the method can confirm the division method of the coupling unit according to the distance between the load, energy storage and distributed power station, the topological connection relationship, etc. For example, the method can support the division of loads, energy storage and distributed power sources under the same transformer area into one coupling unit. In short, the division result can ensure its own healthy operation.

[0041] In addition, for centralized wind farms, since their grid-connected voltage level is higher than that of photovoltaic power generation and they have the characteristics of synchronous or asynchronous machines, the grid-connected lines of wind farms are generally equipped with differential protection. And the capacity of centralized wind farms is relatively high, so they can be used as distributed power sources in coupling units.

[0042] On the other hand, in the case of photovoltaic grid-connected, due to the relatively small capacity and relatively low grid-connected voltage level, it is generally regarded as a load.

[0043] In the present invention, in order to achieve protection when the coupling unit fails, the method calculates the short-circuit ratio of the coupling point, for example, obtained by three-phase short-circuit capacity and injected active power.

[0044] Step 2: When a fault is detected in the distributed power distribution coupling unit, a protection mode of the coupling unit is selected based on the short-circuit ratio of the coupling point.

[0045] Figure 2 The figure is a schematic diagram of the connection relationship between the protection device and the system in the coupling unit in the distributed power distribution integrated protection method in the power system of the present invention. Figure 2 As shown, the connection relationship is that the method adopts a dynamic active distribution network protection method, which transmits the information of the protection equipment in multiple coupling units to the inter-substation protection coordination system through the communication control platform, and uses the protection information comprehensive system to obtain relevant protection information, thereby implementing active distribution network protection. The active distribution network protection here can include grid structure analysis, risk assessment, power quality analysis, power quality control and stability analysis provided in the distributed power grid analysis system.

[0046] For example, in power quality analysis, the method analyzes the three-phase unbalance and maximum voltage deviation by obtaining the voltage deviation at different network nodes. Power quality control can improve or adjust the voltage deviation and three-phase unbalance through internal combustion engines, reactive power compensators, capacitors and other equipment.

[0047] After the distributed distribution coupling unit is detected to have a fault, the method can implement reasonable protection for the distributed distribution network according to the pre-calculated short-circuit ratio.

[0048] Preferably, based on the short-circuit ratio of the coupling point, a protection mode of the coupling unit is selected, including: if the short-circuit ratio of the coupling point is greater than a preset threshold, the coupling point is judged to be a strong coupling point, and the system current regulation mode is selected to protect the coupling unit; if the short-circuit ratio of the coupling point is less than the preset threshold, the coupling point is judged to be a weak coupling point, and the longitudinal differential protection mode or the overcurrent protection mode is selected to protect the coupling unit.

[0049] The system-side protection of each coupling point can be evaluated based on the power system location of the coupling point. If the transient short circuit of the power system is large, the system side of the coupling point can provide enough current to enable the protection to operate correctly when the coupling point fails. In this case, the system current regulation method is used.

[0050] If the short-circuit ratio is insufficient, then for the system side, this coupling point is a weak coupling point, and other protection methods are recommended.

[0051] Preferably, longitudinal differential protection or overcurrent protection is selected to protect the coupling unit, including: longitudinal differential protection for centralized wind farms. If the centralized wind farms are not equipped with differential protection equipment, line zero-sequence current protection is used; and overcurrent protection is used for centralized photovoltaic stations.

[0052] Specifically, for wind farms, since their grid-connected voltage level is higher than that of photovoltaic power plants and they have the characteristics of synchronous machines (asynchronous machines), the grid-connected lines of wind farms are generally equipped with differential protection. Even if differential protection is not configured, if the grid is connected via 110kV, the high-voltage side of the substation can be grounded, and the zero-sequence direction can be used as the main line protection.

[0053] As for the case of photovoltaic grid connection, due to the relatively small capacity and relatively low grid voltage level, it is generally regarded as a load. If the degree of weak coupling makes photovoltaic not provide enough short-circuit current, it can be assumed that the fault point occurs from the high-voltage side of the photovoltaic substation to the end of the grid-connected line, and overcurrent protection is configured. When a fault occurs in the protection area, the photovoltaic station side of the grid-connected line will trip the grid-connected line switch on this side with a relatively low overcurrent setting and a longer action time.

[0054] It can be seen from the specification that the inverter of the photovoltaic power station should have overload capacity. When the current is below 1.2 times the rated current, the continuous reliable working time of the photovoltaic power station shall not be less than 1 minute. Therefore, the overcurrent protection action value can be configured to be 1.2Ie, and the time can be the overload III fixed time, which is 1.7S. Why is the distance protection not selected? First, when the grid-connected power level is low, generally, as long as the voltage is not too low during a fault, overcurrent protection is used as the main protection; second, the distance protection has to consider the influence of the transition resistance in its own algorithm, and its protection action area will increase or decrease. Therefore, it is a simple and effective way to use overcurrent protection for the grid-connected side of the photovoltaic station that is biased towards the load characteristics during a fault. As for the photovoltaic plant station, due to the use of low-resistance grounding or resonant grounding, it is recommended to trip the fault line after the transient protection fault.

[0055] Figure 3 The figure is a schematic diagram of three-level protection of fault area in a distributed power distribution integrated protection method in a power system of the present invention. Figure 3 As shown, preferably, a longitudinal differential protection method or an overcurrent protection method is selected to protect the coupling unit, including: when a fault is detected in the distributed power distribution coupling unit, the fault area is divided according to the outgoing line switch of the distributed power source and the corresponding connecting switch; according to the outgoing line switch, section switch, branch switch and boundary switch of the distributed power source in the fault area, a three-level fault removal and multi-level grounding coordination are constructed to protect and set the fault area.

[0056] In the present invention, the fault area and the non-fault area are first divided according to the monitored fault. The fault area is usually located in a coupling interval. After obtaining the fault area, the method obtains the position and connection relationship of the distributed power supply's outgoing line switch, section switch, branch switch, and boundary switch according to the topology information, so as to implement protection in a hierarchical manner.

[0057] In the protection process, the method constructs three-level fault removal on the one hand, and multi-level grounding coordination on the other hand to perform protection setting on the fault area.

[0058] Preferably, the three-level fault removal is as follows: the first-level fault removal, the second-level fault removal and the third-level fault removal are sequentially constructed on the outgoing line switches, section switches and boundary switches within the fault area; wherein the third-level fault removal adopts the zero-sequence current transient criterion, and the second-level fault removal adopts the time-limited quick-break criterion.

[0059] Preferably, the multi-level grounding coordination is: multiple levels of multi-level grounding coordination are sequentially constructed on the outgoing line switches, section switches, branch switches, and boundary switches in the fault area; based on the number of section switches in the fault area and the connection order with the outgoing line switches, the section switches are deployed in multiple levels respectively.

[0060] In the present invention, the specific coordination relationship diagram based on the three-level protection of the distribution network includes three-level fault removal and five-level grounding coordination, that is, the coordination level of the outgoing line switch, section switch, and boundary switch in the station, as well as the coordination between the outgoing line switch, #1 section, #2 section, branch, and boundary switch. The overcurrent protection setting principle is relatively fixed. The time-limited quick-break requirement for the branch switch is coordinated with the upper-level time-limited quick-break, and it is considered to avoid the transformer excitation surge current and the transformer low-voltage side fault, and it has a certain sensitivity to the outlet fault; the timed overcurrent is coordinated with the upper-level timed overcurrent, and it is ensured that the end fault of this protection range has a sensitivity of 1.2. At the same time, it is required to avoid the maximum load current and the reverse current. When considering the reverse current here, if there is a distributed power supply connected, the reverse current here should consider the maximum value of the upper load current of the distributed power supply connected to the downstream of the lower switch.

[0061] In addition, transient protection is configured below the bottom level of the three-level protection. When a single-phase grounding fault occurs in a branch line, the zero-sequence current transient quantity is used as a criterion to trip the fault branch. Although the low-voltage distribution system still uses a non-effective grounding system, its operation mode has excluded the short-term operation after a single-phase fault due to the refinement of the protection coordination level and the line selection tripping function of the transient protection. Therefore, the vulnerability level of the distribution network level has been fundamentally improved.

[0062] Preferably, the method also includes: performing online calibration of fixed values ​​on transformer substations at different voltage levels of the power system and obtaining calibration results; dividing the vulnerability levels of the substations according to the calibration results; and reconstructing the substations with high vulnerability levels by increasing the number of section switches between the outgoing line switches and the connecting switches.

[0063] In the process of considering the active distribution network fault reconstruction method of new energy flexible load, the vulnerability of the reconstruction area is greatly reduced when considering the new energy island operation mode. To this end, the method also supports that for such areas, the protection configuration and coordination should be improved as much as possible. For example, the method adopts the method of orderly installing section switches, which is more refined in the fixed value coordination, so as to achieve accurate locking of the fault section and reduce the scope of power outage. If necessary, the method can be used to use the method of transient protection tripping to trip the fault section when a single-phase grounding fault occurs in the distribution network, so as to improve its protection level, reduce the load loss, and reduce its vulnerability level.

[0064] Specifically, by subdividing the grid area, the fault location area can be further refined. Based on the protection configuration strategy under the grid area, a more detailed level and a more accurate location interval can be given. Through regional reconstruction, the reconstructed grid area is combined with the three-level protection method to achieve more accurate protection.

[0065] Therefore, through the refinement of the three-level protection, the scope of the fault section can be accurately determined to below the minimum boundary switch, which can effectively improve the vulnerability index of the distribution network and enhance the power supply reliability.

[0066] As for the vulnerability index of the main grid, it is necessary not only to comply with the relevant regulations on protection configuration, but also to consider the degree of risk that the failure, abnormality and adaptability of protection settings of relay protection devices (including circuits) and their related equipment may bring to the safety of the power grid.

[0067] Preferably, the vulnerability levels of the substation area are divided according to the verification results, including: dividing the vulnerability levels based on the number of faults of the relay protection devices in the area, the fault types, and the adaptability of the protection settings.

[0068] In one embodiment of the present invention, the method first obtains the amount of risk data at different voltage levels, different data interfaces, and different regions.

[0069] Methods According to the degree of risk that the relay protection device (including circuit) and its related equipment failure, abnormality and protection setting adaptability may bring to the safety of the power grid, it is divided into one to five levels from severe to mild. For example, level five risk: two or more components (lines, busbars, transformers) lose both sets of main protection or lose both sets of failure protection, and the line backup protection setting does not cooperate. Level one risk: a single component (line, busbar, transformer) loses a single set of main protection. The intermediate level is further subdivided.

[0070] Figure 4 FIG. 1 is a schematic diagram of risk information reporting in a distributed power distribution integrated protection method in a power system of the present invention. Figure 4As shown in the example of a risk analysis report, due to the large value of the main transformer differential quick-acting protection, it is necessary to avoid the excitation surge current, and sometimes the sensitivity may be insufficient. However, as an auxiliary protection, its function is mainly to serve as an auxiliary protection for the main transformer ratio differential, that is, as a supplementary protection for the ratio differential, so it can be rated as a level 5 risk when assessing its risk.

[0071] According to the degree of risk classification, the method further subdivides the areas with high vulnerability levels into gridded areas. For example, the method of installing section switches in an orderly manner can be adopted to make the setting more precise so as to accurately lock the fault section and reduce the scope of power outage.

[0072] Furthermore, system risks often exist in hidden faults, that is, protection setting coordination, or hidden fault risks caused by degradation or radicalization of protection performance when facing temporary or abnormal modes. When the network topology is perfect, its protection coordination is relatively stable, so it has a certain tolerance to local changes in the network. However, when the grid structure undergoes major changes, especially in transitional temporary modes, the network topology parameter changes exceed its tolerance point, and the changes in protection setting are not updated in time, it is necessary to conduct real-time detection of network setting, so as to promptly discover the hidden faults and make corrections in time.

[0073] Especially when a new power source is connected to the network or the grounding point is changed, the change in the protection coordination relationship will have a diffusion radius. The correction of the fixed value can obtain the relevant protection mismatch points and insufficient sensitivity points through risk assessment and accurately obtain their diffusion radius.

[0074] Figure 5 This is a schematic diagram of a protection safety verification system in a distributed power distribution integrated protection system in a power system of the present invention. Figure 5 As shown, in one embodiment of the present invention, the method supports the digital processing of the equipment of the operating plant and substation, the substation network topology is used as the associated network, and each device is used as the connection point of the network topology. The equipment parameters are fully described as the internal feature quantity of the virtual object with a unique ID. The specific application scenario is such as the hierarchical and beam-type flow of the data flow in the hierarchical mapping and information fusion level. Figure 5 shown.

[0075] In the above process, the COBASE system as the protection object and the OMS system as the equipment scheduling management system extract and integrate parameters according to their needs to form meaningful expression objects under their respective systems. In essence, it is the integration of data streams based on network connections after stratification. From the perspective of hierarchy, it can be divided into the cloud layer, COBASE and OMS layer, and security verification layer. The flow of the split data stream is diverted from the cloud layer to the COBASE layer for effective expression of protection, and at the same time diverted to the OMS layer to complete the specific process flow from scheduling specific equipment management to commissioning. The COBASE and OMS layers will also be mapped to each other through IDs, and the protection setting list can be nested into the specific equipment as an auxiliary attribute of the equipment, so as to complete a relatively independent protection setting execution sub-process internally while completing the flow of the scheduling management layer. As a protection safety verification application for an advanced application scenario, it is a panoramic view of the coordination and sensitivity verification of the global level of protection. When the equipment is put into operation, as a node in the network topology, its body protection coordination relationship is included in the whole network protection coordination relationship diagram, and the safety indicators of its regional protection scheme are verified from the perspective of the panoramic view.

[0076] Figure 6 This is a schematic diagram of a protection setting acquisition method in a distributed power distribution integrated protection system in a power system of the present invention. Figure 6 As shown in the figure, through the above data flow, the specific safety application scenario verification interface can display the fixed value verification process. Since the safety verification is based on the quasi-simultaneous verification of the equipment commissioning and the generation of the setting fixed value list, this causes a certain delay in the interface content. However, since it is based on the verification of the fixed value coordination relationship and sensitivity of the global system, to a certain extent, this delay is to meet the solution based on the global protection optimization degree after the information of the local area is fully updated and stabilized.

[0077] like Figure 4 As shown in the figure, the protection setting safety verification platform will reintegrate the conclusive information of the setting list. Its underlying logic is still based on the transient hierarchical coordination relationship formed by the connected node devices in the network topology diagram of the entire network. The ultimate goal is to evaluate the safety results of the regional protection coordination relationship based on the newly added equipment and the corresponding transient quantities.

[0078] Since the coordination relationship is updated in quasi-real time, the stability of the protection is guaranteed based on the existence of the protection reliability coefficient. However, when there is a new power supply and a change in the grounding point, the protection level will be readjusted, and whether the coordination margin still meets the requirements of the global safety margin needs to be re-evaluated. For the problem of insufficient sensitivity of long-line lines and transformers with relatively large short-circuit impedance, the safety assessment system needs to conduct a comprehensive verification based on the distribution gradient of transient quantities.

[0079] The second aspect of the present invention relates to a distributed distribution integrated protection system in an electric power system using the method of the first aspect of the present invention, the system comprising a coupling module and a protection module; wherein the coupling module is used to use the grid connection point of each centralized new energy source as the coupling point of the distributed distribution coupling unit and calculate the short-circuit ratio of the coupling point; the protection module is used to select the protection mode of the coupling unit based on the short-circuit ratio of the coupling point when a fault is detected in the distributed distribution coupling unit.

[0080] A third aspect of the present invention relates to a terminal, comprising a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method in the first aspect of the present invention.

[0081] A fourth aspect of the present invention relates to a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method in the first aspect of the present invention.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A distributed distribution integrated protection method in a power system, characterized in that: The method comprises the following steps: Taking each grid connection point of the centralized new energy as a coupling point of the distributed power distribution coupling unit, and calculating the short-circuit ratio of the coupling point; When a fault is detected in the distributed power distribution coupling unit, a protection mode of the coupling unit is selected based on the short-circuit ratio of the coupling point; If the short-circuit ratio of the coupling point is greater than a preset threshold, the coupling point is judged to be a strong coupling point, and a system current regulation method is selected to protect the coupling unit; If the short-circuit ratio of the coupling point is less than a preset threshold, the coupling point is judged to be a weak coupling point, and a longitudinal differential protection mode or an overcurrent protection mode is selected to protect the coupling unit; A longitudinal differential protection method is adopted for a centralized wind farm. If the centralized wind farm is not equipped with differential protection equipment, line zero-sequence current protection is adopted; Use overcurrent protection for centralized photovoltaic stations; According to the outgoing line switches, section switches, branch switches and boundary switches of the distributed power sources in the fault area, three-level fault removal and multi-level grounding coordination are constructed to perform protection setting on the fault area.

2. A distributed power distribution integrated protection method in a power system according to claim 1, characterized in that: The method of using each centralized new energy grid connection point as a coupling point of a distributed power distribution coupling unit includes: The centralized new energy includes centralized wind farms and centralized photovoltaic stations; The coupling unit includes a distributed power source, an energy storage device and a load for realizing energy coupling within the unit; Among them, centralized wind farms above a preset scale are classified as distributed power sources; Centralized photovoltaic stations above the preset scale are classified as distributed power sources, and centralized photovoltaic stations below the preset scale are classified as loads; For the coupling units belonging to the distributed power sources, energy storage devices and loads respectively, energy coupling is implemented based on the charging and discharging limitations of the distributed power sources, energy storage devices and loads during the grid-connected process.

3. A distributed power distribution integrated protection method in a power system according to claim 2, characterized in that: The step of selecting a longitudinal differential protection mode or an overcurrent protection mode to protect the coupling unit includes: When it is detected that the distributed power distribution coupling unit fails, the fault area is divided according to the outgoing line switch of the distributed power source and the corresponding tie switch.

4. A distributed power distribution integrated protection method in a power system according to claim 3, characterized in that: The three-level fault removal is: Sequentially constructing first-level fault removal, second-level fault removal and third-level fault removal on the outgoing line switch, the section switch and the boundary switch in the fault area; The third-level fault removal adopts the zero-sequence current transient criterion, and the second-level fault removal adopts the time-limited quick-break criterion.

5. A distributed power distribution integrated protection method in a power system according to claim 4, characterized in that: The multi-level grounding coordination is: Sequentially constructing multiple levels of the multi-stage grounding coordination on the outgoing line switch, the section switch, the branch switch, and the boundary switch in the fault area; The section switches are respectively deployed in a plurality of levels based on the number of the section switches in the fault area and the connection sequence with the outgoing line switches.

6. A distributed power distribution integrated protection method in a power system according to claim 1, characterized in that: The method further comprises: Performing online verification of fixed values ​​for transformer substations at different voltage levels of the power system and obtaining verification results; Classifying the vulnerability level of the substation area according to the verification result; The substation area with a high vulnerability level is reconstructed, and the reconstruction is to increase the number of section switches between the outgoing line switch and the connecting switch.

7. A distributed power distribution integrated protection method in a power system according to claim 6, characterized in that: The classifying the vulnerability level of the substation area according to the verification result includes: The vulnerability level is divided based on the number and type of faults of the relay protection devices in the area and the adaptability of the protection settings.

8. A distributed distribution fusion protection system in a power system using the method according to any one of claims 1 to 7, characterized in that: The system comprises a coupling module and a protection module; wherein, The coupling module is used to use each centralized new energy grid connection point as a coupling point of a distributed power distribution coupling unit and calculate the short-circuit ratio of the coupling point; The protection module is used to select a protection mode of the coupling unit based on the short-circuit ratio of the coupling point when a fault is detected in the distributed power distribution coupling unit.

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