Fault reconstruction method and system for new energy access distribution network based on oscillation monitoring

Abstract

The present invention discloses a method and system for fault reconstruction of new energy access distribution network based on oscillation monitoring, which belongs to the technical field of oscillation monitoring and distribution network fault recovery, and mainly includes: collecting broadband data at the new energy grid connection point of the distribution network, and generating and sending an oscillation alarm signal if the disturbance energy shows an increasing trend; injecting a disturbance signal at any node in the distribution network based on the broadband data monitoring range, and generating and sending an oscillation alarm signal if the distribution network oscillates; obtaining the main station SVG graphic model file and parsing it, and the number of new energy access points parsed is N, and constructing a current active model and a reactive model; setting a reconstruction node and its adjacent nodes, constructing a distribution network safe operation constraint condition, using an alarm signal, removing the oscillation point, and restoring power supply with a solution with the shortest recovery time. The present invention solves the problem of safety requirements of the distribution network system and the problem of quickly selecting the most suitable access point interval to join the fault reconstruction.

Description

Technical Field

[0001] The present invention belongs to the technical field of oscillation monitoring and distribution network fault recovery, and more specifically, to a method and system for fault reconstruction of a distribution network accessed by a new energy source based on oscillation monitoring. Background Art

[0002] The recovery of distribution network faults is crucial in the power system, and taking a fast and effective load transfer method is a key measure to reduce further power outage losses. In recent years, with the gradual deepening of market-oriented reforms and new energy construction, new energy access points have become increasingly suitable as backup power points for distribution networks. The "dual carbon" goals proposed by the country will also greatly increase the proportion of new energy access in the future. A large number of access points can effectively support the recovery and reconstruction of distribution network faults.

[0003] However, the fault reconstruction of the distribution network under the access of new energy still faces the following problems:

[0004] 1. New energy oscillation monitoring is not directly linked to fault reconstruction, and cannot provide a basis for load transfer. Some faults are caused by new energy oscillations.

[0005] 2. The access of a large number of new energy sources will have a profound impact on the current distribution of the existing distribution network. There is a lack of power flow models before and after faults to meet the safety requirements of the distribution network system.

[0006] 3. The access of a large number of new energy sources makes fault reconstruction optimization more difficult, and there is a lack of suitable algorithms to select the appropriate new energy access point interval to join the reconstruction. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a method and system for fault reconstruction of new energy access distribution network based on oscillation monitoring. On the one hand, this method establishes a power flow model of the distribution network, and simultaneously performs two methods of oscillation monitoring on the new energy access points within the range, and associates the monitoring results with the power flow results after the fault, thereby solving the problem of safety requirements of the distribution network system; on the other hand, the fault reconstruction model under large-scale new energy access is linearly optimized, solving the problem of being unable to quickly select the most suitable access point interval to join the fault reconstruction.

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

[0009] A first aspect of the present invention provides a method for fault reconstruction of a new energy access distribution network based on oscillation monitoring, comprising:

[0010] Collect broadband data at the renewable energy connection point of the distribution network. If the disturbance energy shows an increasing trend, generate and send the first oscillation alarm signal.

[0011] Based on the monitoring range of the broadband data, a disturbance signal is injected into any node in the distribution network, and if oscillation occurs in the distribution network, a second oscillation alarm signal is generated and sent upward;

[0012] Get the main station SVG image file and parse it. The number of new energy access points parsed is , construct power flow active model and reactive model;

[0013] Set the reconstruction node and its adjacent nodes, and build the safe operation constraints of the distribution network based on the active and reactive models. Use the first oscillation alarm signal and the second oscillation alarm signal to eliminate the oscillation point and restore power supply with the solution with the shortest recovery time.

[0014] Preferably, broadband data is collected at the new energy connection point of the distribution network, and if the disturbance energy shows an increasing trend, a first oscillation alarm signal is generated and sent upward, including:

[0015] Step 1.1: Collect broadband data using a broadband non-injection oscillation monitoring module at all renewable energy connection points in the distribution network;

[0016] Step 1.2: Calculate disturbance energy based on harmonic and interharmonic measurements in broadband data;

[0017] Step 1.3: Determine the change trend of the disturbance energy of a spectrum. If it continues to increase within t seconds compared with the initial value at the 0th second, breaking through the threshold value Set and forming a stable growth trend, execute step 1.4; otherwise, return to step 1.1 and continue to monitor the broadband data;

[0018] Step 1.4: trigger the oscillation monitoring data uploading mechanism to generate and upload the first oscillation alarm signal and broadband data within t seconds.

[0019] Preferably, the disturbance energy is calculated as follows:

[0020] (1)

[0021] Where:

[0022] is the disturbance energy power;

[0023] It is the highest harmonic monitored this time;

[0024] is the harmonic voltage;

[0025] is each harmonic current;

[0026] The stable growth trend is expressed by the following formula (2):

[0027] (2)

[0028] Where:

[0029] t0 is the 0th second; t1 is the 1st second; t2 is the 2nd second;

[0030] Set is the threshold value.

[0031] Preferably, based on the monitoring range of the broadband data, a disturbance signal is injected into any node in the distribution network, and if oscillation occurs in the distribution network, generating and sending a second oscillation alarm signal includes:

[0032] According to the frequency range and frequency interval of the wideband non-injection oscillation monitoring module, the power electronic injection oscillation monitoring module installed at any node of the distribution network generates a disturbance frequency sequence to be measured;

[0033] Generate disturbance signals one by one according to the generated disturbance frequency sequence to be measured;

[0034] Injecting the generated disturbance signal into the distribution network; and then recording the impedance data of each frequency domain of each monitoring point while the disturbance signal is injected;

[0035] Based on the obtained full-measurement frequency-domain impedance data, the stability is determined by calculating the zero-pole distribution in the full-measurement frequency-domain impedance data matrix of the measured object. When a right-half-plane zero appears, it indicates that the distribution network has oscillated, triggering the oscillation data uploading mechanism to upload the impedance data within t seconds; otherwise, the stability of the distribution network continues to be monitored.

[0036] Preferably, the disturbance signal is expressed by the following formula (3):

[0037] (3)

[0038] Where:

[0039] For power electronic equipment grid connection point The voltage disturbance signal with a smaller amplitude injected into the phase For power electronic equipment grid connection point The voltage disturbance signal with a smaller amplitude injected into the phase For power electronic equipment grid connection point A voltage disturbance signal with a smaller amplitude injected into the phase;

[0040] is the amplitude of the first disturbance signal, is the amplitude of the second disturbance signal;

[0041] is the frequency of the first disturbance signal, is the second disturbance signal frequency, the first disturbance signal frequency and the second disturbance signal frequency is the coupling frequency, satisfying ,in, It is the real-time base frequency of the system;

[0042] is the phase of the first disturbance signal, is the phase of the second disturbance signal.

[0043] Preferably, the master station SVG model file is obtained and parsed, the number of new energy access points parsed is n, and the construction of the power flow active model and reactive model includes:

[0044] The active power model for calculating power flow is expressed as follows:

[0045] (4)

[0046] Where:

[0047] ;

[0048] New energy access point Towards new energy access point The trend has been successful;

[0049] , Provides current for new energy access points;

[0050] for Phase angle difference between two points;

[0051] is the line resistance value;

[0052] is the line capacitance value;

[0053] is the angular frequency of alternating current;

[0054] The reactive power model for calculating the flow, if it is an overhead line, is expressed as follows:

[0055] (5)

[0056] Where:

[0057] New energy access point Towards new energy access point The tide is reactive;

[0058] If it is a cable line, it is expressed as follows:

[0059] (6)

[0060] Where:

[0061] is the small resistance grounding resistance value.

[0062] Preferably, the setting of the reconstruction node and its adjacent nodes includes:

[0063] Find the best access interval for new energy access points when a fault occurs, including: using the built active and reactive models to ensure optimal access during fault reconstruction Greater than or equal to the power value before the fault, and Satisfy the constraints of safe operation of distribution network and minimize the fault recovery time, among which is the failed reconstruction node, So A node with centered and spreading outwards. Refactoring for failure The active power of the node, Refactoring for failure Reactive power of the node.

[0064] Preferably, the setting of the reconstruction node and its adjacent nodes, constructing the distribution network safe operation constraint conditions based on the active and reactive models, using the first oscillation alarm signal and the second oscillation alarm signal, removing the oscillation point, and restoring power supply with the solution with the shortest restoration time includes:

[0065] Based on the parsing results of the main site SVG template file, set the reconstruction node to Indicates, setting The adjacent nodes of express, So A node with the center spreading outwards;

[0066] Using the SOCP algorithm, the power flow model and reactive model Transformed into the following form, equation (7) must be satisfied to meet the safe operation requirements of the distribution network:

[0067] (7)

[0068] Where:

[0069] Refactoring for failure The current in the node;

[0070] For The current of a node with the center spreading outwards is based on the historical data of the master station;

[0071] express Node and Phase angle difference of nodes;

[0072] Determine based on the first oscillation alarm signal and the second oscillation alarm signal and Whether the node is an oscillation fault point; if a node is a fault point, then the oscillation fault point is removed; if the node is not a fault point, then it is retained;

[0073] Count all the results of parsing the master station SVG model file to verify that it meets the safe operation requirements of the distribution network. First calculate Node is the center, all adjacent nodes, and then calculate all nodes separated by 1 node, let Greater than or equal to the power value before the fault, and the unsatisfactory results will be eliminated;

[0074] Calculate the power supply restoration time of all results and select the result with the shortest restoration time;

[0075] When a After the node is restored, the node will be The node continues to recover its neighbors.

[0076] Preferably, the energy access point current Less than or equal to the maximum current required on the line;

[0077] The distribution network needs to be connected to the substation 10kV / 20kV busbar to ensure fault recovery.

[0078] A second aspect of the present invention provides a new energy access distribution network fault reconstruction system based on oscillation monitoring, comprising the following modules: a broadband non-injection oscillation monitoring module, a power electronics injection oscillation monitoring module, a new energy flow model algorithm module and a fault reconstruction algorithm module;

[0079] The broadband non-injection oscillation monitoring module is used to collect broadband data at the new energy grid connection point of the distribution network. If the disturbance energy shows an increasing trend, a first oscillation alarm signal is generated and sent up;

[0080] The power electronic injection oscillation monitoring module is used to inject a disturbance signal into any node in the distribution network. If the distribution network oscillates, a second oscillation alarm signal is generated and sent up;

[0081] The new energy power flow model algorithm module is used to obtain and parse the main station SVG model file to build the power flow active model and reactive model;

[0082] The fault reconstruction algorithm module is used to set the reconstruction node and its adjacent nodes. Based on the active and reactive models, it constructs the safe operation constraints of the distribution network. After removing the oscillation points, it uses the sent alarm signals to restore power supply with the solution with the shortest recovery time.

[0083] The third aspect of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is loaded into the processor, the method for fault reconstruction of new energy access to a distribution network based on oscillation monitoring is implemented.

[0084] The fourth aspect of the present invention provides a computer-readable storage medium, which stores a computer program, characterized in that when the computer program is executed by a processor, the method for fault reconstruction of new energy access to a distribution network based on oscillation monitoring is implemented.

[0085] Compared with the prior art, the beneficial effects of the present invention include at least: the present invention provides a method and system for fault reconstruction of a new energy access distribution network based on oscillation monitoring. On the one hand, the method establishes a power flow model of the distribution network, and simultaneously performs two methods of oscillation monitoring on new energy access points within the range, and associates the monitoring results with the power flow results after the fault, thereby solving the problem of safety requirements of the distribution network system; on the other hand, the fault reconstruction model under large-scale new energy access is linearly optimized, thereby solving the problem of being unable to quickly select the most suitable access point interval to join the fault reconstruction. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0087] Figure 2 It is a schematic diagram of the simulation operation of the present invention on the IEEE-19 new energy access node system model. DETAILED DESCRIPTION

[0088] 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 described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0089] like Figure 1 As shown, embodiment 1 of the present invention provides a method for fault reconstruction of new energy access distribution network based on oscillation monitoring, comprising the following steps:

[0090] Step 1: Collect broadband data at the renewable energy connection point of the distribution network. If the disturbance energy shows an increasing trend, generate and upload an oscillation alarm signal and broadband data within t seconds.

[0091] In a preferred but non-limiting embodiment of the present invention, step 1 specifically comprises:

[0092] Step 1.1: Collect broadband data using a broadband non-injection oscillation monitoring module at all renewable energy connection points in the distribution network;

[0093] Step 1.2: Calculate the disturbance energy based on the harmonic and interharmonic measurements in the broadband data; expressed as the following formula (1):

[0094] (1)

[0095] Where:

[0096] is the disturbance energy power;

[0097] It is the highest harmonic monitored this time;

[0098] is the harmonic voltage;

[0099] are the harmonic currents.

[0100] Step 1.3: Determine the change trend of the disturbance energy of a spectrum. If it continues to increase within t seconds compared with the initial value at the 0th second, breaking through the threshold value Set and forming a stable growth trend, it is expressed by the following formula (2), and then execute step 1.4; otherwise, return to step 1.1 and continue to monitor the broadband data;

[0101] (2)

[0102] Where:

[0103] t0 is the 0th second; t1 is the 1st second; t2 is the 2nd second;

[0104] Set is the threshold value.

[0105] It is worth noting that formula (1) is a calculation formula in discrete form. In an alternative but non-limiting embodiment of the present invention, an integral form can also be used. Since the recording file of the injection method needs to be considered, it can be considered that the difference in disturbance energy of several consecutive seconds to the first second exceeds the set value, and this value is preferably but not limited to 2 seconds.

[0106] Step 1.4: trigger the oscillation monitoring data uploading mechanism, generate and upload the oscillation alarm signal and the broadband data within t seconds.

[0107] Step 2: Based on the broadband data monitoring range in step 1, a disturbance signal is injected into any node in the distribution network. If oscillation occurs in the distribution network, an oscillation alarm signal is generated and sent.

[0108] In a preferred but non-limiting embodiment of the present invention, step 2 specifically comprises:

[0109] Step 2.1: According to the frequency range and frequency interval of the wideband non-injection oscillation monitoring module, the power electronic injection oscillation monitoring module installed at any node of the distribution network generates a disturbance frequency sequence to be measured;

[0110] It is worth noting that the broadband non-injection oscillation monitoring module used in step 1 is installed at the renewable energy grid connection point, and the power electronic injection oscillation monitoring module used in step 2 can be installed at any node of the distribution network to measure the impedance of all nodes connected to the distribution network, which can be renewable energy, load, or other forms of power supply. The frequency range and frequency interval are determined by the measurement range of the broadband non-injection oscillation monitoring module under the on-site conditions. If the broadband non-injection oscillation monitoring module is 2.5-2500Hz with an interval of 2.5Hz, then the range of the power electronic injection oscillation monitoring module is the same.

[0111] Step 2.2: Generate disturbance signals one by one according to the disturbance frequency sequence to be measured generated in step 2.1, which can be expressed as the following formula (3):

[0112] (3)

[0113] Where:

[0114] For power electronic equipment grid connection point The voltage disturbance signal with a smaller amplitude injected into the phase For power electronic equipment grid connection point The voltage disturbance signal with a smaller amplitude injected into the phase For power electronic equipment grid connection point A voltage disturbance signal with a smaller amplitude injected into the phase;

[0115] is the amplitude of the first disturbance signal, is the amplitude of the second disturbance signal;

[0116] is the frequency of the first disturbance signal, is the second disturbance signal frequency, the first disturbance signal frequency and the second disturbance signal frequency is the coupling frequency, satisfying ,in, It is the real-time base frequency of the system;

[0117] is the phase of the first disturbance signal, is the phase of the second disturbance signal.

[0118] Step 2.3: Inject the disturbance signal generated in step 2.2 into the distribution network; and then record the impedance data of each frequency domain of each monitoring point while the disturbance signal is injected;

[0119] Step 2.4: Based on the full-measurement frequency domain impedance data obtained in step 2.3, the stability is determined by calculating the zero-pole distribution in the full-measurement frequency domain impedance data matrix of the measured object. When the right half plane zero point appears, it indicates that the system is unstable, that is, the distribution network oscillates, then the oscillation data uploading mechanism is triggered to upload the impedance data within t seconds; otherwise, the stability of the distribution network continues to be monitored. The value of t is preferably, but not limited to, 2s.

[0120] It is worth noting that, as several outstanding substantive features of the present invention: First, the stability of the entire line is judged by the full-frequency impedance data matrix, and the impedance data is sent up when it is unstable as the material for later analysis; second, the t of injection and non-injection can be consistent, preferably but not restrictively considered as 2s; third, if injection and non-injection are used at the same time, simultaneous alarm signals can be obtained. The two methods can complement each other's advantages. The broadband non-injection oscillation monitoring module is small in size and cheap in price compared to the power electronic injection oscillation monitoring module. It can be deployed at multiple points and is more suitable for some sensitive users (such as nursing home ventilators). When the line is long or there are many T contacts, the judgment is relatively more accurate; the power electronic injection oscillation monitoring module is relatively less susceptible to interference and has a lower false alarm rate.

[0121] Step 3: The new energy flow model algorithm module obtains the main station SVG image file and parses it. The number of new energy access points parsed is , construct power flow active model and reactive model;

[0122] The active power model for calculating power flow is expressed as follows:

[0123] (4)

[0124] Where:

[0125] ;

[0126] New energy access point Towards new energy access point The trend has been successful;

[0127] , Provides current for new energy access points;

[0128] for Phase angle difference between two points;

[0129] is the line resistance value;

[0130] is the line capacitance value;

[0131] is the angular frequency of alternating current.

[0132] The reactive power model for calculating the flow, if it is an overhead line, is expressed as follows:

[0133] (5)

[0134] Where:

[0135] New energy access point Towards new energy access point The trend is ineffective.

[0136] If it is a cable line, it is expressed as follows:

[0137] (6)

[0138] Where:

[0139] is the small resistance grounding resistance value.

[0140] Step 4: Set the reconstruction node and its adjacent nodes. Based on the active and reactive models obtained in step 3, construct the constraints for safe operation of the distribution network. Use the alarm signals of steps 1 and 2 to eliminate the oscillation points and restore power supply with the solution that minimizes the recovery time.

[0141] Specifically, the fault reconstruction algorithm module finds the optimal access interval of the new energy access point when the fault occurs, ensuring the optimal access interval of the new energy access point when the fault occurs. Greater than or equal to the power value before the fault, and and Meet the safe operation requirements of the distribution network and minimize the fault recovery time. is the failed reconstruction node, So A node with centered and spreading outwards. Refactoring for failure The active power of the node, Refactoring for failure Reactive power of the node.

[0142] In a preferred but non-limiting embodiment of the present invention, step 4 specifically comprises:

[0143] Step 4.1: Based on the parsing results of step 3, set the reconstruction node to Indicates, setting The adjacent nodes of express, So A node with the center spreading outwards.

[0144] Step 4.2: Use the SOCP (Second-Order Cone programming) algorithm to linearly program the active and reactive power of all fault points and transform the power flow active model in step 3 into and reactive model Transformed into the following form, equation (7) must be satisfied to meet the safe operation requirements of the distribution network:

[0145] (7)

[0146] Where:

[0147] Refactoring for failure The current in the node;

[0148] For The current of a node spreading outward from the center is based on the historical data of the master station;

[0149] express Node and The phase angle difference of the nodes.

[0150] Step 4.3: Judgement and Whether the node is an oscillation fault point. Use the result of the broadband non-injection oscillation monitoring module or the power electronic injection oscillation monitoring module to determine whether the node is an oscillation fault point. If a node is a fault point, remove the oscillation fault point; if the node is a non-fault point, retain it;

[0151] It is worth noting that if If the node is an oscillation point, then the line failure may be caused by this oscillation. If this point is not eliminated, the failure will occur again when reconstructed with new energy. The technical team of the present invention first realized that the integration of new energy into the distribution network is a double-edged sword. On the one hand, it can provide more power support during fault transfer, especially when there is no additional independent external power supply point (such as the terminal power grid), then a certain amount of important load can be carried by new energy; but on the other hand, because new energy can cause broadband oscillations, the cause of some distribution network accidents is due to oscillation, so these oscillation points need to be eliminated during transfer.

[0152] Step 4.4, according to the above steps 3 to 4.2, count all the results, first calculate Node is the center, all adjacent nodes, and then calculate all nodes separated by 1 node, let If the power value is greater than or equal to the power value before the fault, the unsatisfactory results will be eliminated.

[0153] Step 4.5, calculate the power supply recovery time of all results, and select the result with the shortest recovery time.

[0154] Step 4.6, when a After the node is restored, it can be used as The node continues to recover its neighbors.

[0155] Energy access point current Less than or equal to the maximum current required on the line;

[0156] The distribution network needs to be connected to the 10kV / 20kV busbar of the substation to ensure normal recovery after a fault.

[0157] Embodiment 2 of the present invention provides a new energy access distribution network fault reconstruction system based on oscillation monitoring, which runs the new energy access distribution network fault reconstruction method based on oscillation monitoring described in Embodiment 1, including the following modules: a broadband non-injection oscillation monitoring module, a power electronics injection oscillation monitoring module, a new energy flow model algorithm module and a fault reconstruction algorithm module.

[0158] The broadband non-injection oscillation monitoring module is used to collect broadband data at the renewable energy connection point of the distribution network. If the disturbance energy shows an increasing trend, an oscillation alarm signal is generated and sent to the upper layer.

[0159] The power electronic injection oscillation monitoring module is used to inject a disturbance signal into any node in the distribution network. If the distribution network oscillates, an oscillation alarm signal is generated and sent up;

[0160] The new energy power flow model algorithm module is used to obtain and parse the main station SVG model file to build the power flow active model and reactive model;

[0161] The fault reconstruction algorithm module is used to set the reconstruction node and its adjacent nodes. Based on the active and reactive models, it constructs the safe operation constraints of the distribution network. After removing the oscillation points, it uses the sent alarm signals to restore power supply with the solution with the shortest recovery time.

[0162] In a preferred but non-restrictive embodiment of the present invention, a broadband non-injection oscillation monitoring module collects broadband data at all renewable energy grid-connected points in the distribution network with a broadband non-injection oscillation monitoring module; calculates disturbance energy based on harmonic and interharmonic measurement values ​​in the broadband data; determines the disturbance energy change trend of a spectrum, and if it continues to increase within t consecutive seconds compared with the initial value at the 0th second, breaks through the threshold value Set, and becomes a stable growth trend, triggers the oscillation monitoring data uploading mechanism, generates and uploads the first oscillation alarm signal and broadband data within t seconds; otherwise, continues to collect broadband data at all renewable energy grid-connected points in the distribution network with a broadband non-injection oscillation monitoring module.

[0163] In a preferred but non-restrictive embodiment of the present invention, the power electronic injection oscillation monitoring module installed at any node of the distribution network generates a disturbance frequency sequence to be measured according to the frequency range and frequency interval of the wide-band non-injection oscillation monitoring module; generates disturbance signals one by one according to the generated disturbance frequency sequence to be measured; injects the generated disturbance signals into the distribution network; and then records the impedance data of each frequency domain of each monitoring point while injecting the disturbance signal; based on the obtained full-measurement frequency domain impedance data, in the full-measurement frequency domain impedance data matrix of the measured object, determines the stability by calculating the zero-pole distribution, and when a right half-plane zero point appears, it indicates that the distribution network oscillates, then triggers the oscillation data uploading mechanism, and uploads the impedance data within t seconds; otherwise, continues to monitor the stability of the distribution network.

[0164] In a preferred but non-limiting embodiment of the present invention, the new energy flow model algorithm module calculates the flow active model, which is expressed by the following formula:

[0165] (4)

[0166] Where:

[0167] ;

[0168] New energy access point Towards new energy access point The trend has been successful;

[0169] , Provides current for new energy access points;

[0170] for Phase angle difference between two points;

[0171] is the line resistance value;

[0172] is the line capacitance value;

[0173] is the angular frequency of alternating current;

[0174] The reactive power model for calculating the flow, if it is an overhead line, is expressed as follows:

[0175] (5)

[0176] Where:

[0177] New energy access point Towards new energy access point The tide is reactive;

[0178] If it is a cable line, it is expressed as follows:

[0179] (6)

[0180] Where:

[0181] is the small resistance grounding resistance value.

[0182] In a preferred but non-limiting embodiment of the present invention, the fault reconstruction algorithm module sets the reconstruction node based on the parsing result of the master station SVG image file. Indicates, setting The adjacent nodes of express, So A node with the center spreading outwards;

[0183] Using the SOCP algorithm, the power flow model and reactive model Transformed into the following form, equation (7) must be satisfied to meet the safe operation requirements of the distribution network:

[0184] (7)

[0185] Where:

[0186] Refactoring for failure The current in the node;

[0187] For The current of a node with the center spreading outwards is based on the historical data of the master station;

[0188] express Node and Phase angle difference of nodes;

[0189] Determine based on the first oscillation alarm signal and the second oscillation alarm signal and Whether the node is an oscillation fault point; if a node is a fault point, then the oscillation fault point is removed; if the node is not a fault point, then it is retained;

[0190] Count all the results of parsing the master station SVG model file to verify that it meets the safe operation requirements of the distribution network. First calculate Node is the center, all adjacent nodes, and then calculate all nodes separated by 1 node, let Greater than or equal to the power value before the fault, and the unsatisfactory results will be eliminated;

[0191] Calculate the power supply restoration time of all results and select the result with the shortest restoration time;

[0192] When a After the node is restored, it can be used as The node continues to recover its neighbors.

[0193] Embodiment 3 of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is loaded into the processor, the method for fault reconstruction of new energy access to a distribution network based on oscillation monitoring is implemented.

[0194] Embodiment 4 of the present invention provides a computer-readable storage medium, which stores a computer program, and is characterized in that when the computer program is executed by a processor, the method for fault reconstruction of new energy access to a distribution network based on oscillation monitoring is implemented.

[0195] In order to more clearly introduce the outstanding essential features of the present invention and the significant progress it brings to the prior art, an example of applying the present invention is introduced below.

[0196] by Figure 2Taking the IEEE-19 new energy access node system model shown as an example, the numbers in the figure represent the node numbers. The new energy access points cover more than 50% of the power supply nodes, and one or more new energy access points can provide power during fault reconstruction. Node No. 1 deploys a power electronic injection oscillation monitoring module with an injection frequency ranging from 2.5Hz to 2500Hz and an injection frequency interval of 0.5Hz. The remaining points deploy broadband non-injection oscillation monitoring modules with a measurement frequency of 2.5Hz to 2500Hz and a frequency resolution of 5Hz. When a fault occurs, the outlet circuit breaker of node 19 trips and all nodes below lose power. The new energy access distribution network fault reconstruction method based on oscillation monitoring includes the following steps:

[0197] Step 1: The broadband non-injection oscillation monitoring module obtains broadband data and calculates disturbance energy using harmonic and interharmonic measurement values ​​in the broadband data. When the disturbance energy of a spectrum continues to increase within t seconds and breaks through the threshold value Set, forming a stable growth trend, the oscillation monitoring data uploading mechanism is triggered to upload broadband data within t seconds. The specific algorithm is shown in formula (1) and formula (2):

[0198] (1)

[0199] (2)

[0200] Where:

[0201] is the disturbance energy power;

[0202] It is the highest harmonic monitored this time;

[0203] is the harmonic voltage;

[0204] are the harmonic currents.

[0205] t0 is the 0th second; t1 is the 1st second; t2 is the 2nd second;

[0206] Set is the threshold value.

[0207] Step 2: The power electronic injection oscillation monitoring module determines the frequency range and frequency interval of the measurement object, generates a disturbance frequency sequence to be measured, generates disturbance signals one by one according to the disturbance frequency sequence, and injects them into the system, see Announcement (3):

[0208] (3)

[0209] Where:

[0210] It is a voltage disturbance signal with a small amplitude injected into the grid connection point of the power electronic equipment;

[0211] is the amplitude of the first disturbance signal, is the amplitude of the second disturbance signal;

[0212] is the frequency of the first disturbance signal, is the second disturbance signal frequency, the first disturbance signal frequency and the second disturbance signal frequency is the coupling frequency, satisfying ,in, System real-time base frequency;

[0213] is the phase of the first disturbance signal, is the phase of the second disturbance signal.

[0214] Then, while the disturbance signal is injected, the three-phase voltage and current of the grid connection point are recorded, and the recorded data is processed to obtain the closed-loop frequency domain admittance matrix of the measured object. In the process, the stability is determined by calculating the zero-pole distribution. When a right half plane zero appears, it indicates that the system is unstable, and the oscillation data uploading mechanism is triggered to upload the recorded data within a period of time.

[0215] Step 3: The new energy flow model algorithm module obtains the main station SVG image file and parses it. The number of new energy access points parsed is ,exist Figure 2 In the IEEE-19 model shown, the number of new energy access points is 10;

[0216] The active power model for calculating power flow is expressed as follows:

[0217] (4)

[0218] Where:

[0219] ;

[0220] New energy access point Towards new energy access point The trend has been successful;

[0221] , Provides current for new energy access points;

[0222] for Phase angle difference between two points;

[0223] is the line resistance value;

[0224] is the line capacitance value;

[0225] is the angular frequency of alternating current.

[0226] The reactive power model for calculating the flow, if it is an overhead line, is expressed as follows:

[0227] (5)

[0228] If it is a cable line, it is expressed as follows:

[0229] (6)

[0230] Where:

[0231] is the small resistance grounding resistance value.

[0232] Step 4: The fault reconstruction algorithm module finds the optimal access interval of the new energy access point when the fault occurs, ensuring the optimal access interval of the new energy access point when the fault occurs. Greater than or equal to the power value before the fault, and and Meet the safe operation requirements of the distribution network and minimize the fault recovery time. is the failed reconstruction node, So A node with the center spreading outwards.

[0233] like Figure 2 As shown, is node 6, then The node may first be node 5 or node 7, then node 4 and node 8, and so on.

[0234] This step includes the following processes:

[0235] (a) Using the SOCP algorithm, linearly program the active and reactive power of all fault points, then the power flow active and reactive models in step 3 can be transformed into:

[0236] ;

[0237] (b) If If it is an oscillation fault point, the result of the broadband non-injection oscillation monitoring module or the power electronic injection oscillation monitoring module is used to eliminate the oscillation fault point; If it is a non-fault point, the master station data is used;

[0238] (c) According to the above steps 3 to 4-(b), count all the results and let Greater than or equal to the power value before the fault, and the unsatisfactory results will be eliminated;

[0239] (d) Calculate the power supply restoration time of all results and select the result with the shortest restoration time;

[0240] (e) When a near node is restored, the node can continue to restore its adjacent nodes as the resetx node.

[0241] The new energy access point current Less than or equal to the maximum current required on the line.

[0242] The distribution network needs to be connected to the 10kV / 20kV busbar of the substation to ensure normal recovery after the fault.

[0243] In another example of the application of the present invention: a fault occurs between node 12 and node 13. After the fault isolation is completed, the power supply above node 12 can be restored normally, and the main power supply below node 13 is lost and cannot be restored. The new energy access distribution network fault reconstruction method of the present invention can be adopted. Nodes 14, 16, and 18 can all be used as reset nodes, while nodes 13, 15, and 17 are near nodes. According to step 3 and step 4, power support is provided to the surrounding nodes to restore power supply.

[0244] Further: Taking node 13 and node 14 as an example,

[0245] like and If the power value of the node 13 and the node 14 before the failure is greater than or equal to the power value of the node 13 and the node 14 before the failure, the power supply of the node 13 and the node 14 can be restored.

[0246] If not satisfied, then judge is greater than or equal to the power value of the node 14 before the failure. If so, the power supply of the node 14 is restored.

[0247] In another case: taking nodes 13 and 14 as examples, if according to step 1 and step 2, node 14 is determined to be an oscillating node, node 14 is removed and is not used as a reset node.

[0248] In another case: Taking nodes 13 and 14 as an example, if node 13 is determined to be an oscillating node according to steps 1 and 2, node 13 is removed and not used as a near node. is greater than or equal to the power value of the node 14 before the failure. If so, the power supply of the node 14 is restored.

[0249] In another case: taking nodes 13 and 14 as an example, if node 14 is determined to be an oscillating node according to step 1 and step 2, node 14 is removed and not used as a reset node. At this time, if node 18 is a normal reset node, then according to step 3 and step 4, it is first determined whether node 15 can restore power supply. Under the condition that node 15 can restore power supply, node 15 is used as a reset node, and according to step 3 and step 4, it is determined whether node 13 can be restored.

[0250] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0251] 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 fault reconstruction method for accessing a new energy distribution network based on oscillation monitoring, characterized in that: include: Collect broadband data at the renewable energy connection point of the distribution network. If the disturbance energy shows an increasing trend, generate and send the first oscillation alarm signal. Based on the monitoring range of the broadband data, a disturbance signal is injected into any node in the distribution network, and if oscillation occurs in the distribution network, a second oscillation alarm signal is generated and sent upward; Get the main station SVG image file and parse it. The number of new energy access points parsed is , construct the power flow active model and reactive model; including: calculating the power flow active model, expressed as the following formula (1): (1) Where: ; New energy access point Towards new energy access point The trend has been successful; , Provides current for new energy access points; for Phase angle difference between two points; is the line resistance value; is the line capacitance value; is the angular frequency of alternating current; The reactive power model for calculating the flow, if it is an overhead line, is expressed as follows: (2) Where: New energy access point Towards new energy access point If it is a cable line, it can be expressed by the following formula (3): (3) Where: is the small resistance grounding resistance value; The reconstruction node and its adjacent nodes are set, and based on the power flow active and reactive models, the distribution network safe operation constraint conditions are constructed, and the first oscillation alarm signal and the second oscillation alarm signal are used to remove the oscillation point and restore the power supply with the solution with the shortest recovery time; the setting of the reconstruction node and its adjacent nodes includes: finding the best access interval of the new energy access point when the fault occurs, using the constructed power flow active and reactive models to ensure the power supply is restored when the fault occurs. Greater than or equal to the power value before the fault, and The distribution network safety operation constraints are met, and the fault recovery time is the shortest. is the reconstruction node, So A node with centered and spreading outwards. To reconstruct the node The active power, To reconstruct the node The reactive power, Is a reconstruction node To Node The power flow model of Is a reconstruction node To Node Power flow reactive model; The method of setting the reconstruction node and its adjacent nodes, constructing the safe operation constraint conditions of the distribution network based on the active and reactive power models of the power flow, using the first oscillation alarm signal and the second oscillation alarm signal, removing the oscillation point, and restoring the power supply with the solution with the shortest recovery time includes: setting the reconstruction node based on the analysis result of the SVG image file of the master station; using the SOCP algorithm to convert the active power model of the power flow into and reactive model The transformation is performed to meet the safe operation requirements of the distribution network, which is expressed as follows: (4) Where: To reconstruct the node The current in For The current of a node with the center spreading outwards is based on the historical data of the master station; express Node and Phase angle difference of nodes; Determine based on the first oscillation alarm signal and the second oscillation alarm signal and Whether the node is an oscillation fault point; if a node is a fault point, the oscillation fault point is removed; if the node is not a fault point, it is retained; all the results of parsing the master station SVG model file to verify that they meet the requirements of safe operation of the distribution network are calculated first. Node is the center, all adjacent nodes, and then calculate all nodes separated by 1 node, let If the power value is greater than or equal to the power value before the fault, the unsatisfactory results will be eliminated; the power supply recovery time of all results will be calculated, and the result with the smallest recovery time will be selected; when a certain After the node is restored, the node will be The node continues to recover its neighbors.

2. The fault reconstruction method for accessing a new energy distribution network based on oscillation monitoring according to claim 1 is characterized in that: Collect broadband data at the renewable energy connection point of the distribution network. If the disturbance energy shows an increasing trend, generate and send the first oscillation alarm signal, including: Step 1.1: Collect broadband data using a broadband non-injection oscillation monitoring module at all renewable energy connection points in the distribution network; Step 1.2: Calculate disturbance energy based on harmonic and interharmonic measurements in broadband data; Step 1.3: Determine the change trend of the disturbance energy of a spectrum. If it continues to increase within t seconds compared with the initial value at the 0th second, breaking through the threshold value Set and forming a stable growth trend, execute step 1.4; otherwise, return to step 1.1 and continue to monitor the broadband data; Step 1.4: trigger the oscillation monitoring data uploading mechanism to generate and upload the first oscillation alarm signal and broadband data within t seconds.

3. The fault reconstruction method for accessing a new energy distribution network based on oscillation monitoring according to claim 2 is characterized in that: The disturbance energy is calculated as follows: (5) Where: is the disturbance energy power; It is the highest harmonic monitored this time; is the harmonic voltage; is each harmonic current; The stable growth trend is expressed by the following formula (6): (6) Where: t0 is the 0th second; t1 is the 1st second; t2 is the 2nd second; Set is the threshold value.

4. The method for fault reconstruction of new energy access distribution network based on oscillation monitoring according to any one of claims 1 to 3, characterized in that: Based on the monitoring range of the broadband data, a disturbance signal is injected into any node in the distribution network. If the distribution network oscillates, generating and sending a second oscillation alarm signal includes: According to the frequency range and frequency interval of the wideband non-injection oscillation monitoring module, the power electronic injection oscillation monitoring module installed at any node of the distribution network generates a disturbance frequency sequence to be measured; Generate disturbance signals one by one according to the generated disturbance frequency sequence to be measured; The generated disturbance signal is injected into the distribution network; and then the impedance data of each frequency domain of each monitoring point is recorded while the disturbance signal is injected; Based on the obtained full-measurement frequency-domain impedance data, the stability is determined by calculating the zero-pole distribution in the full-measurement frequency-domain impedance data matrix of the measured object. When a right-half-plane zero appears, it indicates that the distribution network has oscillated, triggering the oscillation data uploading mechanism to upload the impedance data within t seconds; otherwise, the stability of the distribution network continues to be monitored.

5. The fault reconstruction method for accessing a new energy distribution network based on oscillation monitoring according to claim 4 is characterized in that: The disturbance signal is expressed as follows: (7) Where: For power electronic equipment grid connection point The voltage disturbance signal with a smaller amplitude injected into the phase For power electronic equipment grid connection point The voltage disturbance signal with a smaller amplitude injected into the phase For power electronic equipment grid connection point A voltage disturbance signal with a smaller amplitude injected into the phase; is the amplitude of the first disturbance signal, is the amplitude of the second disturbance signal; is the frequency of the first disturbance signal, is the second disturbance signal frequency, the first disturbance signal frequency and the second disturbance signal frequency is the coupling frequency, satisfying ,in, It is the real-time base frequency of the system; is the phase of the first disturbance signal, is the phase of the second disturbance signal.

6. The fault reconstruction method for accessing a new energy distribution network based on oscillation monitoring according to claim 1 is characterized in that: Energy access point current Less than or equal to the maximum current required on the line; The distribution network needs to be connected to the substation 10kV / 20kV busbar to ensure fault recovery.

7. A fault reconstruction system for accessing a new energy distribution network based on oscillation monitoring, which runs a fault reconstruction method for accessing a new energy distribution network based on oscillation monitoring as described in any one of claims 1 to 6, characterized in that: It includes the following modules: broadband non-injection oscillation monitoring module, power electronics injection oscillation monitoring module, new energy power flow model algorithm module and fault reconstruction algorithm module; The broadband non-injection oscillation monitoring module is used to collect broadband data at the new energy grid connection point of the distribution network. If the disturbance energy shows an increasing trend, a first oscillation alarm signal is generated and sent up; The power electronic injection oscillation monitoring module is used to inject a disturbance signal into any node in the distribution network. If the distribution network oscillates, a second oscillation alarm signal is generated and sent up; The new energy power flow model algorithm module is used to obtain and parse the main station SVG model file to build the power flow active model and reactive model; The fault reconstruction algorithm module is used to set the reconstruction node and its adjacent nodes. Based on the active and reactive power models of the power flow, it constructs the safe operation constraints of the distribution network. After removing the oscillation points, it uses the sent alarm signals to restore power supply with the solution with the shortest recovery time.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is loaded into the processor, the method for fault reconstruction of new energy access to distribution network based on oscillation monitoring is implemented according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for fault reconstruction of new energy access to a distribution network based on oscillation monitoring is implemented according to any one of claims 1 to 6.

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