Power distribution network risk assessment method based on distributed new energy access

Abstract

The invention discloses a power distribution network risk assessment method based on distributed new energy access, and the method comprises the steps: collecting electric energy parameters of grid-connected nodes of all distributed new energy merged into a power distribution network, constructing an electric energy parameter matrix, and converting the electric energy parameter matrix into a numerical parameter matrix; performing initial risk assessment based on values of elements in the numerical parameter matrix; determining active power change and reactive power change of the grid-connected node, and performing secondary evaluation on the grid-connected node based on the active power change and the reactive power change; and integrating a result of the initial risk assessment and a result of the secondary assessment to obtain a risk level of each distributed new energy merged into the power distribution network. The problem that an existing risk assessment method for the power distribution network connected with the distributed new energy is highly dependent on historical data and difficult to deal with complex scenes is solved, assessment of the stability and the power supply reliability of the power distribution network system is achieved, the accuracy is high, high dependency on the historical data in the prior art is avoided, and the risk assessment method has good application prospects. And the method is suitable for various scenes.

Description

Technical Field

[0001] This application relates to the technical field of distribution network system optimization, and particularly to a risk assessment method for distribution networks based on the access of distributed new energy sources. Background Art

[0002] Distributed new energy refers to an integrated energy utilization system located at the user side. It comprehensively utilizes or generates electricity from the energy located at the user side, can generate electricity at the consumption location (or nearby), has the ability to efficiently utilize the waste energy generated by power generation to produce heat and electricity, and is a system that uses on-site waste gas, waste heat, and excess pressure difference to generate electricity and achieve energy recycling. Distributed new energy mainly includes distributed photovoltaics, decentralized wind power, etc., and has the advantages of on-site and nearby development and construction, on-site and nearby consumption and utilization, and can achieve cascaded utilization of energy and maximization of benefits.

[0003] When multiple distributed new energy sources such as photovoltaics and wind power are connected to the distribution network, during peak power load periods, the distributed new energy system can provide power support and play a role in power peak shaving. When a large-scale power outage occurs in the main grid, some distributed new energy systems can still operate normally, which can improve the safety and reliability of power supply. At the same time, with the expansion of the scale of distributed new energy, the structure and operating state of the traditional distribution network have changed significantly. The randomness and intermittency of distributed new energy generation have increased the complexity of the distribution network power system, and are likely to lead to the following situations: First, the power supply of distributed new energy may exceed the design carrying capacity of the existing distribution network (for example, in some areas, a large number of distributed photovoltaics connected will form a "red area of low-voltage carrying capacity", that is, the grid carrying capacity is close to or exceeds the limit). Second, the output of distributed new energy generation is volatile and intermittent. When the output of distributed new energy generation does not match the load, it will cause voltage fluctuations. Moreover, the frequent start and stop of distributed new energy generation equipment will also cause voltage flicker. Third, a large number of power electronic devices are used in distributed new energy generation equipment, and these devices may generate harmonic currents, which will cause grid voltage distortion and harmonic pollution after being injected into the distribution network. In addition, when a fault occurs or planned maintenance is carried out on the distribution network, the distributed new energy generation equipment may be disconnected from the main grid and form an island. The voltage and frequency in the island may be unstable, which will damage electrical equipment and pose a safety hazard to maintenance personnel.

[0004] However, most of the existing risk assessment methods for distribution networks with distributed new energy access are based on historical data of distributed new energy generation output, historical data of distribution network load demand (studying its variation law), or historical fault data after distributed new energy is connected to the distribution network, etc., to conduct risk assessment on the distribution network with distributed new energy access. The accuracy of the assessment depends on the adaptability of historical data to the current scenario, and it is difficult to cope with complex scenarios (such as extreme weather and multiple distributed new energy sources connected to the distribution network). Summary of the Invention

[0005] By providing a risk assessment method for a distribution network based on distributed new energy access in an embodiment of the present application, the problems that the existing risk assessment methods for distribution networks with distributed new energy access have a high dependence on historical data and are difficult to cope with complex scenarios are solved.

[0006] In a first aspect, an embodiment of the present application provides a risk assessment method for a distribution network based on distributed new energy access, including: collecting electrical energy parameters of grid-connected nodes where each distributed new energy is incorporated into the distribution network, and constructing an electrical energy parameter matrix; converting the electrical energy parameter matrix into a numerical parameter matrix; performing an initial risk assessment based on the values of the elements in the numerical parameter matrix; determining the active power change and reactive power change of the grid-connected nodes according to the distribution network structure and the electrical energy parameter matrix, and performing a secondary assessment on the grid-connected nodes based on them; and comprehensively obtaining the risk levels of each distributed new energy incorporated into the distribution network based on the results of the initial risk assessment and the results of the secondary assessment.

[0007] In combination with the first aspect, in a possible implementation manner, the electrical energy parameters include the current, voltage, power, and frequency of the grid-connected nodes.

[0008] In combination with the first aspect, in a possible implementation manner, the electrical energy parameter matrix is as follows:

[0009]

[0010] In the formula, E represents the electrical energy parameter matrix, A ij represents the current of the i-th grid-connected node at the j-th moment, U ij represents the voltage of the i-th grid-connected node at the j-th moment, W ij represents the power of the i-th grid-connected node at the j-th moment, P ij represents the frequency of the i-th grid-connected node at the j-th moment, and the total number of elements in the electrical energy parameter matrix is the number of samples.

[0011] In combination with the first aspect, in a possible implementation manner, the conversion of the electrical energy parameter matrix into a numerical parameter matrix includes: respectively comparing the sub-elements of each element in the electrical energy parameter matrix with a safety current threshold, a safety voltage threshold, a safety power threshold, and a safety frequency threshold, marking the sub-elements that meet each threshold range as 1 / 4, marking the sub-elements that do not meet each threshold range as 0, and taking the sum of the sub-elements in each element of the electrical energy parameter matrix as the value of the corresponding element, thereby obtaining the numerical parameter matrix.

[0012] In combination with the first aspect, in a possible implementation manner, the initial risk assessment based on the values of the elements in the numerical parameter matrix includes: traversing each element column by column in the numerical parameter matrix, screening out the elements with a value of 0, marking the rows where the elements with a value of 0 are located as first-level fault rows, and skipping the elements in the first-level fault rows when continuing to traverse row by row; removing the first-level fault rows from the numerical parameter matrix, traversing the remaining rows row by row, screening out the elements with a value of 1, and marking the rows where the elements with a value of 1 are located as pending rows; marking the rows where the remaining elements in the numerical parameter matrix that do not have a value of 0 or 1 are located as second-level fault rows; evaluating the grid connection nodes corresponding to the first-level fault rows as high-risk nodes, evaluating the grid connection nodes corresponding to the second-level fault rows as medium-risk nodes, and evaluating the grid connection nodes corresponding to the pending rows as low-risk nodes.

[0013] In combination with the first aspect, in a possible implementation manner, the determination of the active power change and reactive power change of the grid connection nodes according to the distribution network structure and the electrical energy parameter matrix, and the secondary evaluation of the grid connection nodes based on the above includes: determining the phase difference information of each grid connection node based on the distribution network structure; obtaining the voltage and current of each grid connection node at different times based on the electrical energy parameter matrix; respectively determining the active power and reactive power of each grid connection node at different times by using the phase difference information, voltage, and current of each grid connection node; determining the active power change and reactive power change of each grid connection node in different time periods through the active power and reactive power of each grid connection node at different times; and judging whether the active power change and reactive power change in different time periods meet a preset range to perform a secondary evaluation of each grid connection node.

[0014] Combined with the first aspect, in a possible implementation manner, synthesizing the results of the initial risk assessment and the results of the secondary assessment to obtain the risk levels of each distributed new energy incorporated into the distribution network includes: if the result of the initial risk assessment is a high-risk node, the risk level of the distributed new energy corresponding to the high-risk node is a high-risk level; if the result of the initial risk assessment is a medium-risk node and the active power change and reactive power change of this grid-connected node do not satisfy the preset range, the risk level of the distributed new energy corresponding to this grid-connected node is a high-risk level; if the result of the initial risk assessment is a medium-risk node and the active power change or reactive power change of this grid-connected node satisfies the preset range, the risk level of the distributed new energy corresponding to this grid-connected node is a medium-risk level; if the result of the initial risk assessment is a medium-risk node and the active power change and reactive power change of this grid-connected node both satisfy the preset range, the risk level of the distributed new energy corresponding to this grid-connected node is a medium-low risk level; if the result of the initial risk assessment is a low-risk node and the active power change and reactive power change of this grid-connected node do not satisfy the preset range, the risk level of the distributed new energy corresponding to this grid-connected node is a medium-risk level; if the result of the initial risk assessment is a low-risk node and the active power change or reactive power change of this grid-connected node satisfies the preset range, the risk level of the distributed new energy corresponding to this grid-connected node is a medium-low risk level; if the result of the initial risk assessment is a low-risk node and the active power change and reactive power change of this grid-connected node both satisfy the preset range, the risk level of the distributed new energy corresponding to this grid-connected node is a low-risk level.

[0015] In the second aspect, an embodiment of the present application provides a distribution network risk assessment device based on the access of distributed new energy, which is characterized by including: an acquisition and construction module, configured to acquire the electrical energy parameters of the grid-connected nodes of each distributed new energy incorporated into the distribution network and construct an electrical energy parameter matrix; a conversion module, configured to convert the electrical energy parameter matrix into a numerical parameter matrix; an initial risk assessment module, configured to perform an initial risk assessment based on the values of the elements in the numerical parameter matrix; a secondary assessment module, configured to determine the active power change and reactive power change of the grid-connected node according to the distribution network structure and the electrical energy parameter matrix, and perform a secondary assessment on the grid-connected node based on the above; a synthesis module, configured to synthesize the results of the initial risk assessment and the results of the secondary assessment to obtain the risk levels of each distributed new energy incorporated into the distribution network.

[0016] In the third aspect, an embodiment of the present application provides a device, where the device includes: a processor; a memory for storing processor-executable instructions; when the processor executes the executable instructions, the method described in the first aspect or any possible implementation manner of the first aspect is implemented.

[0017] Fourthly, an embodiment of the present application provides a non-volatile computer-readable storage medium, which includes computer programs or instructions for storage. When the computer programs or instructions are executed, the method described in the first aspect or any possible implementation manner of the first aspect is implemented.

[0018] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0019] By constructing an electric energy parameter matrix, the embodiment of the present application can quickly perform an initial risk assessment of grid-connected nodes; through the initial risk assessment, the risk level of grid-connected nodes can be initially determined; through the secondary assessment, the risk level of grid-connected nodes can be more accurately evaluated; by integrating the results of the initial risk assessment and the secondary assessment, various scenarios can be adapted, and the risk level and possible fault types of distributed new energy can also be determined. It effectively solves the problems that the existing risk assessment methods for distribution networks with distributed new energy access have a high dependence on historical data and are difficult to handle complex scenarios. Furthermore, it realizes the assessment of the stability and power supply reliability of the distribution network system with distributed new energy access, and has a high accuracy rate. It avoids the high dependence on historical data in the prior art, can be applied to various scenarios, and can also evaluate instantaneous faults. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments of the present application or the description of the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a flowchart of a risk assessment method for a distribution network based on distributed new energy access provided by an embodiment of the present application;

[0022] Figure 2 It is a schematic structural diagram of a risk assessment device for a distribution network based on distributed new energy access provided by an embodiment of the present application;

[0023] Figure 3 It is a flowchart of performing an initial risk assessment based on the values of the elements in the numerical parameter matrix provided by an embodiment of the present application. Detailed Embodiments

[0024] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] The following explanations are made for some of the technologies involved in the embodiments of the present application to facilitate understanding. It should be considered that they are merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, some descriptions of well-known functions and structures are omitted in the following description.

[0026] Figure 1 is a flowchart of a distribution network risk assessment method based on distributed new energy access provided by the embodiments of the present application, including steps 101 to 105. Among them, Figure 1 This is only an execution order shown in the embodiments of the present application and does not represent the only execution order of a distribution network risk assessment method based on distributed new energy access. Under the condition that the final result can be achieved, Figure 1 the steps shown can be executed in parallel or reversed.

[0027] Step 101: Collect the electrical energy parameters of the grid-connected nodes where each distributed new energy is incorporated into the distribution network, and construct an electrical energy parameter matrix. In the embodiments of the present application, the electrical energy parameters include the current, voltage, power, and frequency of the grid-connected nodes.

[0028] Specifically, in the present application, the current can be measured by a current transformer (CT) installed at the grid-connected node, and the current transformer can convert a large current into a small current. After the distributed new energy is incorporated into the distribution network, the uncertainty of the current flow direction and magnitude increases. In a traditional passive radial network, the current flows unidirectionally from the power supply station to the load nodes. After the distributed new energy is incorporated, the current flow direction may be affected by various factors, such as the power output of each power source and the change of the load.

[0029] The voltage can be measured by a voltage transformer (PT) installed at the grid-connected node, and the voltage transformer can convert a high voltage into a low voltage. The output of distributed new energy power generation has volatility and intermittency. When the output of distributed new energy power generation does not match the load, it will cause voltage fluctuations. If the voltage fluctuation is too large, it may lead to voltage collapse, which will directly affect the stability and power supply quality of the distribution network.

[0030] The power includes active power and reactive power, and can be calculated using the power formula through voltage and current. The power formula is as follows:

[0031] P = UIcosθ, Q = UIsinθ,

[0032] where P is the active power, Q is the reactive power, U is the voltage, I is the current, cosθ is the cosine of the phase difference between the voltage and the current, also known as the power factor, and sinθ is the sine of the phase difference between the voltage and the current, also known as the reactive power factor. The power factor and the reactive power factor can be directly measured by an electricity meter or a power factor meter, or can be calculated by measuring the voltage, the current, and the phase difference between them.

[0033] In practical applications, a power measurement instrument can also be used to directly measure the active power and reactive power of the grid-connected nodes. After distributed new energy is connected to the distribution network, its power will directly affect the power flow distribution and load balance of the distribution network. When the power generation output of distributed new energy does not match the load, it will cause power imbalance, which in turn affects the stability and carrying capacity of the distribution network.

[0034] The frequency is usually determined by measuring the period of the alternating current signal in the distribution network and calculating the number of periodic changes in the waveforms of the voltage and the current, that is, the number of periodic changes per second of the alternating current signal, usually expressed in hertz (Hz). A frequency measurement device or a protection device can also be used to monitor the frequency of the power grid in real time. When a large number of distributed new energy sources are connected to the grid, if the power generation output of distributed new energy does not match the load, it will cause the frequency of the distribution network to be abnormal. The stability of the frequency has an important impact on the stable operation of the distribution network. Although the impact of distributed new energy connection on the frequency is relatively small, in extreme cases, such as a sudden large increase or decrease in the power generation output of distributed new energy, it will have a greater impact on the frequency.

[0035] In the embodiments of the present application, according to the set frequency (10 minutes), the electrical energy parameter matrix constructed by obtaining the electrical energy parameters of each grid-connected node is as follows:

[0036]

[0037] In the formula, E represents the electrical energy parameter matrix, A ij represents the current of the i-th grid-connected node at the j-th moment, U ij represents the voltage of the i-th grid-connected node at the j-th moment, W ij represents the power of the i-th grid-connected node at the j-th moment, P ij represents the frequency of the i-th grid-connected node at the j-th moment. The total number of elements in the electrical energy parameter matrix is the number of samples.

[0038] In the above power parameter matrix, each row represents the power parameters of the same grid-connected node at different times, and each column represents the power parameters of different grid-connected nodes at the same time. In practical applications, there may be dozens of elements in the matrix, which are specifically determined according to the structure of the distribution network (affecting the number of grid-connected nodes) and the evaluation and monitoring duration. To prevent the constructed parameterized matrix from being too large and reducing the data processing efficiency of the computer, those skilled in the art can also segment the distribution network according to its structure, construct a power parameter matrix for the grid-connected nodes in each segment, and construct multiple power parameter matrices for the entire distribution network for parallel processing. The evaluation and monitoring duration can be determined according to the actual situation. Real-time monitoring can be carried out, and the power parameters obtained within each hour are constructed into a power parameter matrix. Or the power parameter matrix can be constructed in stages, with an evaluation and monitoring duration of one hour every three hours to construct the power parameter matrix. This application does not limit this here, and those skilled in the art can determine it according to the actual situation.

[0039] Step 102: Convert the power parameter matrix into a numerical parameter matrix. In the embodiment of the present application, the sub-elements of each element in the power parameter matrix are respectively compared with the safe current threshold, safe voltage threshold, safe power threshold, and safe frequency threshold. The sub-elements that meet the threshold ranges are recorded as 1 / 4, and the sub-elements that do not meet the threshold ranges are recorded as 0. Then, the sum of the sub-elements in the power parameter matrix is used as the value of the corresponding element to obtain the numerical parameter matrix.

[0040] Exemplarily, the safe current threshold is ±10% of the current rated current in the distribution network, that is, the safe current threshold ∈ (current rated current * 90%, current rated current * 110%). Those skilled in the art can simulate and analyze through grid simulation software or models according to the structure of the distribution network to determine the current rated current. Or the current rated current can be estimated based on the historical data of the distribution network (with a lower accuracy than simulation).

[0041] The safe voltage threshold is determined according to the voltage of the power supply output of distributed new energy (affected by the type of distributed new energy, the way of accessing the distribution network, and the design of the distribution network). For power supply with a voltage of 35 kV or above, the safe voltage threshold is ±10% of the rated voltage. For three-phase power supply with a voltage of 10 kV or below, the safe voltage threshold is ±7% of the rated voltage. For single-phase power supply of 220 V, the safe voltage threshold is +7% to -10% of the rated voltage.

[0042] The safety power threshold is determined by factors such as the power generation output of distributed new energy, the load conditions of the distribution network, and the dispatching and control strategies of the power grid. For small-capacity distributed power sources (such as grid connection at the 380V voltage level), the requirements for their safety power threshold are relatively loose. For large-capacity distributed power sources (such as grid connection at 10kV and above voltage levels), the requirements for their safety power threshold are relatively strict. Exemplarily, in this application, the safety power threshold of small-capacity distributed power sources is set to ±5% (active power) and ±8% (reactive power), and the safety power threshold of large-capacity distributed power sources is set to ±3% (active power) and ±6% (reactive power).

[0043] The safety frequency threshold is ±0.6Hz of the normal voltage frequency, and is exemplarily set to (49.4Hz, 50.6Hz).

[0044] It should be noted that the electric energy parameter matrix in this application contains the electric energy parameters of multiple grid connection nodes at multiple moments, and initial risk assessment and secondary assessment have been carried out. Therefore, the requirements for the value ranges of the safety current threshold, safety voltage threshold, safety power threshold, and safety frequency threshold here are not strict. Even if there is a certain error in a certain threshold range, it has no impact on the final risk assessment result.

[0045] Exemplarily, if the current of the first grid connection node at the first moment (i.e., the first element in the electric energy parameter matrix) conforms to the safety current threshold, the value of this sub-element is 1 / 4; if the voltage does not conform to the safety voltage threshold, the value of this sub-element is 0; if the power does not conform to the safety power threshold, the value of this sub-element is 0; if the frequency conforms to the safety frequency threshold, the value of this sub-element is 1 / 4; then the first element is Then the value of this element is 2 / 4 when converted into a numerical parameter matrix. The entire electric energy parameter matrix is converted into a numerical parameter matrix according to the above method. Exemplarily, the following numerical parameter matrix is given:

[0046]

[0047] The above numerical parameter matrix takes the numerical parameter matrix converted from the electric energy parameter matrix constructed by the electric energy parameters of 3 grid connection nodes at 3 different moments as an example.

[0048] Step 103: Based on the values of the elements in the numerical parameter matrix, perform an initial risk assessment. In the embodiment of this application, the specific steps of step 103 are as Figure 3 shown, including steps 301 to 306, specifically as follows.

[0049] Step 301: Traverse each element column by column in the numerical parameter matrix, screen out the elements with a value of 0, and mark the rows where the elements with a value of 0 are located as primary fault rows. In the embodiment of the present application, each element in each column is traversed in sequence column by column. If the element value is 0, the row where the element with a value of 0 is located is marked as a primary fault row.

[0050] Step 302: Determine whether the column-by-column traversal is completed. In the embodiment of the present application, if the column-by-column traversal of the numerical parameter matrix is completed, step 304 is executed. If the traversal of the numerical parameter matrix is not completed, step 303 is executed, which is specifically as follows.

[0051] Step 303: Continue to traverse the remaining columns of the numerical parameter matrix and skip the elements in the primary fault rows. In the embodiment of the present application, if the last element of the numerical parameter matrix has not been traversed, then continue to complete the traversal of the remaining elements in the column where the most recently screened element with a value of 0 is located, and continue to complete the traversal of each element in the remaining columns of the numerical parameter matrix. When traversing each element in the remaining columns, skip the elements in the primary fault rows when encountering a primary fault row, and continue to traverse other elements in the column.

[0052] Step 304: Remove the primary fault rows from the numerical parameter matrix, traverse each row of the remaining rows, screen out the elements with a value of 1, and mark the rows where the elements with a value of 1 are located as undetermined rows. In the embodiment of the present application, if, when traversing the numerical parameter matrix column by column, the last element has been traversed, that is, the column-by-column traversal is completed, at this time, remove the primary fault rows marked during the column-by-column traversal, traverse each row of the remaining rows, and mark the rows where the elements with a value of 1 are located as undetermined rows until the traversal of each row of the remaining rows is completed.

[0053] Step 305: Mark the rows where there are no elements with a value of 0 or 1 remaining in the numerical parameter matrix as secondary fault rows. In the embodiment of the present application, the rows where there are no elements with a value of 0 or 1 are marked as secondary fault rows.

[0054] Step 306: Evaluate the grid connection nodes corresponding to the primary fault rows as high-risk nodes, evaluate the grid connection nodes corresponding to the secondary fault rows as medium-risk nodes, and evaluate the grid connection nodes corresponding to the undetermined rows as low-risk nodes. In the embodiment of the present application, the primary fault rows, that is, the rows where there are elements with a value of 0, indicate that at a certain moment during the evaluation and monitoring period, the grid connection nodes corresponding to these rows have all abnormal conditions of current, voltage, power, and frequency, which means that there are serious faults in these grid connection nodes, and there may be islanding effects, serious harmonic pollution, circuit equipment failures, or power generation equipment failures. At this time, do not refer to the electrical energy parameters of these grid connection nodes at other moments, and classify them as high-risk nodes, which require staff to handle them in a short time.

[0055] At a certain moment within the evaluation and monitoring duration, one to three abnormalities occurred in the current, voltage, power, or frequency of the grid-connected node corresponding to the secondary fault line. Moreover, during the evaluation and monitoring duration, the grid-connected node did not experience a situation where the current, voltage, power, and frequency were all normal, nor did it experience a situation where the current, voltage, power, and frequency were all abnormal. In this case, the fault may be a severe fault or a minor fault. For example, if only the current is abnormal, it may be that the distributed new energy generation equipment or the load near the grid-connected node suddenly increases, exceeding the carrying capacity of the distribution network or equipment. It may also be that there are problems such as insulation damage or wiring errors in the lines or equipment in the distribution network, causing the current to flow through paths where it should not. Additionally, there may be problems such as poor grounding or excessive grounding resistance in the lines or equipment in the distribution network.

[0056]

[0056]

[0057] Step 104: Determine the active power change and reactive power change of the grid-connected node according to the distribution network structure and the electrical energy parameter matrix, and conduct a secondary evaluation of the grid-connected node based on this. In the embodiment of the present application, the phase difference information of each grid-connected node is determined based on the distribution network structure. The voltage and current of each grid-connected node at different times are obtained based on the electrical energy parameter matrix. The active power and reactive power of each grid-connected node at different times are respectively determined using the phase difference information, voltage, and current of each grid-connected node. The active power change and reactive power change of each grid-connected node in different time periods are determined through the active power and reactive power of each grid-connected node at different times. Determine whether the active power change and reactive power change in different time periods meet the preset range to conduct a secondary evaluation of each grid-connected node.

[0058] Step 105: Combine the results of the initial risk assessment and the secondary assessment to obtain the risk levels of each distributed new energy source connected to the distribution network. In the embodiments of the present application, if the result of the initial risk assessment is a high-risk node, the risk level of the distributed new energy source corresponding to the high-risk node is a high-risk level; if the result of the initial risk assessment is a medium-risk node, and both the active power change and the reactive power change of the grid-connected node do not meet the preset range, the risk level of the distributed new energy source corresponding to the grid-connected node is a high-risk level; if the result of the initial risk assessment is a medium-risk node, and either the active power change or the reactive power change of the grid-connected node meets the preset range, the risk level of the distributed new energy source corresponding to the grid-connected node is a medium-risk level; if the result of the initial risk assessment is a medium-risk node, and both the active power change and the reactive power change of the grid-connected node meet the preset range, the risk level of the distributed new energy source corresponding to the grid-connected node is a medium-low risk level; if the result of the initial risk assessment is a low-risk node, and both the active power change and the reactive power change of the grid-connected node do not meet the preset range, the risk level of the distributed new energy source corresponding to the grid-connected node is a medium-risk level; if the result of the initial risk assessment is a low-risk node, and either the active power change or the reactive power change of the grid-connected node meets the preset range, the risk level of the distributed new energy source corresponding to the grid-connected node is a medium-low risk level; if the result of the initial risk assessment is a low-risk node, and both the active power change and the reactive power change of the grid-connected node meet the preset range, the risk level of the distributed new energy source corresponding to the grid-connected node is a low-risk level.

[0059] Specifically, a high-risk node in the result of the initial risk assessment means that at a certain moment during the evaluation and monitoring period, the corresponding grid-connected node has abnormal conditions in current, voltage, power, and frequency all at once, indicating that there is a serious fault in the grid-connected node, and there may be islanding effect, serious harmonic pollution, circuit equipment failure, or power generation equipment failure. At this time, the electrical energy parameters of the grid-connected node at other moments do not need to be referred to, and it is classified as a high-risk node. The risk level of the distributed new energy source corresponding to the high-risk node is a high-risk level (it is easy to have problems with unreasonable settings of distributed new energy). At this time, there are many uncertain factors in the distribution network system, and the stability and power supply reliability are poor, and it needs to be processed by the staff in a short time, otherwise the negative impact will be serious.

[0060] If the result of the initial risk assessment is a medium-risk node, and both the active power change and the reactive power change of the grid-connected node do not meet the preset range. At this time, it may be caused by factors such as equipment failure or abnormality, load imbalance, failure of the regulation system of the distribution network, and unstable output of distributed new energy. The risk level of the distributed new energy source corresponding to the grid-connected node is a high-risk level, and it needs to be processed by the staff in a short time, otherwise the negative impact will be serious.

[0061] If the result of the initial risk assessment is a medium-risk node, and the active power change or reactive power change of this grid-connected node meets the preset range, it may be caused by factors such as power grid dispatching and control problems, insufficient or excessive reactive power compensation, equipment aging or failure, unreasonable distribution network structure, and harmonic influence. The risk level of the distributed new energy corresponding to this grid-connected node is the medium-risk level. At this time, there are fewer uncertain factors in the distribution network system, and the stability and power supply reliability are poor. It is necessary for the staff to handle it within a short time. If there is a delay, the negative impact will be more serious.

[0062] If the result of the initial risk assessment is a medium-risk node, and both the active power change and reactive power change of this grid-connected node meet the preset range, it may be caused by factors such as external environment changes, periodic changes of electrical energy parameters, and equipment failures. The risk level of the distributed new energy corresponding to this grid-connected node is the medium-low risk level. At this time, there are fewer uncertain factors in the distribution network system, and the stability and power supply reliability are poor. It is necessary for the staff to further check for faults.

[0063] If the result of the initial risk assessment is a low-risk node, and both the active power change and reactive power change of this grid-connected node do not meet the preset range, it means that the electrical energy parameters of this grid-connected node are normal at certain moments. It may be an instantaneous fault or unreasonable system settings, such as load fluctuations, improper power grid dispatching or control strategies (or control system failures, dispatching equipment failures), and changes in the output of distributed new energy. The risk level of the distributed new energy corresponding to this grid-connected node is the medium-risk level. At this time, there are more uncertain factors in the distribution network system, and the stability and power supply reliability are poor. It is necessary for the staff to further check and determine.

[0064] If the result of the initial risk assessment is a low-risk node, and the active power change or reactive power change of this grid-connected node meets the preset range, it may be caused by load fluctuations, environmental changes or faulty equipment (with a relatively low possibility). The risk level of the distributed new energy corresponding to this grid-connected node is the medium-low risk level. At this time, there are few uncertain factors in the distribution network system, and the stability and power supply reliability are poor. It may have an impact on the stability and security of the distribution network system, and a new round of assessment is required. If the second round is still the medium-low risk level or a more serious risk level, it is probably an equipment failure. If the second round is the low-risk level, it is an instantaneous fault, and the impact on the stability of the distribution network system is small.

[0065] If the result of the initial risk assessment is a low-risk node, and both the active power change and reactive power change of this grid-connected node meet the preset range, at this time, the risk level of the distributed new energy corresponding to this grid-connected node is the low-risk level. At this time, there are few uncertain factors in the distribution network system, and the stability and power supply reliability are high. It has no impact on the stability of the distribution network system or occasionally has a very small instantaneous impact (negligible).

[0066] Although the present application provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on routine or non-creative labor. The order of steps listed in this embodiment is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the method order shown in this embodiment or the accompanying drawings or in parallel (for example, in an environment of parallel processors or multi-threaded processing).

[0067] As Figure 2 shown, an embodiment of the present application further provides a distribution network risk assessment device 200 based on distributed new energy access. The device includes an acquisition and construction module 201, a conversion module 202, an initial risk assessment module 203, a secondary assessment module 204, and a comprehensive module 205, which are specifically as follows.

[0068] The acquisition and construction module 201 is configured to acquire the electrical energy parameters of the grid-connected nodes where each distributed new energy is incorporated into the distribution network and construct an electrical energy parameter matrix.

[0069] The conversion module 202 is configured to convert the electrical energy parameter matrix into a numerical parameter matrix.

[0070] The initial risk assessment module 203 is configured to perform an initial risk assessment based on the values of the elements in the numerical parameter matrix.

[0071] The secondary assessment module 204 is configured to determine the active power change and reactive power change of the grid-connected nodes according to the distribution network structure and the electrical energy parameter matrix, and perform a secondary assessment on the grid-connected nodes based on them.

[0072] The comprehensive module 205 is configured to comprehensively combine the results of the initial risk assessment and the results of the secondary assessment to obtain the risk levels of each distributed new energy incorporated into the distribution network.

[0073] Some modules in the device described in the present application may be described in a general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform specific tasks or implement specific abstract data types. The present application can also be practiced in a distributed computing environment, where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0074] The devices or modules described in the above application embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. For the convenience of description, when describing the above devices, they are divided into various modules according to functions and described separately. When implementing the application embodiments, the functions of each module can be implemented in the same or multiple software and / or hardware. Of course, the module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0075] The methods, devices or modules described in this application can be implemented in the form of computer-readable program codes. The controller can be implemented in any appropriate manner. For example, the controller can take the form of, for example, a microprocessor or a processor and a computer-readable medium that stores computer-readable program codes (such as software or firmware) executable by the (micro)processor, logic gates, switches, application specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320. The memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program codes, the method steps can be logically programmed to enable the controller to be implemented in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, and embedded microcontrollers to achieve the same function. Therefore, such a controller can be regarded as a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as either software modules for implementing the method or structures within the hardware component.

[0076] The embodiments of this application also provide a device, which includes: a processor; a memory for storing executable instructions of the processor; when the processor executes the executable instructions, the method described in the embodiments of this application is implemented.

[0077] The embodiments of this application also provide a non-volatile computer-readable storage medium, on which a computer program or instruction is stored. When the computer program or instruction is executed, the method described in the embodiments of this application is implemented.

[0078] In addition, in each embodiment of the present invention, the functional modules can be integrated into one processing module, or each module can exist alone, or two or more modules can be integrated into one module.

[0079] The above storage medium includes, but is not limited to, random access memory (English: Random Access Memory; abbreviation: RAM), read-only memory (English: Read-Only Memory; abbreviation: ROM), cache (English: Cache), hard disk (English: Hard Disk Drive; abbreviation: HDD), or memory card (English: Memory Card). The memory can be used to store computer program instructions.

[0080] From the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary hardware. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product, or can also be reflected in the process of data migration. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disc, etc., and includes several instructions for causing a computer device (which can be a personal computer, mobile terminal, server, or network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments of the present application.

[0081] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, reference can be made to each other. The key point of each embodiment is to illustrate the differences from other embodiments. All or part of the present application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, mobile communication terminals, multi-processor systems, microprocessor-based systems, programmable electronic devices, network PCs, small computers, large computers, distributed computing environments including any of the above systems or devices, and so on.

[0082] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A risk assessment method for a distribution network based on the access of distributed new energy, characterized in that Including: Collecting the electrical energy parameters of the grid-connected nodes where each distributed new energy is incorporated into the distribution network, and constructing an electrical energy parameter matrix; Converting the electrical energy parameter matrix into a numerical parameter matrix; Based on the values of the elements in the numerical parameter matrix, performing an initial risk assessment; Determining the active power change and reactive power change of the grid-connected nodes according to the distribution network structure and the electrical energy parameter matrix, and performing a secondary assessment on the grid-connected nodes based on them; Combining the results of the initial risk assessment and the results of the secondary assessment to obtain the risk levels of each distributed new energy incorporated into the distribution network.

2. The method according to claim 1, wherein The electrical energy parameters include the current, voltage, power, and frequency of the grid-connected nodes.

3. The method according to claim 2, characterized in that, The electrical energy parameter matrix is as follows: Wherein, E represents the electrical energy parameter matrix, A ij represents the current of the i-th grid-connected node at the j-th moment, U ij represents the voltage of the i-th grid-connected node at the j-th moment, W ij represents the power of the i-th grid-connected node at the j-th moment, P ij represents the frequency of the i-th grid-connected node at the j-th moment, and the total number of elements in the electrical energy parameter matrix is the number of samples.

4. The method according to claim 1, wherein The conversion of the electrical energy parameter matrix into a numerical parameter matrix includes: Respectively comparing the sub-elements of each element in the electrical energy parameter matrix with the safe current threshold, safe voltage threshold, safe power threshold, and safe frequency threshold, marking the sub-elements that meet each threshold range as 1 / 4, marking the sub-elements that do not meet each threshold range as 0, and taking the sum of the sub-elements in the electrical energy parameter matrix as the value of the corresponding element to obtain the numerical parameter matrix.

5. The method according to claim 1, wherein The performing of the initial risk assessment based on the values of the elements in the numerical parameter matrix includes: In the numerical parameter matrix, traversing each element column by column, screening out the elements with a value of 0, marking the rows where the elements with a value of 0 are located as first-level fault rows, and skipping the elements in the first-level fault rows when continuing to traverse row by row; Removing the first-level fault rows from the numerical parameter matrix, traversing the remaining rows row by row, screening out the elements with a value of 1, and marking the rows where the elements with a value of 1 are located as pending rows; Marking the rows where the remaining elements in the numerical parameter matrix that do not have a value of 0 or 1 are located as second-level fault rows; Evaluating the grid-connected nodes corresponding to the first-level fault rows as high-risk nodes, evaluating the grid-connected nodes corresponding to the second-level fault rows as medium-risk nodes, and evaluating the grid-connected nodes corresponding to the pending rows as low-risk nodes.

6. The method according to claim 1, characterized in that, The determining of the active power change and reactive power change of the grid-connected nodes according to the distribution network structure and the electrical energy parameter matrix, and the performing of the secondary assessment on the grid-connected nodes based on them includes: Determining the phase difference information of each grid-connected node based on the distribution network structure; Obtaining the voltage and current of each grid-connected node at different times based on the electrical energy parameter matrix; Using the phase difference information, voltage, and current of each grid-connected node to respectively determine the active power and reactive power of each grid-connected node at different times; Determining the active power change and reactive power change of each grid-connected node in different time periods through the active power and reactive power of each grid-connected node at different times; Judging whether the active power change and reactive power change in different time periods meet the preset range to perform a secondary assessment on each grid-connected node.

7. The method according to claim 5, characterized in that The combining of the results of the initial risk assessment and the results of the secondary assessment to obtain the risk levels of each distributed new energy incorporated into the distribution network includes: If the result of the initial risk assessment is a high-risk node, the risk level of the distributed new energy corresponding to the high-risk node is a high-risk level; If the result of the initial risk assessment is a medium-risk node, and both the active power change and the reactive power change of the grid-connected node do not meet the preset range, the risk level of the distributed new energy corresponding to the grid-connected node is a high-risk level; If the result of the initial risk assessment is a medium-risk node, and either the active power change or the reactive power change of the grid-connected node meets the preset range, the risk level of the distributed new energy corresponding to the grid-connected node is a medium-risk level; If the result of the initial risk assessment is a medium-risk node, and both the active power change and the reactive power change of the grid-connected node meet the preset range, the risk level of the distributed new energy corresponding to the grid-connected node is a medium-low risk level; If the result of the initial risk assessment is a low-risk node, and both the active power change and the reactive power change of the grid-connected node do not meet the preset range, the risk level of the distributed new energy corresponding to the grid-connected node is a medium-risk level; If the result of the initial risk assessment is a low-risk node, and either the active power change or the reactive power change of the grid-connected node meets the preset range, the risk level of the distributed new energy corresponding to the grid-connected node is a medium-low risk level; If the result of the initial risk assessment is a low-risk node, and both the active power change and the reactive power change of the grid-connected node meet the preset range, the risk level of the distributed new energy corresponding to the grid-connected node is a low-risk level.

8. A risk assessment device for a distribution network based on distributed new energy access, characterized in that, Comprising: An acquisition and construction module, configured to acquire the electrical energy parameters of the grid-connected nodes where each distributed new energy is incorporated into the distribution network, and construct an electrical energy parameter matrix; A conversion module, configured to convert the electrical energy parameter matrix into a numerical parameter matrix; An initial risk assessment module, configured to perform an initial risk assessment based on the values of the elements in the numerical parameter matrix; A secondary assessment module, configured to determine the active power change and the reactive power change of the grid-connected node according to the distribution network structure and the electrical energy parameter matrix, and perform a secondary assessment on the grid-connected node based on the above; An integration module, configured to integrate the result of the initial risk assessment and the result of the secondary assessment to obtain the risk level of each distributed new energy incorporated into the distribution network.

9. Equipment for implementing a risk assessment method of a distribution network based on distributed new energy access, characterized in that, Comprising: A processor; A memory for storing executable instructions of the processor; When the processor executes the executable instructions, the method described in any one of claims 1 to 7 is implemented.

10. A non-volatile computer-readable storage medium, characterized in that, Comprising a computer program or instructions for storing, and when the computer program or instructions are executed, the method described in any one of claims 1 to 7 is implemented.

Images