Online loop current calculation and risk analysis method for network configuration

Abstract

The present application relates to the technical field of electric power engineering, and particularly relates to a distribution network online closing loop current calculation and risk analysis method, comprising the following steps: determining the specific position of closing loop operation, and obtaining the distribution network topology structure and power equipment parameters before and after the closing loop operation; calculating the closing loop steady-state current according to the distribution network topology structure and power equipment parameters before and after the closing loop operation; establishing a calculation model of closing loop impact current according to the distribution network topology structure before and after the closing loop operation; calculating the closing loop impact current based on the power equipment parameters before and after the closing loop operation and the calculation model of closing loop impact current; checking whether the closing loop steady-state current and the closing loop impact current meet the safe and stable operation requirements; and if the closing loop steady-state current and the closing loop impact current do not meet the safe and stable operation requirements, regulating and controlling the closing loop operation. The present application can ensure the safe and stable operation of the distribution network during the closing loop operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power engineering methods, in particular to a distribution network online looped-in current calculation and risk analysis method. BACKGROUND

[0002] With the development of the national economy, users' demand for power supply reliability is increasing, and the operation and management of the power grid are also facing new challenges, requiring the power grid to be more reliable, reasonable and efficient. After large-scale urban power grid reconstruction, the distribution network in most parts of the country has reached the power supply mode of "closed loop connection and open loop operation", and the tie switch is generally in the open state. This operation mode improves the reliability of power supply to a certain extent, but in some cases, such as when a distribution line needs to be repaired or there are other emergencies, looped-in operation is required to ensure the continuity of power supply.

[0003] However, looped-in operation is not simply connecting two loops, because the lines and transformer branches of the power grid contain resistance and reactance, and looped-in steady-state current and looped-in impulse current will be generated after looped-in, the size and direction of this current depend on multiple factors, such as the voltage difference on both sides of the looped-in point, the total impedance of the looped-in network, etc. If the looped-in steady-state current and looped-in impulse current are too large, it may cause overload of the power grid equipment, or even trigger protection action, resulting in power supply interruption. Therefore, before looped-in operation, the looped-in steady-state current and looped-in impulse current need to be accurately calculated, and the risk of looped-in operation needs to be evaluated.

[0004] Traditional looped-in steady-state current and looped-in impulse current calculation methods are often based on some simplified assumptions and models, such as treating the power grid as a pure resistance or pure reactance network, or accumulating the impedance of the looped-in path, etc. These methods can reflect the characteristics of looped-in steady-state current and looped-in impulse current to a certain extent, but the calculation accuracy is limited, and it is difficult to meet the requirements of modern power grid for power supply reliability and safety.

[0005] In addition, with the access of distributed power and the development of smart grid, the structure and operation mode of the distribution network have become more complex, and the risk of looped-in operation has also increased accordingly. Therefore, a more accurate and comprehensive distribution network looped-in current calculation and risk analysis method is needed to guide looped-in operation and ensure the safe and stable operation of the power grid. SUMMARY

[0006] In order to overcome the problems raised in the background art, the present application provides a distribution network online looped-in current calculation and risk analysis method, which can ensure the safe and stable operation of the distribution network during looped-in operation.

[0007] The technical scheme of the present application is as follows:

[0008] In a first aspect, the present application provides a distribution network online looped-in current calculation and risk analysis method, comprising:

[0009] determining the specific location of the loop closing operation, acquiring the power grid topology and power equipment parameters before and after the loop closing operation through the power sensor group;

[0010] calculating the loop closing steady-state current according to the power grid topology and power equipment parameters before and after the loop closing operation;

[0011] establishing a calculation model of the loop closing impact current according to the power grid topology before and after the loop closing operation; and calculating the loop closing impact current based on the power equipment parameters before and after the loop closing operation and the calculation model of the loop closing impact current;

[0012] verifying whether the loop closing steady-state current and the loop closing impact current meet the safe and stable operation requirements; and if the loop closing steady-state current and the loop closing impact current do not meet the safe and stable operation requirements, regulating and controlling the loop closing operation.

[0013] In a possible implementation, the power equipment parameters include a voltage V, a voltage phase angle O, an active power Pload of the loop closing point, a reactive power Qload of the loop closing point, a total resistance Z of the loop network loop and a buffer coefficient β.

[0014] The power sensor group includes a voltage sensor, a phase angle measuring instrument, a power meter, a line impedance test device, and a power system simulation tool.

[0015] The voltage amplitude V, the voltage phase angle O, the voltage load active power Pload, and the voltage load reactive power Qload are acquired through the voltage sensor, the phase angle measuring instrument, and the power meter.

[0016] The total resistance Z of the loop network is acquired through the line impedance test device. loop

[0017] The buffer coefficient β is acquired by simulating the decay process of the impact current using the power system simulation tool.

[0018] In a possible implementation, the loop closing steady-state current is calculated according to the power grid topology and the power equipment parameters before and after the loop closing operation, including:

[0019] The loop closing steady-state current is calculated using the superposition method and the direct flow calculation method respectively according to the power grid topology and the power equipment parameters before and after the loop closing operation; and the final loop closing steady-state current is obtained by combining the calculation results of the superposition method and the direct flow calculation method.

[0020] In a possible implementation, the loop closing steady-state current is calculated using the superposition method according to the power grid topology and the power equipment parameters before and after the loop closing operation, including:

[0021] ​The voltage values on both sides of the closing point before the closing operation are calculated, and the difference between them is calculated to obtain the voltage difference on both sides of the closing point before closing; the total impedance of the looped network is calculated; based on the voltage difference on both sides of the closing point before closing and the total impedance of the looped network, the circulating current is calculated using Ohm's law;

[0022] By power flow analysis of the power grid, the load current of each branch before the closing operation (in an open-loop state) is calculated;

[0023] The load current and the circulating current are superimposed to obtain the closing steady-state current.

[0024] In a possible implementation, the superposition method is used to calculate the closing steady-state current formula:

[0025]

[0026] wherein Isteady is the closing steady-state current, Yi represents the admittance value of the ith parallel branch, n is the total number of branches parallel to the main power supply line of the looped network; e represents an exponential function, and j represents the imaginary part of a complex number;

[0027] The Yi is calculated by analyzing the voltage and current at both ends of the parallel branch and using Ohm's law to calculate the admittance, and the specific algorithm formula is Ii represents the current of the ith parallel branch, and Vi represents the voltage at both ends of the ith parallel branch.

[0028] V1 and V2 are the voltage amplitudes of the nodes on both sides of the closing point, and O1 and O2 are the voltage phase angles of the corresponding nodes.

[0029] ΔPload and ΔQload are the change amounts of active and reactive power at the closing point, respectively.

[0030] The parallel branch includes a backup line, a capacitor bank / reactor, and a load branch.

[0031] Backup line: a backup line for ensuring the redundancy of the power system, which is parallel to the main power supply line of the looped network.

[0032] Capacitor bank / reactor: used to access the looped network to improve the power factor or adjust the reactive power;

[0033] Load branch: a branch connected to a specific load, which is parallel to the main power supply line of the looped network.

[0034] In a possible implementation, after the closing steady-state current is calculated using the superposition method, the closing impact current is calculated according to the following formula:

[0035]

[0036] Where, Ishock is the closing-inrush current, K is the inrush coefficient, τ is the decay time constant, t is the time variable, β represents the inrush damping coefficient, and the decay process of the inrush current is obtained by using a power system simulation tool;

[0037] Ish1 and Ish2 are the maximum currents of the nodes on both sides of the closing-in point in the closing-in process, which are extracted by recording the current waveforms of the nodes on both sides of the closing-in point in the closing-in process by using a power system simulation tool.

[0038] In a possible implementation, the closing-in steady-state current is calculated by using a power flow direct algorithm according to the power distribution network topologies and power equipment parameters before and after the closing-in operation, including:

[0039] The power distribution network topologies and power equipment parameters before and after the closing-in operation are input into a power flow calculation software;

[0040] The power flow calculation conditions are set to simulate the actual operation state of the power grid;

[0041] The power flow calculation software is run to perform power flow analysis on the power distribution network, and the result of the power flow calculation is obtained;

[0042] The closing-in steady-state current is extracted from the result of the power flow calculation.

[0043] In a possible implementation, the power flow calculation conditions include:

[0044] The parameters in the network topologies before and after the closing-in operation need to satisfy the following equation:

[0045] A power balance equation, that is, for each node i, there is:

[0046]

[0047] Where, P i and Q i are the active power and reactive power injected into the node i, V i is the voltage of the node i, I ik is the current flowing from the node i to the node k, j is an imaginary unit, and * represents conjugate; and neighbors(i) represents a neighbor node set of the node i.

[0048] A current balance equation, that is, for each branch (i, k), there is:

[0049]

[0050] Where, V k is the voltage of the node k, and Z ik is the impedance of the branch (i, k).

[0051] The voltage equation, i.e., for each node i, the voltage V i satisfies:

[0052] V i = V0-∑ k∈neighbors(i) Z ik ·I ik ;

[0053] wherein V0 is the voltage of the reference node.

[0054] In a possible implementation, a calculation model of the closing-inrush current is established according to the power distribution network topologies before and after the closing operation; and the closing-inrush current is calculated based on the power equipment parameters before and after the closing operation and the calculation model of the closing-inrush current, including:

[0055] The calculation model of the closing-inrush current is established, and the calculation model of the closing-inrush current is used to describe the equivalent inductance and equivalent resistance of the closing point, the damping time constant, the system rated angular frequency, and the change of the initial phase angle difference of the voltage at the closing point at the closing time;

[0056] The professional circuit simulation software is used to calculate the equivalent inductance and equivalent resistance of the closing point by using the network topology and the power equipment parameters;

[0057] The closing-inrush current is solved by substituting the equivalent inductance, the equivalent resistance, the damping time constant, the system rated angular frequency, and the initial phase angle difference of the voltage at the closing point at the closing time into the calculation model of the closing-inrush current.

[0058] After the closing-inrush current is solved, the final closing-inrush current can be obtained in combination with the closing-inrush current Ishock calculated above.

[0059] In a possible implementation, the closing-inrush current and the closing steady-state current are verified to meet the safe and stable operation requirements; and if the closing-inrush current and the closing steady-state current do not meet the safe and stable operation requirements, the closing operation is regulated, including:

[0060] Current protection setting value verification: the closing-inrush current and the closing steady-state current calculated are compared with the rated current and the protection setting value of the power equipment;

[0061] Device bearing capacity evaluation: the bearing capacity of the power equipment to the closing-inrush current and the closing steady-state current is evaluated;

[0062] The risk level of the closing operation is evaluated by comprehensively considering the current protection setting value verification result, the device bearing capacity evaluation result, and the power distribution network topology, and corresponding closing operation regulation measures are adopted according to the risk level; wherein the closing operation regulation measures include adjusting the closing time and reducing the closing current.

[0063] In a possible implementation, the method further includes: monitoring the magnitude and variation trend of the loop closing steady-state current and the loop closing impulse current in real time during the loop closing operation, and issuing a pre-warning signal if the loop closing steady-state current and the loop closing impulse current abnormally increase and exceed predetermined first and second threshold values.

[0064] In a second aspect, the present application provides an electronic device, comprising: a memory and a processor;

[0065] The memory is configured to store a computer program.

[0066] The processor is configured to invoke the computer program to execute the method as described above.

[0067] In a third aspect, the present application provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program, when executed on an electronic device, causes the electronic device to implement the method as described above.

[0068] In a fourth aspect, the present application provides a computer program product, comprising a computer program, and the computer program, when executed on an electronic device, causes the electronic device to implement the method as described above.

[0069] The specific implementation of the second to fourth aspects of the present application can refer to the implementation of the first aspect, which will not be described here.

[0070] Advantages of the present application:

[0071] 1. By specifying the loop closing operation position, obtaining the power distribution network topology structure and the power equipment parameters, the accurate calculation of the loop closing steady-state current and the loop closing impulse current of the power distribution network online is realized. Meanwhile, the technical solution also verifies whether the loop closing steady-state current and the loop closing impulse current meet the safe and stable operation requirements, and regulates and controls the loop closing operation that does not meet the requirements, effectively avoiding the risk of equipment overload and protection action, thereby ensuring the safe and stable operation of the power distribution network during the loop closing operation.

[0072] 2. When the superposition method is used to calculate the loop closing steady-state current, the loop closing steady-state current is obtained by accurately calculating the load current before loop closing, the voltage difference on both sides of the loop closing point and the total impedance of the loop network, ensuring the accuracy of the calculation. Meanwhile, for the loop closing impulse current, the formula is used to calculate the current peak value at the moment of loop closing by introducing the impulse coefficient, the decay time constant and the time variable, effectively predicting the current peak value at the moment of loop closing, which provides an important guarantee for the safe and stable operation of the power grid. This technical solution not only improves the accuracy of the calculation, but also provides a scientific basis for the decision of the loop closing operation.

[0073] 3. In the calculation using the direct current flow calculation method, by ensuring that the parameters in the network topology before and after the closing operation satisfy the power balance equation, the current balance equation and the voltage equation, the technical scheme can comprehensively and accurately reflect the actual operation state of the power grid, these equations not only ensure the power balance and current distribution of each node in the power grid, but also accurately describe the voltage distribution, providing a solid theoretical basis for the calculation of the closing steady-state current, thereby effectively improving the accuracy and reliability of the calculation, and providing a strong guarantee for the safe and stable operation of the power grid. BRIEF DESCRIPTION OF DRAWINGS

[0074] Figure 1 Flowchart of an embodiment of the present application;

[0075] Figure 2 Flowchart of another embodiment of the present application. DETAILED DESCRIPTION

[0076] The present application will be further described below in conjunction with the drawings and embodiments.

[0077] Please refer to Figure 1 The embodiment of the present application provides a kind of distribution network online closing current calculation and risk analysis method, comprising:

[0078] S11, preliminary preparation: first determine the specific location of closing operation, so that subsequent network topology analysis and calculation are carried out, then the distribution network topology structure before and after closing operation is obtained by path search algorithm, and finally the power equipment parameters before and after closing operation are obtained by power sensor group collection;

[0079] Among them, the power equipment parameters before and after closing operation can include the impedance and capacity of transformer, line and distributed power supply;

[0080] S12, closing steady-state current calculation: according to the distribution network topology structure and power equipment parameters before and after closing operation, the closing steady-state current is calculated;

[0081] S13, closing impact current calculation: first, according to the actual situation of closing network, the calculation model of closing impact current is established, and based on the power equipment parameters before and after closing operation and the calculation model of closing impact current, the closing impact current is calculated;

[0082] S14, verification and regulation: first, verify whether closing steady-state current and closing impact current meet the requirements of safe and stable operation;If closing steady-state current and closing impact current do not meet the requirements of safe and stable operation, the closing operation is regulated.

[0083] Among them, the regulation mode of closing operation includes adjusting closing time, adjusting load distribution and changing closing path to reduce closing current.

[0084] As described above, the present application can realize the accurate calculation of the online loop closing steady-state current and the loop closing impact current of the distribution network, including the maximum instantaneous value and the maximum effective value of the loop closing steady-state current and the loop closing impact current, by determining the loop closing operation position, obtaining the distribution network topology and the power equipment parameters. Meanwhile, the technical solution also verifies whether the loop closing steady-state current and the loop closing impact current meet the safe and stable operation requirements, and regulates the loop closing operation that does not meet the requirements, effectively avoiding the risk of equipment overload and protection action, thereby ensuring the safe and stable operation of the distribution network in the loop closing operation process.

[0085] According to the distribution network topology and the power equipment parameters before and after the loop closing operation;

[0086] The power equipment parameters include voltage V, voltage phase angle O, active power Pload at the loop closing point, reactive power Qload at the loop closing point, and total loop resistance Z loop and buffer coefficient β;

[0087] The power sensor group includes a voltage sensor, a phase angle measuring instrument, a power meter, a line impedance test device, and a power system simulation tool;

[0088] The voltage amplitude V, the voltage phase angle O, the active power Pload at the loop closing point, and the reactive power Qload at the loop closing point are collected and obtained by the voltage sensor, the phase angle measuring instrument, and the power meter;

[0089] The total loop resistance Z loop is collected and obtained by the line impedance test device;

[0090] The buffer coefficient β is obtained by simulating the decay process of the impact current using the power system simulation tool;

[0091] The loop closing steady-state current is calculated using the following calculation methods:

[0092] (1) Superposition method, a current calculation method based on the superposition principle of the circuit, considering the branch current after loop closing as consisting of two parts, one part is the current in the branch before loop closing, and the other part is the loop current caused by the voltage difference on both sides of the loop closing point;

[0093] (2) Direct current calculation method, a calculation method based on the power flow analysis of the power grid, directly using the current calculation algorithm to calculate the current distribution after loop closing according to the line conditions and known conditions of the power grid.

[0094] As described above, the superposition method and the power flow direct algorithm can be used to calculate the closing loop steady-state current, wherein the superposition method is based on the circuit superposition principle, and the branch current after closing loop is decomposed into two parts for calculation, thereby improving the accuracy and flexibility of calculation; and the power flow direct algorithm directly uses the line condition and known conditions of the power grid to calculate the power flow, and can more comprehensively reflect the actual situation of the power grid, and the combination of the two methods can make the calculation of the closing loop steady-state current more accurate and reliable, thereby providing strong support for subsequent checking and regulation.

[0095] As preferred, the superposition method is used to calculate the closing loop steady-state current according to the power distribution network topology and the power equipment parameters before and after the closing loop operation, including:

[0096] S21, first, the voltage values on both sides of the closing loop point before the closing loop operation are calculated, and the difference between them, i.e. the voltage difference on both sides of the closing loop point before the closing loop, is obtained;

[0097] S22, the total impedance of the looped network is calculated;

[0098] S23, based on the voltage difference on both sides of the closing loop point before the closing loop and the total impedance of the looped network, the circulating current is calculated using Ohm's law;

[0099] S24, through the power flow analysis of the power grid, the load current of each branch in the open loop state, i.e. the load current before the closing loop, is calculated;

[0100] S25, the load current and the circulating current are superposed to obtain the closing loop steady-state current.

[0101] As described above, the closing loop steady-state current is calculated by the superposition method, the voltage difference on both sides of the closing loop point before the closing loop and the total impedance of the looped network are calculated first, then the circulating current is obtained by applying Ohm's law, the load current in the open loop state is analyzed, and finally the load current and the circulating current are superposed to obtain the closing loop steady-state current, which effectively improves the accuracy of the calculation of the closing loop steady-state current and the closing loop impact current, provides solid data support for the safe and stable operation of the power grid, and ensures the feasibility and safety of the closing loop operation.

[0102] The principle formula for calculating the closing loop steady-state current by the superposition method is as follows:

[0103]

[0104] wherein Isteady is the closing loop steady-state current, Z loop is the total impedance of the looped network, Yi is the admittance value of the i-th parallel branch, n is the total number of branches parallel to the main power supply line of the looped network; e represents the exponential function, and j represents the imaginary part of the complex number.

[0105] The Yi is calculated by using Ohm's law through analyzing the voltage and current at both ends of the parallel branch, and the specific algorithm formula is Ii represents the current of the i-th parallel branch, and Vi represents the voltage at both ends of the i-th parallel branch.

[0106] V1 and V2 are the voltage amplitudes of the nodes on both sides of the loop point, and O1 and O2 are the voltage phase angles of the corresponding nodes.

[0107] ΔPload and ΔQload are the change amounts of active and reactive power at the loop point, respectively.

[0108] Among them, the parallel branch includes a standby line, a capacitor bank / reactor and a load branch.

[0109] Standby line: a standby line for ensuring the redundancy of the power system, which is parallel to the ring network main power supply line.

[0110] Capacitor bank / reactor: used to access the ring network to improve the power factor or adjust the reactive power.

[0111] Load branch: a branch connected to a specific load, which is parallel to the ring network main power supply line.

[0112] As a preferred, after calculating the loop steady-state current using the superposition method, the loop impact current is calculated according to the following formula:

[0113]

[0114] Where Ishock is the loop impact current, K is the impact coefficient, τ is the decay time constant, t is the time variable, and β represents the impact buffer coefficient, which is obtained by simulating the decay process of the impact current using a power system simulation tool.

[0115] Ish1 and Ish2 are the maximum values of the current at the nodes on both sides of the loop point in the loop process, which are extracted by recording the current waveform at the nodes on both sides of the loop point in the loop process using a power system simulation tool.

[0116] As described above, when calculating the loop steady-state current using the superposition method, the present application accurately calculates the voltage difference on both sides of the loop point and the total impedance of the ring network, and uses the formula to obtain the steady-state current, ensuring the accuracy of the calculation. At the same time, for the loop impact current, by introducing the impact coefficient, the decay time constant and the time variable, the formula is used to calculate, effectively predicting the current peak value at the loop moment, providing an important guarantee for the safe and stable operation of the power grid. This technical scheme not only improves the accuracy of the calculation, but also provides a scientific basis for the decision of loop operation.

[0117] Compared with the traditional calculation of the closed-loop steady-state current by the superposition method, the technical scheme considers the dynamic fluctuation of the system voltage and current during the closed-loop operation. In the calculation of the closed-loop steady-state current by the superposition method, not only the static steady-state value is calculated, but also the load time variation factor and the line impedance correction term are added. The voltage difference AV is no longer a simple static difference between the two sides of the voltage, but an effective voltage difference calculated based on the dynamic characteristics of the node, which combines the time-varying relationship between the amplitude and the phase angle of the node voltage. In the calculation of the loop network impedance, the dynamic admittance correction of the parallel branch is added to consider the influence of the complex topology of the loop network on the steady-state current. At the same time, the introduction of the impact buffer coefficient β comprehensively evaluates the buffer capacity of the power grid, making the calculation of the impact current more practical and providing a quantitative basis for optimizing the closed-loop operation.

[0118] The improved superposition method combined with the power flow calculation not only improves the calculation accuracy of the steady-state current and the impact current, but also enhances the adaptability to complex power grids by introducing dynamic parameters and nonlinear characteristics. Especially in the scene of complex loop network topology and dynamic changes of multiple loads, the improved scheme can significantly improve the reliability of safety and stability evaluation.

[0119] As a preferred, in the calculation of the closed-loop steady-state current by the power flow direct algorithm according to the power distribution network topology structure and power equipment parameters before and after the closed-loop operation, the power flow direct algorithm is used for calculation, including:

[0120] S31, inputting the power distribution network topology structure and power equipment parameters before and after the closed-loop operation into the power flow calculation software;

[0121] S32, setting the power flow calculation condition, the calculation condition being used for simulating the actual operation state of the power grid;

[0122] S33, running the power flow calculation software to perform power flow analysis on the power distribution network, and obtaining the result of the power flow calculation;

[0123] S34, extracting the closed-loop steady-state current from the result of the power flow calculation.

[0124] As described above, the present application calculates the closed-loop steady-state current by the power flow direct algorithm, only needs to input the power grid parameters and the calculation condition into the power flow calculation software, runs the software to perform power flow analysis, and finally extracts the closed-loop steady-state current from the result. This method not only simplifies the calculation process, but also improves the calculation accuracy and efficiency, provides a reliable decision basis for the closed-loop operation of the power grid, and ensures the safe and stable operation of the power grid.

[0125] As a preferred, in the calculation by the power flow direct algorithm, the parameters in the network topology before and after the closed-loop operation need to satisfy the following equation,

[0126] A21, power balance equation, that is, for each node i, there is,

[0127]

[0128] where P i and Q i are the active and reactive power injected at node i, V i is the voltage at node i, I ik is the current flowing from node i to node k, j is the imaginary unit, and * denotes the conjugate; neighbors(i) denotes the set of neighbor nodes of node i;

[0129] A22, the current balance equation, i.e., for each branch (i, k), there is,

[0130]

[0131] where Z ik is the impedance of branch (i, k);

[0132] A23, the voltage equation, i.e., for each node i, the voltage can be expressed as,

[0133] V i = V0-∑ k∈neighbors(i) Z ik ·I ik ;

[0134] where V0is the voltage of the reference node.

[0135] As described above, when the power flow direct algorithm is used for calculation, by ensuring that the parameters in the network topology before and after the closing operation satisfy the power balance equation, the current balance equation and the voltage equation, the technical scheme can comprehensively and accurately reflect the actual operation state of the power grid, these equations not only ensure the power balance and current distribution of each node in the power grid, but also accurately describe the voltage distribution, which provides a solid theoretical basis for the calculation of the closing steady-state current, thereby effectively improving the accuracy and reliability of the calculation, and providing a strong guarantee for the safe and stable operation of the power grid.

[0136] As a preferred, a closing impact current calculation model is established according to the topology structure of the distribution network before and after the closing operation; the closing impact current is calculated based on the power equipment parameters before and after the closing operation and the closing impact current calculation model, including:

[0137] S41, a closing impact current calculation model is established; the closing impact current calculation model is used to describe the equivalent inductance and equivalent resistance of the closing impact current closing point, the decay time constant, the system rated angular frequency, and the change of the initial phase angle difference of the voltage at both ends of the closing point at the closing time;

[0138] The step considers the energy storage effect of the inductive element and the energy consumption effect of the resistor, and selects a suitable mathematical model to describe the change process of the closing-in impulse current.

[0139] S42, using professional circuit simulation software, using network topology and power equipment parameters, calculating the equivalent inductance and equivalent resistance of the closing-in point;

[0140] S43, according to the calculation model of the closing-in impulse current, substituting the equivalent inductance and equivalent resistance of the closing-in point, the decay time constant, the system rated angular frequency and the initial phase angle difference of the closing-in point at the closing-in moment, solving the closing-in impulse current.

[0141] As described above, the application establishes an accurate closing-in impulse current calculation model by comprehensively considering the inductive energy storage, the resistive energy consumption and their influence on the impulse current, and accurately calculates the equivalent inductance and resistance of the closing-in point by using professional circuit simulation software combined with network topology and power equipment parameters. By substituting the related parameters, the maximum instantaneous value and the maximum effective value of the closing-in impulse current can be solved, which provides a scientific basis for evaluating the influence of the closing-in operation on the power grid and effectively improves the safety and stability of the power grid operation.

[0142] As preferred, the application verifies whether the closing-in steady-state current and the closing-in impulse current meet the safe and stable operation requirements; if the closing-in steady-state current and the closing-in impulse current do not meet the safe and stable operation requirements, the closing-in operation is regulated, including:

[0143] The calculated closing-in steady-state current and closing-in impulse current are compared with the power equipment parameters to evaluate the risk level of the closing-in operation, and corresponding closing-in operation regulation measures are adopted according to the risk level.

[0144] As described above, by accurately obtaining the key parameters of the closing-in operation based on the previous preparation and the calculation of the closing-in steady-state current and the closing-in impulse current, and then performing risk evaluation, the closing-in operation regulation measures are developed according to the evaluation results, which effectively reduces the risk of the closing-in operation.

[0145] As preferred, when the calculated closing-in steady-state current and closing-in impulse current are compared with the power equipment parameters to evaluate the risk level of the closing-in operation, and corresponding closing-in operation regulation measures are adopted according to the risk level, the following steps are included,

[0146] S61, current protection setting value verification, comparing the calculated closing-in steady-state current and closing-in impulse current with the rated current and protection setting value of the power equipment to verify whether the closing-in operation will cause equipment overload and protection action;

[0147] S62, device withstand capability evaluation, evaluating the withstand capability of the device in the power grid to the closed-loop steady-state current and the closed-loop impulse current;

[0148] S63, comprehensively considering the closed-loop steady-state current and the closed-loop impulse current, the device withstand capability and the distribution network topology structure, evaluating the risk level of the closed-loop operation, and adopting corresponding closed-loop operation control measures according to the risk level; wherein the closed-loop operation control measures include adjusting the closed-loop time and reducing the closed-loop current.

[0149] As described above, the application comprehensively considers the closed-loop steady-state current and the closed-loop impulse current, the device withstand capability and the grid structure factors, accurately evaluates the risk level of the closed-loop operation, and formulates targeted closed-loop operation control measures accordingly, effectively controls the risk, ensures the safe operation of the grid device, and significantly improves the reliability and safety of the closed-loop operation.

[0150] As preferred, the method further comprises: during the closed-loop operation, monitoring the size and change trend of the closed-loop steady-state current and the closed-loop impulse current in real time, and if the closed-loop steady-state current and the closed-loop impulse current abnormally increase and exceed the predetermined first threshold and the second threshold, immediately issuing a warning signal;

[0151] The risk level is output by comprehensively calculating the closed-loop steady-state current Isteady and the closed-loop impulse current Ishock to obtain a risk level coefficient R;

[0152] The risk level coefficient R is calculated and output by the following algorithm formula;

[0153] R=a1·Isteady+a2·Ishock+a3·Ctopo+a4·△V;

[0154] Wherein, a1, a2, a3 and a4 respectively represent the weight values of the closed-loop steady-state current Isteady, the closed-loop impulse current Ishock, the topology structure factor Ctopo and the closed-loop voltage fluctuation amplitude △V; and a1+a2+a3+a4=1, and the specific values are set by the user;

[0155] Ctopo represents the topology structure factor, which represents the degree of influence of the distribution network topology structure on the risk, which is usually related to the redundancy of the network, the branch carrying capacity, etc.;

[0156] △V represents the closed-loop voltage fluctuation amplitude;

[0157] The above parameters are all dimensionless processed values;

[0158] The specific evaluation content of the risk level of the closed-loop operation is as follows;

[0159] When the risk level coefficient R is less than or equal to the first threshold value, it is classified as a first-level risk, and no pre-warning needs to be generated; the distribution network and the power equipment can withstand the steady state and the impact current after the closing operation, the system stability is strong, and the operation is safe;

[0160] When the first threshold value is less than the risk level coefficient R and the risk level coefficient R is less than the second threshold value, it is classified as a second-level risk, a second-level pre-warning is generated, the power equipment load is close to the rated value or the distribution network topology structure has certain problems, and the risk of the impact current needs to be concerned. The risk can be alleviated by adjusting the operation time, load distribution and the like;

[0161] When the risk level coefficient is greater than the second threshold value, it is classified as a third-level risk, a first-level pre-warning is generated, the current is close to or exceeds the carrying capacity of the power equipment, the distribution network topology structure design is weak, and the power equipment damage or the power grid failure can be caused, and immediate control measures need to be taken, such as adjusting the closing time and reducing the closing current;

[0162] The risk level is ranked as: first-level risk < second-level risk < third-level risk, and in the pre-warning level, the first-level pre-warning > the second-level pre-warning;

[0163] The first threshold value is less than the second threshold value; the first threshold value is a lower limit value, and the second threshold value is an upper limit value.

[0164] As described above, by introducing the real-time monitoring and pre-warning mechanism, the closing steady state current and the closing impact current anomaly can be found and responded to in time, and according to the pre-warning signal, corresponding processing measures are taken to ensure the safe and stable operation of the power grid, and the safety and reliability of the distribution network online closing operation are significantly improved.

[0165] The embodiment also provides an electronic device, comprising a memory and a processor.

[0166] The memory is used for storing a computer program.

[0167] The processor is used for calling the computer program to execute the method as described in Embodiments One to Three.

[0168] The embodiment also provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program runs on an electronic device to enable the electronic device to implement the method as described in Embodiments One to Three.

[0169] The embodiment also provides a computer program product comprising a computer program, and the computer program runs on an electronic device to enable the electronic device to implement the method as described in the above embodiments.

[0170] The specific implementation manners of the system, the electronic device, the computer readable storage medium and the computer program product provided by the embodiments of the present application can refer to the specific embodiments of the above method, and details are not described herein.

[0171] Obviously, those skilled in the art should understand that each unit or each step of the present application described above can be realized by a general computing device, which can be concentrated on a single computing device or distributed on a network composed of multiple computing devices, and optionally, each unit or each step can be realized by program code executable by a computing device, so that each unit or each step can be stored in a storage device and executed by a computing device, or each unit or each step can be made into an individual integrated circuit module, or multiple modules or steps among them can be made into a single integrated circuit module to realize. Thus, the present application is not limited to any specific combination of hardware and software.

[0172] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application.

Claims

1. A method for online loop current calculation and risk analysis of network configuration, characterized in that, The method comprises the following steps: Determine the specific location of the closing operation, and collect the power grid topology and power equipment parameters before and after the closing operation through the power sensor group; According to the power distribution network topology and power equipment parameters before and after the closing operation, the closing steady-state current is calculated, including: according to the power distribution network topology and power equipment parameters before and after the closing operation, the closing steady-state current is calculated by using the superposition method and the power flow direct algorithm respectively; and combining the calculation results of the superposition method and the power flow direct algorithm, the final closing steady-state current is obtained; wherein, using the superposition method to calculate the closing steady-state current, including: calculating the voltage values on both sides of the closing point before the closing operation, and obtaining the difference between them to obtain the voltage difference on both sides of the closing point before the closing; calculating the total impedance of the loop network; based on the voltage difference on both sides of the closing point before the closing and the total impedance of the loop network, the circulating current is calculated using Ohm's law; through the power flow analysis of the power grid, the load current of each branch before the closing operation is calculated; the load current and the circulating current are superimposed to obtain the closing steady-state current; the calculation formula is: ; wherein, is the closing steady-state current, Z loop represents the total impedance of the loop network, Yi represents the admittance value of the ith parallel branch, n is the total number of branches parallel to the main power supply line of the loop network; e represents the exponential function, j represents the imaginary part of the complex number; the Yi is calculated by analyzing the voltage and current at both ends of the parallel branch using Ohm's law to calculate the admittance, and the specific algorithm formula is , Ii represents the current of the ith parallel branch, Vi represents the voltage at both ends of the ith parallel branch; V1 and V2 are the voltage amplitudes of the nodes on both sides of the closing point, O1 and O2 are the voltage phase angles of the corresponding nodes; ΔPload and ΔQload are the active and reactive power changes of the closing point respectively; Pload and Qload are the active and reactive power of the closing point respectively; wherein, the parallel branch includes a backup line, a capacitor bank / reactor and a load branch; the backup line: a backup line for ensuring the redundancy of the power system, which is parallel to the main power supply line of the loop network; the capacitor bank / reactor: used to access the loop network to improve the power factor or adjust the reactive power; the load branch: a branch connected by a specific load, which is parallel to the main power supply line of the loop network; According to the power grid topology before and after the closing operation, a calculation model of the closing impact current is established; based on the power equipment parameters before and after the closing operation and the calculation model of the closing impact current, the closing impact current is calculated; Verify whether the closing steady-state current and the closing impact current meet the safe and stable operation requirements; if the closing steady-state current and the closing impact current do not meet the safe and stable operation requirements, the closing operation is regulated.

2. The method of claim 1, wherein, After calculating the closing steady-state current using the superposition method, the closing impact current is calculated according to the following formula: ； wherein, is the ring closing inrush current, K is the inrush coefficient, is the decay time constant, t is the time variable, denotes the inrush damping coefficient, which is obtained by simulating the decay process of the inrush current using a power system simulation tool; ; Ish1 and Ish2 are the maximum values of the current at the nodes on both sides of the closing point in the closing process, which are extracted by simulating the closing process using a power system simulation tool and recording the current waveform at the nodes on both sides of the closing point in the closing process.

3. The method of claim 1, wherein, According to the power grid topology and power equipment parameters before and after the closing operation, the closing steady-state current is calculated using a direct power flow algorithm, including: Input the power grid topology and power equipment parameters before and after the closing operation into the power flow calculation software; Set the power flow calculation conditions to simulate the actual operating state of the power grid; Run the power flow calculation software to perform power flow analysis on the power grid and obtain the results of the power flow calculation; Extract the closing steady-state current from the results of the power flow calculation.

4. The method of claim 3, wherein, The power flow calculation conditions include: The parameters in the network topology before and after the closing operation need to satisfy the following equations: The power balance equation, that is, for each node i, there is: ； wherein, and Pi and Qi are the active and reactive power injected at node i respectively, Vi is the voltage at node i, Ijk is the current flowing from node i to node k, j is the imaginary unit, and * denotes the conjugate; N(i) denotes the set of neighbor nodes of node i; The current balance equation, that is, for each branch (i, k), there is: ； wherein, is the voltage of node k, is the impedance of branch (i, k); The voltage equation, i.e. for each node i, the voltage satisfies: ； wherein is the voltage of the reference node.

5. The method of claim 4, wherein, According to the power grid topology before and after the closing operation, a calculation model of the closing impact current is established; Based on the power equipment parameters before and after the closing operation and the calculation model of the closing impact current, the closing impact current is calculated, including: Establish a closing impact current calculation model, which is used to describe the equivalent inductance and equivalent resistance of the closing point, the decay time constant, the system rated angular frequency, and the change of the initial phase angle difference of the voltage at both ends of the closing point at the closing time; Using professional circuit simulation software, the equivalent inductance and equivalent resistance of the closing point are calculated using the network topology and power equipment parameters; According to the calculation model of the closing impact current, the equivalent inductance, equivalent resistance, decay time constant, system rated angular frequency, and initial phase angle difference of the voltage at both ends of the closing point at the closing time are substituted to solve the closing impact current.

6. The method of claim 5, wherein, Verify whether the closing steady-state current and the closing impact current meet the safe and stable operation requirements; If the closing steady-state current and the closing impact current do not meet the safe and stable operation requirements, the closing operation is regulated, including: Current protection setting value verification: compare the calculated closing steady-state current and closing impact current with the rated current and protection setting value of the power equipment; Device bearing capacity evaluation: evaluate the bearing capacity of the power equipment to the closing steady-state current and the closing impact current; Comprehensively consider the current protection setting value verification result, the device bearing capacity evaluation result, and the power grid topology to evaluate the risk level of the closing operation, and according to the risk level, adopt the corresponding closing operation regulation measures; wherein, the closing operation regulation measures include adjusting the closing time and reducing the closing current.

7. The network-on-line loop closing risk analysis method according to claim 6, wherein, The method further comprises: monitoring the size and variation trend of the closing steady-state current and the closing impact current in real time during the closing operation, and issuing a pre-warning signal if the closing steady-state current and the closing impact current abnormally increase or exceed predetermined first and second thresholds respectively.

8. An electronic device, comprising: Comprise: a memory and a processor; the memory is configured to store a computer program; the processor is configured to call the computer program to execute the method according to any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer program is stored in the computer readable storage medium, and when the computer program runs on the electronic device, the electronic device implements the method according to any one of claims 1 to 7.

10. A computer program product comprising a computer program, characterized in that, The computer program runs on the electronic device, and the electronic device implements the method according to any one of claims 1 to 7.

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