Distribution network on-line loop closing current calculation and risk analysis method

Abstract

The invention relates to the technical field of electric power engineering, in particular to a distribution network online loop closing current calculation and risk analysis method, which comprises the following steps: determining a specific position of loop closing operation, and acquiring a distribution network topological structure and electric power equipment parameters before and after the loop closing operation; calculating a loop closing steady-state current according to the distribution network topology structure and the power equipment parameters before and after the loop closing operation; according to the distribution network topology structure before and after the loop closing operation, establishing a calculation model of the loop closing impact current; calculating the loop closing impact current based on the parameters of the power equipment before and after the loop closing operation and the calculation model of the loop closing impact current; checking whether the loop closing steady-state current and the loop closing impact current meet the safe and stable operation requirements or not; 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. According to the invention, safe and stable operation of the distribution network in the loop closing operation process can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of electric power engineering methods, and in particular to a distribution network online closed-loop current calculation and risk analysis method. Background Art

[0002] With the development of the national economy, users' requirements for power supply reliability are constantly 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 transformation, the distribution network in most parts of the country has achieved a "closed-loop connection, open-loop operation" power supply mode. The interconnecting switch is generally in the open state. This operation mode has improved 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, it is necessary to perform a closed-loop operation to ensure the continuity of power supply.

[0003] However, the closing operation is not simply connecting the two loops, because the lines and transformer branches of the power grid contain resistance and reactance. After the loop is closed, a closed-loop steady-state current and a closed-loop impulse current will be generated. The size and direction of this current depend on multiple factors, such as the voltage difference on both sides of the closing point, the total impedance of the ring network, etc. If the closed-loop steady-state current and the closed-loop impulse current are too large, it may cause overload to the power grid equipment and even trigger protection action, resulting in power supply interruption. Therefore, before performing the closing operation, it is necessary to accurately calculate the closed-loop steady-state current and the closed-loop impulse current, and evaluate the risks of the closing operation.

[0004] Traditional methods for calculating closed-loop steady-state current and closed-loop impulse current are often based on some simplified assumptions and models, such as considering the power grid as a pure resistance or pure reactance network, or accumulating the impedance of the closed-loop path. Although these methods can reflect the characteristics of closed-loop steady-state current and closed-loop impulse current to a certain extent, their calculation accuracy is limited and it is difficult to meet the requirements of modern power grids for power supply reliability and safety.

[0005] In addition, with the access of distributed power sources and the development of smart grids, the structure and operation mode of distribution networks have become more complex, and the risks of closed-loop operations have also increased accordingly. Therefore, a more accurate and comprehensive distribution network closed-loop current calculation and risk analysis method is needed to guide closed-loop operations and ensure the safe and stable operation of the power grid. Summary of the invention

[0006] In order to overcome the problems raised in the above background technology, the present invention provides a distribution network online closing loop current calculation and risk analysis method, which can ensure the safe and stable operation of the distribution network during the closing loop operation.

[0007] The technical solution of the present invention is:

[0008] In a first aspect, the present application provides a method for calculating and analyzing online closed-loop current of a distribution network, including:

[0009] Determine the specific location of the loop closing operation, and obtain the distribution network topology and power equipment parameters before and after the loop closing operation through the power sensor group;

[0010] Calculate the closed-loop steady-state current based on the distribution network topology and power equipment parameters before and after the closed-loop operation;

[0011] According to the distribution network topology before and after the closing operation, a calculation model for the closing impulse current is established; based on the power equipment parameters before and after the closing operation and the calculation model for the closing impulse current, the closing impulse current is calculated;

[0012] Verify whether the closed-loop steady-state current and the closed-loop impulse current meet the requirements for safe and stable operation; if the closed-loop steady-state current and the closed-loop impulse current do not meet the requirements for safe and stable operation, adjust the closed-loop operation.

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

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

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

[0016] The total ring network impedance Z loop Acquired through line impedance test equipment;

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

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

[0019] According to the distribution network topology and power equipment parameters before and after the closing operation, the closing steady-state current is calculated using the superposition method and the direct flow algorithm respectively; and the calculation results of the superposition method and the direct flow algorithm are combined to obtain the final closing steady-state current.

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

[0021] Calculate the voltage values ​​on both sides of the closing point before the closing operation, and find the difference between them to obtain the voltage difference on both sides of the closing point before the closing operation; calculate the total impedance of the ring network; based on the voltage difference on both sides of the closing point before the closing operation and the total impedance of the ring network, use Ohm's law to calculate the circulating current;

[0022] By analyzing the power flow of the power grid, calculate the load current of each branch before the closing loop operation (under the open loop state);

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

[0024] In a possible implementation, the closed-loop steady-state current formula is calculated using the superposition method:

[0025]

[0026] Where, Isteady is the closed-loop steady-state current, Yi represents the admittance value of the i-th parallel branch, n is the total number of branches connected in parallel with the main power supply line of the ring network; e represents the exponential function, and j represents the imaginary part of the complex number;

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

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

[0029] ΔPload and ΔQload are the changes in active and reactive power at the closing point, respectively;

[0030] Among them, the parallel branch includes the standby line, capacitor bank / reactor and load branch;

[0031] Backup line: A backup line used to ensure power system redundancy, connected in parallel with the main power supply line of the ring network;

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

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

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

[0035]

[0036] Where Ishock is the closed-loop impulse current, K is the impulse coefficient, τ is the decay time constant, t is the time variable, and β represents the impulse buffer coefficient, which is obtained by simulating the decay process of the impulse current using a power system simulation tool;

[0037] Ish1 and Ish2 are the maximum current values ​​of the nodes on both sides of the closing point extracted by simulating the closing process with a power system simulation tool and recording the current waveforms of the nodes on both sides of the closing point during the closing process.

[0038] In a possible implementation, the closed-loop steady-state current is calculated using a power flow direct algorithm based on the distribution network topology and power equipment parameters before and after the closed-loop operation, including:

[0039] Input the distribution network topology and power equipment parameters before and after the ring closing operation into the power flow calculation software;

[0040] Set the flow calculation conditions to simulate the actual operation status of the power grid;

[0041] Run the power flow calculation software to perform power flow analysis on the distribution network and obtain the results of power flow calculation;

[0042] The closed-loop steady-state current is extracted from the results of the power flow calculation.

[0043] In a possible implementation, the power flow calculation condition includes:

[0044] The parameters in the network topology before and after the ring closing operation need to satisfy the following equations:

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

[0046]

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

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

[0049]

[0050] Among them, V k is the voltage at node k, Z ik is the impedance of branch (i, k);

[0051] Voltage equation, that is, for each node i, the voltage V i satisfy:

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

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

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

[0055] Establishing a closed-loop impulse current calculation model, the closed-loop impulse current calculation model is used to describe the equivalent inductance and equivalent resistance of the closed-loop impulse 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 closed-loop point at the closing time;

[0056] Use professional circuit simulation software, network topology and power equipment parameters to calculate the equivalent inductance and equivalent resistance of the loop closing point;

[0057] According to the calculation model of the closing-loop impact current, the equivalent inductance, equivalent resistance, attenuation time constant, system rated angular frequency and the initial phase angle difference of the voltage across the closing point at the closing moment are substituted to solve the closing-loop impact current.

[0058] After the closed-loop impact current is obtained by solving this method, it can be combined with the closed-loop impact current Ishock obtained by the above calculation to obtain the final closed-loop impact current.

[0059] In a possible implementation, the checking whether the closed-loop steady-state current and the closed-loop impulse current meet the safe and stable operation requirements; if the closed-loop steady-state current and the closed-loop impulse current do not meet the safe and stable operation requirements, regulating the closed-loop operation includes:

[0060] Current protection setting value verification: Compare the calculated closed-loop steady-state current and closed-loop impulse current with the rated current and protection setting value of the power equipment;

[0061] Equipment bearing capacity assessment: assess the power equipment's ability to withstand closed-loop steady-state current and closed-loop impulse current;

[0062] Taking into account the current protection setting verification results, equipment bearing capacity assessment results and distribution network topology, the risk level of the closing operation is assessed, and corresponding closing operation control measures are adopted according to the risk level; among them, the closing operation control measures include adjusting the closing time and reducing the closing current.

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

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

[0065] The memory is used to store computer programs;

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

[0067] In a third aspect, the present application provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed on an electronic device, the electronic device implements the method as described above.

[0068] In a fourth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed on an electronic device, the electronic device implements the method as described above.

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

[0070] Beneficial effects of the present invention:

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

[0072] 2. When the superposition method is used to calculate the steady-state current of the closed loop, the load current before the closed loop, the voltage difference on both sides of the closed loop point and the total impedance of the ring network are accurately calculated, and the steady-state current is obtained using the formula to ensure the accuracy of the calculation. At the same time, for the closed loop impact current, the impact coefficient, attenuation time constant and time variable are introduced, and the formula is used for calculation to effectively predict the current peak value at the moment of closing the loop, 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-making of the closed loop operation;

[0073] 3. When using the direct flow algorithm for calculation, by ensuring that the parameters in the network topology before and after the closing operation satisfy the power balance equation, current balance equation and voltage equation, this technical solution can fully and accurately reflect the actual operating status 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 closed-loop 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 THE DRAWINGS

[0074] Figure 1 This is a flow chart of an embodiment of the present application;

[0075] Figure 2 This is a flow chart of another embodiment of the present application. DETAILED DESCRIPTION

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

[0077] See also Figure 1 The present application embodiment provides a method for calculating and analyzing online closed-loop current of a distribution network, including:

[0078] S11, preliminary preparation: first determine the specific location of the ring closing operation, so as to conduct subsequent network topology analysis and calculation, then use the path search algorithm to obtain the distribution network topology structure before and after the ring closing operation, and finally use the power sensor group to collect and obtain the power equipment parameters before and after the ring closing operation;

[0079] The power equipment parameters before and after the ring closing operation may include the impedance and capacity of transformers, lines and distributed power sources;

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

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

[0082] S14, verification and regulation: First, verify whether the closed-loop steady-state current and the closed-loop impulse current meet the requirements for safe and stable operation; if the closed-loop steady-state current and the closed-loop impulse current do not meet the requirements for safe and stable operation, regulate the closed-loop operation.

[0083] Among them, the control methods of the closed-loop operation include adjusting the closed-loop time, adjusting the load distribution, and changing the closed-loop path to reduce the closed-loop current.

[0084] As described above, the present invention can realize the accurate calculation of the online closed-loop steady-state current and closed-loop impulse current of the distribution network by clarifying the closed-loop operation position, obtaining the distribution network topology structure and power equipment parameters, including the maximum instantaneous value and the maximum effective value of the closed-loop steady-state current and the closed-loop impulse current. At the same time, the technical solution also verifies whether the closed-loop steady-state current and the closed-loop impulse current meet the requirements of safe and stable operation, and regulates the closed-loop operation that does not meet the requirements, thereby effectively avoiding the risks of equipment overload and protection action, thereby ensuring the safe and stable operation of the distribution network during the closed-loop operation process.

[0085] Based on the distribution network topology and power equipment parameters before and after the ring closing operation;

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

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

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

[0089] The total ring network impedance Z loop Acquired through line impedance test equipment;

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

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

[0092] (1) Superposition method: A current calculation method based on the circuit superposition principle. It considers the branch current after the loop is closed as consisting of two parts: one is the current in the branch before the loop is closed, and the other is the circulating current caused by the voltage difference on both sides of the loop closing point.

[0093] (2) Direct power flow algorithm: Based on the calculation method of power grid power flow analysis, the power flow calculation algorithm is directly used to calculate the current distribution after the loop is closed according to the line conditions and known conditions of the power grid.

[0094] As mentioned above, the superposition method and the direct flow algorithm can be used to calculate the closed-loop steady-state current. The superposition method is based on the circuit superposition principle and decomposes the branch flow after the closed loop into two parts for calculation, which improves the accuracy and flexibility of the calculation; while the direct flow algorithm directly uses the line conditions and known conditions of the power grid for flow calculation, which can more comprehensively reflect the actual situation of the power grid. The combination of these two methods can make the calculation of the closed-loop steady-state current more accurate and reliable, providing strong support for subsequent verification and regulation.

[0095] Preferably, the closed-loop steady-state current is calculated using a superposition method according to the distribution network topology and power equipment parameters before and after the closed-loop operation, including:

[0096] S21, firstly calculate the voltage values ​​on both sides of the closing point before the closing operation, and find the difference between them, that is, the voltage difference on both sides of the closing point before the closing operation;

[0097] S22, calculate the total impedance of the ring network;

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

[0099] S24, by analyzing the power flow of the power grid, calculating the load current of each branch in the open loop state, that is, the load current before closing the loop;

[0100] S25. Superimpose the load current and the circulating current to obtain a closed-loop steady-state current.

[0101] As described above, the present invention calculates the closed-loop steady-state current by the superposition method, firstly calculates the voltage difference on both sides of the closing point and the total impedance of the ring network before closing the loop, and then applies Ohm's law to obtain the circulating current, and then analyzes the load current in the open-loop state, and finally superimposes the load current and the circulating current to obtain the closed-loop steady-state current. This method effectively improves the accuracy of the calculation of the closed-loop steady-state current and the closed-loop impulse current, provides solid data support for the safe and stable operation of the power grid, and ensures the feasibility and safety of the closed-loop operation.

[0102] The principle formula for calculating the closed-loop steady-state current using the superposition method is:

[0103]

[0104] Among them, Isteady is the closed-loop steady-state current, Z loop represents the total impedance of the ring network, Yi represents the admittance value of the ith parallel branch, n represents the total number of branches connected in parallel with the main power supply line of the ring network; e represents the exponential function, and j represents the imaginary part of the complex number;

[0105] The Yi calculates the admittance by analyzing the voltage and current at both ends of the parallel branch using Ohm's law. The specific algorithm formula is: Ii represents the current of the ith parallel branch, and Vi represents the voltage across the ith parallel branch;

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

[0107] ΔPload and ΔQload are the changes in active and reactive power at the closing point, respectively;

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

[0109] Backup line: A backup line used to ensure power system redundancy, connected in parallel with the main power supply line of the ring network;

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

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

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

[0113]

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

[0115] Ish1 and Ish2 are the maximum current values ​​of the nodes on both sides of the closing point extracted by simulating the closing process with a power system simulation tool and recording the current waveforms of the nodes on both sides of the closing point during the closing process.

[0116] As described above, when the present invention adopts the superposition method to calculate the closed-loop steady-state current, the voltage difference on both sides of the closed-loop point and the total impedance of the ring network are accurately calculated, and the steady-state current is obtained by using a formula, thereby ensuring the accuracy of the calculation. At the same time, for the closed-loop impulse current, the impulse coefficient, the attenuation time constant and the time variable are introduced, and the formula is used for calculation, so that the current peak value at the moment of the closed-loop is effectively predicted, 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-making of the closed-loop operation.

[0117] Compared with the traditional method of calculating the closed-loop steady-state current by superposition, this technical solution takes into account the dynamic fluctuations of system voltage and current during closed-loop operation. When calculating the closed-loop steady-state current by superposition, not only the static steady-state value is calculated, but also the load time variation factor and line impedance correction term are added. The voltage difference ΔV is no longer a simple static voltage difference between the two sides, but an effective voltage difference calculated based on the dynamic characteristics of the node, combining the time-varying relationship between the node voltage amplitude and phase angle. In the calculation of the ring network impedance, the dynamic admittance correction of the parallel branch is added, and the influence of the complex topology of the ring network on the steady-state current is considered. At the same time, the introduction of the impact buffering coefficient β comprehensively evaluates the buffering 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 power flow calculation not only improves the calculation accuracy of steady-state current and impulse current, but also enhances the adaptability to complex power grids by introducing dynamic parameters and nonlinear characteristics. Especially in scenarios with complex ring network topology and dynamic changes in multiple loads, the improved solution can significantly improve the reliability of safety and stability assessment.

[0119] Preferably, when the closed-loop steady-state current is calculated using a power flow direct algorithm according to the distribution network topology and power equipment parameters before and after the closed-loop operation, the calculation using the power flow direct algorithm includes:

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

[0121] S32, setting power flow calculation conditions, the calculation conditions are used to simulate the actual operation state of the power grid;

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

[0123] S34. Extract the closed-loop steady-state current from the results of the power flow calculation.

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

[0125] As a preference, when the power flow direct algorithm is used for calculation, the parameters in the network topology before and after the ring closing operation need to satisfy the following equations:

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

[0127]

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

[0129] A22. Current balance equation, that is, for each branch (i, k), there is:

[0130]

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

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

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

[0134] Where V0 is the voltage of the reference node.

[0135] As described above, when the present invention adopts the direct flow algorithm 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, this technical solution can comprehensively and accurately reflect the actual operating status 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 closed-loop 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] Preferably, a calculation model of the closed-loop impact current is established according to the distribution network topology before and after the closed-loop operation; and the closed-loop impact current is calculated based on the power equipment parameters before and after the closed-loop operation and the calculation model of the closed-loop impact current, including:

[0137] S41, establishing a closed-loop impulse current calculation model; the closed-loop impulse current calculation model is used to describe the equivalent inductance and equivalent resistance of the closed-loop impulse current, 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 closed-loop point at the time of closing the loop;

[0138] This step considers the energy storage effect of the inductor and the energy consumption effect of the resistor, as well as their influence on the impulse current, and selects a suitable mathematical model to describe the change process of the closed-loop impulse current;

[0139] S42. Use professional circuit simulation software, network topology and power equipment parameters to calculate the equivalent inductance and equivalent resistance of the loop closing point;

[0140] S43. According to the calculation model of the closing-loop impact current, substitute the equivalent inductance and equivalent resistance of the closing point, the decay time constant, the rated angular frequency of the system and the initial phase angle difference of the voltage across the closing point at the closing moment to solve the closing-loop impact current.

[0141] As described above, the present invention establishes an accurate closed-loop impulse current calculation model by comprehensively considering the inductive energy storage, the resistive energy consumption and their effects on the impulse current, and uses professional circuit simulation software, combined with the network topology and the power equipment parameters, to accurately calculate the equivalent inductance and resistance of the closed-loop point. By substituting the relevant parameters, the scheme can solve the maximum instantaneous value and the maximum effective value of the closed-loop impulse current, which provides a scientific basis for evaluating the impact of the closed-loop operation on the power grid, and effectively improves the safety and stability of the power grid operation.

[0142] Preferably, the checking whether the closed-loop steady-state current and the closed-loop impulse current meet the safe and stable operation requirements; if the closed-loop steady-state current and the closed-loop impulse current do not meet the safe and stable operation requirements, regulating the closed-loop operation includes:

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

[0144] As described above, by calculating the key parameters of the closing-loop operation based on preliminary preparation and the closing-loop steady-state current and closing-loop impulse current, a risk assessment is conducted, and closing-loop operation control measures are formulated based on the assessment results, thereby effectively reducing the risk of the closing-loop operation.

[0145] Preferably, when comparing the calculated closed-loop steady-state current and closed-loop impulse current with the parameters of the power equipment, evaluating the risk level of the closed-loop operation, and adopting corresponding closed-loop operation control measures according to the risk level, the following steps are included:

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

[0147] S62, equipment bearing capacity assessment, assessing the bearing capacity of the closed-loop steady-state current and the closed-loop impulse current on the equipment in the power grid;

[0148] S63. Comprehensively consider the size of the closing-loop steady-state current and the closing-loop impulse current, the equipment's bearing capacity, and the distribution network topology, evaluate the risk level of the closing-loop operation, and adopt corresponding closing-loop operation control measures according to the risk level; among them, the closing-loop operation control measures include adjusting the closing-loop time and reducing the closing-loop current.

[0149] As described above, the present invention comprehensively considers the size of the closed-loop steady-state current and the closed-loop impulse current, the equipment tolerance and the grid structure factors through current protection setting verification and equipment tolerance assessment, accurately assesses the risk level of the closed-loop operation, and formulates targeted closed-loop operation control measures accordingly, which effectively controls the risks, ensures the safe operation of the grid equipment, and significantly improves the reliability and safety of the closed-loop operation.

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

[0151] The risk level is calculated by comprehensively calculating the closed-loop steady-state current Isteady and the closed-loop impact current Ishock to output 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·ΔV;

[0154] Among them, a1, a2, a3 and a4 represent the weights of the steady-state current Isteady, the closed-loop impact current Ishock, the topological structure factor Ctopo and the voltage fluctuation amplitude △V when the loop is closed, respectively; and a1+a2+a3+a4=1, and the specific values ​​are set by the user;

[0155] Ctopo represents the topology factor, which indicates the degree of impact of the distribution network topology on risk, and is usually related to the redundancy of the network and the carrying capacity of the branch lines.

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

[0157] The above parameters are all dimensionless values;

[0158] The specific assessment contents of the risk level of the loop closing operation are as follows:

[0159] When the risk level coefficient R≤the first threshold, it is classified as the first-level risk and no early warning is required; the distribution network and power equipment can withstand the steady-state and impact current after the loop closing operation, the system is relatively stable and the operation is safe;

[0160] When the first threshold value is less than the risk level coefficient R and less than the second threshold value, it is classified as a secondary risk and a secondary warning is generated. The load of the power equipment is close to the rated value or there are certain problems with the distribution network topology structure, and attention should be paid to the risk of impact current. The risk can be mitigated by adjusting the operation time, load distribution and other measures;

[0161] When the risk level coefficient is greater than the second threshold, it is classified as a third-level risk and a first-level warning is generated. The current is close to or exceeds the carrying capacity of the power equipment, and the distribution network topology design is weak, which may cause damage to the power equipment or grid failure. Immediate control measures need to be taken, such as adjusting the timing of closing the loop and reducing the closing current.

[0162] Among them, the risk level is ranked as follows: Level 1 risk < Level 2 risk < Level 3 risk. At the same time, in the warning level, Level 1 warning > Level 2 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 mentioned above, by introducing a real-time monitoring and early warning mechanism, it is possible to promptly detect and respond to abnormalities in the closed-loop steady-state current and closed-loop impact current, and take corresponding processing measures based on the early warning signals to ensure the safe and stable operation of the power grid. This technical solution significantly improves the safety and reliability of online closed-loop operations in the distribution network.

[0165] This embodiment also provides an electronic device, including: a memory and a processor;

[0166] The memory is used to store computer programs;

[0167] The processor is used to call the computer program to execute the methods described in embodiments 1 to 3.

[0168] This embodiment further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed on an electronic device, the electronic device implements the methods described in Embodiments 1 to 3.

[0169] This embodiment further provides a computer program product, including a computer program. When the computer program is executed on an electronic device, the electronic device implements the method described in the above embodiment.

[0170] The specific implementation methods of a system, electronic device, computer-readable storage medium, and computer program product provided in the embodiments of the present application can refer to the specific embodiments of the above-mentioned method and will not be repeated here.

[0171] Obviously, those skilled in the art should understand that the above-mentioned units or steps of the present application can be implemented by a general-purpose computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. In this way, the present application is not limited to any specific combination of hardware and software.

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

Claims

1. A method for calculating and analyzing the online closed-loop current of a distribution network, characterized in that: include: Determine the specific location of the loop closing operation, and obtain the distribution network topology and power equipment parameters before and after the loop closing operation through the power sensor group; Calculate the closed-loop steady-state current based on the distribution network topology and power equipment parameters before and after the closed-loop operation; According to the distribution network topology before and after the closing operation, a calculation model for the closing impulse current is established; Calculate the loop-closing impulse current based on the power equipment parameters before and after the loop-closing operation and the calculation model of the loop-closing impulse current; Verify whether the closed-loop steady-state current and closed-loop impulse current meet the requirements for safe and stable operation; If the closed-loop steady-state current and the closed-loop impact current do not meet the requirements for safe and stable operation, the closed-loop operation is regulated.

2. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 1, characterized in that: The distribution network topology and power equipment parameters before and after the ring closing operation; Calculate the closed-loop steady-state current, including: According to the distribution network topology and power equipment parameters before and after the closing operation, the closing steady-state current is calculated using the superposition method and the power flow direct algorithm respectively; The final closed-loop steady-state current is obtained by combining the calculation results of the superposition method and the direct power flow algorithm.

3. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 2, characterized in that: According to the distribution network topology and power equipment parameters before and after the closing operation, the closing steady-state current is calculated using the superposition method, including: Calculate the voltage values ​​on both sides of the closing point before the closing operation, and find the difference between them to obtain the voltage difference on both sides of the closing point before the closing operation; calculate the total impedance of the ring network; based on the voltage difference on both sides of the closing point before the closing operation and the total impedance of the ring network, use Ohm's law to calculate the circulating current; By analyzing the power flow 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 closed-loop steady-state current.

4. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 3 is characterized in that: The formula for calculating the closed-loop steady-state current using the superposition method is: Among them, Isteady is the closed-loop steady-state current, Z loop represents the total impedance of the ring network, Yi represents the admittance value of the ith parallel branch, n represents the total number of branches connected in parallel with the main power supply line of the ring network; e represents the exponential function, and j represents the imaginary part of the complex number; The Yi calculates the admittance by analyzing the voltage and current at both ends of the parallel branch using Ohm's law. The specific algorithm formula is: Ii represents the current of the ith parallel branch, and Vi represents the voltage across the ith parallel branch; V1 and V2 are the voltage amplitudes of the nodes on both sides of the closed loop point, and O1 and O2 are the voltage phase angles of the corresponding nodes; ΔPload and ΔQload are the changes in active and reactive power at the closing point, respectively; Pload and Qload are the active and reactive power at the closing point, respectively; The parallel branch includes the standby line, capacitor bank / reactor and load branch; Backup line: A backup line used to ensure power system redundancy, connected in parallel with the main power supply line of the ring network; Capacitor bank / reactor: used to connect to the ring network to improve power factor or adjust reactive power; Load branch: A branch to which a specific load is connected, connected in parallel with the main power supply line of the ring network.

5. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 4 is characterized in that: After calculating the closed-loop steady-state current using the superposition method, calculate the closed-loop inrush current using the following formula: Where Ishock is the closed-loop impulse current, K is the impulse coefficient, τ is the decay time constant, t is the time variable, and β represents the impulse buffer coefficient, which is obtained by simulating the decay process of the impulse current using a power system simulation tool; Ish1 and Ish2 are the maximum current values ​​of the nodes on both sides of the closing point extracted by simulating the closing process with a power system simulation tool and recording the current waveforms of the nodes on both sides of the closing point during the closing process.

6. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 2, characterized in that: According to the distribution network topology and power equipment parameters before and after the closing operation, the direct flow algorithm is used to calculate the closing steady-state current, including: Input the distribution network topology and power equipment parameters before and after the ring closing operation into the power flow calculation software; Set the power flow calculation conditions to simulate the actual operation status of the power grid; Run the power flow calculation software to perform power flow analysis on the distribution network and obtain the results of power flow calculation; The closed-loop steady-state current is extracted from the results of the power flow calculation.

7. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 6, characterized in that: The power flow calculation conditions include: The parameters in the network topology before and after the ring closing operation need to satisfy the following equations: The power balance equation, that is, for each node i, is: Among them, P i and Q i are the active power and reactive power injected into node i, V i is the voltage at node i, I ik is the current flowing from node i to node k, j is an imaginary unit, and * represents conjugation; neighbors(i) represents the set of neighbor nodes of node i; The current balance equation, that is, for each branch (i, k), is: Among them, V k is the voltage at node k, Z ik is the impedance of branch (i, k); Voltage equation, that is, for each node i, the voltage V i satisfy: V i =V0-∑ k∈neighbors(i) Z ik ·I ik ; Where V0 is the voltage of the reference node.

8. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 7, characterized in that: According to the distribution network topology before and after the closing operation, a calculation model for the closing impulse current is established; Based on the power equipment parameters before and after the closing operation and the calculation model of the closing impulse current, the closing impulse current is calculated, including: Establishing a closed-loop impulse current calculation model, the closed-loop impulse current calculation model is used to describe the equivalent inductance and equivalent resistance of the closed-loop impulse 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 closed-loop point at the closing time; Use professional circuit simulation software, network topology and power equipment parameters to calculate the equivalent inductance and equivalent resistance of the loop closing point; According to the calculation model of the closing-loop impact current, the equivalent inductance, equivalent resistance, attenuation time constant, system rated angular frequency and the initial phase angle difference of the voltage across the closing point at the closing moment are substituted to solve the closing-loop impact current.

9. The method for calculating and analyzing the online closed-loop current of a distribution network according to claim 8, characterized in that: The verification of whether the closed-loop steady-state current and the closed-loop impulse current meet the requirements for safe and stable operation; If the closed-loop steady-state current and closed-loop impulse current do not meet the requirements for safe and stable operation, the closed-loop operation is regulated, including: Current protection setting value verification: Compare the calculated closed-loop steady-state current and closed-loop impulse current with the rated current and protection setting value of the power equipment; Equipment bearing capacity assessment: assess the power equipment's ability to withstand closed-loop steady-state current and closed-loop impulse current; Taking into account the current protection setting verification results, equipment bearing capacity assessment results and distribution network topology, the risk level of the closing operation is assessed, and corresponding closing operation control measures are adopted according to the risk level; among them, the closing operation control measures include adjusting the closing time and reducing the closing current.

10. The distribution network online loop closing risk analysis method according to claim 9 is characterized in that: The method also includes: during the closing loop operation, real-time monitoring of the size and change trend of the closing loop steady-state current and the closing loop impulse current, and immediately issuing a warning signal if the closing loop steady-state current and the closing loop impulse current increase abnormally or exceed a predetermined first threshold and a second threshold respectively.

11. An electronic device, characterized in that: include: Memory and processor; The memory is used to store computer programs; The processor is configured to call the computer program to execute the method according to any one of claims 1 to 10.

12. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed on an electronic device, the electronic device implements the method according to any one of claims 1 to 10.

13. A computer program product, comprising a computer program, characterized in that When the computer program is executed on an electronic device, the electronic device implements the method according to any one of claims 1 to 10.

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