A simulation analysis method for fast switching process of auxiliary power of petrochemical power grid

Abstract

This invention belongs to the field of power system simulation and safety control technology, and relates to a simulation analysis method for fast switching processes of petrochemical power grids. The method involves inputting electrical and motor parameters based on generated substation diagrams to complete refined automatic modeling of the power grid; establishing a fast switching logic model for switches based on fast switching setting sheets, starting methods, and switching methods; ensuring the established refined power grid model is consistent with the actual operating conditions of the petrochemical power grid; activating the fast switching logic model under set fault scenarios, and performing dynamic simulation through the fast switching logic model to conduct multi-dimensional and visualized quantitative evaluation of the safety and stability of the switching process. Through standardized modeling and dynamic simulation, this invention can accurately simulate the fast switching process under real operating conditions of petrochemical power grids, quantitatively evaluate the safety and stability of switching strategies, provide comprehensive reference solutions for operation and maintenance personnel, and effectively improve the continuous power supply reliability of petrochemical enterprises.

Description

Technical Field

[0001] This invention belongs to the field of power system simulation and safety control technology, and relates to a simulation analysis method for fast power switching process of petrochemical power grid. Background Technology

[0002] The plant power rapid switching system is one of the core guarantee devices for the safe operation of the petrochemical power grid. Its reliability is directly related to the stability of the continuous production process, avoiding plant-wide power outages and significant economic losses caused by power switching failures. The performance of the rapid switching system is highly dependent on the rationality of its setting strategy, and simulation analysis is a key technical means to verify the setting strategy. However, the accuracy of existing general-purpose rapid switching simulation models is insufficient. They fail to accurately simulate the collective effects of large motor groups losing power on the residual voltage and frequency attenuation of the bus, the impact of complex distribution networks on the closing transient process, and the impact of inrush current when the backup power transformer is put into operation. This leads to deviations between simulation results and actual conditions, making it difficult to accurately reflect the special characteristics of the petrochemical power grid and effectively predict switching failures or equipment impact risks. At the same time, the analysis relies heavily on manually setting fault scenarios, which is inefficient and cannot cover all operating modes. The analysis of the results is mostly at the qualitative level of "success / failure," lacking quantitative evaluation of key indicators such as inrush current and voltage recovery time.

[0003] In summary, the inherent limitations of existing technologies in terms of model accuracy and analytical intelligence prevent them from meeting the design and evaluation requirements of petrochemical power grids for high-reliability fast switching strategies. Therefore, a simulation and analysis technology for fast switching processes of plant power supplies in petrochemical power grids is urgently needed to address this issue. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a simulation method for fast power switching processes in petrochemical power grids. point Analysis methods By adopting a collaborative approach of "modeling-simulation-evaluation-optimization," the system can accurately simulate the real operating conditions of petrochemical power grids, quantitatively evaluate fast switching strategies, provide comprehensive reference solutions for electrical maintenance personnel, improve the continuous power supply of petrochemical enterprises, and promote the standardization and informatization of petroleum refining enterprises.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] Step 1: Automated modeling of power grid.

[0007] (1) Fill in the primary circuit list of the station and complete the model parameter input: Based on the characteristics of the power grid of petrochemical enterprises, the electrical monitoring data configuration system embedded in the technology has a built-in primary circuit list input template. The electrical monitoring data configuration system adopts the method described in the prior published patent CN120370865A_An Electrical Monitoring Data Configuration System.

[0008] Specifically, this includes location information, primary circuit information, equipment nameplate information, and electrical rated parameters. The location information includes the substation name, distribution room name, and busbar section name. The primary circuit information includes circuit classification, cabinet / circuit number, circuit name, busbar section location, voltage level, and circuit capacity. The nameplate information includes primary equipment model, rated current, equipment class, serial number, and manufacturing date. The electrical rated parameters must be specifically described according to the model classification. For transformers, this includes at least the short-circuit voltage percentage and connection group; for power supplies, it includes at least the power flow type, positive and negative sequence impedance, and operating power; and for motors, it includes at least the starting current, starting speed, maximum torque, and rated speed.

[0009] (2) Automatic drawing: Import the primary circuit list into the electrical monitoring data configuration system. The electrical monitoring data configuration system can match different model elements according to the circuit classification and voltage level. Then, customize the layout information, and the substation diagram can be obtained in the electrical monitoring data configuration system. After all the substation diagrams are drawn, the inter-station relationship can be entered. With the help of the composite network module, the main electrical wiring diagram of the entire petrochemical plant can be obtained.

[0010] (3) Model Electrical Parameter Supplementation: The electrical monitoring data configuration system supports multiple data entry methods to adapt to data initialization work under different conditions. Manual Entry: Provides a user-friendly human-computer interaction interface, allowing electrical maintenance personnel to double-click model elements in the main wiring diagram to add, delete, modify, and query data. Batch Import: Supports batch data modification and import by exporting power grid parameter spreadsheets, greatly improving the efficiency of large-scale data entry.

[0011] (4) Motor parameter identification: The stator and rotor impedance and excitation reactance of the motor directly affect the residual voltage and frequency difference of the bus after fast switching. However, the values ​​of the stator and rotor impedance and excitation reactance of the motor are usually not available at the petrochemical site. Existing models generally regard them as static impedance or simple motor models, which fail to accurately simulate the attenuation characteristics of the residual voltage amplitude and frequency caused by inertial rotation after the working power supply is cut off. The electrical monitoring data configuration system has a built-in parameter identification program. Using the available nameplate parameters, the stator and rotor impedance and excitation reactance required for simulation are identified. That is, according to the nameplate parameters given by the motor manufacturer: rated power Pn, rated current In, rated torque Tn, starting current Ist, starting torque Tst, maximum torque Tmax, rated speed nn, rated efficiency hn, rated power factor cosjn, and using the attached parameters, the values ​​of the stator and rotor impedance and excitation reactance of the motor are identified. Figure 2 For the circuit shown, establish the equivalent equation and identify the equivalent circuit parameters: stator resistance Rs, stator reactance Xs, magnetizing reactance Xm, rotor resistance Rr, and rotor reactance Xr.

[0012] Step 2: Custom logic modeling for the fast-switching device.

[0013] (1) Quick cut model information: as attached Figure 3 As shown, the fast-switching device can detect input signals and control the switch action. Each fast-switching device on the platform has the field information described in Table 1.

[0014] Table 1 Key parameter fields of the fast-switching device in the electrical monitoring data configuration system

[0015] Field Name unit Field type Keywords Information Classification Remark Pressure set value % float V Quick-start device start-up criterion set value No-flow constant A float I Quick-start device start-up criterion set value Directional starting current setting A float FXI Quick-start device start-up criterion set value Directional start delay s float FXTdelay Quick-start device start-up criterion set value Frequency voltage abnormal starting voltage setting % float PZV Quick-start device start-up criterion set value abnormal starting frequency difference setpoint Hz float PZDF Quick-start device start-up criterion set value Frequency voltage abnormal start delay ms float PZTdelya Quick-start device start-up criterion set value No-current start frequency difference Hz float WLDF Quick-start device start-up criterion set value No-current start delay ms float WLTdelay Quick-start device start-up criterion set value Undervoltage starting voltage setting % float SYV Quick-start device start-up criterion set value Underpressure start delay ms float SYTdelay Quick-start device start-up criterion set value Switch position change start-up float BWType Quick-start device start-up criterion set value 2: Simultaneously; 1: Series connection; 0: Exit Protect starting input float Btype Quick-start device start-up criterion set value 2: Simultaneously; 1: Series connection; 0: Exit Reverse power start-up float NGLType Quick-start device start-up criterion set value 2: Simultaneously; 1: Series connection; 0: Exit Frequency voltage abnormal start-up input float PYType Quick-start device start-up criterion set value 2: Simultaneously; 1: Series connection; 0: Exit underpressure start-up float SYType Quick-start device start-up criterion set value 2: Simultaneously; 1: Series connection; 0: Exit No current start-up input float WLType Quick-start device start-up criterion set value 2: Simultaneously; 1: Series connection; 0: Exit Fast closing frequency difference Hz float QDF Fast-switching device closing setting value Fast closing phase difference ° float QDP Fast-switching device closing setting value Same-capture closing frequency difference limit Hz float TBDF Fast-switching device closing setting value Residual voltage closing voltage setting % float CYV Fast-switching device closing setting value Residual voltage closing delay s float CYTdelay Fast-switching device closing setting value Long delay closing delay s float Ltdelay Fast-switching device closing setting value Quick closing and commissioning float Qstate Fast-switching device closing setting value 1: Investment; 0: Exit Simultaneous capture and sluice gate operation float Tstate Fast-switching device closing setting value 1: Investment; 0: Exit Residual voltage closing and input float CYstate Fast-switching device closing setting value 1: Investment; 0: Exit Long-delay closing input float Ltstate Fast-switching device closing setting value 1: Investment; 0: Exit Simultaneously switch closing delay ms float TTS Fast-switching device closing setting value Quick name cut float ID Basic information on quick-cut device Busbar corresponding to incoming line 1 float Bus1 Basic information on quick-cut device Busbar corresponding to incoming line 2 float Bus2 Basic information on quick-cut device Incoming Line 1 Switch float Break1 Basic information on quick-cut device Incoming Line 2 Switch float Break2 Basic information on quick-cut device Incoming Line 1 Switch Opening and Closing Time ms float Tb1 Basic information on quick-cut device Incoming Line 2 Switch Opening and Closing Time ms float Tb2 Basic information on quick-cut device Bus tie switch opening and closing time ms float Tbs Basic information on quick-cut device Time of judgment by the stability control device ms float Tscddt Basic information on quick-cut device Device transmission time ms float Tscdtt Basic information on quick-cut device Inter-station transmission time ms float Tstations Basic information on quick-cut device Device determines time on-site ms float Tlddt Basic information on quick-cut device I-stage switch status float Istate Monitoring information 1: Closed; 0: Open Section I power float Ip Monitoring information Current in segment I A float Ic Monitoring information Section I bus voltage % float Ibv Monitoring information Phase angle of bus voltage in section I ° float Iva Monitoring information I segment voltage frequency Hz float Ivf Monitoring information Second stage switch status float Iistate Monitoring information 1: Closed; 0: Open Second-stage power float IIp Monitoring information Second stage current A float IIc Monitoring information Section II bus voltage % float IIbv Monitoring information Phase angle of bus voltage in section II ° float IIva Monitoring information Second-stage voltage frequency Hz float IIvf Monitoring information Bus tie switch status float Bstate Monitoring information 1: Closed; 0: Open Main bus voltage phase angle difference ° float Ad Monitoring information Main bus voltage frequency difference Hz float Fd Monitoring information

[0016] (2) Starting method: as shown in the appendix Figure 4 Fast-start devices typically offer start-up via switch position change, protection start-up, reverse power start-up, no-current start-up, frequency and voltage abnormal start-up, and undervoltage start-up.

[0017] The switch change-start is initiated when the system is running normally. If the switch that was in the closed position trips and there is no current in the incoming line, the device will perform a switch change-start.

[0018] The protection activation means that when the fast main protection contacts of power supply side equipment such as lines / line transformer groups / main transformers are introduced into the fast-switching device, the fast-switching device will start immediately once the main protection action on the power supply side is detected during normal system operation.

[0019] The reverse power start-up time is generally set to the operating time of the main protection of the adjacent line plus the tripping time of the incoming line switch, and must meet the following requirements:

[0020] 1) Phase currents are reversed, and the positive direction of current is defined as the flow from the incoming line to the busbar;

[0021] 2) Phase current is greater than 0.1A;

[0022] 3) If the line voltage is less than the reverse power voltage threshold, the corresponding phase reverse power component will be activated;

[0023] The no-current start function is activated when the device detects that the incoming line current changes from current (greater than the no-current start setting value) to no current (less than the no-current start setting value) and the bus frequency is less than the no-current start frequency setting value. The device then starts the switching function after a set delay.

[0024] The no-current starting method is mainly used when the protection on the incoming line side cannot be connected to the device. When a fault occurs in the incoming line and it is tripped by other protection (which may be the protection on the opposite side), the incoming line current will inevitably show a downward trend, and the frequency will also decrease.

[0025] The aforementioned frequency-voltage abnormal start is mainly used in situations where the incoming line operating current is very small, or even where power may be supplied to the grid, and where no-current start and reverse power start are not suitable. The operating principle is that when the incoming power supply disappears for various reasons, the working load operates in an isolated grid, and the frequency of the working bus will deviate from the power frequency.

[0026] For the undervoltage abnormal start-up, the device provides two criteria for user selection: undervoltage detection of incoming line voltage and undervoltage detection of incoming line current, which are selected via the "Undervoltage Start-up Detection Incoming Line U" control word. When the "Undervoltage Start-up Detection Incoming Line U" control word is 1, if the device detects that both the three-phase bus voltage and the incoming line voltage are lower than the undervoltage start-up setting value, the switching function is initiated after a setting delay. When the "Undervoltage Start-up Detection Incoming Line U" control word is 0, if it detects that both the three-phase bus voltage are lower than the undervoltage start-up setting value and there is no current in the incoming line, the switching function is initiated after a setting delay.

[0027] (3) Switching Mode: After startup, the fast-switching device will operate the working power switch and the standby power switch in a certain sequence. In the fast-switching principle, the term "switching mode" is used to describe different switching operation sequences. Switching modes include: parallel, series, and simultaneous. Appendix Figure 5 Taking the single-bus segmented operation mode as an example, the various switching methods are briefly explained. The single-bus operation mode is similar.

[0028] During series switching, after the start signal is issued, and after the action time of the fast-switching device, a command to open switch 1 is issued. After the action time of the switch, switch 1 is opened. After the switch is opened, and after the action time of the fast-switching device, a command to close switch 00 is issued. After the action time of the switch, switch 00 is closed. The bus de-energization time is the action time of switch 00 and the fast-switching device.

[0029] During parallel switching, after the start signal is issued, and after the fast-switching device's operating time, a closing command is issued for switch 00. After the switch's operating time, switch 00 closes. After closing, and after the fast-switching device's operating time, a opening command is issued for switch 1. After the switch's operating time, switch 1 opens. In this mode, the power supplies operate in parallel, and the operating time is the operating time of switch 1 and the fast-switching device. In the event of a system fault, this switching method carries the risk of expanding the scope of the fault's impact.

[0030] During simultaneous switching, after the start signal is issued and the fast-switching device has been in operation, a command to open switch 1 is issued simultaneously. After the switch's operation time, switch 1 opens and switch 00 closes. When the operation times of the switches are inconsistent, and the operation time of switch 00 is longer than that of switch 1, the bus power loss time is the difference between the operation times of switch 00 and switch 1. In this mode, closing switch 00 without determining whether switch 1 is open poses a risk of expanding the scope of the fault.

[0031] (4) Implementation method: as shown in the appendix Figure 8 The closing methods of fast-acting switches include: fast switching, simultaneous switching, residual voltage switching, and long-delay switching.

[0032] Based on the equivalent circuit diagram (see Appendix 7) and phasor diagram (see Appendix 8) of the motor when the power is reconnected... Figure 8 The analysis aims to identify the conditions under which switching on backup power minimizes the impact on the power supply system and electrical equipment. (See attached...) Figure 8 Power supply voltage U s With bus motor residual U d From the angle θ between them, we can see that different θ values ​​correspond to different ΔU values. When θ is 180°, that is, the direction of the residual voltage of the motor is opposite to the direction of the power supply voltage, ΔU is the largest. If the backup power supply is switched on at this time, the motor will suffer the most severe impact. If the working power supply is suddenly disconnected, the working bus will react according to the beat voltage ΔU = U between the voltage fed back by the motor and the power supply voltage. d -U s .

[0033] Therefore, the closing criterion typically employs a three-dimensional criterion model that includes frequency difference blocking, voltage difference blocking, and dynamic phase prediction. The criterion for allowing closing is as follows:

[0034] (1)

[0035] (a) Quick Switching

[0036] When the incoming power supply has just lost power, and the incoming circuit breaker's fault-free protection has blocked the disturbance-free fast-switching device, if the frequency difference and phase angle difference meet the fast-switching device's switching conditions, the fast-switching device will be activated. This is because the combined voltage when all power supplies are switched on cannot exceed 1.1 times the rated voltage. (U is used as an example.) s =1.0;U D =1.1; the residual voltage Ud is between [0.1~1.1]; the closing limit angle is approximately 63°; the fast switching closing criterion expression is as follows:

[0037] (2)

[0038] At time t1, the phase angle difference between the backup power supply and the system side; At time t1, the difference in angular velocity between the two sides; At time t1, the first derivative of the angular velocity difference with respect to time; T is the inherent closing time of the switch.

[0039] (b) Simultaneous capture switching

[0040] In actual operation, if a large initial phase angle is caused by various reasons, or if a fault causes an increase in the residual voltage frequency of the busbar or phase lead, resulting in the loss of a suitable time for rapid switching, the fast-switching device will use a synchronization capture method to switch the backup power supply. Synchronization capture involves the working busbar voltage phasor rotating around the backup power supply's incoming voltage phasor. At the minimum differential voltage, the phase angle difference is zero, enabling switching. Based on the Taylor expansion formula with a 360° phase difference as the closing target, the following criterion can be obtained:

[0041] (3)

[0042] The value is a fixed small value; T is the inherent closing time of the switch, and only T needs to be fixed.

[0043] (c) Residual voltage switching

[0044] When neither backup power supply switching nor synchronous capture switching satisfies the requirements for fast switching and synchronous capture switching, residual voltage switching is initiated. This switching occurs when the bus residual voltage decays to 20%~40% of the rated voltage. Residual voltage switching serves as a backup function for fast switching and synchronous capture switching, and there is no need to judge phase angle difference and frequency difference during closing. Although residual voltage switching ensures motor safety, prolonged power outages can significantly impact the success and time of motor self-starting.

[0045] (d) Long delay switching

[0046] If the conditions for rapid switching, synchronous capture switching, and residual voltage switching cannot meet the conditions for switching on the backup power supply, then after a long delay, when the residual voltage on the bus has decayed sufficiently to fully meet the conditions for switching on the backup power supply, long-delay switching is initiated. Long-delay switching serves as the final backup to achieve power supply switching. The long-delay action time setting must exceed the long-delay action time.

[0047] Step 3: Online data integration and trend initialization.

[0048] (1) Online data integration: Using the data interface of the big data platform, primary and secondary equipment are connected and the Modbus or 61850 protocol is used to obtain real-time operation data of the petrochemical power grid;

[0049] (2) Perform power flow calculations and debugging based on online data to ensure that the initial state of the simulation model is consistent with the actual operating conditions of the power grid, so as to provide accurate initial conditions for subsequent dynamic simulations; The specific operation steps are as follows:

[0050] (a) Fast-switching device status modeling: The status of the working switch, standby switch, bus tie switch and fast-switching activation / lockdown flag associated with the fast-switching device are used as the initial conditions for power flow and participate in the node type setting;

[0051] (b) Multi-scenario preset sections: For three typical fast-switching start-up scenarios, namely incoming line tripping, bus fault, and transformer backup protection action, the initial sections are preset and can be directly called according to the actual triggering events during simulation start-up.

[0052] (c) Event-driven time discretization: Automatically triggers power flow reinitialization at the moment of switch action (opening, closing), providing independent initial values ​​for each stage of the fast switching process.

[0053] Power flow algorithms rely on three built-in calculation models in system simulation software: Newton-Raphson, adaptive Newton-Raphson, and fast decoupling. These models differ significantly in their convergence mechanisms and applicable scenarios. Therefore, the optimal calculation method must be selected based on grid conditions, system scale, and other factors. The specific steps are as follows:

[0054] (a) Newton-Raphson

[0055] This method directly solves the nonlinear power flow equations, linearizes them through Taylor expansion, and corrects the solution vector using the Jacobian matrix. The nonlinear model and the corrected equations are shown in equations (4) and (5), respectively:

[0056] (4)

[0057] (5)

[0058] The Jacobian matrix J contains partial derivatives. , , , The expression is as follows:

[0059] , , ,

[0060] In the formula, ΔV is the bus voltage phasor;

[0061] The Newton-Raphson method holds a central position in power flow calculations due to its unique quadratic convergence characteristics. By correcting the solution vector in real time using the Jacobian matrix, the Newton-Raphson method exhibits an exponentially accelerated convergence rate, demonstrating significant advantages in large-scale power grid analysis. This algorithm allows users to directly set the convergence thresholds for the bus active and reactive power detuning rates, thereby precisely controlling the calculation accuracy of the power flow results and ensuring that the power balance error at key nodes strictly meets engineering requirements. However, this algorithm is highly dependent on the initial bus voltage. Therefore, the software employs a hybrid strategy: when running the Newton-Raphson method, it first performs 3-5 Gauss-Seidel iterations to generate an initial voltage distribution close to the convergence region, making it suitable for small- to medium-sized systems or scenarios with high accuracy requirements.

[0062] (b) Adaptive Newton-Raphson

[0063] A hybrid iterative strategy is adopted, combining the Gauss-Seidel method and the Newton-Raphson method. First, the Gauss-Seidel method is used to iterate and generate initial values ​​close to the true solution, and then the Newton-Raphson method is switched to accelerate convergence.

[0064] The system node voltage equations and iterative calculation models are shown in equations (6) and (7):

[0065] (6)

[0066] (7)

[0067] Where ΔP and ΔQ are the active and reactive power phasors of the bus, ΔV is the bus voltage phasor, and [I] is the column vector of node injected currents, i.e., the complex currents injected into the grid at each node; [V] is the system matrix, describing the power grid topology and branch parameters; [V] is the node voltage column vector, i.e., the complex voltage of each node. ] is the transpose of the nodal voltage column vector, [ ] is the conjugate of the nodal admittance matrix, [ ] represents the conjugate of the node voltage column vectors.

[0068] This algorithm reduces the number of Jacobian matrix calculations and is more efficient than the Newton-Raphson algorithm. It is suitable for large-scale systems or real-time computing, but a balance between efficiency and accuracy is required.

[0069] (c) Fast decoupling method

[0070] For lines where the reactance is much greater than the resistance ( In a system where active power mainly depends on the phase angle θ and reactive power mainly depends on the voltage amplitude V.

[0071] The decoupling correction equation is:

[0072] (8)

[0073] Where B′ and B′′ are constant matrices, the non-dominant elements of the Jacobian matrix are ignored by decoupling the active and reactive equations.

[0074] θ is the active power dependent phase angle, V is the reactive power dependent voltage amplitude, Δθ is the node voltage phase angle correction, and ΔV is the node voltage amplitude correction (per unit value). The Jacobian matrix is ​​fixed and does not need to be recalculated in each iteration. Moreover, the solution efficiency of sparse matrices is high, which is suitable for long radial networks or systems containing long-distance transmission lines.

[0075] When X / R < 3 or a ring network exists, linearization is performed using Taylor expansion, and the solution vector is corrected using the Jacobian matrix. The nonlinear model expression is as follows:

[0076]

[0077] In the formula, ΔP and ΔQ are the active and reactive power phasors of the bus; Active power injected into the node; The active power of this node is calculated based on the current voltage phase angle θ and voltage amplitude V; : Reactive power injected into the node; The reactive power of this node is calculated based on the current voltage phase angle θ and voltage amplitude V.

[0078] Step 4: Dynamic simulation and switching quantification evaluation.

[0079] (1) Fast switching calculation: The dynamic simulation process is started under the set fault scenario. The system not only records whether the switching is successful or not, but also captures and displays the dynamic change curves of key electrical parameters (such as bus voltage, frequency difference, phase angle difference) throughout the process.

[0080] The numerical solution process is as follows: Figure 9As shown, the main steps include: inputting the power grid topology and initializing the system; calculating the characteristic parameters of fast switching; constructing the node admittance matrix and iteratively solving the network equations considering the impedance when the fast switching device starts; discretizing the dynamic process of the motor during fast switching into a small time step dynamic analysis to accelerate the process; determining whether the system is stable when the fast switching closing conditions are met; and outputting the voltage, voltage phase angle, and frequency difference change curves of the main and backup buses during the fast switching process.

[0081] The specific method for dynamically reconstructing the nodal admittance matrix in the above steps is as follows:

[0082] Suppose the power system has n independent nodes, and the node admittance matrix Y(t) is an n×n complex matrix with its elements defined as follows:

[0083] Diagonal elements (self-admittance):

[0084] Y ii (t)=∑ j∈Ni yij(t)+y i0 (t)

[0085] Where N i Let y{ij}(t) be the set of nodes directly connected to node i, y{i0}(t) be the branch admittance between node i and node j, and y{i0}(t) be the ground admittance of node i.

[0086] Off-diagonal elements (mutual admittance):

[0087]

[0088] As the switching state changes, the nodal admittance matrix is ​​dynamically reconstructed according to the following rules:

[0089] (a) When the working switch is opened: Set the mutual admittance element corresponding to the working power supply branch to zero, and subtract the admittance of the branch from the self-admittance of the corresponding node, so that the matrix is ​​updated as follows:

[0090]

[0091] (b) When the standby switch is closed: Add or restore the standby power supply branch, add the corresponding mutual admittance and self-admittance elements, and update the matrix as follows:

[0092]

[0093] (c) When the bus tie switch operates: if the bus tie switch changes from open to closed, the nodes corresponding to the two bus sections are merged into one node, and the matrix order is reduced by one; if the bus tie switch changes from closed to open, the original merged node is split into two independent nodes, and the matrix order is increased by one.

[0094] The dynamically reconstructed nodal admittance matrix can be uniformly represented as:

[0095] Y(t) = Y base +ΔY sw (t)

[0096] Among them, Y base The nodal admittance matrix ΔY is based on a fixed topology. sw (t) is the correction matrix caused by the change in switch state.

[0097] (2) Based on these data, the system constructs a quantitative evaluation index system to conduct a multi-dimensional and visualized comprehensive evaluation of the safety and stability of the switching process.

[0098] Beneficial effects

[0099] This invention provides a simulation of the fast switching process of plant power supply for petrochemical power grids. Analytical methods It has the following beneficial effects:

[0100] Improve work efficiency and automation: By using standardized data entry templates and automated setpoint calculation and verification processes, the traditional model of relying on manual calculation and verification has been changed. It can complete the batch verification of setpoints for the entire plant within minutes, reducing the workload of electrical maintenance personnel and improving the overall efficiency of setpoint management.

[0101] Significantly improved modeling accuracy and scenario applicability: Through refined automatic power grid modeling technology, this invention overcomes the shortcomings of traditional general-purpose models that are too idealistic. The model can accurately simulate the residual voltage attenuation characteristics of large motor groups in petrochemical power grids and the transient response of complex distribution networks, greatly improving the consistency between simulation results and engineering realities, and significantly enhancing the credibility of simulation analysis and its decision-making reference value.

[0102] The system enhances the real-time performance of simulation analysis results: online data integration and power flow initialization functions enable automatic alignment between simulation scenarios and actual power grid operation, reducing manual intervention and achieving full automation from model building and scenario setting to result analysis, significantly improving work efficiency. Furthermore, the calculation results not only include whether the switchover was successful but also allow viewing the change curves of key evaluation indicators, providing more accurate reference data for petrochemical electrical maintenance personnel. This allows for timely adjustments to fast-switching settings based on the calculation results, greatly improving the power supply continuity of petrochemical enterprises.

[0103] The system achieves rapid optimization and forward-looking guidance of setpoint strategies: its core contribution lies in forming a complete closed loop of "modeling-simulation-evaluation-optimization". By combining custom logic modeling of fast-switching devices with quantitative evaluation results, the system can provide data-driven intelligent decision support for petrochemical operation and maintenance personnel to design optimal plant power safety strategies based on massive simulation data, realizing the transformation from "post-event verification" to "pre-event optimization".

[0104] Promote enterprise informatization and standardization: Integrate scattered modeling, calculation, simulation and analysis functions into a unified platform, and reduce the threshold for use by using technologies such as automatic graph generation and online data docking, thereby improving the ease of use of the system and its application value in actual engineering.

[0105] Therefore, this invention provides a simulation analysis technology for the rapid switching process of plant power supply in petrochemical power grids. Its beneficial effects include improving model accuracy and scenario applicability, enhancing work efficiency and real-time analysis, enabling rapid optimization and forward-looking guidance of setpoint strategies, providing data-driven intelligent decision support for operation and maintenance personnel, and promoting enterprise informatization and standardization. This system effectively solves the problems of traditional methods such as reliance on manual labor, idealized models, and shallow analysis dimensions, and has significant engineering application and promotion value in improving the continuity and security of power supply in petrochemical power grids. Attached Figure Description

[0106] Appendix Figure 1 This is a flowchart of the simulation analysis method for fast power switching process of petrochemical power grids as described in this invention;

[0107] Appendix Figure 2 The equivalent circuit diagram of the motor described in this invention is shown below.

[0108] Appendix Figure 3 This is a simplified diagram of the operation of the fast-cutting device described in this invention;

[0109] Appendix Figure 4 This is a logic diagram of the starting method of the fast-switching device described in this invention;

[0110] Appendix Figure 5 This is a logic diagram of the switching action of the fast-switching device described in this invention;

[0111] Appendix Figure 6 This is the operation logic diagram of the fast-switching device described in this invention;

[0112] Appendix Figure 7 This is the equivalent circuit diagram of the motor after the fast cut described in this invention;

[0113] Appendix Figure 8 This is the voltage vector diagram after fast switching as described in this invention;

[0114] Appendix Figure 9 This is a flowchart of the fast-cut numerical calculation described in this invention;

[0115] Appendix Figure 10 This is the main wiring diagram automatically generated for substation A in the case described in this invention;

[0116] Appendix Figure 11This is a diagram of the quick-switch setpoint configuration interface in the case described in this invention;

[0117] Appendix Figure 12 This is a real-time operating numerical diagram of a motor in the case described in this invention;

[0118] Appendix Figure 13 This is a diagram showing the result of the fast switching operation of substation A in the case described in this invention;

[0119] Appendix Figure 14 This is a graph showing the voltage change trend of the main and backup busbars during the fast switching process of substation A in the case described in this invention.

[0120] Appendix Figure 15 This is a trend diagram of the phase angle change of the main and backup bus voltages during the fast switching process of substation A in the case described in this invention;

[0121] Appendix Figure 16 This is a graph showing the frequency difference trend of the main and backup bus voltages during the fast switching process of substation A in the case described in this invention. Detailed Implementation

[0122] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0123] Take substation A of a petrochemical company as an example.

[0124] Step 1: Automated Modeling of Refined Power Grid

[0125] Substation A is a 6kV substation. Section I has 5 motors, 3 transformers, 1 capacitor, and 1 PT cabinet. Section II has 6 motors, 3 transformers, 1 capacitor, and 1 PT cabinet. Fill in the primary circuit list; some contents are shown in Table 2. After importing and adjusting the layout on the platform, the attached... Figure 10 The main wiring diagram shown is shown.

[0126] Table 2 Partial List of Primary Circuits

[0127]

[0128] Except for the standby motor, the rated parameters of this station are as described in Table 3.

[0129] Table 3 Rated parameters of the motor

[0130]

[0131] The parameters obtained after identification are shown in Table 4.

[0132] Table 4 Data after motor identification

[0133]

[0134] Step 2: Custom Logic Modeling of the Fast Switching Device

[0135] The quick-switch setting sheet for this station is shown in the table. Configure the parameters to the system; the configuration interface is shown in the attached figure. Figure 11 As shown:

[0136] Table 5 Substation A Section Fast Switching Setting Sheet

[0137]

[0138] Step 3: Online Data Integration and Trend Initialization

[0139] In the system, after data is integrated, double-clicking the model allows you to view real-time power values, as shown in the attached figure. Figure 12 As shown.

[0140] Step 4: Dynamic Simulation and Switching Quantitative Evaluation

[0141] Taking the case of the 6kV I-section incoming switch of substation A being tripped without authorization as an example, the method described in this invention is used for dynamic simulation and quantitative evaluation.

[0142] (1) Simulation settings and initial conditions

[0143] The fault is set to disconnect the 6kV I# incoming line of the incoming switch at 0.1s. The settings for the fast-closing device are as follows: switch action time is 50ms, fast closing frequency difference is set to 1Hz, fast closing phase difference is set to 30°, synchronous closing frequency difference is set to 10Hz, and bus tie switch closing time is 50ms. Figure 12 )

[0144] (2) Dynamic simulation process

[0145] The simulation employs a variable step-size discretization method with a step size of 1 ms. At 100 ms, a sudden tripping of the incoming line switch in section I is simulated, triggering the fast-switching device. The multi-level criteria described in claim 4 are used to sequentially determine the following:

[0146] After a 30ms judgment time, at 130ms, the voltage phase angle difference between the main and backup buses was detected as 19.26°, and the frequency difference as 0.48Hz, satisfying the fast switching conditions (|Δf|≤1 Hz and |Δδ|≤30°). The device determined to use the fast switching mode, and after a 50ms action time, the bus tie switch closed at 180ms. Figure 13-16 )

[0147] (3) Quantitative evaluation results: After the simulation, a quantitative evaluation was conducted according to the indicators, and the results are as follows:

[0148] (a) Voltage index: During the fault, the bus voltage is as low as 60%. After the bus tie switch is closed, the voltage quickly recovers to 96% and the recovery time does not exceed 100ms. The voltage index is qualified.

[0149] (b) Frequency index: The frequency difference at the closing time is 0.48Hz, which is less than the fast switching setting (1Hz), so the frequency index is qualified.

[0150] (c) Phase angle index: The phase angle difference at the closing time is 19.26°, which is less than the fast switching setting (30°), and the phase angle index is qualified.

[0151] (d) Time indicator: The total time from start-up to closing is 80ms, which is less than the locking value (150ms), and the time is qualified.

[0152] (e) Switching result: The 6kV bus section of the substation and its connected motor group were able to return to normal operation after the switching process was completed. The system was stable and the switching was successful.

[0153] This system is a local power system consisting of the working bus, the standby bus, all motor loads on the bus, and the standby power supply network associated with the fast switching device after switching.

[0154] The results of the station's rapid switching action are attached. Figure 13 As shown in the attached figure, the voltage, voltage phase angle, and frequency difference curves of the main and backup buses during the fast switching process are respectively as follows. Figure 14-16 As shown.

[0155] The results show that the system was stable after the fast-switching device was activated, and the fast-switching setpoint was set reasonably.

[0156] This example demonstrates the effectiveness and feasibility of the simulation analysis technology for fast power switching in petrochemical power grids proposed in this invention. The system adopts a collaborative approach of "modeling-simulation-evaluation-optimization," which can accurately simulate the real operating conditions of petrochemical power grids, quantitatively evaluate fast switching strategies, provide comprehensive reference solutions for electrical maintenance personnel, improve the continuous power supply of petrochemical enterprises, and promote the standardization and informatization of petroleum refining enterprises.

[0157] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A simulation analysis method for fast power switching process of petrochemical power grid, characterized in that, Step S1: Based on the data configuration system for electrical monitoring, input the primary circuit list, match different model elements according to circuit classification and voltage level, and define layout information; the big data system platform generates a substation diagram; input electrical parameters and motor parameters according to the generated substation diagram to complete the refined automatic modeling of the power grid; Step S2: Establish a key parameter field information table for the fast switching device, and determine the start-up mode of the switch based on the key parameter field information table; establish a fast switching logic model based on the switching mode of the switch according to the series switching mode, parallel switching mode, or simultaneous switching mode. Step S3: Use the electrical monitoring data configuration system to obtain real-time operating data of the petrochemical power grid. Based on the real-time operating data of the petrochemical power grid, ensure that the refined power grid model established in step S1 is consistent with the actual operating conditions of the petrochemical power grid through power flow initialization. Step S4: Activate the fast switching logic model under the set fault scenario, and perform dynamic simulation through the fast switching logic model to conduct multi-dimensional and visualized quantitative evaluation of the safety and stability of the switching process.

2. The simulation analysis method for fast power switching process of petrochemical power grid according to claim 1, characterized in that, The primary circuit list in step S1 includes: substation location information, primary circuit information, equipment nameplate information, and electrical rated parameter information; Based on the information provided by the primary circuit list, the data configuration system for electrical monitoring is used to generate multiple substation diagrams in the petrochemical power grid. The total electrical main wiring diagram of the petrochemical power grid is generated by using the composite network module to combine all the substation diagrams in the petrochemical power grid.

3. Simulation of fast power switching process for petrochemical power grids according to claim 1 Analytical methods Its characteristics are, The starting methods of the fast-switching device determined in step S2 based on the key parameter field information table include: switch change start, protection start, reverse power start, frequency and voltage abnormal start, and voltage loss abnormal start. Based on the switching change start, protection start, reverse power start, frequency and voltage abnormal start, and undervoltage abnormal start, a three-dimensional criterion model including frequency difference blocking, voltage difference blocking, and dynamic phase prediction is used as the criterion for allowing closing. Its expression is as follows: ； The absolute value of the difference between the primary and backup bus frequencies; The absolute value of the voltage difference between the main and backup busbars; System nominal voltage; Phase difference between main and backup buses; Backup side angle frequency; System side angular frequency; Maximum allowed phase angle difference setting for closing Based on the criteria for allowing closing, the fast closing methods are divided into: fast switching, simultaneous capture switching, residual voltage switching, and long delay switching; The criterion expression for the fast switching closing with a closing limit angle of 63° is as follows: ； At time t1, the phase angle difference between the backup power supply and the system side; At time t1, the difference in angular velocity between the two sides; At time t1, the first derivative of the angular velocity difference with respect to time; T is the inherent closing time of the switch; The simultaneous switching is based on a 360° phase difference as the closing target, and the criterion expression is as follows: ； At time t1, the phase angle difference between the backup power supply and the system side; At time t1, the difference in angular velocity between the two sides; At time t1, the first derivative of the angular velocity difference with respect to time; To use a fixed small value, T is the inherent closing time of the switch, so only T needs to be fixed; The residual voltage switching is achieved when the bus residual voltage decays to 20%~40% of the rated voltage; The long-delay switching is initiated after the bus residual voltage has decayed to the point where the conditions for switching to the backup power supply are met.

4. The simulation analysis method for fast power switching process of petrochemical power grid according to claim 1, characterized in that, In step S3, online data integration uses the data interface of the electrical monitoring data configuration system to connect primary and secondary equipment and use Modbus or 61850 protocol to obtain real-time operation data of the petrochemical power grid. The power flow initialization steps of fast switching calculation include taking the status of the working switch, standby switch, bus tie switch and fast switching engagement / lockout flag associated with the fast switching device as the initial conditions for power flow, and taking three actions as the typical starting scenarios for fast switching: line non-fault tripping, bus fault and transformer backup protection, and presetting the initial section state; automatically triggering power flow reinitialization at the moment of switch action, providing independent initial conditions for each stage of the fast switching process. Based on online data, the adaptive power flow algorithm employs a hierarchical adaptive strategy for power flow calculation. When X / R ≥ 3 and it is a radial network, a fast decoupling method is used, and the decoupling correction equation is: ； Where B′ and B′′ are constant matrices, and by decoupling the active and reactive power equations, the non-dominant elements of the Jacobian matrix are ignored; θ is the active power dependent phase angle, V is the reactive power dependent voltage magnitude, Δθ is the node voltage phase angle correction, and ΔV is the node voltage magnitude correction. When X / R < 3 or a ring network exists, linearization is performed using Taylor expansion, and the solution vector is corrected using the Jacobian matrix. The nonlinear model expression is as follows: ； In the formula, ΔP and ΔQ are the active and reactive power phasors of the bus; Active power injected into the node; The active power at this node is calculated based on the current voltage phase angle θ and voltage amplitude V. Reactive power injected into the node; The reactive power of this node is calculated based on the current voltage phase angle θ and voltage amplitude V. The corrected equation is expressed as follows: ； In the formula, ΔV is the bus voltage phasor; The Jacobian matrix J contains partial derivatives ∂P / ∂θ, ∂P / ∂V, ∂Q / ∂θ, and ∂Q / ∂V, expressed as follows: ， ， ， ； When the number of system nodes is ≥100, the adaptive Newton-Raphson method is adopted; the initial values ​​close to the true solution are generated iteratively using the Gauss-Seidel method, and then the Newton-Raphson method is switched to accelerate convergence. The system node voltage expression is as follows: ； [I] represents the column vector of node-injected currents, i.e., the complex currents injected into the grid by each node; [V] is the system matrix, describing the power grid topology and branch parameters; [V] is the node voltage column vector, i.e., the complex voltage of each node; The iterative generation expression is as follows: ； Y BUS For the system matrix, [ ] is the transpose of the nodal voltage column vector, [ ] is the conjugate of the nodal admittance matrix, [ ] is the conjugate of the node voltage column vector; if the iteration does not converge, it reverts to the Gauss-Seidel method and adds a damping factor.

5. The simulation analysis method for fast switching process of plant power supply for petrochemical power grids according to claim 1, characterized in that, Step four, dynamic simulation and switching quantification evaluation, are as follows: (1) Input the power grid topology and initialize the system; the fast switching device calculates the closing criteria setpoints corresponding to fast switching, simultaneous switching, residual voltage switching and long delay switching based on the initial phase angle difference, initial frequency difference and initial value of bus residual voltage between the working power supply and the backup power supply. (2) Based on the change of the switching state after the fast switching device starts, the node admittance matrix is ​​dynamically reconstructed, and the network equation is iteratively solved within each simulation step according to the transient impedance change of the motor load. The switch state changes are as follows: working switch open, standby switch closed, bus tie switch activated. (3) During the fast switching process, the fast switching device discretizes the electromechanical transient process of the motor group into a small time step Δt for dynamic analysis. In each time step, the slip, electromagnetic torque, rotor voltage and bus frequency of the motor are updated synchronously. (4) Based on each time step, determine in turn whether the closing conditions of fast mode, simultaneous capture mode, residual voltage mode, and long delay switching mode are met; If any of the conditions for fast mode, simultaneous capture mode, residual voltage mode, or long delay switching mode are met, the closing command under the corresponding switching mode is output, and the voltage, phase angle, and frequency difference change curves at the closing moment are recorded. (5) After the simulation is completed, the closing fast switching process is quantitatively evaluated; The frequency index is the frequency difference at the moment of closing, in Hz; The phase angle index is the phase angle difference at the actual closing moment, in degrees; The time indicator refers to the total time from start-up to completion of closing, in milliseconds. The switching result is determined as either success or failure.

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