A method, apparatus, computer device, and storage medium for evaluating static voltage stability.

Abstract

This application provides a method, apparatus, computer equipment, and storage medium for assessing static voltage stability. The method comprehensively considers the impact of distributed generation's voltage sustaining capability and low-voltage tripping characteristics on the system's static voltage stability, providing a more accurate voltage stability assessment. Through a distributed continuous power flow algorithm, the response of distributed generation under different operating conditions can be effectively simulated, improving the reliability of the assessment results. Furthermore, it provides accurate voltage stability assessments regardless of whether the distributed generation penetration is low or high. In addition, this invention only requires the exchange of limited voltage and power data at the transmission and distribution boundaries between the transmission system operator and the distribution system operator, reducing data exchange volume and communication requirements while ensuring efficient algorithm operation.

Description

Technical Field

[0001] This application relates to the field of power system stability assessment technology, and in particular to a static voltage stability assessment method, apparatus, computer equipment, and storage medium. Background Technology

[0002] In modern power systems, the rapid development and widespread application of distributed generation technology have brought new challenges to the voltage stability of the power system. Traditional voltage stability assessment methods mainly focus on the assessment of the transmission network or distribution network alone, without fully considering the interaction between the transmission and distribution networks. Especially when distributed generation units are connected, they also fail to consider the voltage maintenance capability and tripping characteristics of distributed power sources under low voltage conditions. These characteristics have a significant impact on the static voltage stability of the power system, resulting in inaccurate assessment results and increasing the risk of system operation. Summary of the Invention

[0003] The purpose of this application is to at least address one of the aforementioned technical deficiencies, and in particular to provide a more accurate static voltage stability assessment scheme.

[0004] In a first aspect, this application provides a method for evaluating static voltage stability, including:

[0005] Based on the current power growth direction, the power flow equations for the distribution network and the transmission network are constructed respectively.

[0006] Based on the current first boundary vector, solve the power flow equations of the distribution network to obtain the first solution vector;

[0007] Based on the first solution vector, determine whether there is a low-voltage trip of a distributed power source. If so, update the power growth direction and return to the steps of constructing the power flow equations of the distribution network and the transmission network respectively based on the current power growth direction. If not, obtain the second boundary vector of the distribution network to the transmission network based on the first solution vector.

[0008] Based on the second boundary vector, solve the power flow equations of the transmission network to obtain the second solution vector;

[0009] Based on the second solution vector, update the first boundary vector of the transmission network to the distribution network, and return to the steps of solving the power flow equations of the distribution network based on the current first boundary vector to obtain the first solution vector, until the first solution vector and the second solution vector converge;

[0010] According to the continuous power flow algorithm, the second solution vector after convergence is predicted and corrected according to the set step size to obtain the second solution vector after load parameter iteration;

[0011] Based on the second solution vector after iterating the load parameters, update the first boundary vector, and return to the steps of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the load parameters reach the critical point to calculate the static voltage stability margin.

[0012] In one embodiment, the static voltage stability assessment method includes:

[0013] If the first and second solution vectors fail to converge, adjust the set step size.

[0014] Based on the adjusted set step size and the second solution vector after the previous convergence, prediction and correction are performed to obtain the second solution vector after load parameter iteration. Then, the process jumps to the second solution vector after load parameter iteration, updates the first boundary vector, and returns to the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector. This process continues until the load parameters reach the critical point, and then the step of calculating the static voltage stability margin continues.

[0015] In one embodiment, adjusting the set step size includes:

[0016] Reduce the set step size before it reaches the lower limit.

[0017] In one embodiment, reducing the set step size includes:

[0018] Reduce the set step size to half of the original size.

[0019] In one embodiment, determining whether a distributed power source has experienced a low-voltage trip based on the first solution vector includes:

[0020] The node in the distribution network connected to the distributed generation source is designated as the first node;

[0021] Extract the voltage of the first node from the first solution vector;

[0022] If the voltage at the first node is less than the low-voltage tripping threshold of the distributed power source, it is determined that the distributed power source connected to the first node has experienced a low-voltage tripping.

[0023] In one embodiment, the power growth direction includes a load growth direction and an output growth direction, and updating the power growth direction includes:

[0024] Retain the output growth direction corresponding to the first node, and lower the load growth direction corresponding to the first node.

[0025] In one embodiment, according to the continuous power flow algorithm, the converged second solution vector is predicted and corrected based on a set step size to obtain the second solution vector after load parameter iteration, including:

[0026] According to the continuous power flow algorithm, a natural parameterization strategy is selected, and the second solution vector after convergence is predicted and corrected according to the set step size to obtain the second solution vector after load parameter iteration.

[0027] Secondly, this application provides a static voltage stability evaluation device, comprising:

[0028] The module is used to construct the power flow equations for the distribution network and the transmission network respectively, based on the current power growth direction;

[0029] The first solution module is used to solve the power flow equations of the distribution network based on the current first boundary vector to obtain the first solution vector;

[0030] The first extraction module is used to determine whether there is a low-voltage trip of a distributed power source based on the first solution vector. If so, the power growth direction is updated and the steps of constructing the power flow equations of the distribution network and the transmission network respectively based on the current power growth direction are returned. If not, the second boundary vector of the distribution network to the transmission network is obtained based on the first solution vector.

[0031] The second solution module is used to solve the power flow equations of the transmission network based on the second boundary vector, and obtain the second solution vector.

[0032] The second extraction module is used to update the first boundary vector of the transmission network to the distribution network according to the second solution vector, and return the steps of solving the power flow equation of the distribution network according to the current first boundary vector to obtain the first solution vector, until the first solution vector and the second solution vector converge.

[0033] The simulation growth module is used to predict and correct the converged second solution vector according to the continuous power flow algorithm and the set step size, so as to obtain the second solution vector after the load parameters are iterated.

[0034] The loop module is used to update the first boundary vector based on the second solution vector after iterating the load parameters, and return the steps of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the load parameters reach the critical point to calculate the static voltage stability margin.

[0035] Thirdly, this application provides a computer device including one or more processors and a memory storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, they perform the steps of the static voltage stability evaluation method in any of the above embodiments.

[0036] Fourthly, this application provides a storage medium storing computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to perform the steps of the static voltage stability evaluation method in any of the above embodiments.

[0037] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0038] This method comprehensively considers the impact of distributed generation's voltage maintenance capability and low-voltage tripping characteristics on the system's static voltage stability, providing a more accurate voltage stability assessment. Through a distributed continuous power flow algorithm, it effectively simulates the response of distributed generation under different operating conditions, improving the reliability of the assessment results. Furthermore, it provides accurate voltage stability assessments regardless of whether distributed generation penetration is low or high. In addition, this invention only requires the exchange of limited voltage and power data at the transmission and distribution boundaries between the transmission and distribution system operators, reducing data exchange volume and communication requirements while ensuring efficient algorithm operation. The method also has a short computation time, meeting the needs of real-time assessment and possessing high practical value. Moreover, this method requires no additional hardware investment and can be implemented using existing power system equipment and software resources, reducing costs. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a flowchart illustrating a static voltage stability assessment method in one embodiment of this application;

[0041] Figure 2 This is an internal structural diagram of a computer device provided in one embodiment of this application. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] This application provides a method for evaluating static voltage stability, including steps S102 to S114.

[0044] S102, based on the current power growth direction, construct the power flow equations for the distribution network and the transmission network respectively.

[0045] It is understandable that the continuous power flow algorithm introduces a parameter into the traditional power flow algorithm to simulate load growth; this introduced parameter is called the load parameter. The basic equation in the continuous power flow algorithm can be simply described as: f(x,λ) = g(x) +λb = 0. Here, λ is the load parameter, x is the system state variable (including the voltage and phase angle of each node in the system), b is the power growth direction, and g(x) is the system power balance equation. This application addresses a scenario where distributed generation is introduced and the distribution network and transmission network are coupled. The power growth direction includes both the load growth direction and the output growth direction. The load growth direction reflects the proportion of load growth at each node when the load increases uniformly, characterizing the imbalance of load growth in different locations from an operational perspective. The output growth direction reflects the proportion of output growth at each distributed generation when the power generation output increases uniformly. The initial power growth direction can be determined based on the total load of the transmission and distribution networks and the generation capacity of the distributed generation. The initial power growth direction will be used in the first round of calculations, but it may be changed depending on the results of subsequent calculations.

[0046] A transmission network can be connected to multiple distribution networks. The connection nodes between transmission and distribution networks are called boundary nodes. Boundary nodes serve as bridges for establishing connections and exchanging information between transmission and distribution networks, and they satisfy the following power relationship:

[0047]

[0048] S X S represents the apparent power of the external network injected into the X system. XX S represents the apparent power between the two buses in system X. XY Vx represents the apparent power injected from system X into system Y. Vx represents the voltage vector of system X. Subscripts 1, 2, and 3 represent the transmission network, boundary node, and distribution network, respectively.

[0049] To accommodate the deep coupling of transmission and distribution networks, this embodiment requires the separate construction of power flow equations for the distribution network and the transmission network. The transmission network power flow equation is constructed by simplifying the distribution network using the network equivalence method and using its equivalent model as the nodes of the transmission network. This equation considers not only the parameters of each component within the network but also the load parameters mentioned above. The distribution network power flow equation can be calculated independently, obtaining all information such as power, voltage, and phase angle of each node in the network. Based on this, the voltage of each boundary node can also be determined. The distribution network can then treat the boundary nodes as slack nodes and formulate its own power flow equations separately to obtain the distribution network power flow equation. After the voltage of the boundary nodes is determined, the corresponding distribution network can treat the boundary nodes as slack nodes and perform independent power flow calculations based on the given root node voltage. The two power flow equations exchange voltage, power, and phase angle information through the boundary nodes and are repeatedly calculated until final convergence, thus obtaining the power flow calculation results of the coupled transmission and distribution networks under a given operating condition.

[0050] S104. Based on the current first boundary vector, solve the power flow equation of the distribution network to obtain the first solution vector.

[0051] It can be understood that the first boundary vector includes the electrical quantities input from the transmission network to the distribution network through the boundary nodes, such as voltage and phase angle. These boundary nodes will act as slack nodes. Given the first boundary vector, it is equivalent to determining part of the boundary conditions of the distribution network. Based on these boundary conditions, the power flow equations of the distribution network can be solved. For example, if the first boundary vector contains the voltage magnitude and phase angle information at the connection point between the distribution network and the transmission network, then the voltages at these boundary points become known quantities in the node power balance equations (i.e., power flow equations) within the distribution network. The power of other nodes in the distribution network can be calculated based on the network structure and component parameters, through their association with these boundary points. Taking the node injection power equation as an example, for an ordinary node in the distribution network, its injected power is a function related to the voltage magnitude, phase angle, and connecting line parameters of adjacent nodes. When the voltage of the boundary point is known, through iterative calculations (such as the Newton-Raphson method and other commonly used power flow calculation methods), the voltage magnitude and phase angle of other nodes can be gradually adjusted so that the power injection equations of all nodes are satisfied, thus obtaining the first solution vector.

[0052] The initial first boundary vector can be obtained by solving the power flow equations of the transmission network when the load parameter is 0, thus obtaining the second solution vector. Then, the voltage and magnitude of the boundary nodes are extracted from the second solution vector and used as the initial first boundary vector input into the power flow equations of the distribution network. The subsequent first boundary vector is continuously updated during the alternating solution process of the distribution network and the transmission network.

[0053] The first solution vector is the result vector obtained after solving the power flow equations of the distribution network. It contains information such as voltage magnitude, phase angle, and power of each node in the distribution network, and represents the power flow state solution of the distribution network under the current boundary conditions (defined by the first boundary vector). This solution vector describes the power flow distribution and node voltage states within the distribution network.

[0054] S106. Determine whether there is a low-voltage trip of a distributed power source based on the first solution vector. If yes, update the power growth direction and return to the steps of constructing the power flow equations of the distribution network and the transmission network respectively based on the current power growth direction. If no, obtain the second boundary vector of the distribution network to the transmission network based on the first solution vector.

[0055] It's understandable that in determining whether a distributed generation (DG) has experienced a low-voltage trip, the first solution vector contains voltage information from each node in the distribution network. For nodes connected to DGs, if the voltage amplitude is lower than the DG's low-voltage protection threshold, it can be determined that the DG has tripped due to low voltage. When this happens, it indicates that the current load growth pattern will cause some DGs to experience voltage drops due to insufficient power supply, leading to tripping and changing the overall system's operating state. For example, if a DG was originally injecting power into the distribution network, a trip is equivalent to a sudden change in power injection at that node, affecting the power flow of both the distribution and transmission networks. This indicates an error in the previously selected power growth direction, requiring modification to reduce load growth allocation to nodes experiencing low-voltage issues. Specifically, the node experiencing low voltage is designated as the first node. The output growth direction corresponding to the first node can be retained, while the load growth direction corresponding to the first node can be lowered. In this way, when the load grows uniformly, the growth ratio of the first node is reduced, lowering the requirements on the DGs at the first node and reducing the occurrence of low-voltage trips.

[0056] After updating the power growth direction, all calculations need to be redone because the power flow equations for both the distribution network and the transmission network change. Therefore, it is necessary to return to step S102. If no voltage tripping occurs, the second boundary vector can be obtained from the first solution vector. The second boundary vector describes the electrical quantities input from the distribution network to the transmission network through the boundary nodes. It is obtained based on the power flow solution of the distribution network (first solution vector) and includes information on the impact of the distribution network on the transmission network under the current operating state, such as the power output from the distribution network to the transmission network and the voltage state at the connection points. It is an important input condition in the transmission network operation analysis.

[0057] Extracting the second boundary vector is based on the interaction between the distribution network and the transmission network. After obtaining the first solution vector of the distribution network, this solution vector contains information such as the voltage magnitude and phase angle of each node within the distribution network. For the connection points between the distribution network and the transmission network, the voltage magnitude, phase angle of these nodes, and the power exchange situation (including active power and reactive power) of the distribution network at these nodes constitute the boundary conditions for the transmission network, i.e., the second boundary vector.

[0058] S108. Solve the power flow equations of the transmission network based on the second boundary vector to obtain the second solution vector.

[0059] The second solution vector is understood to be the result vector after solving the power flow equations of the transmission network. It contains information such as the voltage magnitude and phase angle of each node in the transmission network, reflecting the power flow state solution of the transmission network considering the boundary influence of the distribution network (represented by the second boundary vector). When the second boundary vector is used as input, the principle for solving the power flow equations of the transmission network is similar to that of the distribution network. The power flow equations of the transmission network are also a set of nonlinear equations based on Kirchhoff's laws. The second boundary vector defines the conditions at the boundary between the transmission network and the distribution network. For example, if the second boundary vector contains information about the power injected into the transmission network from the distribution network and the voltage at the connection points, these boundary conditions become known quantities for the node power balance equations in the transmission network. The power of other nodes in the transmission network can be calculated based on the network structure, component parameters, and their association with the boundary points. Through iterative algorithms (such as the Newton-Raphson method), the voltage magnitude and phase angle of each node in the transmission network are gradually adjusted so that the power injection equations of all nodes are satisfied, thus obtaining the second solution vector. The network structure characteristics of the power transmission network (such as large generator sets, long-distance transmission lines, etc.) will be reflected in the equation solving process. For example, the impact of the capacitance and inductance of the transmission line on voltage and power will be reflected in the power flow equation, and these factors need to be considered in the iterative solution process to obtain an accurate second solution vector.

[0060] S110, based on the second solution vector, update the first boundary vector of the transmission network to the distribution network, and return to the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the first solution vector and the second solution vector converge.

[0061] In power system power flow calculation, convergence refers to the state where the solution vectors obtained through iterative calculations (such as the first and second solution vectors) gradually approach the true solution. Specifically, convergence can be considered achieved when the difference between the solution vectors obtained from two consecutive iterations is less than a preset error threshold. During the iterative calculation process, a new first solution vector is obtained by continuously updating the first boundary vector and resolving the distribution network power flow equations. Similarly, a new second solution vector is obtained by updating the second boundary vector based on the new first solution vector and resolving the transmission network power flow equations. This process is repeated until the first and second solution vectors converge. This is because the distribution and transmission networks are interconnected systems; the operating state of the distribution network affects the transmission network, and vice versa. Only when both solution vectors converge can the entire interconnected system be considered to have reached a stable power flow state. In each iteration, the updating of the first and second solution vectors makes the calculation results closer to the actual system operating state. When the convergence condition is met, a power flow solution for the distribution and transmission networks that meets the accuracy requirements is obtained. Steps S104 and S106 can be executed by the distribution network operator, while steps S108 and S110 can be executed by the transmission network operator. Both operators continuously transmit the first boundary vector and the second boundary vector to achieve iterative calculations. The amount of data transmitted in this process is very small, which reduces communication requirements while ensuring the efficient operation of the algorithm.

[0062] S112, according to the continuous power flow algorithm, predict and correct the converged second solution vector according to the set step size to obtain the second solution vector after load parameter iteration.

[0063] In continuous power flow algorithms, the set step size refers to the coefficient used to adjust the change in the second solution vector during each iteration or prediction-correction process. It determines the step size for transitioning from one known power flow solution to another in continuous power flow calculations. The core idea of ​​continuous power flow algorithms is to continuously solve the power flow equations from a known solution along a certain path to the solution of interest by introducing continuous parameters (such as load growth factors). In this step, the set step size is a key factor. For the converged second solution vector, prediction is performed based on the set step size. The prediction is based on the derivative information of the load parameters and transmission network state variables contained in the second solution vector. For example, if the load parameters are considered as independent variables and the solutions to the power flow equations (such as node voltage magnitude, phase angle, etc.) are considered as dependent variables, the trend of solution changes near the current solution point can be obtained by differentiating the power flow equations. Based on this trend and the set step size, the next possible solution point can be predicted. Then, correction operations are performed using the predicted point as the initial value. The correction operation typically employs iterative methods such as the Newton-Raphson method to solve the extended power flow equations (considering the changes in load parameters), thereby obtaining the accurate second solution vector after iterative load parameter changes. Furthermore, as is crucial in continuous power flow algorithms, the choice of parameterization strategy is paramount; in this application, the natural parameterization strategy can be selected.

[0064] S114, based on the second solution vector after iterating the load parameters, update the first boundary vector, and return to the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the load parameters reach the critical point, so as to calculate the static voltage stability margin.

[0065] It is understandable that the principle of updating the first boundary vector based on the second solution vector obtained from the load parameter iteration is similar to that before, because the second solution vector reflects the operating state of the transmission network, and the information it contains, such as voltage and power at the connection point with the distribution network, can be used to update the first boundary vector. By continuously solving the distribution network power flow equations based on the new first boundary vector to obtain the first solution vector, and then updating the second boundary vector based on the first solution vector and solving the transmission network power flow equations to obtain the second solution vector, this process is continuously repeated as the load parameters increase according to a set step size.

[0066] When load parameters reach a critical point, the voltage stability of the system changes significantly. This process allows observation of changes in voltage, power, and other states in the distribution and transmission networks. As load parameters gradually increase from their initial values ​​to the critical point, the static voltage stability margin can be calculated. For example, the margin can be calculated based on the load parameter values ​​at the critical point and the initial load parameter values. A larger margin indicates that the system is further from a voltage instability state under its current operating condition, and the better the system's voltage stability. This calculation process is crucial for assessing power system stability, planning power system development (such as determining whether to increase generation or transmission capacity), and formulating power system operation strategies. Alternatively, the PV and QV curves of each node can be plotted based on the converged first and second solution vectors obtained in each round of calculation, allowing for further calculation of other stability margin indices.

[0067] This method comprehensively considers the impact of distributed generation's voltage maintenance capability and low-voltage tripping characteristics on the system's static voltage stability, providing a more accurate voltage stability assessment. Through a distributed continuous power flow algorithm, it effectively simulates the response of distributed generation under different operating conditions, improving the reliability of the assessment results. Furthermore, it provides accurate voltage stability assessments regardless of whether distributed generation penetration is low or high. In addition, this invention only requires the exchange of limited voltage and power data at the transmission and distribution boundaries between the transmission and distribution system operators, reducing data exchange volume and communication requirements while ensuring efficient algorithm operation. The method also has a short computation time, meeting the needs of real-time assessment and possessing high practical value. Moreover, this method requires no additional hardware investment and can be implemented using existing power system equipment and software resources, reducing costs.

[0068] In one embodiment, the static voltage stability assessment method further includes:

[0069] (1) When the first solution vector and the second solution vector cannot converge, adjust the set step size.

[0070] (2) Based on the adjusted set step size and the second solution vector after the previous convergence, perform prediction and correction to obtain the second solution vector after the load parameter iteration, and jump to the step of updating the first boundary vector based on the second solution vector after the load parameter iteration, and return to the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the load parameter reaches the critical point, and continue to execute the step of calculating the static voltage stability margin.

[0071] It is understandable that when the first and second solution vectors fail to converge, it means that under the current set step size, a stable power flow solution cannot be obtained according to the normal iterative process, and the problem falls into the unstable region of numerical solution. The principle of adjusting the set step size is based on the consideration of factors affecting the convergence of power flow calculation. If the set step size is too large, the region near the true solution may be skipped during the prediction and correction process, causing the iteration to fail to converge to an accurate solution. Conversely, if the set step size is too small, although the accuracy of the calculation may be improved, the number of iterations will increase, resulting in low computational efficiency. Since the previous iteration was based on the second solution vector after the previous convergence and the set step size, after the set step size is changed, it is necessary to re-predict based on the second solution vector after the previous convergence and the new set step size, and jump to step S114 to update the first boundary vector, and continue the loop iteration until the critical point is reached. Specifically, the way to adjust the set step size is to reduce the set step size before it reaches the lower limit. The lower limit of the step size is the minimum allowed step size, which is a preset parameter, usually taken as 10^(–5). The specific method of reduction can be to reduce it proportionally, such as reducing it to half of the original size.

[0072] In one embodiment, determining whether a distributed generation has experienced a low-voltage trip based on a first solution vector includes: identifying a node in the distribution network connected to a distributed generation as a first node; extracting the voltage of the first node from the first solution vector; and determining that a distributed generation connected to the first node has experienced a low-voltage trip if the voltage of the first node is less than the low-voltage trip threshold of the distributed generation.

[0073] It is understandable that the connection points of distributed generation (DG) sources in a distribution network are areas requiring close monitoring. Due to power interaction between DG and the distribution network, the voltage state of these connection points is affected by various factors, such as the output power of the DG, the load distribution of the distribution network, and the network topology. By designating the nodes connected to DG as the primary nodes, voltage monitoring and analysis of these key nodes can be conducted in a targeted manner, thereby promptly identifying voltage issues that may affect the operation of DG and the stability of the distribution network.

[0074] The first solution vector contains information such as voltage magnitude and phase angle at each node in the distribution network. Once the first node is determined, extracting its voltage from this solution vector is a direct way to obtain crucial information. By extracting the voltage of the first node, the actual voltage levels of these critical nodes connected to distributed generation sources can be obtained, providing data support for subsequent assessments of whether low-voltage tripping will occur in the distributed generation system.

[0075] The low-voltage tripping threshold for distributed generation (DG) is an important parameter set based on its equipment characteristics and operational requirements. When the voltage of the first node extracted from the first solution vector is less than this threshold, it means that the voltage level of that node has fallen below the range within which the DG can operate normally. In this situation, to avoid damage to the DG equipment and to prevent potential adverse effects on the distribution network (such as power imbalance, increased voltage fluctuations, etc.), the DG will activate its protection mechanism, i.e., a low-voltage trip will occur.

[0076] This application provides a static voltage stability evaluation device, including a construction module, a first solution module, a first extraction module, a second solution module, a second extraction module, a simulation growth module, and a loop module.

[0077] The construction module is used to construct the power flow equations for the distribution network and the transmission network respectively based on the current power growth direction. The first solution module is used to solve the distribution network power flow equations based on the current first boundary vector, obtaining the first solution vector. The first extraction module is used to obtain the second boundary vector of the distribution network to the transmission network based on the first solution vector, and to determine whether there is a low-voltage tripping of distributed generation sources based on the first solution vector. If so, it updates the power growth direction and returns to the steps of constructing the distribution network power flow equations and the transmission network power flow equations respectively based on the current power growth direction. The second solution module is used to solve the transmission network power flow equations based on the second boundary vector, obtaining the second solution vector. The second extraction module is used to update the first boundary vector of the transmission network to the distribution network based on the second solution vector, and returns to the steps of solving the distribution network power flow equations based on the current first boundary vector, obtaining the first solution vector, until the first and second solution vectors converge. The simulation growth module is used to predict and correct the converged second solution vector according to a set step size using a continuous power flow algorithm, obtaining the second solution vector after load parameter iteration. The loop module is used to update the first boundary vector based on the second solution vector after iterating the load parameters, and return to the steps of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the load parameters reach the critical point to calculate the static voltage stability margin.

[0078] Specific limitations regarding the static voltage stability assessment device can be found in the above-described limitations of the static voltage stability assessment method, and will not be repeated here. The above modules can be embedded in hardware or independent of the processor in a computer device, or stored in software in the memory of a computer device, so that the processor can call and execute the operations corresponding to each module. It should be noted that the module division in this embodiment is illustrative and only represents a logical functional division; other division methods may be used in actual implementation.

[0079] This application provides a computer device including one or more processors and a memory storing computer-readable instructions. When executed by one or more processors, the computer-readable instructions perform the steps of the static voltage stability evaluation method in any of the above embodiments.

[0080] Indicatively, such as Figure 2 As shown, Figure 2 This is a schematic diagram of the internal structure of a computer device provided in an embodiment of this application. (Refer to...) Figure 2 The computer device 200 includes a processing component 202, which further includes one or more processors, and memory resources represented by memory 201 for storing instructions, such as application programs, that can be executed by the processing component 202. The application programs stored in memory 201 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 202 is configured to execute instructions to perform the steps of the static voltage stability assessment method in any of the above embodiments.

[0081] The computer device 200 may also include a power supply component 203 configured to perform power management of the computer device 200, a wired or wireless network interface 204 configured to connect the computer device 200 to a network, and an input / output (I / O) interface 205.

[0082] Those skilled in the art will understand that Figure 2 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0083] This application provides a storage medium storing computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to perform the steps of the static voltage stability evaluation method in any of the above embodiments.

[0084] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0085] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating static voltage stability, characterized in that, include: Based on the current power growth direction, the power flow equations for the distribution network and the transmission network are constructed respectively. Based on the current first boundary vector, solve the power flow equations of the distribution network to obtain the first solution vector; Based on the first solution vector, determine whether there is a low-voltage trip of a distributed power source. If so, update the power growth direction and return to the step of constructing the power flow equations of the distribution network and the transmission network respectively based on the current power growth direction. If not, obtain the second boundary vector of the distribution network to the transmission network based on the first solution vector. Based on the second boundary vector, solve the power flow equations of the transmission network to obtain the second solution vector; Based on the second solution vector, update the first boundary vector of the transmission network to the distribution network, and return to the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the first solution vector and the second solution vector converge; According to the continuous power flow algorithm, the second solution vector after convergence is predicted and corrected according to the set step size to obtain the second solution vector after load parameter iteration; The first boundary vector is updated based on the second solution vector after iterating the load parameters, and the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector is returned until the load parameters reach the critical point to calculate the static voltage stability margin.

2. The static voltage stability evaluation method according to claim 1, characterized in that, Also includes: When the first solution vector and the second solution vector fail to converge, the set step size is adjusted. Based on the adjusted set step size and the second solution vector after the previous convergence, prediction and correction are performed to obtain the second solution vector after load parameter iteration. Then, the process jumps to the step of updating the first boundary vector based on the second solution vector after load parameter iteration, and returns to the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector. This process continues until the load parameters reach the critical point, and the step of calculating the static voltage stability margin continues.

3. The static voltage stability evaluation method according to claim 2, characterized in that, The adjustment of the set step size includes: Before the set step size reaches the lower limit, the set step size is reduced.

4. The static voltage stability assessment method according to claim 3, characterized in that, The reduction of the set step size includes: The set step size is reduced to half of the original size.

5. The static voltage stability evaluation method according to claim 1, characterized in that, The step of determining whether a distributed power source has experienced a low-voltage trip based on the first solution vector includes: The node in the distribution network connected to the distributed power source is designated as the first node; Extract the voltage of the first node from the first solution vector; If the voltage at the first node is less than the low-voltage tripping threshold of the distributed power supply, it is determined that the distributed power supply connected to the first node has experienced a low-voltage trip.

6. The static voltage stability evaluation method according to claim 5, characterized in that, The power growth direction includes the load growth direction and the output growth direction, and updating the power growth direction includes: The output growth direction corresponding to the first node is retained, and the load growth direction corresponding to the first node is lowered.

7. The static voltage stability evaluation method according to claim 1, characterized in that, The step of predicting and correcting the converged second solution vector according to a set step size using a continuous power flow algorithm to obtain the second solution vector after load parameter iteration includes: According to the continuous power flow algorithm, a natural parameterization strategy is selected, and the converged second solution vector is predicted and corrected according to the set step size to obtain the second solution vector after load parameter iteration.

8. A static voltage stability evaluation device, characterized in that, include: The module is used to construct the power flow equations for the distribution network and the transmission network respectively, based on the current power growth direction; The first solution module is used to solve the power flow equations of the distribution network based on the current first boundary vector to obtain the first solution vector; The first extraction module is used to determine whether there is a low-voltage trip of a distributed power source based on the first solution vector. If so, the power growth direction is updated and the step of constructing the power flow equation of the distribution network and the power flow equation of the transmission network based on the current power growth direction is returned. If not, the second boundary vector of the distribution network to the transmission network is obtained based on the first solution vector. The second solution module is used to solve the power flow equations of the transmission network based on the second boundary vector to obtain the second solution vector; The second extraction module is used to update the first boundary vector of the transmission network to the distribution network according to the second solution vector, and return the step of solving the power flow equation of the distribution network according to the current first boundary vector to obtain the first solution vector, until the first solution vector and the second solution vector converge. The simulation growth module is used to predict and correct the converged second solution vector according to the continuous power flow algorithm and the set step size, so as to obtain the second solution vector after the load parameters are iterated. The loop module is used to update the first boundary vector based on the second solution vector after iterating the load parameters, and return to the step of solving the power flow equation of the distribution network based on the current first boundary vector to obtain the first solution vector, until the load parameters reach the critical point to calculate the static voltage stability margin.

9. A computer device, characterized in that, It includes one or more processors and a memory storing computer-readable instructions, which, when executed by the one or more processors, perform the steps of the static voltage stability assessment method as described in any one of claims 1-7.

10. A storage medium, characterized in that, The storage medium stores computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of the static voltage stability assessment method as described in any one of claims 1-7.

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