Static voltage stability evaluation method and device, computer equipment and storage medium

Abstract

The invention provides a static voltage stability evaluation method and device, computer equipment and a storage medium. According to the method, the influence of the voltage maintaining capability and the low-voltage tripping characteristic of the distributed power supply on the static voltage stability of the system is comprehensively considered, and more accurate voltage stability evaluation is provided. Through the distributed continuous power flow algorithm, the response of the distributed power supply under different working conditions can be effectively simulated, and the reliability of an evaluation result is improved. And moreover, accurate voltage stability evaluation can be provided no matter whether low distributed power supply penetration or distributed power supply penetration exists. In addition, only the voltage and power data at the limited transmission and distribution boundary need to be exchanged between the power transmission system operator and the power distribution system operator, the data exchange amount is reduced, the communication requirement is lowered, and meanwhile efficient operation of the algorithm is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of power system stability assessment, and in particular to a static voltage stability assessment method, device, computer equipment and storage medium. Background Art

[0002] In modern power systems, with the rapid development and widespread application of distributed generation technology, it has brought new challenges to the voltage stability of power systems. Traditional voltage stability assessment methods mainly focus on the assessment of transmission networks or distribution networks alone, without fully considering the interaction between transmission networks and distribution networks, especially when distributed generation units are connected, and without considering 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 of the voltage stability of the power system, increasing the risk of system operation. Summary of the invention

[0003] The purpose of this application is to solve at least one of the above-mentioned technical deficiencies, and in particular to provide a more accurate static voltage stability evaluation solution.

[0004] In a first aspect, the present application provides a static voltage stability evaluation method, comprising:

[0005] According to the current power growth direction, the power flow equation of the distribution network and the power flow equation of the transmission network are constructed respectively;

[0006] According to the current first boundary vector, solving the power flow equation of the distribution network to obtain a first solution vector;

[0007] According to the first solution vector, it is determined whether there is a low voltage trip of the distributed power source. If so, the power growth direction is updated, and the steps of constructing the power flow equation of the distribution network and the power flow equation of the transmission network are returned according to the current power growth direction. If not, the second boundary vector of the distribution network to the transmission network is obtained according to the first solution vector;

[0008] Solving the power flow equation of the transmission network according to the second boundary vector to obtain a second solution vector;

[0009] According to the second solution vector, updating the first boundary vector of the transmission network to the distribution network, and returning to the step of solving the distribution network power flow equation according to 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 converged second solution vector is predicted and corrected according to the set step size to obtain the second solution vector after load parameter iteration;

[0011] According to the second solution vector after load parameter iteration, the first boundary vector is updated, and the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector is returned until the load parameter reaches a critical point to calculate the static voltage stability margin.

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

[0013] When the first solution vector and the second solution vector cannot converge, adjust the set step size;

[0014] Prediction and correction are performed according to the adjusted set step size and the second solution vector after the previous convergence to obtain the second solution vector after the load parameter iteration, and then jump to the second solution vector after the load parameter iteration, update the first boundary vector, and return to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector, until the load parameter reaches the critical point, and the step of calculating the static voltage stability margin is continued.

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

[0016] Before the set step size reaches the lower limit of the step size, reduce the set step size.

[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 a low voltage trip according to the first solution vector includes:

[0020] Determine a node in the distribution network connected to a distributed power source as a first node;

[0021] extracting a voltage of a first node from a first solution vector;

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

[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] The output growth direction corresponding to the first node is retained, and the load growth direction corresponding to the first node is adjusted down.

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

[0026] According to the continuous power flow algorithm, the 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.

[0027] In a second aspect, the present application provides a static voltage stability assessment device, comprising:

[0028] A construction module is used to construct the power flow equation of the distribution network and the power flow equation of the transmission network respectively according to the current power growth direction;

[0029] A first solving module, used for solving the power flow equation of the distribution network according to the current first boundary vector to obtain a first solution vector;

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

[0031] A second solving module is used to solve the power flow equation of the transmission network according to the second boundary vector to obtain a second solution vector;

[0032] A 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 to the step of solving the distribution network power flow equation 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 set step size according to the continuous power flow algorithm to obtain the second solution vector after load parameter iteration;

[0034] The loop module is used to update the first boundary vector according to the second solution vector after load parameter iteration, and return to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector until the load parameter reaches a critical point to calculate the static voltage stability margin.

[0035] In a third aspect, the present application provides a computer device comprising one or more processors and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the static voltage stability evaluation method in any of the above-mentioned embodiments are executed.

[0036] In a fourth aspect, the present application provides a storage medium storing computer-readable instructions. When the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the static voltage stability evaluation method in any of the above-mentioned embodiments.

[0037] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0038] The method comprehensively considers the influence of the voltage maintenance capability and low-voltage tripping characteristics of distributed power sources on the static voltage stability of the system, and provides a more accurate voltage stability assessment. Through the distributed continuous power flow algorithm, the response of distributed power sources under different working conditions can be effectively simulated, and the reliability of the evaluation results is improved. Moreover, whether it is low distributed power source penetration or distributed power source penetration, accurate voltage stability assessment can be provided. In addition, the present invention only needs to exchange voltage and power data at limited transmission and distribution boundaries between the transmission system operator and the distribution system operator, which reduces the amount of data exchange, reduces communication requirements, and ensures the efficient operation of the algorithm. The calculation time of this method is also short, which can meet the needs of real-time evaluation and has high practical value. At the same time, the method does not require additional hardware investment, and can be implemented using existing power system equipment and software resources, reducing cost expenditure. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0040] Figure 1 This is a flow chart of a static voltage stability evaluation method according to an embodiment of the present application;

[0041] Figure 2 An internal structure diagram of a computer device provided for one embodiment of the present application. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] The present application provides a static voltage stability evaluation method, including steps S102 to S114.

[0044] S102: constructing a power flow equation for the distribution network and a power flow equation for the transmission network respectively according to the current power growth direction.

[0045] It can be understood that the continuous power flow algorithm introduces a parameter in the traditional power flow algorithm to simulate the growth of the load. The 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. Among them, 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 is aimed at the scenario where distributed power sources are introduced and the distribution network and the transmission network are coupled with each other. The power growth direction includes the load growth direction and the output growth direction. The load growth direction reflects the proportion of the load growth of each node when the load grows uniformly when the load grows, which can characterize the imbalance of load growth in various places from the perspective of actual operation. The output growth direction reflects the proportion of the output growth of each distributed power source when the power output grows uniformly. The initial power growth direction can be determined based on the total load of the transmission network and the distribution network and the power generation capacity of the distributed power source. This initial power growth direction will be used in the first round of calculations, but may change later depending on the calculation results.

[0046] The transmission network can be connected to multiple distribution networks. The connection nodes of the transmission and distribution networks are called boundary nodes. Boundary nodes can serve as bridges to establish connections and exchange information between transmission and distribution networks. The following power relationship is satisfied between them:

[0047]

[0048] S X represents the external network apparent power injected into the X system, S XX represents the apparent power between the two buses in the X system, S XY 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] In order to be applicable to the situation where the transmission network and the distribution network are deeply coupled, this embodiment needs to construct the distribution network power flow equation and the transmission network power flow equation respectively. The transmission network power flow equation is a power flow equation constructed by simplifying the distribution network according to the network equivalence method and taking its equivalent model as the node of the transmission network. In addition to considering the parameters of each component in the network, the power flow equation also introduces the load parameters mentioned above. The distribution network power flow equation can perform power flow calculation separately to obtain all information such as power, voltage, phase angle, etc. of each node in the network. Based on this, the voltage of each boundary node can also be determined. The distribution network can use the boundary node as a balancing node and list the power flow equation for itself separately to obtain the distribution network power flow equation. After the voltage of the boundary node is determined, the corresponding distribution network can use the boundary node as a balancing node and perform a separate power flow calculation according to the given root node voltage. The two power flow equations exchange voltage, power, phase angle and other information through the boundary node, and repeatedly calculate until they finally converge, so as to obtain the power flow calculation of the coupling of the transmission network and the distribution network under one working condition.

[0050] S104, solving the power flow equation of the distribution network according to the current first boundary vector to obtain a first solution vector.

[0051] It can be understood that the first boundary vector includes the electrical quantities input by the transmission network to the distribution network through the boundary node, such as voltage, phase angle, etc. The boundary node will be used as a balance node. When the first boundary vector is given, it is equivalent to determining part of the boundary conditions of the distribution network. According to these boundary conditions, the power flow equation of the distribution network can be solved. For example, if the first boundary vector contains the voltage amplitude and phase angle information of the connection point between the distribution network and the transmission network, then in the node power balance equation (i.e., power flow equation) inside the distribution network, the voltage of these boundary points becomes a known quantity. The power of other nodes in the distribution network can be calculated according to the network structure and component parameters through the association relationship with these boundary points. Taking the node injection power equation as an example, for an ordinary node in the distribution network, its injection power is a function related to the voltage amplitude, phase angle and connection line parameters of the adjacent nodes. When the voltage of the boundary point is known, through cyclic calculation (such as the commonly used power flow calculation method such as the Newton-Raphson method), the voltage amplitude and phase angle of other nodes can be gradually adjusted so that the power injection equation of all nodes is satisfied, thereby obtaining the first solution vector.

[0052] The first boundary vector used initially can be the second solution vector obtained by solving the power flow equation of the transmission network when the load parameter is 0, and then the voltage and amplitude of the boundary node are extracted from the second solution vector as the initial first boundary vector and input into the power flow equation of the distribution network. The first boundary vector used subsequently is continuously updated in the process of alternately solving the distribution network and the transmission network.

[0053] The first solution vector is the result vector obtained after solving the power flow equation of the distribution network. It contains information such as the voltage amplitude, phase angle, and power of each node in the distribution network, and is 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 state within the distribution network.

[0054] S106, determine whether a distributed power source has a low voltage trip based on the first solution vector. If so, update the power growth direction and return to the step of constructing the distribution network power flow equation and the transmission network power flow equation respectively according to 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.

[0055] It can be understood that in determining whether a distributed power source has a low voltage trip, the first solution vector contains the voltage information of each node in the distribution network. For the node to which the distributed power source is connected, if its voltage amplitude is lower than the low voltage protection threshold of the distributed power source, it can be determined that the distributed power source has a low voltage trip. When this happens, it means that with the current load growth method, some distributed power sources will have a voltage drop problem due to difficulty in supply, resulting in tripping, and then the operating state of the entire system will change. For example, if a distributed power source originally injects power into the distribution network, after the trip, it is equivalent to a sudden change in the power injection of the distribution network at the node, which will affect the power flow of the entire distribution network and the transmission network. This means that the power growth direction originally selected is wrong and needs to be modified to reduce the load growth distribution of these nodes with low voltage problems. Specifically, the node with low voltage is called the first node, the output growth direction corresponding to the first node can be retained, and 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, which will reduce the requirements for the distributed power source on the first node and reduce the occurrence of low voltage tripping.

[0056] After the power growth direction is updated, all calculations need to be repeated because the power flow equations of the distribution network and the transmission network have changed. Therefore, it is necessary to return to step S102. If there is no voltage trip, the second boundary vector can be obtained from the first solution vector. The second boundary vector describes the electrical quantity input from the distribution network to the transmission network through the boundary node. It is obtained based on the power flow solution (first solution vector) of the distribution network, and contains information about the impact of the distribution network on the transmission network under the current operating state, such as the power output of the distribution network to the transmission network, the voltage state of the connection point, etc. It is an important input condition in the operation analysis of the transmission network.

[0057] The extraction of the second boundary vector is based on the interaction between the distribution network and the transmission network. When the first solution vector of the distribution network is obtained, this solution vector contains information such as the voltage amplitude and phase angle of each node in the distribution network. For the connection points between the distribution network and the transmission network, the voltage amplitude and phase angle of these nodes and the power exchange of the distribution network at these nodes (including active power and reactive power) constitute the boundary conditions for the transmission network, namely the second boundary vector.

[0058] S108, solving the power flow equation of the power transmission network according to the second boundary vector to obtain a second solution vector.

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

[0060] S110, updating the first boundary vector of the transmission network to the distribution network according to the second solution vector, and returning to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector, until the first solution vector and the second solution vector converge.

[0061] It can be understood that in the power system flow calculation, convergence refers to the state in which the solution vector (such as the first solution vector and the second solution vector) obtained by iterative calculation gradually approaches the real solution. Specifically, when the difference between the solution vectors obtained by two adjacent iterative calculations is less than a preset error threshold, the calculation is considered to be converged. In the iterative calculation process, the first boundary vector is continuously updated and the distribution network flow equation is re-solved to obtain a new first solution vector, and the second boundary vector is updated according to the new first solution vector and the transmission network flow equation is solved to obtain a new second solution vector. This process is repeated until the first solution vector and the second solution vector converge. This is because the distribution network and the transmission network are interrelated systems, and the operating state of the distribution network will affect the transmission network, and vice versa. Only when both solution vectors converge can it be considered that the entire interconnected system has reached a stable flow state. In each iteration, the update of the first solution vector and the second solution vector will make the calculation result closer to the real system operation state. When the convergence condition is reached, the flow solution of the distribution network and the transmission network that meets the accuracy requirements is obtained. Steps S104 and S106 can be performed by the distribution network operator, and steps S108 and S110 can be performed by the transmission network operator, and the two continuously transmit the first boundary vector and the second boundary vector to implement iterative operations. The amount of data required to be transmitted in this process is very small, which reduces the communication requirements and ensures the efficient operation of the algorithm.

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

[0063] It can be understood that in the continuous power flow algorithm, the step size is the coefficient for adjusting the change of the second solution vector in each iteration or prediction-correction process. It determines the step size of the transition from one known power flow solution to another power flow solution in the continuous power flow calculation. The core idea of ​​the continuous power flow algorithm is to continuously solve the power flow equation from a known solution along a certain path to the solution of interest by introducing continuous parameters (such as load growth factor). In this step, setting the step size is the key factor. For the converged second solution vector, a prediction will be made according to the set step size. The prediction will be based on the derivative information of the load parameters and the state variables of the transmission network contained in the second solution vector. For example, if the load parameters are regarded as independent variables and the solutions of the power flow equation (such as node voltage amplitude, phase angle, etc.) are regarded as dependent variables, the trend of the solution near the current solution point can be obtained by differentiating the power flow equation. According to this trend and the set step size, the next possible solution point can be predicted. Then, the correction operation is performed with the predicted point as the initial value. The correction operation usually uses an iterative method such as the Newton-Raphson method to solve the expanded power flow equations (the power flow equations after the load parameter changes are considered), thereby obtaining an accurate second solution vector after the load parameter iteration. In addition, according to another key part of the continuous power flow algorithm, the parameterization strategy can be selected as the natural parameterization strategy in this application.

[0064] S114, updating the first boundary vector according to the second solution vector after load parameter iteration, and returning to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector, until the load parameter reaches a critical point to calculate the static voltage stability margin.

[0065] It can be understood that the principle of updating the first boundary vector according to the second solution vector after load parameter iteration is similar to the previous one, because the second solution vector reflects the operating state of the transmission network, and the information such as the voltage and power of the connection point with the distribution network contained therein can be used to update the first boundary vector. The first solution vector is obtained by continuously solving the distribution network power flow equation according to the new first boundary vector, and then the second boundary vector is updated according to the first solution vector and the transmission network power flow equation is solved to obtain the second solution vector. This process is continuously cycled as the load parameter increases according to the set step size.

[0066] When the load parameter reaches the critical point, the voltage stability of the system changes significantly. Through this process, the changes in the voltage, power and other states of the distribution network and the transmission network can be observed. In the process of the load parameter gradually increasing from the initial value to the critical point, the static voltage stability margin can be calculated. For example, the margin can be calculated based on the load parameter value at the critical point and the initial load parameter value. The larger the margin, the farther the system is from the voltage instability state under the current operating state, and the better the voltage stability of the system. This calculation process is of great significance for evaluating the stability of the power system, planning the development of the power system (such as determining whether it is necessary to increase the power generation capacity or transmission capacity), and formulating the operation strategy of the power system. Of course, the PV curve and QV curve of each node can also be drawn based on the converged first solution vector and second solution vector obtained in each round of calculation, so as to further calculate other stability margin indicators.

[0067] The method comprehensively considers the influence of the voltage maintenance capability and low-voltage tripping characteristics of distributed power sources on the static voltage stability of the system, and provides a more accurate voltage stability assessment. Through the distributed continuous power flow algorithm, the response of distributed power sources under different working conditions can be effectively simulated, and the reliability of the evaluation results is improved. Moreover, whether it is low distributed power source penetration or distributed power source penetration, accurate voltage stability assessment can be provided. In addition, the present invention only needs to exchange voltage and power data at limited transmission and distribution boundaries between the transmission system operator and the distribution system operator, which reduces the amount of data exchange, reduces communication requirements, and ensures the efficient operation of the algorithm. The calculation time of this method is also short, which can meet the needs of real-time evaluation and has high practical value. At the same time, the method does not require additional hardware investment, and can be implemented using existing power system equipment and software resources, reducing cost expenditure.

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

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

[0070] (2) Predict and correct according to the adjusted set step size and the second solution vector after the previous convergence to obtain the second solution vector after the load parameter iteration, and jump to the second solution vector after the load parameter iteration, update the first boundary vector, and return to the step of solving the distribution network power flow equation according to 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 can be understood that when the first solution vector and the second solution vector cannot 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 solution falls into the instability region of the numerical solution. The principle of adjusting the set step size is based on the consideration of the factors affecting the convergence of the power flow calculation. If the set step size is too large, the vicinity of the true solution may be skipped during the prediction and correction process, resulting in the inability of the iteration to converge to an accurate solution. On the contrary, if the set step size is too small, although the accuracy of the calculation may be improved, the number of iterations of the calculation will be increased, resulting in low calculation efficiency. Since the previous iteration is predicted based on the second solution vector and the set step size after the previous convergence, after the set step size is changed, it is necessary to re-predict based on the second solution vector and the new set step size after the previous convergence, and jump to step S114 to update the first boundary vector, and continue to iterate until the critical point is reached. Specifically, the way to adjust the set step size is to reduce the set step size before the set step size reaches the lower limit of the step size. The lower limit of the step size is the minimum allowed step size, which is a preset parameter and is usually 10^(–5). The specific method of reduction can be to reduce it proportionally, such as reducing it to half of the original value.

[0072] In one embodiment, judging whether a distributed power source has a low voltage trip according to a first solution vector includes: determining a node in a distribution network connected to a distributed power source as a first node. Extracting a voltage of the first node from the first solution vector. When the voltage of the first node is less than a low voltage trip threshold of the distributed power source, judging that the distributed power source connected to the first node has a low voltage trip.

[0073] It is understandable that in the distribution network, the access point of the distributed power source is an area that needs to be focused on. Due to the power interaction between the distributed power source and the distribution network, the voltage state of its access node will be affected by many factors, such as the output power of the distributed power source, the load distribution of the distribution network, and the network topology. By determining the node connected to the distributed power source as the first node, the voltage of these key nodes can be monitored and analyzed in a targeted manner, so as to promptly discover voltage problems that may affect the operation of the distributed power source and the stability of the distribution network.

[0074] The first solution vector contains information such as the voltage amplitude and phase angle of each node in the distribution network. After the first node has been determined, extracting the voltage of the first node from this solution vector is a direct way to obtain key information. By extracting the voltage of the first node, the actual voltage level of these key nodes connected to the distributed power source can be obtained, providing data support for the subsequent judgment of whether the distributed power source will have a low voltage trip.

[0075] The low voltage trip threshold of the distributed power source is an important parameter set according to its equipment characteristics and operating 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 the node is already lower than the range within which the distributed power source can operate normally. In this case, in order to avoid damage to the distributed power source equipment and prevent possible adverse effects on the distribution network (such as power imbalance, increased voltage fluctuations, etc.), the distributed power source will start the protection mechanism, that is, a low voltage trip occurs.

[0076] The present application provides a static voltage stability assessment device, comprising 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 circulation module.

[0077] The construction module is used to construct the distribution network power flow equation and the transmission network power flow equation respectively according to the current power growth direction. The first solution module is used to solve the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector. The first extraction module is used to obtain the second boundary vector of the distribution network to the transmission network according to the first solution vector, and determine whether there is a low voltage trip of the distributed power source according to the first solution vector. If so, the power growth direction is updated, and the steps of constructing the distribution network power flow equation and the transmission network power flow equation respectively according to the current power growth direction are returned. The second solution module is used to solve the transmission network power flow equation according to 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 to the step of solving the distribution network power flow equation 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 set step size according to the continuous power flow algorithm to obtain the second solution vector after the load parameter iteration. The loop module is used to update the first boundary vector according to the second solution vector after load parameter iteration, and return to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector until the load parameter reaches a critical point to calculate the static voltage stability margin.

[0078] For the specific limitations of the static voltage stability assessment device, please refer to the limitations of the static voltage stability assessment method above. For the specific limitations of the static voltage stability assessment device, please refer to the limitations of the static voltage stability assessment method above, which will not be repeated here. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules. It should be noted that the division of modules in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation.

[0079] The present application provides a computer device, including one or more processors and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the static voltage stability evaluation method in any of the above embodiments are executed.

[0080] Indicatively, Figure 2 As shown, Figure 2 A schematic diagram of the internal structure of a computer device provided in an embodiment of the present application. Figure 2 The computer device 200 includes a processing component 202, which further includes one or more processors, and a memory resource represented by a memory 201 for storing instructions executable by the processing component 202, such as an application. The application stored in the memory 201 may include one or more modules, each corresponding to a set of instructions. In addition, the processing component 202 is configured to execute instructions to perform the steps of the static voltage stability evaluation method in any of the above embodiments.

[0081] The computer device 200 may further 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 in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0083] The present application provides a storage medium, in which computer-readable instructions are stored. When the computer-readable instructions are executed by one or more processors, the one or more processors execute 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, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can refer to each other.

[0085] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be 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 the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A static voltage stability evaluation method, characterized in that: include: According to the current power growth direction, the power flow equation of the distribution network and the power flow equation of the transmission network are constructed respectively; Solving the power flow equation of the distribution network according to the current first boundary vector to obtain a first solution vector; According to the first solution vector, it is determined whether a distributed power source has a low voltage trip. 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 according to the current power growth direction is returned. If not, a second boundary vector of the distribution network to the transmission network is obtained according to the first solution vector; Solving the power transmission network power flow equation according to the second boundary vector to obtain a second solution vector; According to the second solution vector, updating the first boundary vector of the transmission network to the distribution network, and returning to the step of solving the distribution network power flow equation according to 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, predicting and correcting the second solution vector after convergence according to the set step size, to obtain the second solution vector after load parameter iteration; According to the second solution vector after load parameter iteration, the first boundary vector is updated, and the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector is returned until the load parameter reaches a 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 cannot converge, adjusting the set step size; Prediction and correction are performed according to the adjusted set step size and the second solution vector after the previous convergence to obtain the second solution vector after load parameter iteration, and the step of jumping to the second solution vector after load parameter iteration, updating the first boundary vector, and returning to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector, until the load parameter reaches a critical point, and the step of calculating the static voltage stability margin is continued.

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

4. The static voltage stability evaluation method according to claim 3, characterized in that: The reducing the set step size comprises: The set step size is reduced to half of the original one.

5. The static voltage stability evaluation method according to claim 1, characterized in that: The step of judging whether a distributed power source has a low voltage trip according to the first solution vector includes: Determine a node in the distribution network connected to the distributed power source as a first node; extracting the voltage of the first node from the first solution vector; When the voltage of 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 a low voltage tripping.

6. The static voltage stability evaluation method according to claim 5, characterized in that: The power growth direction includes a load growth direction and an 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 method predicts and corrects the converged second solution vector according to the continuous power flow algorithm and the set step size to obtain the second solution vector after load parameter iteration, including: 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.

8. A static voltage stability assessment device, characterized in that: include: A construction module is used to construct the power flow equation of the distribution network and the power flow equation of the transmission network respectively according to the current power growth direction; A first solving module, used for solving the power flow equation of the distribution network according to the current first boundary vector to obtain a first solution vector; A first extraction module is used to determine whether a distributed power source has a low voltage trip according to the first solution vector, and if so, update the power growth direction, and return to the step of constructing the distribution network power flow equation and the transmission network power flow equation according to the current power growth direction, and if not, obtain a second boundary vector of the distribution network to the transmission network according to the first solution vector; A second solving module, used for solving the power flow equation of the transmission network according to the second boundary vector to obtain a second solution vector; a second extraction module, configured to update the first boundary vector of the transmission network to the distribution network according to the second solution vector, and return to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector, until the first solution vector and the second solution vector converge; A simulation growth module, used for predicting and correcting the second solution vector after convergence according to a set step size according to a continuous power flow algorithm, to obtain the second solution vector after load parameter iteration; A loop module is used to update the first boundary vector according to the second solution vector after load parameter iteration, and return to the step of solving the distribution network power flow equation according to the current first boundary vector to obtain the first solution vector until the load parameter reaches a critical point to calculate the static voltage stability margin.

9. A computer device, characterized in that: The method comprises one or more processors and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the one or more processors, the steps of the static voltage stability evaluation method according to any one of claims 1 to 7 are executed.

10. A storage medium, characterized in that: The storage medium stores computer-readable instructions, and when the computer-readable instructions are executed by one or more processors, the one or more processors execute the steps of the static voltage stability evaluation method according to any one of claims 1 to 7.

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