Static voltage stability evaluation method and system for new energy station

Abstract

The invention discloses a static voltage stability evaluation method and system for a new energy station, and the method comprises the steps: obtaining the active power and reactive power injected into an AC power grid, so as to obtain the voltage amplitude of the power grid; jacobian matrixes of active power and reactive power are calculated, and a power grid voltage minimum value for maintaining static voltage stability is obtained in combination with a voltage stability critical condition; and based on a system power balance relation, combining a power grid voltage amplitude and utilizing a power flow solution criterion to analyze voltage stability, establishing a first problem model, performing convex relaxation processing to obtain a second problem model, and solving a globally optimal solution. According to the method, the Jacobian matrix is combined with the voltage stability critical condition to determine the minimum voltage value for maintaining the static voltage stability, so that risk points causing voltage instability can be identified in advance; and a mathematical programming problem model is constructed, convex relaxation processing is performed, so that evaluation is not influenced by an initial value any more and can be converged to be globally optimal, and the solving efficiency and practicability are improved.

Description

Technical Field

[0001] The present invention relates to the field of power system analysis and control, and in particular to a static voltage stability assessment method and system for a new energy station. Background Art

[0002] As an important carrier of new energy utilization, new energy stations convert new energy into electricity or other forms of energy that can be used by society in a large-scale and centralized manner, which is of great significance for promoting the transformation of energy structure and achieving sustainable development. New energy stations not only provide society with a steady supply of clean electricity, but also effectively reduce the consumption of fossil energy and greenhouse gas emissions, which is of great significance for alleviating environmental pressure and promoting sustainable development. With the advancement of technology and the reduction of costs, the construction scale of new energy stations is expanding, and the power generation efficiency is constantly improving, which is gradually becoming an important force in the transformation of energy structure. At the same time, new energy stations are also intelligent and automated. Through advanced monitoring systems and operation and maintenance management platforms, remote monitoring and real-time dispatching of power generation equipment are realized, ensuring the safe and stable operation of the power system. In addition, new energy stations are also actively used in a complementary manner with other forms of energy, such as combining with energy storage technology and hydrogen energy technology, to improve the comprehensive utilization efficiency of energy.

[0003] Among them, static voltage stability refers to the ability of the power system to withstand load increase or system failure without voltage collapse under specific operating conditions. With the widespread access of new energy sites, the evaluation of the static voltage stability of the power system has become particularly important. Due to the randomness and volatility of the output power of new energy sites, traditional evaluation methods often fail to fully consider these uncertainties. The evaluation assumptions are too idealized, lack consideration of dynamic characteristics, and easily ignore nonlinear effects, which affects the accuracy and reliability of the evaluation results. Summary of the invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a static voltage stability assessment method and system for a new energy station to solve the problems that the current traditional assessment method cannot fully consider the randomness and volatility of the output power, the assessment assumptions are too idealized, lack consideration of dynamic characteristics, easily ignore nonlinear effects, and the reliability of the assessment results is low.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for evaluating static voltage stability of a new energy station, comprising:

[0008] Obtaining the active power and reactive power injected into the AC grid to obtain the grid voltage amplitude;

[0009] Calculate the Jacobian matrix of active power and reactive power, and combine it with the critical conditions of voltage stability to obtain the minimum value of the grid voltage to maintain static voltage stability;

[0010] Based on the system power balance relationship, combined with the grid voltage amplitude, and using the power flow solution criterion to analyze the voltage stability, the first problem model is established;

[0011] The first problem model is subjected to convex relaxation processing to obtain a second problem model, and a global optimal solution is obtained to achieve voltage stability evaluation.

[0012] As a preferred solution of the static voltage stability evaluation method for a new energy station described in the present invention, the active power and reactive power when the phase-locked loop realizes synchronous operation are obtained, which is expressed as:

[0013]

[0014] Among them, P and Q represent active power and reactive power respectively, E and U represent the grid voltage amplitude and grid connection point voltage value respectively, and X g represents the equivalent inductive reactance of the power grid, and θ represents the voltage phase angle;

[0015] The grid voltage amplitude is derived based on the acquired active power and reactive power, and is expressed as:

[0016]

[0017] As a preferred solution of the static voltage stability assessment method for a new energy station described in the present invention, the Jacobian matrix of active power and reactive power is calculated and expressed as:

[0018]

[0019] As a preferred solution of the static voltage stability assessment method for a new energy station described in the present invention, the minimum grid voltage for maintaining static voltage stability is obtained in combination with the voltage stability critical condition, including:

[0020] Using the critical condition of voltage stability, the analytical formula of critical voltage is obtained, which is expressed as:

[0021]

[0022] Based on the obtained critical voltage analytical expression, the minimum grid voltage to maintain static voltage stability is obtained, which is expressed as:

[0023]

[0024] As a preferred solution of the static voltage stability assessment method for a new energy station described in the present invention, the system power balance relationship is calculated by polar coordinates and is expressed as:

[0025]

[0026] Among them, P i and Q i Respectively represent the active power and reactive power of node i, V i represents the voltage at node i, G ik and B ik denote the conductance and susceptance between node i and node k, respectively, θ i and θ k represent the phase angles of node i and node k respectively.

[0027] As a preferred solution of the static voltage stability assessment method for a new energy station described in the present invention, the voltage amplitude of the power grid is combined, and the voltage stability is analyzed using the power flow solvable criterion, and a first problem model is established, which is expressed as:

[0028]

[0029] As a preferred solution of the static voltage stability assessment method for a new energy station described in the present invention, the first problem model is subjected to convex relaxation to obtain a second problem model, which is expressed as:

[0030]

[0031] Among them, P i and Q i Represent the active power and reactive power of node i respectively, P ij and Q ij are the active power and reactive power on line (i, j), Q ij represents the station line set, P ki and Q ki are the active power and reactive power on line (k, j), r ki and x ki Respectively represent the resistance and inductance on the line (i, j), l ki is the square of the current amplitude on line (k, j), v i and v j Represents the square of the voltage amplitude at node i and j, I ijmax Represents the maximum current at line (i, j).

[0032] In a second aspect, the present invention provides a static voltage stability assessment system for a new energy station, comprising:

[0033] An acquisition module is used to acquire the active power and reactive power injected into the AC power grid to obtain the voltage amplitude of the power grid;

[0034] A calculation module is used to calculate the Jacobian matrix of active power and reactive power, and to obtain the minimum value of the grid voltage to maintain static voltage stability in combination with the critical conditions of voltage stability;

[0035] A model building module is used to analyze voltage stability based on the system power balance relationship, combined with the grid voltage amplitude, and using the power flow solution criterion to establish the first problem model;

[0036] The model solving module is used to perform convex relaxation processing on the first problem model to obtain a second problem model and solve the global optimal solution to achieve voltage stability evaluation.

[0037] In a third aspect, the present invention provides an electronic device, comprising:

[0038] Memory and processor;

[0039] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the static voltage stability assessment method for a new energy station are implemented.

[0040] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the static voltage stability assessment method for a new energy station.

[0041] Compared with the prior art, the present invention has the following beneficial effects: the present invention calculates the active power and reactive power injected into the AC power grid, derives the voltage amplitude of the power grid, and uses the Jacobian matrix in combination with the critical condition of voltage stability to determine the minimum voltage value for maintaining static voltage stability, which helps to identify risk points that may cause voltage instability in advance; constructs a mathematical programming problem model, and obtains a typical convex optimization problem by performing convex relaxation on the original data planning problem, which is no longer affected by the initial value and can converge to the global optimum, while achieving solution efficiency and increasing the practicality of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0043] Figure 1This is a schematic diagram of the overall process of a method for evaluating static voltage stability in a new energy station according to an embodiment of the present invention;

[0044] Figure 2 A schematic diagram of a single-machine grid-connected system of a converter in a method for evaluating static voltage stability in a new energy station according to an embodiment of the present invention;

[0045] Figure 3 A schematic diagram of an IEEE33 node system in a static voltage stability assessment method for a new energy station according to an embodiment of the present invention;

[0046] Figure 4 A schematic diagram of a 33-node topology of a new energy station in a method for evaluating static voltage stability of a new energy station according to an embodiment of the present invention;

[0047] Figure 5 A schematic diagram of the relationship between the minimum voltage and the active power in the static voltage stability assessment method for a new energy station according to an embodiment of the present invention;

[0048] Figure 6 A schematic diagram of the relationship between minimum voltage and reactive power in a static voltage stability assessment method for a new energy station according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0050] Example 1

[0051] Reference Figure 1 , which is an embodiment of the present invention, provides a method for evaluating static voltage stability of a new energy station, comprising:

[0052] S100: Acquire active power and reactive power injected into the AC power grid to obtain a grid voltage amplitude;

[0053] S200: Calculate the Jacobian matrix of active power and reactive power, and obtain the minimum value of the grid voltage for maintaining static voltage stability in combination with the critical condition of voltage stability;

[0054] S300: Based on the system power balance relationship, combined with the grid voltage amplitude, and using the power flow solution criterion to analyze the voltage stability, a first problem model is established;

[0055] S400: Perform convex relaxation processing on the first problem model to obtain a second problem model, and solve a global optimal solution to achieve voltage stability evaluation.

[0056] It should be noted that traditional evaluation methods are usually based on deterministic models and relatively stable load and power generation patterns for analysis, and fail to fully consider the uncertainty of load demand, power generation output (especially from intermittent energy sources such as wind and solar energy) and weather changes in actual power systems. At the same time, they generally focus on steady-state analysis, that is, evaluating voltage stability under the assumption that all components are in a stable state; however, when new energy sites are connected to the grid, they will produce rapidly changing dynamic behaviors, such as frequency fluctuations, phase angle differences, etc., which have an impact on voltage stability, but are usually factors that will be ignored in the evaluation process. In addition, some phenomena in the power system are nonlinear, especially when approaching the point of voltage instability; traditional evaluation methods usually use linearized models to simplify calculations, which may lead to a misunderstanding of system behavior in some cases.

[0057] Therefore, through steps S100-S400 of this solution, the relationship between active power and reactive power and the grid voltage amplitude is obtained to reflect the actual operating status of the power system; the Jacobian matrix is ​​combined with the voltage stability critical condition to determine the minimum voltage value for maintaining static voltage stability, and the risk points that may cause voltage instability are identified in advance; the first problem model is converted into the second problem model by convex relaxation, ensuring that the global optimal solution can be quickly found even in a complex and changeable power system environment, with good scalability and flexibility, and can adapt to future structural changes in the power system.

[0058] Example 2

[0059] Reference Figure 1-Figure 2 , which is an embodiment of the present invention, provides a static voltage stability assessment method for a new energy station based on the above embodiment.

[0060] In the embodiment of the present application, in step S100, according to the structure of the single-machine grid-connected system of the converter, Figure 2 As shown, the active power and reactive power are obtained when the phase-locked loop realizes synchronous operation, which is expressed as:

[0061]

[0062] Among them, P and Q represent active power and reactive power respectively, E and U represent the grid voltage amplitude and grid connection point voltage value respectively, and X g represents the equivalent inductive reactance of the power grid, and θ represents the voltage phase angle;

[0063] The grid voltage amplitude is derived based on the acquired active power and reactive power and is expressed as:

[0064]

[0065] In an optional implementation, the grid voltage amplitude may be obtained in step S100 through state estimation, using various measurement data in the power system in combination with a system model to perform state estimation calculations, thereby obtaining the grid voltage amplitude.

[0066] In another optional implementation, the grid voltage amplitude may be obtained in step S100 by building a power system model using a real-time digital simulator (RTDS) to simulate the operating status under different working conditions to obtain the voltage amplitude.

[0067] It should be noted that in the present application, deriving the grid voltage amplitude by active power and reactive power can provide a more accurate voltage stability assessment, especially when the uncertainty caused by the access of new energy power generation increases.

[0068] In the implementation manner of the present application, the Jacobian matrix of active power and reactive power is calculated in step S200, which is expressed as:

[0069]

[0070] In the implementation manner of the present application, in step S200, the minimum value of the grid voltage for maintaining static voltage stability is obtained in combination with the voltage stability critical condition, including:

[0071] Using the critical condition of voltage stability, the analytical formula of critical voltage is obtained, which is expressed as:

[0072]

[0073] Based on the obtained critical voltage analytical expression, the minimum grid voltage to maintain static voltage stability is obtained, which is expressed as:

[0074]

[0075] It should be noted that using the Jacobian matrix in combination with the voltage stability critical condition to determine the minimum voltage value for maintaining static voltage stability helps to identify risk points that may cause voltage instability in advance, so that preventive measures can be taken before problems occur.

[0076] In the implementation manner of the present application, the system power balance relationship is calculated by polar coordinates in step S300, which is expressed as:

[0077]

[0078] Among them, P i and Q i Respectively represent the active power and reactive power of node i, Vi represents the voltage at node i, G ik and B ik denote the conductance and susceptance between node i and node k, respectively, θ i and θ k represent the phase angles of node i and node k respectively.

[0079] In an optional implementation, in step S300, the system power balance relationship may also be represented by a rectangular coordinate system;

[0080] In another optional implementation, in step S300, state variables may also be used to describe the dynamic behavior of the power system, such as generator rotor angle, frequency, etc. The rate of change of these state variables is associated with the input of the system (such as power generation, load demand), and then a nonlinear differential equation group is established to describe the power balance relationship.

[0081] In the implementation manner of the present application, in step S300, the voltage amplitude of the power grid is combined, and the voltage stability is analyzed using the power flow solvability criterion to establish a first problem model, which is expressed as:

[0082]

[0083] It should be noted that based on the system power balance relationship, combined with the grid voltage amplitude, and using the power flow solution criterion to analyze the voltage stability, the established model not only considers the static voltage stability, but also comprehensively considers the dynamic characteristics of the power system, which can improve the comprehensiveness and applicability of the model.

[0084] In the implementation manner of the present application, in step S400, convex relaxation is performed on the first problem model to obtain a second problem model, which is expressed as:

[0085]

[0086]

[0087] Among them, P i and Q i Represent the active power and reactive power of node i respectively, P ij and Q ij are the active power and reactive power on line (i, j), Q ij represents the station line set, P ki and Q ki are the active power and reactive power on line (k, j), r ki and x ki Respectively represent the resistance and inductance on the line (i, j), l ki is the square of the current amplitude on line (k, j), vi and v j Represents the square of the voltage amplitude at node i and j, I ijmax Represents the maximum current at line (i, j).

[0088] It should be noted that by performing convex relaxation on the first problem model, it can ensure that the global optimal solution can be found quickly even in a complex and changeable power system environment. The convex optimization technology can greatly reduce the solution time and improve the solution efficiency, while also ensuring the quality of the solution and avoiding the problem of local optimality. It is no longer affected by the initial value and can converge to the global optimal solution, which increases the robustness and reliability of the solution. It can perform voltage stability assessment under real-time or near real-time conditions and respond quickly to modern power systems.

[0089] Example 3

[0090] Reference Figure 3-Figure 6 Based on the previous embodiment, this embodiment provides an application case of a static voltage stability assessment method for an energy station to illustrate the feasibility and beneficial effects of our solution.

[0091] The standard example uses Figure 3 The IEEE 33-bus system parameters shown are as follows: the system reference voltage is 12.66 kV and the reference power is 10 MW.

[0092] The actual example uses Figure 4 The 33-node topology diagram containing new energy stations is shown, in which nodes 9, 16 and 26 are wind farms, nodes 12, 21 and 30 are photovoltaic power stations, the reference voltage is 35kV, and the reference power is 100MW.

[0093] By calculating the optimization problem through the above steps S100-S400, the relationship between the minimum voltage and active power is obtained as follows: Figure 5 As shown, the relationship between the minimum voltage and reactive power is as follows Figure 6 shown.

[0094] Depend on Figure 5 It can be seen that with the increase of power factor, the minimum voltage amplitude used to solve the optimization problem also increases, which means that when the active power injected into the grid by the new energy station is increased, the voltage stability of the system will decrease.

[0095] Depend on Figure 6 It can be seen that when the reactive power of the renewable energy station grid connection point is increased within a certain range, the stability of the system can be improved.

[0096] Example 4

[0097] The above is a schematic scheme of a static voltage stability assessment method for a new energy station in this embodiment. It should be noted that the technical scheme of the static voltage stability assessment system for the new energy station is the same as the technical scheme of the static voltage stability assessment method for the new energy station mentioned above. For details not described in detail in the technical scheme of the static voltage stability assessment system for the new energy station in this embodiment, please refer to the description of the technical scheme of the static voltage stability assessment method for the new energy station mentioned above.

[0098] This embodiment also provides a system for evaluating the static voltage stability of a new energy station, including:

[0099] An acquisition module is used to acquire the active power and reactive power injected into the AC power grid to obtain the voltage amplitude of the power grid;

[0100] A calculation module is used to calculate the Jacobian matrix of active power and reactive power, and to obtain the minimum value of the grid voltage to maintain static voltage stability in combination with the critical conditions of voltage stability;

[0101] A model building module is used to analyze voltage stability based on the system power balance relationship, combined with the grid voltage amplitude, and using the power flow solution criterion to establish the first problem model;

[0102] The model solving module is used to perform convex relaxation processing on the first problem model to obtain the second problem model and solve the global optimal solution to achieve voltage stability evaluation.

[0103] This embodiment also provides an electronic device suitable for the situation of static voltage stability assessment of new energy stations, including: a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the static voltage stability assessment method of new energy stations proposed in the above embodiment.

[0104] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for evaluating static voltage stability of a new energy station proposed in the above embodiment is implemented.

[0105] The storage medium proposed in this embodiment and the method for realizing static voltage stability assessment of new energy stations proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0106] Through the above description of the implementation methods, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course can also be implemented by hardware. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (Random Access Memory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0107] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A static voltage stability assessment method for a new energy station, characterized in that: include: Obtaining the active power and reactive power injected into the AC grid to obtain the grid voltage amplitude; Calculate the Jacobian matrix of active power and reactive power, and combine it with the critical conditions of voltage stability to obtain the minimum value of the grid voltage to maintain static voltage stability; Based on the system power balance relationship, combined with the grid voltage amplitude, and using the power flow solution criterion to analyze the voltage stability, the first problem model is established; The first problem model is subjected to convex relaxation processing to obtain a second problem model, and a global optimal solution is obtained to achieve voltage stability evaluation.

2. The static voltage stability assessment method for a new energy station according to claim 1, characterized in that: Get the active power and reactive power when the phase-locked loop achieves synchronous operation, expressed as: Among them, P and Q represent active power and reactive power respectively, E and U represent the grid voltage amplitude and grid connection point voltage value respectively, and X g represents the equivalent inductive reactance of the power grid, and θ represents the voltage phase angle; The grid voltage amplitude is derived based on the acquired active power and reactive power, and is expressed as:

3. The static voltage stability assessment method for a new energy station according to claim 2, characterized in that: Calculate the Jacobian matrix of active power and reactive power, expressed as:

4. The static voltage stability assessment method for a new energy station as claimed in claim 3, characterized in that The minimum grid voltage value that maintains static voltage stability is obtained by combining the voltage stability critical conditions, including: Using the critical condition of voltage stability, the analytical formula of critical voltage is obtained, which is expressed as: Based on the obtained critical voltage analytical expression, the minimum grid voltage to maintain static voltage stability is obtained, which is expressed as:

5. The static voltage stability assessment method for a new energy station according to claim 4, characterized in that: The power balance relationship of the system is calculated by polar coordinates and is expressed as: Among them, P i and Q i Respectively represent the active power and reactive power of node i, V i represents the voltage at node i, G ik and B ik denote the conductance and susceptance between node i and node k, respectively, θ i and θ k represent the phase angles of node i and node k respectively.

6. The static voltage stability assessment method for a new energy station according to claim 5, characterized in that: Combined with the voltage amplitude of the power grid, the voltage stability is analyzed using the power flow solution criterion, and the first problem model is established, which is expressed as: minE 7. The static voltage stability assessment method for a new energy station according to claim 6, characterized in that: The first problem model is subjected to convex relaxation to obtain the second problem model, which is expressed as: my E 2 Among them, P i and Q i Represent the active power and reactive power of node i respectively, P ij and Q ij are the active power and reactive power on line (i, j), Q ij represents the station line set, P ki and Q ki are the active power and reactive power on line (k, j), r ki and x ki Respectively represent the resistance and inductance on the line (i, j), l ki is the square of the current amplitude on line (k, j), v i and v j Represents the square of the voltage amplitude at node i and j, I ijmax Represents the maximum current at line (i, j).

8. A system applied to the static voltage stability assessment method of a new energy station according to any one of claims 1 to 7, characterized in that: include: An acquisition module is used to acquire the active power and reactive power injected into the AC power grid to obtain the voltage amplitude of the power grid; A calculation module is used to calculate the Jacobian matrix of active power and reactive power, and to obtain the minimum value of the grid voltage to maintain static voltage stability in combination with the critical conditions of voltage stability; A model building module is used to analyze voltage stability based on the system power balance relationship, combined with the grid voltage amplitude, and using the power flow solution criterion to establish the first problem model; The model solving module is used to perform convex relaxation processing on the first problem model to obtain a second problem model and solve the global optimal solution to achieve voltage stability evaluation.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the static voltage stability assessment method for a new energy station described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the static voltage stability assessment method for a new energy station as described in any one of claims 1 to 7.

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