System voltage stability evaluation method and device and storage medium

Abstract

The invention discloses a system voltage stability evaluation method and device and a storage medium, and relates to the technical field of power system analysis. The method is used for a power system comprising new energy power generation equipment and a system electrical load, the new energy power generation equipment and the system electrical load are connected to a power grid through a grid-connected point, and the method comprises the following steps: obtaining working parameters of the new energy power generation equipment and the system electrical load and system parameters of the power system; determining a voltage stability index about the node voltage at the grid-connected point according to the working parameters and the system parameters; and introducing a voltage stability index to carry out system voltage stability evaluation on the power system to obtain an evaluation result. According to the method, the influence of the new energy power generation equipment and the system power load is comprehensively considered to define the voltage stability index, and more comprehensive and more accurate system voltage stability evaluation can be performed on the power system.

Description

Technical Field

[0001] This application relates to the technical field of power system stability analysis, and particularly relates to a system voltage stability evaluation method, device, and storage medium. Background Art

[0002] A dual-high power system refers to a power system that connects a high proportion of new energy and power electronic devices. Compared with the traditional power system dominated by synchronous machines, the voltage support characteristics of the dual-high power system are significantly different. Therefore, the evaluation of voltage support ability is an important basis for the safe and stable operation of the dual-high power system.

[0003] In related technologies, indicators such as the multi-terminal DC short-circuit ratio and the short-circuit ratio of multiple new energy stations are proposed to evaluate the voltage support ability of the power system after connecting to the DC system or new energy stations. The problem with this evaluation method is that the evaluation is too simple and cannot take into account the influence of other co-connected devices on the voltage support ability, resulting in a relatively single evaluation result and being unable to comprehensively and truly evaluate the voltage support ability of the dual-high power system. Summary of the Invention

[0004] The main purpose of this application is to provide a system voltage stability evaluation method, device, and storage medium, aiming to solve the technical problem that the evaluation method in related technologies fails to consider sufficient influencing factors, resulting in a single evaluation result.

[0005] To achieve the above objective, this application proposes a system voltage stability evaluation method for a power system. The power system includes new energy power generation equipment and system electrical loads, and the new energy power generation equipment and system electrical loads are connected to the power grid through the connection point; the method includes: Obtain the operating parameters of the new energy power generation equipment and the system electrical loads, as well as the system parameters of the power system; Determine the voltage stability index regarding the node voltage at the connection point according to the operating parameters and system parameters; Introduce the voltage stability index to evaluate the system voltage stability of the power system and obtain the evaluation result.

[0006] In one embodiment, determining the voltage stability index regarding the node voltage at the connection point according to the operating parameters and system parameters includes: Establish a system power flow equation according to the operating parameters and system parameters; Solve the system power flow equation to obtain the node voltage expression of the connection point; According to the system voltage stability requirements, determine the voltage stability conditions based on the node voltage expression; Perform calculation formula conversion and simplification processing on the voltage stability conditions to obtain the voltage stability index.

[0007] In one embodiment, the operating parameters of the new energy power generation equipment include the active power and reactive power output by the new energy power generation equipment; the operating parameters of the system power consumption load include the active power and reactive power consumed by the system power consumption load; the system parameters of the power system include the system electromotive force and the grid impedance.

[0008] In one embodiment, a system power flow equation is established according to the operating parameters and system parameters, including: The system active power is obtained according to the difference between the active power output by the new energy power generation equipment and the active power consumed by the system power consumption load; The system reactive power is obtained according to the difference between the reactive power output by the new energy power generation equipment and the reactive power consumed by the system power consumption load; According to the system active power, system reactive power, system electromotive force, resistance component and reactance component of the grid impedance, a system power flow equation about the node voltage of the grid connection point is established, and the system power flow equation is: , Wherein, P t represents the system active power, Q t represents the system reactive power, j represents the imaginary unit, U PCC represents the amplitude of the node voltage of the grid connection point, represents the node voltage phasor, represents the conjugate complex number of, E represents the system electromotive force, represents the conjugate complex number of the system electromotive force E, R g represents the grid impedance Z g the resistance component of, X g represents the grid impedance Z g the reactance component of, Z g =R g +jX g .

[0009] In one embodiment, the node voltage expression is the mathematical expression of the node voltage amplitude U PCC ; Solving the system power flow equation to obtain the node voltage expression of the grid connection point, including: According to the system power flow equation, establish the system active power P t and the system reactive power Qt Respectively with the node voltage amplitude U PCC of the relational expressions, the system of equations is obtained: ; The system of equations is solved by simultaneous equations and the unknown variables θ are eliminated, and the node voltage expression is obtained: .

[0010] In one embodiment, for the system voltage stability requirement, the voltage stability condition is determined according to the node voltage expression, including: For the system voltage stability requirement, the mathematical solvability condition of the node voltage expression is determined, and the voltage stability condition is obtained. The voltage stability condition is: .

[0011] In one embodiment, the voltage stability condition is subjected to calculation formula conversion and simplification processing to obtain the voltage stability index, including: The voltage stability condition is subjected to calculation formula conversion to obtain the voltage stability relational expression: ; By ignoring the resistance component of the power grid impedance Z g to simplify the voltage stability relational expression, the voltage stability index R g is obtained: h v : , wherein, S sc represents the system short-circuit capacity of the power system, P r represents the active power output by the new energy power generation equipment, Q r represents the reactive power output by the new energy power generation equipment, P l represents the active power consumed by the system electrical load, Q l represents the reactive power consumed by the system electrical load.

[0012] In one embodiment, the calculation formula of the voltage stability index is: , wherein, h v represents the voltage stability index, S sc represents the system short-circuit capacity of the power system,P r represents the active power output by the new energy power generation equipment Q r represents the reactive power output by the new energy power generation equipment P l represents the active power consumed by the system electrical load Q l represents the reactive power consumed by the system electrical load; Introduce a voltage stability index to evaluate the system voltage stability of the power system, and obtain the evaluation result, including: the short-circuit capacity of the system S sc and the active power output by the new energy power generation equipment P r and the reactive power output by the new energy power generation equipment Q r and the active power consumed by the system electrical load P l and the reactive power consumed by the system electrical load Q l Substitute their values into the calculation formula of the voltage stability index to obtain the voltage stability index value; Judge whether the voltage stability index value is less than the preset threshold; If so, obtain the evaluation result that there is a system voltage imbalance in the power system, otherwise, obtain the evaluation result of the system voltage stability of the power system.

[0013] In addition, to achieve the above object, the present application also proposes a system voltage stability evaluation device, including: a memory, a processor, and a computer program stored on the memory and running on the processor, and the computer program is configured to implement the steps of the system voltage stability evaluation method as described above.

[0014] In addition, to achieve the above object, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium, and when the computer program is executed by the processor, it implements the steps of the system voltage stability evaluation method as described above.

[0015] One or more technical solutions proposed by the present application have at least the following technical effects: A method for evaluating system voltage stability is proposed for the stability analysis of a power system including new energy power generation equipment and system electrical loads. In this power system, the new energy power generation equipment and system electrical loads are connected to the power grid through the grid connection point. In this method, a voltage stability index regarding the node voltage at the grid connection point is determined according to the operating parameters of the new energy power generation equipment and system electrical loads and the system parameters of the power system, and then this voltage stability index is introduced to evaluate the system voltage stability of the power system. By comprehensively considering the influence of the new energy power generation equipment and system electrical loads in the power system on the system voltage stability, the voltage stability index is defined, and a new index applicable to a high-renewable and high-inverter power system is proposed, which can conduct a more comprehensive and accurate evaluation of the system voltage stability of the power system. Moreover, by directly introducing this voltage stability index for evaluation, the operation is simple, and the stability analysis rate of the power system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings here are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application and, together with the specification, are used to explain the principles of the present application.

[0017] To more clearly illustrate the technical solutions in the embodiments of the present application or in the related art, the following will briefly introduce the drawings required for use in the description of the embodiments or the related art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a schematic flowchart of an embodiment of the method for evaluating system voltage stability of the present application; Figure 2 It is a detailed flowchart of step S200 in another embodiment of the method for evaluating system voltage stability of the present application; Figure 3 It is a schematic diagram of an equivalent circuit of a high-renewable and high-inverter power system provided in another embodiment of the method for evaluating system voltage stability of the present application; Figure 4 It is a schematic diagram of the hardware structure of the device for evaluating system voltage stability provided in the embodiment of the present application.

[0019] The implementation, functional features, and advantages of the present application will be further described in conjunction with the embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application. To better understand the technical solutions of the present application, the following will be described in detail in conjunction with the drawings of the specification and the specific embodiments.

[0021] A dual - high power system refers to a power system that integrates a high proportion of new energy and power electronic devices. Compared with the traditional power system dominated by synchronous machines, there are obvious differences in the voltage support characteristics of the dual - high power system, posing challenges to voltage security and stability. Therefore, the evaluation of the voltage support ability of the power system is an important basis for the safe and stable operation of the dual - high power system.

[0022] Among the related technologies for evaluating the voltage support ability of the power system, indicators such as the multi - DC feeding short - circuit ratio and the short - circuit ratio of multiple new - energy stations are proposed to evaluate the voltage support ability of the power system after connecting to the DC system or new - energy stations. For example, the short - circuit ratio index considering only the access of new - energy power generation equipment is used to evaluate the voltage bearing capacity of the power system for the access of new energy. The short - circuit ratio SCR is defined as: , Where, S sc represents the system short - circuit capacity, E represents the potential of new energy accessing the infinite - bus power system, P e represents the rated capacity of new - energy power generation equipment, Z g represents the grid impedance, Z g =R g +jX g , R g represents the resistance component, X g represents the reactance component, j represents the imaginary unit; If E is taken as the voltage base value, P e is taken as the power base value, then the short - circuit ratio SCR can be rewritten as: , Where, Z pu represents the per - unit value of the grid impedance.

[0023] According to the rewritten calculation formula of the short - circuit ratio, the problem with this evaluation method is that the evaluation is too simple and cannot consider the impact of other co - connected devices on the voltage support ability, resulting in a relatively single evaluation result and being unable to comprehensively and truly evaluate the voltage support ability of the dual - high power system. For example, there is currently no relevant theoretical or practical result to explain the impact mechanism of the load access on the voltage support ability of the power system.

[0024] In view of the problem that the influencing factors in the related art evaluation method are not fully considered, resulting in a single evaluation result, the main solution proposed in the embodiments of this application is: Obtain the operating parameters of new energy power generation equipment and system power consumption loads in the power system, as well as the system parameters of the power system, where the new energy power generation equipment and the system power consumption loads are connected to the power grid through the grid connection point; determine the voltage stability index regarding the node voltage at the grid connection point according to the operating parameters and system parameters; introduce the voltage stability index to evaluate the system voltage stability of the power system, and obtain the evaluation result.

[0025] The solution provided in the embodiments of this application defines the voltage stability index by comprehensively considering the influence of new energy power generation equipment and system power consumption loads in the power system on the system voltage stability, and proposes a new index applicable to the dual-high power system, which can perform a more comprehensive and accurate system voltage stability evaluation on the power system; moreover, directly introducing this voltage stability index for evaluation is simple in operation and can improve the stability analysis rate of the power system.

[0026] In this embodiment, for the convenience of description, the following will elaborate in detail with the system voltage stability evaluation device as the execution subject. It should be noted that the system voltage stability evaluation device is a computing service device with data processing, network communication, and program running functions, such as a server, network terminal, embedded computer, industrial control computer, etc.

[0027] The embodiments of this application provide a method for evaluating system voltage stability.

[0028] In one embodiment, referring to Figure 1 , Figure 1 is a schematic flowchart of an embodiment of the method for evaluating system voltage stability of this application. This method for evaluating system voltage stability can be used for a power system, which includes new energy power generation equipment and system power consumption loads. The new energy power generation equipment and the system power consumption loads are connected to the power grid through the grid connection point.

[0029] It should be noted that the power system can be a dual-high power system, specifically a power system with a high proportion of new energy power generation equipment and a high density of system power consumption loads, and the new energy power generation equipment and the system power consumption loads are jointly connected to the power grid, specifically connected to the power grid together at the grid connection point. In this power system, the new energy power generation equipment and the system power consumption loads converge at the grid connection point and have a common effect on the voltage at the grid connection point. Starting from this point, this embodiment proposes a method for analyzing the system voltage stability that comprehensively considers the common effect of new energy power generation equipment and system power consumption loads on the grid connection point voltage.

[0030] It should also be noted that new energy power generation equipment can include equipment for generating electricity using clean energy such as wind power, photovoltaic power, and hydropower. The number of new energy power generation equipment in a power system can be one or more, and the types of power generation equipment can also be one or more. For example, a new energy power station where a hydropower station group and a photovoltaic power station operate in coordination. The system power consumption load can include related power consumption equipment that realizes real-time monitoring, optimized dispatching, and self-healing capabilities of the power system by using technologies such as the Internet of Things (IoT), artificial intelligence (AI), big data analysis, and blockchain. The number of system power consumption loads in a power system can be one or more, and the types of power consumption equipment can also be one or more. For example, different loads that consume constant power. In actual application, the power system can be configured according to needs, and no specific limitation is made here.

[0031] In this embodiment, the system voltage stability evaluation method can include steps S100 to S300: Step S100, obtain the operating parameters of the new energy power generation equipment and the system power consumption load, as well as the system parameters of the power system.

[0032] It should be noted that the operating parameters of the new energy power generation equipment can be the power parameters of the equipment. For example, it includes parameters such as the active power and reactive power output by the new energy power generation equipment. Among them, the output active power refers to the actual active power output by the new energy power generation equipment, representing the actual work ability of the new energy power generation equipment; when the system includes multiple new energy power generation equipment, the output active power can be the total active power directly superimposed by the active powers output by multiple new energy power generation equipment, or the equivalent active power obtained by multiplying the total active power by a preset equivalent capacity coefficient; correspondingly, the output reactive power can be the total reactive power directly superimposed by the reactive powers output by multiple new energy power generation equipment, or the product of the total reactive power and the preset equivalent capacity coefficient. The operating parameters of the system power consumption load can be the power parameters of the load. For example, it includes parameters such as the active power and reactive power consumed by the system power consumption load; when the system includes multiple power consumption loads, the consumed active power can be the total active power directly superimposed by the active powers consumed by multiple power consumption loads, and the consumed reactive power can be the total reactive power directly superimposed by the reactive powers consumed by multiple power consumption loads. The system parameters of the power system can include parameters such as system electromotive force, grid impedance, and system short-circuit capacity. The above parameters can be selected according to actual needs, and no specific limitation is made here.

[0033] Step S200, determine the voltage stability index regarding the node voltage at the grid connection point according to the operating parameters and system parameters.

[0034] Among them, the voltage stability index is an evaluation index for voltage stability in the scenario where a high proportion of new energy power generation equipment and high-density system power consumption loads are jointly connected to the power grid. This voltage stability index can be an index related to the system parameters of the power system, the operating parameters of the new energy power generation equipment, and the operating parameters of the system power consumption load. Specifically, it can be an index related to the system short-circuit capacity of the power system, the output power of the new energy power generation equipment, the power consumption of the system power consumption load, etc.

[0035] Exemplarily, the calculation formula of the voltage stability index can be: , where, h v represents the voltage stability index, S sc represents the system short-circuit capacity of the power system, P r represents the active power output by the new energy power generation equipment, Q r represents the reactive power output by the new energy power generation equipment, P l represents the active power consumed by the system power consumption load, Q l represents the reactive power consumed by the system power consumption load.

[0036] In the specific implementation process, the specific values of the above parameters of the power system to be evaluated actually obtained can be substituted into this calculation formula to calculate the actual value of the voltage stability index, and then the system voltage stability can be evaluated based on this actual value.

[0037] Step S300, introduce the voltage stability index to evaluate the system voltage stability of the power system to obtain an evaluation result.

[0038] In the specific implementation process, the evaluation can be carried out according to the comparison between the actual value and the preset value of the voltage stability index to obtain different evaluation results. For example, if the value of the voltage stability index is less than the preset value, it means that the power system cannot maintain the system voltage stability, and the obtained evaluation result is that there is a system voltage imbalance in the power system under the current operating mode; if the value of the voltage stability index is exactly equal to the preset value, it means that the system voltage of the power system is at the critical point, and the obtained evaluation result can be that the power system is at the critical state of system voltage stability under the current operating mode; if the value of the voltage stability index is greater than the preset value, it means that the power system can maintain the system voltage stability, and the obtained evaluation result is that the system voltage of the power system is stable under the current operating mode.

[0039] This embodiment provides a method for evaluating the system voltage stability, which is used for the stability analysis of a power system including new energy power generation equipment and system electrical loads. In this power system, the new energy power generation equipment and system electrical loads are connected to the power grid through the grid connection point. In this method, a voltage stability index regarding the node voltage at the grid connection point is determined according to the operating parameters of the new energy power generation equipment and system electrical loads and the system parameters of the power system, and then this voltage stability index is introduced to evaluate the system voltage stability of the power system. By comprehensively considering the influence of the new energy power generation equipment and system electrical loads in the power system on the system voltage stability, the voltage stability index is defined, and a new index applicable to a dual-high power system is proposed, which can conduct a more comprehensive and accurate evaluation of the system voltage stability of the power system. Moreover, by directly introducing this voltage stability index for evaluation, the operation is simple, and the stability analysis rate of the power system can be improved.

[0040] In a feasible implementation manner, the system parameters of the power system may include the system short-circuit capacity of the power system S sc ; the operating parameters of the new energy power generation equipment may include the active power output by the new energy power generation equipment P r and the reactive power Q r ; the operating parameters of the system electrical loads may include the active power consumed by the system electrical loads P l and the reactive power Q l . The calculation formula of the voltage stability index h v is: .

[0041] In this implementation manner, step S300 may include steps S310 to S330: Step S310, substitute the values of the system short-circuit capacity S sc , the active power output by the new energy power generation equipment P r , the reactive power output Q r , the active power consumed by the system electrical loads P l and the reactive power consumed by the system electrical loads Q l into the calculation formula of the voltage stability index h v to obtain the voltage stability index value; Step S320: Judge whether the voltage stability index value is less than a preset threshold; Step S330: If so, obtain the evaluation result that the power system has system voltage imbalance; otherwise, obtain the evaluation result that the system voltage of the power system is stable.

[0042] It should be noted that the preset threshold can be adjusted according to the possible fluctuation ranges of new energy power generation equipment and system power consumption load. Optionally, a range can be taken near 4 or a specific value can be selected within this range to leave enough stability margin to meet more actual needs. Exemplarily, after obtaining the voltage stability index value according to the calculation formula of the voltage stability index h v judge whether the voltage stability index value is less than the preset threshold. If the voltage stability index value is less than the preset threshold, the obtained evaluation result is that the power system has system voltage imbalance; if the voltage stability index value is greater than or equal to the preset threshold, the obtained evaluation result is that the system voltage of the power system is stable.

[0043] In this embodiment, a voltage stability index related only to the system short-circuit capacity, power parameters of new energy power generation equipment and system power consumption load is proposed. Introducing it into the system voltage stability evaluation process of the power system can quickly evaluate the system voltage stability.

[0044] In another embodiment, the same or similar content as the above embodiment can be referred to the above introduction and will not be elaborated hereinafter. On the basis of the above embodiment, refer to Figure 2 , Figure 2 which is a schematic diagram of the refined process of step S200 in another embodiment of the system voltage stability evaluation method of this application. Step S200 may include steps S210 to S240: Step S210, establish a system power flow equation according to the working parameters and system parameters.

[0045] Among them, the working parameters of the new energy power generation equipment include the active power and reactive power output by the new energy power generation equipment; the working parameters of the system power consumption load include the active power and reactive power consumed by the system power consumption load; the system parameters of the power system include the system electromotive force and the grid impedance. The system power flow equation refers to the power flow equation used to calculate the voltage amplitude, phase angle and power distribution of each node in the power system.

[0046] In a feasible embodiment, step S210 may include steps S211 to S213: Step S211, obtain the system active power according to the difference between the active power output by the new energy power generation equipment and the active power consumed by the system power consumption load; Step S212, obtain the system reactive power according to the difference between the reactive power output by the new energy power generation equipment and the reactive power consumed by the system power consumption load; Step S213: Establish a system power flow equation for the node voltage at the point of common coupling based on the active power of the system, the reactive power of the system, the system electromotive force, the resistance component and the reactance component of the grid impedance. The system power flow equation is as follows: , where, P t represents the active power of the system, Q t represents the reactive power of the system, j represents the imaginary unit, U PCC represents the amplitude of the node voltage at the point of common coupling, represents the node voltage phasor, represents the conjugate complex number of,E represents the system electromotive force, represents the conjugate complex number of the system electromotive force E, R g represents the grid impedance Z g 's resistance component, X g represents the grid impedance Z g 's reactance component, Z g =R g +jX g .

[0047] As Figure 3 shown is a schematic diagram of the equivalent circuit of a dual-high power system provided in this embodiment. Hereinafter, this system will be taken as an example for illustrative purposes. In this dual-high power system, after the new energy power generation equipment and the system power consumption load are aggregated at the point of common coupling (PCC), they are connected to the grid together. Figure 3 In, P r +jQ r represents the output power of the new energy power generation equipment, where, P r represents the active power output by the new energy power generation equipment, Q r represents the reactive power output by the new energy power generation equipment; jX l represents the equivalent reactance of the aggregation line of the new energy power generation equipment; P l +jQ l represents the power consumed by the system power consumption load, where, Pl represents the active power, Q l represents the reactive power; P t +jQ t represents the total system power injected into the system by new energy power generation equipment and system electrical loads in this power system. Among them, P t represents the system active power, Q t represents the system reactive power; U PCC represents the node voltage u PCC at the point of common coupling PCC Z g represents the grid impedance of this power system, Z g =R g +jX g , R g represents the grid impedance Z g of the resistance component, X g represents the grid impedance Z g of the reactance component; E represents the system electromotive force of this power system.

[0048] Exemplarily, referring to Figure 3 , according to the active power P r output by the new energy power generation equipment P l and the active power P t consumed by the system electrical load, the system active power P t =P r -P l is obtained; according to the reactive power Q r output by the new energy power generation equipment Q l and the reactive power Q t consumed by the system electrical load, the system reactive power Q t =Q r -Q l is obtained; according to the system active powerP t and the reactive power of the system Q t , the system electromotive force E, and the resistance component of the power grid impedance Z g of the resistance component R g and the reactance component X g , establish the system power flow equation for the node voltage at the point of common coupling PCC: .

[0049] Step S220, solve the system power flow equation to obtain the expression of the node voltage at the point of common coupling.

[0050] Among them, the node voltage expression is the mathematical expression of the node voltage amplitude U PCC . Therefore, the goal of solving the system power flow equation is to obtain the mathematical expression of the node voltage amplitude U PCC . After that, the voltage stability of the system can be determined according to the solvability condition of this mathematical expression.

[0051] In a feasible implementation manner, step S220 may include steps S221 to S222: Step S221, according to the system power flow equation, establish the system active power P t and the reactive power of the system Q t respectively with the node voltage amplitude U PCC of the relationship, to obtain the equations: ; Step S222, perform the processing of simultaneous equation solving and eliminating the unknown variable θ on the equations, to obtain the node voltage expression: .

[0052] Exemplarily, on the basis of the foregoing example, first, transform the system power flow equation: , where θ is the temporarily introduced unknown variable.

[0053] Then, establish the relationship between the system active power P t and the node voltage amplitude U PCC , and the reactive power of the system Qt The relational expression with the node voltage amplitude U PCC results in a system of equations: .

[0054] Next, by solving the system of equations simultaneously and eliminating the unknown variables θ processing, the calculation formula for can be obtained: .

[0055] Finally, by solving the above calculation formula for the node voltage amplitude U PCC The mathematical expression, that is, the node voltage expression, can be obtained: .

[0056] Step S230, for the system voltage stability requirement, determine the voltage stability condition according to the node voltage expression.

[0057] Specifically, the system voltage stability requirement can be that the node voltage amplitude U PCC is stable within a certain range. Based on the above node voltage expression, the voltage stability condition can be correspondingly determined.

[0058] In a feasible implementation manner, step S230 may include step S231: Step S231, for the system voltage stability requirement, determine the solvability condition of the mathematics of the node voltage expression to obtain the voltage stability condition, and this voltage stability condition is specifically: .

[0059] According to the node voltage expression, when the above voltage stability condition is satisfied, the mathematical expression of the node voltage amplitude U PCC holds and is solvable. When the node voltage expression has a solution, Figure 3 the system voltage of the double - high power system shown can meet the system voltage stability requirement.

[0060] Step S240, perform calculation formula conversion and simplification processing on the voltage stability condition to obtain a voltage stability index.

[0061] Among them, by reverse - deducing the previously determined voltage stability condition, the voltage stability index h v can be determined.

[0062] In a feasible implementation manner, step S240 may include steps S241 - S242: Step S241, perform a computational transformation on the voltage stability condition to obtain a voltage stability relational expression: ; Step S242, simplify the voltage stability relational expression by ignoring the resistance component Z g of the power grid impedance R g to obtain a voltage stability index h v : , wherein, S sc represents the system short-circuit capacity of the power system, P r represents the active power output by the new energy power generation equipment, Q r represents the reactive power output by the new energy power generation equipment, P l represents the active power consumed by the system electrical load, Q l represents the reactive power consumed by the system electrical load.

[0063] Exemplarily, based on the foregoing example, by transforming the computational expression of the voltage stability condition, a voltage stability relational expression can be obtained: ; Generally, since the resistance component Z g in the power grid impedance R g is much smaller than the reactance component X g , the above voltage stability relational expression can be simplified by ignoring the reactance component X g , and the simplification process is: ; Based on the above voltage stability condition and the simplified relational expression, it can be known that the voltage stability index h v = 4 is the voltage critical stability condition. When h v < 4, there will be a system voltage imbalance in the power system. When h v > 4, the system voltage of the power system is stable. Thus, the voltage stability index h v can be determined as: .

[0064] It is understandable that, compared with the related technologies where the evaluation index can only consider the impact of new energy access or load access singly, the voltage stability index determined in this embodiment h v On the basis of considering the impact of new energy power stations on the system voltage stability, the impact of constant power load access on the system voltage stability is also considered. Combining the above examples, it can be seen that the system voltage stability depends on the sum of the output power of new energy power generation equipment and the power consumption of the system electrical load. If the new energy power generation equipment and the system electrical load can provide reactive power support to the system, then the access capacity of new energy and load can be increased; otherwise, the total active power of the new energy power generation equipment and the system electrical load that the system can accommodate will be reduced.

[0065] This embodiment provides a method for evaluating system voltage stability. First, a system power flow equation is established based on the operating parameters of new energy power generation equipment and the system electrical load and the system parameters of the power system. Then, the system power flow equation is solved to obtain the node voltage expression of the connection point. Next, according to the system voltage stability requirements and the node voltage expression, a voltage stability index is obtained, a new index is proposed and a corresponding index determination method is provided. Subsequently, this voltage stability index can be directly introduced to evaluate the system voltage stability of the power system, thus proposing a new voltage stability analysis method; for the scenario where a high proportion of new energy power generation equipment and high-density loads are jointly connected to the power grid, the impacts of the active and reactive power consumption or support of new energy power generation equipment and loads on the system voltage stability are comprehensively considered, which has feasibility in theory and practice and makes up for the limitation of existing research that can only analyze new energy or load singly and cannot analyze the characteristics of their joint access; at the same time, the method for evaluating system voltage stability introducing this voltage stability index has the advantages of being more systematic and comprehensive, can be applied to the complex scenario of a high proportion of new energy power generation equipment connected to a high-density load power grid, expands the application range, and improves the voltage stability evaluation and control capabilities of the power grid under complex operating conditions.

[0066] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the method for evaluating system voltage stability of this application. Based on this technical concept, more forms of simple transformations are within the protection scope of this application.

[0067] This application also provides a device for evaluating system voltage stability. The device may include: at least one processor; and a memory communicatively connected to the at least one processor; wherein, the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method for evaluating system voltage stability in the above embodiment.

[0068] Next, refer to Figure 4 ,Figure 4 The figure shows a schematic hardware structure of a system voltage stability assessment device suitable for implementing the method of the embodiments of the present application. The device may include, but is not limited to, fixed terminals such as servers, network terminals, embedded computers, industrial control computers, desktop computers, PCs (Personal Computers), and the like. Figure 4 The shown system voltage stability assessment device is merely an example and should not impose any limitations on the functions and usage scope of the embodiments of the present application.

[0069] As Figure 4 shown, the system voltage stability assessment device may include a processing device 1001 (such as a central processing unit, a graphics processing unit, etc.), which may perform various appropriate actions and processes according to the program stored in the read-only memory (ROM: Read Only Memory) 1002 or the program loaded from the storage device 1003 into the random access memory (RAM: Random Access Memory) 1004. In the RAM 1004, various programs and data required for the operation of the system voltage stability assessment device are also stored. The processing device 1001, the ROM 1002, and the RAM 1004 are connected to each other through a bus 1005. The input / output (I / O) interface 1006 is also connected to the bus 1005. Generally, the following systems may be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touchpad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 may allow the system voltage stability assessment device to communicate with other devices wirelessly or wiredly to exchange data. Although the figure shows a system voltage stability assessment device with various systems, it should be understood that it is not required to implement or have all the shown systems, and more or fewer systems may be alternatively implemented or had.

[0070] In particular, according to the embodiments disclosed in the present application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program contains program codes for executing the methods shown in the flowcharts. In such an embodiment, the computer program can be downloaded and installed from the network through the communication device 1009, or installed from the storage device 1003, or installed from the ROM 1002. When the computer program is executed by the processing device 1001, it executes the above functions defined in the system voltage stability assessment method disclosed in the embodiments of the present application.

[0071] The system voltage stability assessment device provided by the present application adopts the system voltage stability assessment method in the above embodiments, and can solve the technical problem that the influencing factors of the evaluation method in the related art are not considered enough, resulting in a single evaluation result. Compared with the related art, the beneficial effects of the system voltage stability assessment device provided by the present application are the same as those of the system voltage stability assessment method provided by the above embodiments, and other technical features in the system voltage stability assessment device are the same as those disclosed in the system voltage stability assessment method of the above embodiments, and will not be elaborated here.

[0072] It should be understood that the various parts disclosed in the present application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0073] The above are only the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0074] The present application also provides a computer-readable storage medium, which has computer-readable program instructions (i.e., computer programs) stored thereon, and the computer-readable program instructions are used to execute the system voltage stability assessment method in the above embodiments.

[0075] The computer-readable storage medium provided by the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination of the above. More specific examples of the computer-readable storage medium may include, but are not limited to: portable computer disks with electrical connections having one or more wires, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM) or flash memory, optical fibers, optical storage devices, magnetic storage devices, and so on, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium that contains or stores a program, which can be used by an instruction execution system or device, or both in combination. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency), and so on, or any suitable combination of the above.

[0076] The above computer-readable storage medium may be included in the system voltage stability evaluation device; or it may exist independently without being assembled into the system voltage stability evaluation device.

[0077] The above computer-readable storage medium carries one or more programs. When the above one or more programs are executed by the system voltage stability evaluation device, the system voltage stability evaluation device can implement the above functions defined in the system voltage stability evaluation method disclosed in the embodiments of the present application.

[0078] Computer program code for performing the operations of the present application may be written in one or more programming languages or combinations thereof. The above programming languages include object-oriented programming languages - such as Java, Smalltalk, C++; and also include conventional procedural programming languages - such as the "C" language or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network - including a local area network (LAN) or a wide area network (WAN) - or connected to an external computer, for example, using the Internet connection provided by an Internet service provider.

[0079] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, functions, and operations of methods, apparatuses, and computer program products according to various embodiments of the present application. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the boxes may occur in a different order than that marked in the accompanying drawings. For example, two consecutive boxes shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, as well as the combination of boxes in the block diagram and / or flowchart, may be implemented by a dedicated hardware-based system that performs the specified functions or operations, or may be implemented by a combination of dedicated hardware and computer instructions.

[0080] The modules described in the embodiments of the present application can be implemented in software or in hardware. Among them, the name of the module does not constitute a limitation to the unit itself in some cases.

[0081] The storage medium provided by the present application is a computer-readable storage medium, on which computer-readable program instructions (i.e., computer programs) for executing the above-mentioned system voltage stability evaluation method are stored, which can solve the technical problem that the influencing factors of the evaluation method in the related art are not fully considered, resulting in a single evaluation result. Compared with the related art, the beneficial effects of the computer-readable storage medium provided by the present application are the same as those of the system voltage stability evaluation method provided by the above embodiments, and will not be elaborated here.

[0082] The above are only some embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent structural transformation made by using the description of the present application and the content of the accompanying drawings under the technical concept of the present application, or direct / indirect application in other related technical fields, is included in the protection scope of the present application.

Claims

1. A method for evaluating the voltage stability of a system, characterized in that, For a power system, the power system includes new energy power generation equipment and system electrical loads, and the new energy power generation equipment and the system electrical loads are connected to the power grid through a connection point; the method includes: Obtain the operating parameters of the new energy power generation equipment and the system electrical loads and the system parameters of the power system; Establish a system power flow equation according to the operating parameters and the system parameters; Solve the system power flow equation to obtain the node voltage expression of the connection point; For the system voltage stability requirement, determine the voltage stability condition according to the node voltage expression; Perform calculation formula conversion and simplification processing on the voltage stability condition to obtain a voltage stability index regarding the node voltage at the connection point; Introduce the voltage stability index to evaluate the system voltage stability of the power system to obtain an evaluation result.

2. The method for evaluating system voltage stability according to claim 1, wherein The operating parameters of the new energy power generation equipment include the active power and reactive power output by the new energy power generation equipment; the operating parameters of the system electrical loads include the active power and reactive power consumed by the system electrical loads; the system parameters of the power system include system electromotive force and grid impedance.

3. The system voltage stability evaluation method according to claim 2, wherein, The establishing a system power flow equation according to the operating parameters and the system parameters includes: Obtain the system active power according to the difference between the active power output by the new energy power generation equipment and the active power consumed by the system electrical loads; Obtain the system reactive power according to the difference between the reactive power output by the new energy power generation equipment and the reactive power consumed by the system electrical loads; Establish a system power flow equation regarding the node voltage at the connection point according to the system active power, the system reactive power, the system electromotive force, the resistance component and the reactance component of the grid impedance, and the system power flow equation is: ， Among them, P t represents the active power of the system, Q t represents the reactive power of the system, j represents the imaginary unit, U PCC represents the magnitude of the node voltage at the grid connection point, represents the node voltage phasor, represents the conjugate complex number of, E represents the system electromotive force, represents the conjugate complex number of the system electromotive force E, R g represents the grid impedance Z g the resistance component of, X g represents the grid impedance Z g the reactance component of, Z g =R g +jX g .

4. The system voltage stability evaluation method according to claim 3, characterized in that The node voltage expression is the mathematical expression of the node voltage amplitude U PCC ; The solving the system power flow equation to obtain the node voltage expression of the connection point includes: Based on the power flow equations of the system, establish the active power of the system P t and the reactive power of the system Q t respectively with the relationship of the node voltage magnitude U PCC to obtain the system of equations: ； Solve the system of equations by simultaneous equations and eliminate the unknown variables θ to obtain the node voltage expression: 。 5. The system voltage stability assessment method according to claim 4, wherein The determining the voltage stability condition according to the node voltage expression for the system voltage stability requirement includes: For the system voltage stability requirement, determine the mathematical solvability condition of the node voltage expression to obtain the voltage stability condition, and the voltage stability condition is: 。 6. The system voltage stability evaluation method according to claim 5, wherein The performing calculation formula conversion and simplification processing on the voltage stability condition to obtain a voltage stability index regarding the node voltage at the connection point includes: Perform calculation formula conversion on the voltage stability condition to obtain a voltage stability relation formula: ； By ignoring the resistance component of the grid impedance Z g to simplify the voltage stability relation, a voltage stability index is obtained R g : h v : ， Among them, S sc represents the system short-circuit capacity of the power system, P r represents the active power output by the new energy power generation equipment, Q r represents the reactive power output by the new energy power generation equipment, P l represents the active power consumed by the system electrical load, Q l represents the reactive power consumed by the system electrical load.

7. The method for evaluating the system voltage stability according to any one of claims 1 to 6, characterized in that, The calculation formula of the voltage stability index is: ， Among them, h v represents the voltage stability index, S sc represents the system short-circuit capacity of the power system, P r represents the active power output by the new energy power generation equipment, Q r represents the reactive power output by the new energy power generation equipment, P l represents the active power consumed by the system electrical load, Q l represents the reactive power consumed by the system electrical load; The introducing the voltage stability index to evaluate the system voltage stability of the power system to obtain an evaluation result includes: Short-circuit capacity of the system S sc and the active power output by the new energy power generation equipment P r and the reactive power output by the new energy power generation equipment Q r and the active power consumed by the system's electrical load P l and the reactive power consumed by the system's electrical load Q l Substitute the values into the calculation formula of the voltage stability index to obtain the voltage stability index value; Judge whether the value of the voltage stability index is less than a preset threshold; If so, obtain the evaluation result that there is a system voltage imbalance in the power system, otherwise, obtain the evaluation result that the system voltage of the power system is stable.

8. A system voltage stability evaluation device, characterized in that, The device includes a memory, a processor, and a computer program stored on the memory and running on the processor, and the computer program is configured to implement the steps of the system voltage stability evaluation method according to any one of claims 1 to 7.

9. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the system voltage stability evaluation method according to any one of claims 1 to 7 are implemented.

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