Method and system for evaluating bearing capacity of power system

Abstract

The invention discloses a bearing capacity evaluation method and system of a power system. The method comprises the steps of determining the number N of nodes and the number M of branches for power transmission according to a power grid topological structure, collecting voltage data of each node in a power grid operation period, establishing a voltage data set, and screening abnormal data; constructing a balance equation of active power and a balance equation of reactive power; calculating a surplus bearing power item of active power and a surplus bearing power item of reactive power, and calculating a bearing imbalance coefficient F of the power grid; calculating a reserve coefficient KQ of reactive power of the power grid; and evaluating the carrying capacity of the power grid. The system comprises a power grid management matching module, a power grid operation monitoring module, a data preprocessing module, a data analysis module and a data output module. According to the method, the problems of inaccurate evaluation of the bearing capacity of the power system and incomprehensive consideration of a complex operation scene in the prior art are solved, and a reliable basis is provided for planning, operation and scheduling of the power system.

Description

Technical Field

[0001] The present invention relates to the field of power system management, and in particular to a method and system for evaluating the carrying capacity of a power system. Background Art

[0002] With the continuous growth of electricity demand and the large-scale integration of new energy sources, the structure and operating characteristics of the power system are becoming increasingly complex. Accurately assessing the carrying capacity of the power system is crucial to ensuring the safe, stable and economical operation of the system. Traditional power system carrying capacity assessment methods have many limitations. For example, they do not fully consider complex operating scenarios and cannot accurately reflect the actual carrying capacity of the system under multiple constraints. Some methods only focus on a single factor, such as only considering the power transmission limit, while ignoring key factors such as the grid carrying capacity and reactive power reserves. This leads to a large deviation between the assessment results and the actual situation, and cannot provide a reliable basis for the planning, operation and scheduling of the power system. There is an urgent need for a more comprehensive, accurate and adaptable power system carrying capacity assessment method and system that is adaptable to the characteristics of complex systems. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method and system for evaluating the carrying capacity of an electric power system.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] A method for evaluating the carrying capacity of a power system is provided, comprising the following steps:

[0006] S1: Determine the number of nodes N and branches M for power transmission based on the grid topology, and collect the voltage value V of each node during grid operation. n , the load power P on the branch connected to the node m and reactive load power Q m ; n is the node number, m is the branch number;

[0007] S2: Collect voltage data of each node during the power grid operation period, establish a voltage data set, calculate the mean and standard deviation of the voltage data, and filter out abnormal data;

[0008] S3: Obtain a voltage data set after removing abnormal data, based on the active load power P on the m-th branch connected to node n. m and reactive load power Q m , construct the balance equation of active power and the balance equation of reactive power;

[0009] S4: Based on the established active power balance equation and reactive power balance equation, calculate the surplus load power term of active power and the surplus load power term of reactive power, calculate the branch load unbalance coefficient, and then calculate the load unbalance coefficient F of the power grid;

[0010] S5: Use the maximum value of the surplus carrying power term ΔQ of the calculated reactive power of the M branches max , calculate the reactive power reserve coefficient K of the power grid Q ;

[0011] S6: Reserve factor K based on reactive power of the power grid Q The carrying capacity coefficient η of the power grid is calculated based on the load imbalance coefficient F, and the carrying capacity of the power grid is evaluated.

[0012] Furthermore, step S2 includes:

[0013] S21: Collect voltage data of each node during the power grid operation period and establish a voltage data set a is the number of times voltage data is collected, and the average value of voltage data is calculated

[0014]

[0015] Among them, u is the number of voltage data, is the u-th voltage data;

[0016] S22: Calculate the standard deviation σ of the current data in the voltage data set V ;

[0017]

[0018] Calculate the difference between voltage data and current data and the standard deviation to filter out abnormal data;

[0019] like Then determine the voltage data For abnormal data, the voltage data Delete from the voltage data set, otherwise, determine the voltage data Normal data, retain voltage data

[0020] Furthermore, the balance equations of active power and reactive power are:

[0021]

[0022] Among them, λ P ,λ Q are the growth coefficients of active power and reactive power respectively, are the active and reactive power components in the load growth direction of branch m, V max To remove the maximum voltage in the voltage data set of abnormal data, V m is the voltage on branch m, G nm 、B nm is the admittance matrix element of node n, θ n is the phase angle of node n, θ m is the phase angle of branch m.

[0023] Furthermore, the maximum voltage V max The value of is:

[0024] S31: Extract the acquisition time of each voltage data and establish a data set of acquisition time of voltage data {t1, t3, ..., t a}, in the period t1-t a According to the time point t0 of the branch fault report, the time data set {t1, t3, ..., t a}Filter the collection time t′ that is closest to the time point t0 and located on the left end a , from the acquisition time t′ a Start traversing the set number of acquisition times to the left and obtain the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a}, w is the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a} the number of collection times within;

[0025] S32: Extract the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a}, as the operating voltage data segment {V1, V2, ..., V w}, V w For the voltage data segment {V1, V2, ..., V w}wth voltage data in ;

[0026] S33: Calculate the operating voltage data segment {V1, V2, ..., V w The average value of and standard deviation σ w ;

[0027]

[0028] S34: If Then determine the voltage data V w For abnormal data, the voltage data Vw From the operating voltage data segment {V1, V2, ..., V w}, otherwise, the voltage data V w Normal data, retain voltage data V w ;

[0029] S35: Obtaining the operating voltage data segment after the abnormal data is deleted, and extracting the maximum value V′ in the operating voltage data segment after the abnormal data is deleted. max , as the reference voltage amplitude before reporting the fault at time point t0;

[0030] S36: Repeat steps S31-S35 to obtain the time period t1-t a The reference voltage amplitude corresponding to the time point of all faults reported on the internal branch is obtained to obtain the reference voltage amplitude data set {V′ max，1 ,V′ max，2 ,…,V′ max，d}, d is the time period t1-t a The number of reported faults, V′ max，d is the reference voltage amplitude corresponding to the dth reported fault;

[0031] S37: Calculate the reference voltage amplitude data set {V′ max，1 ,V′ max，2 ,…,V′ max，d}, as the maximum voltage V max ;

[0032] Furthermore, step S4 includes:

[0033] S41: Based on the established active power balance equation and reactive power balance equation, calculate the surplus carrying power term of active power and the surplus carrying power term of reactive power According to the surplus load power term ΔP m and the surplus carrying power term ΔQ m Calculate the branch load unbalance factor f of branch m m ;

[0034]

[0035] Wherein, ΔP0 is the set surplus carrying power threshold of active power, and ΔQ0 is the set surplus carrying power threshold of reactive power;

[0036] S42: According to the load imbalance coefficient f of each branch of the power grid m , calculate the load imbalance coefficient F of the power grid;

[0037]

[0038] Among them, α m is the importance coefficient of the mth branch, and satisfies

[0039] Furthermore, the reserve coefficient K Q The calculation method is:

[0040]

[0041] Furthermore, step S6 includes:

[0042] S61: Reserve factor K based on reactive power of the power grid Q Calculate the grid's carrying capacity coefficient η using the load imbalance coefficient F;

[0043]

[0044] Among them, K0 is the set reserve coefficient threshold, F0 is the set load imbalance coefficient threshold, ε1 and ε2 are the weight coefficients of the impact of reserve capacity and load imbalance state on the grid load capacity respectively;

[0045] S62: Setting an evaluation threshold η0 of the grid carrying capacity coefficient. If η≥η0, it is determined that the grid carrying capacity meets the requirements; otherwise, it is determined that the grid carrying capacity does not meet the requirements.

[0046] A power system carrying capacity evaluation system is provided, which executes the above-mentioned power system carrying capacity evaluation method, and includes:

[0047] The power grid management matching module is used to number and locate each node in the power grid and obtain the branch circuit information connected to each node;

[0048] The power grid operation monitoring module is used to obtain the operation information of each node in the power grid and the operation information of the branches connected to the corresponding nodes, including node voltage data, branch voltage data and branch load power;

[0049] Data preprocessing module, used to preprocess the collected operating information and delete abnormal voltage data;

[0050] The data analysis module establishes active power balance equations and reactive power balance equations to calculate the grid's load imbalance coefficient and reactive power reserve coefficient, thereby evaluating the grid's load-carrying capacity.

[0051] The data output module inputs the grid's carrying capacity assessment structure into the grid management system.

[0052] The beneficial effects of the present invention are as follows: the present invention solves the problems of inaccurate assessment of the carrying capacity of the power system and incomplete consideration of complex operating scenarios in the prior art. Starting from the nodes of circuit transmission and the branches connected to each node, a comprehensive analysis of the branches is performed, which can accurately assess the carrying capacity of the entire power grid system under different working conditions, and provide a reliable basis for the planning, operation and scheduling of the power system. Starting from the load power balance on each branch, the present invention comprehensively analyzes the power carrying capacity of each branch under load balance conditions, and then calculates the branch load imbalance coefficient, obtains the branch load imbalance coefficient of the entire power grid, and combines the reactive power reserve coefficient on each branch to comprehensively analyze the carrying capacity of the power grid system. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Flowchart of the method for evaluating the carrying capacity of a power system.

[0054] Figure 2 Schematic diagram of the system for evaluating the carrying capacity of the power system. DETAILED DESCRIPTION

[0055] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0056] like Figure 1 As shown, a method for evaluating the carrying capacity of a power system includes the following steps:

[0057] S1: Determine the number of nodes N and branches M for power transmission based on the grid topology, and collect the voltage value V of each node during grid operation. n , the load power P on the branch connected to the node m and reactive load power Q m ; n is the node number, m is the branch number;

[0058] S2: Collect voltage data of each node during the power grid operation period, establish a voltage data set, calculate the mean and standard deviation of the voltage data, and filter out abnormal data. Step S2 specifically includes:

[0059] S21: Collect voltage data of each node during the power grid operation period and establish a voltage data set a is the number of times voltage data is collected, and the average value of voltage data is calculated

[0060]

[0061] Among them, u is the number of voltage data, is the u-th voltage data;

[0062] S22: Calculate the standard deviation σ of the current data in the voltage data set V ;

[0063]

[0064] Calculate the difference between voltage data and current data and the standard deviation to filter out abnormal data;

[0065] like Then determine the voltage data For abnormal data, the voltage data Delete from the voltage data set, otherwise, determine the voltage data Normal data, retain voltage data

[0066] The present invention introduces the 3σ criterion to clean data in the data preprocessing link, and greatly improves the accuracy of evaluation results from data processing to model calculation, which is conducive to discovering potential problems in the power grid system.

[0067] S3: Obtain a voltage data set after removing abnormal data, based on the active load power P on the m-th branch connected to node n. m and reactive load power Q m , construct the balance equation of active power and the balance equation of reactive power;

[0068] The balance equations of active power and reactive power are specifically:

[0069]

[0070] Among them, λ P ,λ Q are the growth coefficients of active power and reactive power respectively, are the active and reactive power components in the load growth direction of branch m, V max To remove the maximum voltage in the voltage data set of abnormal data, V m is the voltage on branch m, G nm 、B nm is the admittance matrix element of node n, θ n is the phase angle of node n, θ m is the phase angle of branch m;

[0071] The stability of node voltage in the power system is the key to reliable operation of the system. When the node voltage approaches the critical value, the system stability decreases, which can easily lead to faults such as voltage collapse. By introducing the voltage amplitude and solving the load growth parameter λ with the system power balance equation, the increase term of the load power is obtained. The power balance equation in polar coordinates fully considers the electrical connection relationship between nodes (given by the node admittance matrix element G nm 、B nm The influence of voltage amplitude and phase angle can be reflected) to accurately find the critical point of voltage instability and the increaseable item of load power.

[0072] The maximum voltage V in step S3 max The value of is:

[0073] S31: Extract the acquisition time of each voltage data and establish a data set of acquisition time of voltage data {t1, t3, ..., t a}, in the period t1-t a According to the time point t0 of the branch fault report, the time data set {t1, t3, ..., t a}Filter the collection time t′ that is closest to the time point t0 and located on the left end a , from the acquisition time t′ a Start traversing the set number of acquisition times to the left and obtain the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a}, w is the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a} the number of collection times within;

[0074] S32: Extract the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a}, as the operating voltage data segment {V1, V2, ..., V w}, V w For the voltage data segment {V1, V2, ..., V w}wth voltage data in ;

[0075] S33: Calculate the operating voltage data segment {V1, V2, ..., V w The average value of and standard deviation σ w ;

[0076]

[0077] S34: If Then determine the voltage data V w For abnormal data, the voltage data V w From the operating voltage data segment {V1, V2, ..., V w}, otherwise, the voltage data V w Normal data, retain voltage data V w ;

[0078] S35: Obtaining the operating voltage data segment after the abnormal data is deleted, and extracting the maximum value V′ in the operating voltage data segment after the abnormal data is deleted. max , as the reference voltage amplitude before reporting the fault at time point t0;

[0079] S36: Repeat steps S31-S35 to obtain the time period t1-t a The reference voltage amplitude corresponding to the time point of all faults reported on the internal branch is obtained to obtain the reference voltage amplitude data set {V′ max，1 ,V′ max，2 ,…,V′ max，d}, d is the time period t1-t a The number of reported faults, V′ max，d is the reference voltage amplitude corresponding to the dth reported fault;

[0080] S37: Calculate the reference voltage amplitude data set {V′ max，1 ,V′ max，2 ,…,V′ max，d}, as the maximum voltage V max ;

[0081] S4: Based on the established active power balance equation and reactive power balance equation, calculate the surplus load power term of active power and the surplus load power term of reactive power, calculate the branch load imbalance coefficient, and then calculate the load imbalance coefficient F of the power grid. Step S4 specifically includes:

[0082] S41: Based on the established active power balance equation and reactive power balance equation, calculate the surplus carrying power term of active power and the surplus carrying power term of reactive power According to the surplus load power term ΔP m and the surplus carrying power term ΔQ m Calculate the branch load unbalance factor f of branch m m ;

[0083]

[0084] Wherein, ΔP0 is the set surplus carrying power threshold of active power, and ΔQ0 is the set surplus carrying power threshold of reactive power;

[0085] S42: According to the load imbalance coefficient f of each branch of the power grid m , calculate the load imbalance coefficient F of the power grid;

[0086]

[0087] Among them, α m is the importance coefficient of the mth branch, and satisfies

[0088] S5: Use the calculated maximum value ΔQ of the surplus carrying power items of the M branches max , calculate the reactive power reserve coefficient K of the power grid Q ;

[0089]

[0090] S6: Reserve factor K based on reactive power of the power grid Q The load-carrying capacity coefficient η of the power grid is calculated by using the load-carrying unbalance coefficient F to evaluate the load-carrying capacity of the power grid. Step S6 specifically includes:

[0091] S61: Reserve factor K based on reactive power of the power grid Q Calculate the grid's carrying capacity coefficient η using the load imbalance coefficient F;

[0092]

[0093] Among them, K0 is the set reserve coefficient threshold, F0 is the set load imbalance coefficient threshold, ε1 and ε2 are the weight coefficients of the impact of reserve capacity and load imbalance state on the grid load capacity respectively;

[0094] S62: Setting an evaluation threshold η0 of the grid carrying capacity coefficient. If η≥η0, it is determined that the grid carrying capacity meets the requirements; otherwise, it is determined that the grid carrying capacity does not meet the requirements.

[0095] like Figure 2 As shown, a power system carrying capacity evaluation system executes the above-mentioned power system carrying capacity evaluation method, including:

[0096] The power grid management matching module is used to number and locate each node in the power grid and obtain the branch circuit information connected to each node;

[0097] The power grid operation monitoring module is used to obtain the operation information of each node in the power grid, including node voltage data and branch voltage data;

[0098] Data preprocessing module, used to preprocess the collected operating information and delete abnormal voltage data;

[0099] The data analysis module calculates the grid's load imbalance coefficient and reactive power reserve coefficient by establishing active power and reactive power balance equations, and evaluates the grid's load-carrying capacity.

[0100] The data output module inputs the grid's carrying capacity assessment structure into the grid management system.

[0101] The present invention solves the problems of inaccurate assessment of the power system's carrying capacity and incomplete consideration of complex operating scenarios in the prior art. Starting from the nodes transmitted by the circuit and the branches connected to each node, a comprehensive analysis of the branches is performed, which can accurately assess the carrying capacity of the entire power grid system under different working conditions, providing a reliable basis for the planning, operation and scheduling of the power system. Starting from the load power balance on each branch, the present invention comprehensively analyzes the power carrying capacity of each branch under load balance conditions, and then calculates the branch load imbalance coefficient to obtain the branch load imbalance coefficient of the entire power grid. Combined with the reactive power reserve coefficient on each branch, the carrying capacity of the power grid system is comprehensively analyzed.

Claims

1. A method for evaluating the carrying capacity of a power system, characterized in that: The following steps are involved: S1: Determine the number of nodes N and branches M for power transmission based on the grid topology, and collect the voltage value V of each node during grid operation. n , the load power P on the branch connected to the node m and reactive load power Q m ; n is the node number, m is the branch number; S2: Collect voltage data of each node during the power grid operation period, establish a voltage data set, calculate the mean and standard deviation of the voltage data, and filter out abnormal data; S3: Obtain a voltage data set after removing abnormal data, based on the active load power P on the m-th branch connected to node n. m and reactive load power Q m , construct the balance equation of active power and the balance equation of reactive power; S4: Based on the established active power balance equation and reactive power balance equation, calculate the surplus load power term of active power and the surplus load power term of reactive power, calculate the branch load unbalance coefficient, and then calculate the load unbalance coefficient F of the power grid; S5: Use the maximum value of the surplus carrying power term ΔQ of the calculated reactive power of the M branches max , calculate the reactive power reserve coefficient K of the power grid Q ; S6: Reserve factor K based on reactive power of the power grid Q The carrying capacity coefficient η of the power grid is calculated based on the load imbalance coefficient F, and the carrying capacity of the power grid is evaluated.

2. The method for evaluating the carrying capacity of a power system according to claim 1, wherein: The step S2 comprises: S21: Collect voltage data of each node during the power grid operation period and establish a voltage data set a is the number of times voltage data is collected, and the average value of voltage data is calculated Among them, u is the number of voltage data, is the u-th voltage data; S22: Calculate the standard deviation σ of the current data in the voltage data set V ; Calculate the difference between voltage data and current data and the standard deviation to filter out abnormal data; like Then determine the voltage data For abnormal data, the voltage data Delete from the voltage data set, otherwise, determine the voltage data Normal data, retain voltage data 3. The method for evaluating the carrying capacity of a power system according to claim 2, wherein: The balance equations of active power and reactive power are: Among them, λ P ,λ Q are the growth coefficients of active power and reactive power respectively, are the active and reactive power components in the load growth direction of branch m, V max To remove the maximum voltage in the voltage data set of abnormal data, V m is the voltage on branch m, G nm 、B nm is the admittance matrix element of node n, θ n is the phase angle of node n, θ m is the phase angle of branch m.

4. The method for evaluating the carrying capacity of a power system according to claim 3, wherein: The maximum voltage V max The value of is: S31: Extract the acquisition time of each voltage data and establish a data set of acquisition time of voltage data {t1, t3, ..., t a }, in the period t1-t a According to the time point t0 of the branch fault report, the time data set {t1, t3, ..., t a }Filter the collection time t′ that is closest to the time point t0 and located on the left end a , from the acquisition time t′ a Start traversing the set number of acquisition times to the left and obtain the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a }, w is the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a } the number of collection times within; S32: Extract the acquisition time period {t′ a-w ,t′ a-w+1 ,…,t′ a }, as the operating voltage data segment {V1, V2, ..., V w }, V w For the voltage data segment {V1, V2, ..., V w }wth voltage data in ; S33: Calculate the operating voltage data segment {V1, V2, ..., V w The average value of and standard deviation σ w ; S34: If Then determine the voltage data V w For abnormal data, the voltage data V w From the operating voltage data segment {V1, V2, ..., V w }, otherwise, the voltage data V w Normal data, retain voltage data V w ; S35: Obtaining the operating voltage data segment after the abnormal data is deleted, and extracting the maximum value V′ in the operating voltage data segment after the abnormal data is deleted. max , as the reference voltage amplitude before reporting the fault at time point t0; S36: Repeat steps S31-S35 to obtain the time period t1-t a The reference voltage amplitude corresponding to the time point of all faults reported on the internal branch is obtained to obtain the reference voltage amplitude data set {V′ max，1 ,V′ max，2 ,…,V′ max，d }, d is the time period t1-t a The number of reported faults, V′ max，d is the reference voltage amplitude corresponding to the dth reported fault; S37: Calculate the reference voltage amplitude data set {V′ max，1 ,V′ max，2 ,…,V′ max，d }, as the maximum voltage V max ; 5. The method for evaluating the carrying capacity of a power system according to claim 4, wherein: The step S4 comprises: S41: Based on the established active power balance equation and reactive power balance equation, calculate the surplus carrying power term of active power and the surplus carrying power term of reactive power According to the surplus load power term ΔP m and the surplus carrying power term ΔQ m Calculate the branch load unbalance factor f of branch m m ; Wherein, ΔP0 is the set surplus carrying power threshold of active power, and ΔQ0 is the set surplus carrying power threshold of reactive power; S42: According to the load imbalance coefficient f of each branch of the power grid m , calculate the load imbalance coefficient F of the power grid; Among them, α m is the importance coefficient of the mth branch, and satisfies 6. The method for evaluating the carrying capacity of a power system according to claim 5, wherein: The reserve coefficient K Q The calculation method is:

7. The method for evaluating the carrying capacity of a power system according to claim 6, wherein: The step S6 comprises: S61: Reserve factor K based on reactive power of the power grid Q Calculate the grid's carrying capacity coefficient η using the load imbalance coefficient F; Among them, K0 is the set reserve coefficient threshold, F0 is the set load imbalance coefficient threshold, ε1 and ε2 are the weight coefficients of the impact of reserve capacity and load imbalance state on the grid load capacity respectively; S62: Setting an evaluation threshold η0 of the grid carrying capacity coefficient. If η≥η0, it is determined that the grid carrying capacity meets the requirements; otherwise, it is determined that the grid carrying capacity does not meet the requirements.

8. A power system carrying capacity evaluation system, executing the power system carrying capacity evaluation method according to claim 7, characterized in that: include: The power grid management matching module is used to number and locate each node in the power grid and obtain the branch circuit information connected to each node; The power grid operation monitoring module is used to obtain the operation information of each node in the power grid and the operation information of the branches connected to the corresponding nodes, including node voltage data, branch voltage data and branch load power; Data preprocessing module, used to preprocess the collected operation information and delete abnormal voltage data; The data analysis module establishes active power balance equations and reactive power balance equations to calculate the grid's load imbalance coefficient and reactive power reserve coefficient, thereby evaluating the grid's load-carrying capacity. The data output module inputs the grid's carrying capacity assessment structure into the grid management system.

Images