Evaluation method for emergency recovery scheme of urban rail power supply system

Abstract

The invention relates to an evaluation method for an emergency recovery scheme of an urban rail power supply system. The method comprises the steps of selecting constraint conditions of a support power supply scheme according to urban rail power supply reliability requirements; constructing an AC / DC power supply system model for the system under different schemes, and carrying out load flow calculation; verifying whether each power recovery scheme meets the requirement according to calculation, and outputting a corresponding scheme set; establishing evaluation indexes, and calculating each index value according to a load flow calculation result to form an evaluation index matrix; calculating objective weights of different indexes by using an entropy weight method based on the evaluation index matrix; and calculating the relative closeness between different schemes and the optimal scheme by using a cosine similarity method, establishing a scoring mechanism, and screening out the optimal support power supply scheme in different fault modes according to a scoring result. The method has the advantages that the difference of power supply performance of different schemes can be obviously distinguished, and misjudgment caused by similarity of evaluation index values is avoided; and the influence of the sparsity of the evaluation index matrix on the evaluation result can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of rail transit, and in particular to an evaluation method for an emergency recovery plan of an urban rail power supply system. Background Art

[0002] The rail transit power supply system is the source of power for vehicles, stations, control centers and depots. Its reliability and stability are crucial to the safe operation of the entire rail transit network.

[0003] At present, most first-tier cities such as Shanghai, Guangzhou, and Shenzhen are gradually realizing the sharing of main transformer resources. When the main transformer of a line is out of operation due to a fault, in addition to using the normal power supply partition within the line to complete the support power supply, the main transformer of the adjacent line can also be used to complete the temporary power supply. This changes the power restoration strategy during the fault and greatly increases the selectivity of the emergency recovery plan. However, due to the urgent execution time and large number of emergency recovery plans during the fault, the rapidity and reliability of fault recovery are required to be high. The lack of a reasonable evaluation system for support power supply plans will make it difficult to select the optimal plan during the fault, which may cause waste of resources, extend the power outage time, and even expand the scope of power outage, resulting in the consequence of secondary support, which is extremely unfavorable to ensure the safe operation of the urban rail power supply system. Summary of the invention

[0004] The present invention provides an evaluation method for an emergency recovery plan of an urban rail power supply system, which accurately screens out the optimal support power supply plan under different fault modes by establishing reasonable constraints and evaluation indicators and coordinating with a designed scoring mechanism.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] An evaluation method for an emergency recovery plan of an urban rail power supply system, characterized in that the evaluation method comprises the following steps:

[0007] The constraints for selecting the support power supply scheme according to the reliability requirements of urban rail power supply;

[0008] Construct AC and DC power supply system models for systems under different schemes and perform power flow calculations;

[0009] Verify whether each power restoration plan meets the requirements based on calculations, and output the corresponding plan set;

[0010] Select the traction load shedding amount of the supporting line, the traction load shedding amount of the supported line, the distribution load shedding amount of the supporting line, the load shedding amount of the supported line and the number of switch operations as evaluation indicators, calculate the values ​​of each indicator according to the results of the power flow calculation, and form an evaluation indicator matrix;

[0011] Calculate the objective weights of different indicators using the entropy weight method based on the evaluation indicator matrix;

[0012] The cosine similarity method is used to calculate the relative closeness between different schemes and the optimal scheme, and a scoring mechanism is established to screen out the optimal support power supply scheme under different fault modes based on the scoring results.

[0013] The constraints of the support power supply solution include voltage deviation, line load, main transformer capacity and feeder capacity.

[0014] The node admittance matrix is ​​calculated according to the system architecture under different power restoration schemes until the launch conditions are met.

[0015] The evaluation indexes include load shedding amount and switch operation times.

[0016] The index values ​​are calculated according to the power flow calculation results under different schemes to form the evaluation index matrix x, which is then normalized to obtain the index matrix nx. Due to the differences in importance of different indicators, the entropy weight method is used to calculate the objective weights of the indicators based on the index matrix nx.

[0017] The indicator matrix nx is processed by weights to form a matrix z, and the maximum values ​​of each column of z are obtained to form the positive ideal solution and negative ideal solution of the evaluation scheme; the cosine similarity method is used to obtain the relative distance between the indicator values ​​of different schemes and the ideal solution, and a scoring mechanism is established to output the support power supply scheme with the highest score.

[0018] Advantages of the present invention include:

[0019] 1) It can significantly distinguish the differences in power supply performance of different schemes, avoid misjudgment caused by similar evaluation index values, and thus improve the evaluation accuracy of the emergency restoration plan of the urban rail power supply system;

[0020] 2) It can avoid the impact of the sparsity of the evaluation index matrix on the evaluation results and improve the accuracy of the evaluation results;

[0021] 3) It can accurately calculate the load shedding under different power restoration schemes and provide engineering advice for driving plan arrangements during faults. It has strong applicability and is suitable for use in various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of calculation results of constraints supporting the power supply scheme in the present invention;

[0023] Figure 2 A schematic diagram of calculation results of evaluation indicators for supporting power supply solutions in the present invention;

[0024] Figure 3 It is a schematic diagram of the scoring results of the power supply scheme supported by the present invention. DETAILED DESCRIPTION

[0025] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art:

[0026] Embodiment: The evaluation method of the emergency recovery plan of the urban rail power supply system in this embodiment includes the following steps:

[0027] 1) Calculate the line load. Simulate the train traction characteristic curve and obtain its maximum operating power, which is generally 3.7M·VA. Combined with the train operation logarithm m at peak times, the total traction load is obtained. Calculate the distribution load of a single substation based on the distribution load configuration of a typical subway power supply system, and combine the number of line substations to obtain the total line distribution load.

[0028] 2) According to the reliability requirements of urban rail power supply, select voltage deviation, line load, main transformer capacity and feeder capacity as the constraints of the emergency recovery plan. Calculate the node admittance matrix according to the system architecture under different power restoration plans, and determine the PQ, PV, and balance nodes in the system. Set the number of iterations k = 0, set the iteration exit condition ε, and set the initial value of the voltage of each node and Determine the unbalance value ΔP i , ΔQ i and Based on the unbalanced quantity formula, the partial derivatives of the real and imaginary parts of the voltage are calculated to form the Jacobian matrix J. The correction value is obtained according to the iterative formula, and the node voltage is updated as and The number of iterations is k = 1. Repeat the above steps until the exit condition ε is met. If the solution does not meet the constraints, set the number of train pairs to m-1, reduce the distribution load by 10%, and repeat the power flow calculation steps until the number of train pairs is m = 1 and the distribution load is reduced to 50% of the original. If the constraints are still not met, the solution is abandoned.

[0029] 3) Select load shedding and switch operation times as evaluation indicators for the power supply support scheme, calculate the indicator values ​​according to the power flow calculation results under different schemes, form the evaluation indicator matrix x, and perform normalization to obtain nx. Due to the differences in importance of different indicators, the entropy weight method is used to calculate the objective weight of the indicator based on nx.

[0030] 4) For nx, weighted processing is performed to form a matrix z, and the maximum values ​​of each column of z are obtained to form the positive ideal solution and negative ideal solution of the evaluation scheme. The cosine similarity method is used to obtain the relative distance between the index values ​​of different schemes and the ideal solution, and a scoring mechanism is established to output the support power supply scheme with the highest score.

[0031] In the specific implementation of this embodiment: the local network topology modeling of the Shanghai subway power supply system is carried out to obtain a simplified topology containing 34 power supply nodes, 457 load nodes and 531 lines. By simulating the failure of the main transformer out of operation in the People's Square power supply section of Line 1, the Jing'an Temple power supply section of Line 2, and the Yaohua Road power supply section of Line 8, different support power supply methods are used to complete the fault recovery. The final calculation result is as follows: Figures 1 to 3 shown.

[0032] Although the above embodiments have described in detail the concepts and embodiments of the present invention with reference to the accompanying drawings, ordinary technicians in this field can recognize that various improvements and changes can still be made to the present invention without departing from the scope of the claims, so they are not described one by one here.

Claims

1. A method for evaluating an emergency restoration plan for an urban rail power supply system, characterized in that: The evaluation method comprises the following steps: The constraints for selecting the support power supply scheme according to the reliability requirements of urban rail power supply; Construct AC and DC power supply system models for systems under different schemes and perform power flow calculations; Verify whether each power restoration plan meets the requirements based on calculations, and output the corresponding plan set; Establish evaluation indicators, calculate the values ​​of each indicator according to the results of power flow calculation, and form an evaluation indicator matrix; Calculate the objective weights of different indicators using the entropy weight method based on the evaluation indicator matrix; The cosine similarity method is used to calculate the relative closeness between different schemes and the optimal scheme, and a scoring mechanism is established to screen out the optimal support power supply scheme under different fault modes based on the scoring results.

2. The evaluation method for an emergency recovery plan of an urban rail power supply system according to claim 1 is characterized in that: The constraints of the support power supply solution include voltage deviation, line load, main transformer capacity and feeder capacity.

3. The evaluation method for an emergency restoration plan of an urban rail power supply system according to claim 1 is characterized in that: The evaluation indicators include the amount of traction load shedding of the supporting line, the amount of traction load shedding of the supported line, the amount of distribution load shedding of the supporting line, the amount of load shedding of the supported line and the number of switch operations.

4. The evaluation method for an emergency recovery plan of an urban rail power supply system according to claim 1 is characterized in that: The node admittance matrix is ​​calculated according to the system architecture under different power restoration schemes until the launch conditions are met.

5. The evaluation method for an emergency restoration plan of an urban rail power supply system according to claim 1 is characterized in that: The evaluation indexes include load shedding amount and switch operation times.

6. The evaluation method for an emergency restoration plan of an urban rail power supply system according to claim 4 is characterized in that: The index values ​​are calculated according to the power flow calculation results under different schemes to form the evaluation index matrix x, which is then normalized to obtain the index matrix nx. Due to the differences in importance of different indicators, the entropy weight method is used to calculate the objective weights of the indicators based on the index matrix nx.

7. The evaluation method for an emergency restoration plan of an urban rail power supply system according to claim 5 is characterized in that: The indicator matrix nx is processed by weights to form a matrix z, and the maximum values ​​of each column of z are obtained to form the positive ideal solution and negative ideal solution of the evaluation scheme; the cosine similarity method is used to obtain the relative distance between the indicator values ​​of different schemes and the ideal solution, and a scoring mechanism is established to output the support power supply scheme with the highest score.

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