Bidirectional converter site selection and characteristic collaborative optimization method

Abstract

The invention provides a bidirectional converter site selection and characteristic collaborative optimization method, and relates to the field of rail transit power supply traction station transformation construction optimization, and the method comprises the steps: obtaining traction station data and operation data of a train in each time period, and taking the data as the basis of bidirectional converter site selection and characteristic optimization; initializing site selection and characteristic schemes of the bidirectional converter; constructing a circuit topology to carry out power flow calculation to obtain the power of the transformer substation at each moment; constructing an optimization model with the lowest daily average cost after bidirectional converter site selection and characteristic collaborative optimization as the target; and solving the optimization model to obtain a bidirectional converter site selection and characteristic scheme which enables the daily average cost to be the lowest. According to the method, the system operation cost is reduced under the condition that the train operation power supply requirement is met, the optimal scheme including the number, the position and the corresponding characteristics is provided for adding the bidirectional converter under the transformation of the current urban rail transit traction station, and the problems of site selection and parameter setting of adding the bidirectional converter in the traction substation are solved.

Description

Technical Field

[0001] The present invention relates to the field of reconstruction and construction optimization of rail transit power supply and traction stations, and in particular to a method for coordinated optimization of site selection and characteristics of a bidirectional converter. Background Art

[0002] At present, the rail transit power supply built at home and abroad is mainly rectifier traction depot, which cannot effectively recover the regenerative energy of the train. Bidirectional converter has the functions of rectification and inversion. It is applied to rail transit and can feed back the regenerative energy to the circulating network to improve the utilization rate of regenerative energy. Therefore, operators are currently starting to transform the current rectifier traction depot based on bidirectional converters to reduce system operating costs. Considering the construction and maintenance costs required for adding bidirectional converters, as well as the site selection and characteristic parameters of bidirectional converters, they will affect the system power flow and energy consumption. Therefore, an optimization model is established with the goal of minimizing the system cost under train operation, and a method for coordinated optimization of the site selection and characteristics of bidirectional converters for the transformation of urban rail transit traction depots is proposed to improve the economy of rail transit operations.

[0003] At present, there are no relevant documents and patents to solve the site selection and characteristic problems of bidirectional converters for urban rail transit traction station transformation. Conventional site selection optimization problems, such as the site selection and sizing of energy storage systems, usually consider the capacity of the device, but this parameter does not affect the energy consumption of the system. The characteristic parameters of the bidirectional converter in this patent affect the power and voltage of the system. When the train operation conditions remain unchanged, different characteristic parameters of the bidirectional converter will affect the energy consumption of the system. Therefore, this patent proposes a method for coordinated optimization of the site selection and characteristics of bidirectional converters to achieve system loss reduction and regenerative energy recovery, thereby reducing costs comprehensively. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for coordinated optimization of site selection and characteristics of a bidirectional converter. The present invention is for coordinated optimization of site selection and characteristics of a bidirectional converter for the transformation of an urban rail transit traction depot. The present invention takes into account the electricity cost of train operation and the construction and maintenance cost of adding a bidirectional converter, and can obtain a bidirectional converter solution (site selection and characteristic solution of a bidirectional converter) with the lowest operating cost, providing an effective method for the site selection and characteristic optimization of bidirectional converters under the current transformation of rail transit traction depots.

[0005] In order to achieve the above objectives, the technical solution adopted by the present invention is: a method for coordinated optimization of site selection and characteristics of a bidirectional converter, comprising the following steps:

[0006] Obtain traction depot data and train operation data;

[0007] Determine the bidirectional converter location set based on the traction depot data, and determine the location and power information of the train at each time based on the train operation data;

[0008] Initializing a site selection and characteristic scheme of a bidirectional converter, wherein the characteristics of the bidirectional converter are a droop slope and an inverter start voltage;

[0009] Combined with the location and power information of the trains at each time, as well as the site selection and characteristic scheme of the bidirectional converter, a circuit topology is constructed to solve the power flow and obtain the power of the substation at each time.

[0010] Based on the power of the substation at each moment, the electricity cost of train operation is calculated, and the construction and maintenance costs are calculated based on the number of additional bidirectional converters. An optimization model is constructed with the goal of minimizing the daily average cost after the coordinated optimization of the bidirectional converter site selection and characteristics.

[0011] The optimization model is solved to obtain the bidirectional converter site selection and characteristic scheme that minimizes the daily average cost, and the result of the bidirectional converter site selection and characteristic collaborative optimization is output, wherein the location of the bidirectional converter site selection belongs to the bidirectional converter site selection set.

[0012] Furthermore, the expression of the power information of train k is as follows:

[0013]

[0014] in, F k (t)v k (t) and They respectively represent the power, control force, speed and auxiliary system power of train k at time t, and t represents the time.

[0015] Furthermore, the site selection and characteristic scheme of the bidirectional converter is expressed as:

[0016] X=[x1,x2,...,x N ,U st1 ,U st2 ,...,U stN ,k1,k2,...,k N ]

[0017] Where X represents the site selection and characteristic scheme of the bidirectional converter, N represents the number of traction stations, and x i Indicates whether the i-th traction station in the bidirectional converter site selection set is equipped with a bidirectional converter, x N Indicates whether to add a bidirectional converter to the Nth traction station, U sti and k i They represent the inverter start-up voltage and droop slope of the bidirectional converter added in the i-th traction station, U stN and k N They are respectively the inverter start-up voltage and the droop slope of the bidirectional converter added in the Nth traction station, i=1,2,3,...,N.

[0018] Furthermore, the circuit topology is constructed by combining the position and power information of the train at each time and the site selection and characteristic scheme of the bidirectional converter, which is specifically as follows:

[0019] The train is regarded as a power source node, and its position at different times is different, which determines the connection scheme and connection impedance of each power source node; the traction depot is regarded as a voltage node, and the rectifier traction depot is transformed into a hybrid traction depot after adding a bidirectional converter, which has both inverter and rectifier functions. The characteristics of the hybrid traction depot are obtained by the parallel equivalent circuit of the droop characteristics of the rectifier and the inverter start-up voltage and droop characteristic parameters of the bidirectional converter.

[0020] Furthermore, the power flow solution is specifically as follows:

[0021] The node voltage equation is constructed based on the circuit topology, and the power flow iteration is performed based on the Newton-Raphson method or Gauss-Seidel method to obtain the voltage and power information of each node. This process is called power flow settlement. The power of the substation at each moment is calculated based on the node voltage matrix power flow of the circuit topology, which is expressed as:

[0022]

[0023] Where, f represents the power flow calculation process, P train (t) represents the power information of all trains on the line at time t, S train (t) represents the location information of all trains on the line at time t, Sub(X) represents the location and characteristic scheme information of adding bidirectional converters, and They represent the power information of traction station i, the power information and position information of train k at time t, respectively. and They respectively represent the power information of traction station N, the power information and position information of train K at time t.

[0024] Furthermore, the expression of the train operation electricity cost is as follows:

[0025]

[0026] Among them, C ele represents the electricity cost of train operation per day, c e (t) represents the unit price of electricity, P sub (t) represents the power of the substation at time t, t0 and t f They respectively represent the start and end times of the train’s daily operations.

[0027] Furthermore, the expressions of the construction and maintenance costs are as follows:

[0028]

[0029] Among them, C BC represents the average daily cost of construction and maintenance of additional bidirectional converters, N' represents the number of additional bidirectional converters, c1 and c2 represent the construction and annual maintenance unit price of a single bidirectional converter, Y represents the service life cycle of the bidirectional converter, and γ represents the annual economic expansion rate.

[0030] Furthermore, the objective function of the optimization model is expressed as follows:

[0031] J=min(C ele +C BC )

[0032] Among them, J represents the objective function of the optimization model, C ele represents the electricity cost of train operation per day, C BC It represents the average daily cost of construction and maintenance of additional bidirectional converters, and min represents the minimum value.

[0033] Furthermore, the constraint condition of the optimization model is that the value range of the decision variable is expressed as:

[0034]

[0035] Among them, U stmin and U stmax They represent the minimum and maximum values ​​of the inverter start-up voltage of the bidirectional converter, k min and k max Respectively represent the minimum and maximum values ​​of the droop slope, x i Indicates whether to add a bidirectional converter to the i-th traction station, k i represents the droop slope of the bidirectional converter added in the i-th traction station, U sti It represents the inverter start-up voltage of the bidirectional converter added in the i-th traction station.

[0036] Beneficial effects of the present invention:

[0037] (1) The present invention provides a method for the coordinated optimization of bidirectional converter site selection and characteristics for the transformation of urban rail transit traction depots. Based on the distribution of line traction depots and the actual operation of trains, the bidirectional converter site selection set and the required power of the train are determined. After adding bidirectional converters, the operation requirements of the train can be met.

[0038] (2) When constructing the objective function of train operation and bidirectional converter construction and maintenance costs, the present invention comprehensively considers the operating electricity costs of the train at different times of the day and the life cycle maintenance costs of the bidirectional converter, establishes the daily average cost, and accurately evaluates the economic feasibility of the plan; and performs coordinated optimization of the site selection and characteristics of the bidirectional converter, so that the site selection and characteristic solutions finally obtained have better results. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of the method. DETAILED DESCRIPTION

[0040] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0041] Example

[0042] like Figure 1 As shown, the present invention provides a method for site selection and characteristic coordinated optimization of a bidirectional converter, and the implementation method thereof is as follows:

[0043] S1. Obtain traction depot data and train operation data;

[0044] S2. Determine the bidirectional converter site set according to the traction station data, and determine the position and power information of the train at each time according to the train operation data;

[0045] In this embodiment, the characteristics of the bidirectional converter are the droop slope and the inverter start-up voltage, both of which will affect the system power and energy consumption.

[0046] In this embodiment, the acquired traction depot data includes the location of the traction depot, and the acquired train data includes the power of the on-board auxiliary system, the location, speed and control force of the train at different times.

[0047] In this embodiment, the bidirectional converter site selection set is the location set S of all traction depots; the train operation data includes the train position, speed, control force and on-board auxiliary system power, and the train power is obtained by the following formula:

[0048] P train (t)=F(t)v(t)+P aux

[0049] Among them, P train (t), F(t) and v(t) represent the power, control force and speed of the train at time t, respectively. auxrepresents the auxiliary system power, and t represents the time.

[0050] In this embodiment, the train running electricity cost is the electricity cost of the substation, which is expressed as:

[0051]

[0052] Among them, C ele represents the electricity cost of train operation per day, c e (t) represents the unit price of electricity, P sub (t) represents the power of the substation at time t, t0 and t f They respectively represent the start and end times of the train’s daily operations.

[0053] S3, initializing the site selection and characteristic scheme of the bidirectional converter, wherein the characteristics of the bidirectional converter are a droop slope and an inverter start voltage;

[0054] In this embodiment, the site selection and characteristic scheme of the bidirectional converter is expressed as follows:

[0055] X=[x1,x2,...,x N ,U st1 ,U st2 ,...,U stN ,k1,k2,...,k N ]

[0056] Where X represents the site selection and characteristic scheme of the bidirectional converter, N represents the number of traction stations, and x i Indicates whether the i-th traction station in the bidirectional converter site selection set is equipped with a bidirectional converter, x N Indicates whether to add a bidirectional converter to the Nth traction station, U sti and k i They represent the inverter start-up voltage and droop slope of the bidirectional converter added in the i-th traction station, U stN and k N They are respectively the inverter start-up voltage and the droop slope of the bidirectional converter added in the Nth traction station, i=1,2,3,...,N.

[0057] S4. Based on the location and power information of the train at each time, as well as the site selection and characteristic scheme of the bidirectional converter, a circuit topology is constructed to perform power flow calculation to obtain the power of the substation at each time;

[0058] In this embodiment, the circuit topology is constructed by combining the position and power information of the train at each time and the site selection and characteristic scheme of the bidirectional converter, which is specifically as follows:

[0059] The train is regarded as a power source node, and its position at different times is different, which determines the connection scheme and connection impedance of each power source node; the traction depot is regarded as a voltage node, and the rectifier traction depot is transformed into a hybrid traction depot after adding a bidirectional converter, which has both inverter and rectifier functions. The characteristics of the hybrid traction depot are obtained by the parallel equivalent circuit of the droop characteristics of the rectifier and the inverter start-up voltage and droop characteristic parameters of the bidirectional converter.

[0060] In this embodiment, the power flow solution is specifically as follows:

[0061] The node voltage equation is constructed based on the circuit topology, and the power flow iteration is performed based on the Newton-Raphson method or Gauss-Seidel method to obtain the voltage and power information of each node. This process is called power flow settlement. The power of the substation at each moment is calculated based on the node voltage matrix power flow of the circuit topology, which is expressed as:

[0062]

[0063] Where, f represents the power flow calculation process, P train (t) represents the power information of all trains on the line at time t, S train (t) represents the location information of all trains on the line at time t, Sub(X) represents the location and characteristic scheme information of adding bidirectional converters, and They represent the power information of traction station i, the power information and position information of train k at time t, respectively. and They respectively represent the power information of traction station N, the power information and position information of train K at time t.

[0064] S5. Calculate the electricity cost of train operation based on the power of the substation at each moment, and calculate the construction and maintenance costs based on the number of additional bidirectional converters, and build an optimization model with the goal of minimizing the daily average cost after the coordinated optimization of the site selection and characteristics of the bidirectional converter;

[0065] In this embodiment, the expression of the train operation electricity cost is as follows:

[0066]

[0067] Among them, C ele represents the electricity cost of train operation per day, c e (t) represents the unit price of electricity, P sub (t) represents the power of the substation at time t, t0 and t f They respectively represent the start and end times of the train’s daily operations.

[0068] In this embodiment, the construction and maintenance cost of adding a bidirectional converter is expressed as:

[0069]

[0070] Among them, C BC represents the average daily cost of construction and maintenance of additional bidirectional converters, N' represents the number of additional bidirectional converters, c1 and c2 represent the construction and annual maintenance unit price of a single bidirectional converter, Y represents the service life cycle of the bidirectional converter, and γ represents the annual economic expansion rate.

[0071] In this embodiment, the optimization model aims to minimize the daily average cost after the site selection and characteristics of the bidirectional converter are coordinated and optimized. The objective function of the optimization model is expressed as:

[0072] J=min(C ele +C BC )

[0073] Among them, J represents the objective function of the optimization model, C ele represents the electricity cost of train operation per day, C BC It represents the average daily cost of construction and maintenance of additional bidirectional converters, and min represents the minimum value.

[0074] In this embodiment, the decision variables of the optimization model are the location and characteristics of the bidirectional converter, which are expressed as:

[0075] X=[x1,x2,...,x N ,U st1 ,U st2 ,...,U stN ,k1,k2,...,k N ]

[0076] Among them, X represents the decision variable of the optimization model, N represents the number of traction stations, and x i Indicates whether to add a bidirectional converter to the ith traction station, x N Indicates whether to add a bidirectional converter to the Nth traction station, U sti and k i They represent the inverter start-up voltage and droop slope of the bidirectional converter added in the i-th traction station, U stN and k N They are respectively the inverter start-up voltage and the droop slope i=1, 2, 3, ..., N of the bidirectional converter added in the Nth traction station.

[0077] The constraints of the optimization model are the value range of the decision variables, expressed as:

[0078]

[0079] Among them, U stmin and U stmaxThey represent the minimum and maximum values ​​of the inverter start-up voltage of the bidirectional converter, k min and k max Respectively represent the minimum and maximum values ​​of the droop slope, x i Indicates whether to add a bidirectional converter to the i-th traction station, k i It represents the droop slope of the bidirectional converter added in the i-th traction station.

[0080] S6. Solve the optimization model to obtain the bidirectional converter site selection and characteristic scheme that minimizes the daily average cost, and output the result of the bidirectional converter site selection and characteristic collaborative optimization, wherein the location of the bidirectional converter site selection belongs to the bidirectional converter site selection set.

[0081] In this embodiment, the optimization model may be solved based on a heuristic algorithm or a planning algorithm.

[0082] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for coordinated optimization of bidirectional converter site selection and characteristics, characterized in that: The following steps are involved: Obtain traction depot data and train operation data; Determine the bidirectional converter location set based on the traction depot data, and determine the location and power information of the train at each time based on the train operation data; Initializing a site selection and characteristic scheme of a bidirectional converter, wherein the characteristics of the bidirectional converter are a droop slope and an inverter start voltage; Combined with the location and power information of the trains at each time, as well as the site selection and characteristic scheme of the bidirectional converter, a circuit topology is constructed to solve the power flow and obtain the power of the substation at each time. Based on the power of the substation at each moment, the electricity cost of train operation is calculated, and the construction and maintenance costs are calculated based on the number of additional bidirectional converters. An optimization model is constructed with the goal of minimizing the daily average cost after the coordinated optimization of the bidirectional converter site selection and characteristics. The optimization model is solved to obtain the bidirectional converter site selection and characteristic scheme that minimizes the daily average cost, and the result of the bidirectional converter site selection and characteristic collaborative optimization is output, wherein the location of the bidirectional converter site selection belongs to the bidirectional converter site selection set.

2. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 1, characterized in that: The expression of the power information of train k is as follows: in, F k (t)v k (t) and They respectively represent the power, control force, speed and auxiliary system power of train k at time t, and t represents the time.

3. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 1, characterized in that: The site selection and characteristic scheme of the bidirectional converter is expressed as: X=[x1,x2,...,x N ,IN st1 ,IN st2 ,...,IN stN ,k1,k2,...,k N ] Where X represents the site selection and characteristic scheme of the bidirectional converter, N represents the number of traction stations, and x i Indicates whether the i-th traction station in the bidirectional converter site selection set is equipped with a bidirectional converter, x N Indicates whether to add a bidirectional converter to the Nth traction station, U sti and k i They represent the inverter start-up voltage and droop slope of the bidirectional converter added in the i-th traction station, U stN and k N They are respectively the inverter start-up voltage and the droop slope of the bidirectional converter added in the Nth traction station, i=1,2,3,...,N.

4. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 1, characterized in that: The circuit topology is constructed by combining the position and power information of the train at each time and the location and characteristic scheme of the bidirectional converter, which is specifically as follows: The train is regarded as a power source node, and its position at different times is different, which determines the connection scheme and connection impedance of each power source node; the traction depot is regarded as a voltage node, and the rectifier traction depot is transformed into a hybrid traction depot after adding a bidirectional converter, which has both inverter and rectifier functions. The characteristics of the hybrid traction depot are obtained by the parallel equivalent circuit of the droop characteristics of the rectifier and the inverter start-up voltage and droop characteristic parameters of the bidirectional converter.

5. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 4, characterized in that: The power flow solution is specifically as follows: The node voltage equation is constructed based on the circuit topology, and the power flow iteration is performed based on the Newton-Raphson method or Gauss-Seidel method to obtain the voltage and power information of each node. This process is called power flow settlement. The power of the substation at each moment is calculated based on the node voltage matrix power flow of the circuit topology, which is expressed as: Where, f represents the power flow calculation process, P train (t) represents the power information of all trains on the line at time t, S train (t) represents the location information of all trains on the line at time t, Sub(X) represents the location and characteristic scheme information of adding bidirectional converters, and They represent the power information of traction station i, the power information and position information of train k at time t, respectively. and They respectively represent the power information of traction station N, the power information and position information of train K at time t.

6. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 1, characterized in that: The expression of the train operation electricity cost is as follows: Among them, C ele represents the electricity cost of train operation per day, c e (t) represents the unit price of electricity, P sub (t) represents the power of the substation at time t, t0 and t f They respectively represent the start and end times of the train’s daily operations.

7. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 1, characterized in that: The expressions for the construction and maintenance costs are as follows: Among them, C BC represents the average daily cost of construction and maintenance of additional bidirectional converters, N' represents the number of additional bidirectional converters, c1 and c2 represent the construction and annual maintenance unit price of a single bidirectional converter, Y represents the service life cycle of the bidirectional converter, and γ represents the annual economic expansion rate.

8. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 1, characterized in that: The expression of the objective function of the optimization model is as follows: J=min(C ele +C BC ) Among them, J represents the objective function of the optimization model, C ele represents the electricity cost of train operation per day, C BC It represents the average daily cost of construction and maintenance of additional bidirectional converters, and min represents the minimum value.

9. The method for coordinated optimization of bidirectional converter site selection and characteristics according to claim 5, characterized in that: The constraint condition of the optimization model is that the value range of the decision variable is expressed as: Among them, U stmin and U stmax They represent the minimum and maximum values ​​of the inverter start-up voltage of the bidirectional converter, k min and k max Respectively represent the minimum and maximum values ​​of the droop slope, x i Indicates whether to add a bidirectional converter to the i-th traction station, k i represents the droop slope of the bidirectional converter added in the i-th traction station, U sti It represents the inverter start-up voltage of the bidirectional converter added in the i-th traction station.

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