A method, device, equipment and medium for optimizing operation of a flexible interconnected distribution network

Abstract

This invention relates to a method, apparatus, equipment, and medium for optimizing the operation of a flexible interconnected distribution network. The method includes: approximating the nonlinear power flow calculation equations of the AC portion of the AC / DC distribution network to construct a DC power flow model for the AC portion; approximating the nonlinear power flow calculation equations of the DC portion of the AC / DC distribution network to construct a DC power flow model for the DC portion; constructing an optimized operation model for the flexible interconnected distribution network, with the goal of minimizing network losses and using the DC power flow models of the AC and DC portions as constraints; solving the optimized operation model to obtain an optimized operation scheme for the flexible interconnected distribution network; and controlling the operation of the flexible interconnected distribution network using the optimized operation scheme. This invention avoids cone relaxation of large-scale nonlinear constraints, improving the efficiency of optimization calculations.

Description

Technical Field

[0001] This invention relates to the field of power distribution network planning and optimization scheduling technology, and in particular to a method, apparatus, equipment and medium for optimizing the operation of a flexible interconnected power distribution network. Background Technology

[0002] As a new form of distribution network, AC / DC flexible interconnected distribution networks have potential advantages in power supply modes for new energy sources and new DC loads. Flexible interconnected devices (FIDs), as a new type of distribution equipment, play a crucial role in enhancing the new energy carrying capacity of AC / DC interconnected distribution networks and have received widespread attention in low-voltage systems of distribution networks. FIDs, as flexible interconnected devices, aim to replace traditional circuit breaker tie switches with controllable power electronic equipment to achieve flexible connections between feeders, providing high-efficiency control and power flow optimization.

[0003] Currently, the optimal scheduling of existing flexible interconnected switches typically requires first predicting the power output of the distribution network's source loads, and then establishing a model with optimization objectives such as maximizing the capacity of new energy connections and minimizing network losses, based on the distribution network topology and the operating characteristics of the physical equipment within the network. The decision variables of this model include not only the connection location of the flexible interconnected switches (0-1 variables) and their connection capacity (integer variables), but also the operating power of the connected equipment (continuous variables). Furthermore, the power balance constraint in this model is a non-convex nonlinear constraint. There are two existing methods for handling this nonlinear constraint: 1) piecewise linearization, which uses piecewise linearization to obtain an approximate optimal solution for the high-order non-convex model; 2) second-order cone relaxation, which transforms the model into a second-order cone programming model for solution. Linearization methods generally decouple nonlinear power flow by relaxing constraints, achieving good results in relatively simple application scenarios, but often altering the physical meaning of the power flow and making it difficult to guarantee the feasibility of the solution domain. The second-order cone relaxation method requires setting an appropriate objective function to drive the relaxation to gradually "tighten" towards the optimal solution. However, it has stringent relaxation conditions, low versatility, and poor convergence. As the scale of the distribution network increases, the relaxation of numerous constraints will significantly impact the model's solution speed, making it unsuitable for rapid optimization solutions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method, device, equipment and medium for optimizing the operation of a flexible interconnected distribution network, which can avoid cone relaxation of large-scale nonlinear constraints and improve the efficiency of optimization calculation.

[0005] The technical solution adopted by this invention to solve its technical problem is: to provide a method for optimizing the operation of a flexible interconnected distribution network, comprising the following steps:

[0006] The nonlinear power flow calculation equations of the AC part of the AC / DC distribution network are approximated and linearized to construct the DC power flow model of the AC part.

[0007] The nonlinear power flow calculation equations of the DC portion of the AC / DC distribution network are approximated and linearized to construct a DC power flow model for the DC portion.

[0008] With the goal of minimizing network losses in the flexible interconnected distribution network, and constrained by the DC power flow models of the AC and DC components, an optimized operation model for the flexible interconnected distribution network is constructed.

[0009] The optimized operation model of the flexible interconnected distribution network is solved to obtain the optimized operation scheme of the flexible interconnected distribution network;

[0010] The flexible interconnected distribution network is controlled to operate using the optimized operation scheme of the flexible interconnected distribution network.

[0011] The DC power flow model of the AC section is expressed as: ΔS = A s ·ΔV, where ΔS is the node injected power correction vector, ΔV is the correction vector for the node voltage magnitude reference value vector, and A s =diag[Y + V b ]+diag[V b ]Y + V b Y is the reference vector for the node voltage magnitude. + Let be the admittance matrix.

[0012] The DC power flow model of the DC section is expressed as: P L =B s ·V, where P L B is the active power vector of the DC line. s V is a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages.

[0013] The objective function of the optimized operation model for the flexible interconnected distribution network is: Where f is the objective function of the flexible interconnected distribution network optimization operation model, T is the number of daily sampling points within the optimization period, and N is the objective function of the flexible interconnected distribution network optimization operation model. L R is the sum of AC and DC distribution network lines. ij Let I be the resistance value of branch ij. ij,t Let N be the effective value of the current in branch ij at time t. SOP This refers to the number of flexible interconnection switches connected in the distribution network. Let be the active power loss value of the i′-th flexible interconnection switch at time t.

[0014] The constraints of the optimized operation model of the flexible interconnected distribution network include: operation constraints of flexible interconnected switches, operation constraints of voltage source converter stations, line power flow constraints based on the DC power flow model of the AC part, node voltage constraints based on the DC power flow model of the AC part, line power flow constraints based on the DC power flow model of the DC part, and node voltage constraints based on the DC power flow model of the DC side.

[0015] The operational constraints of the flexible interconnection switch are expressed as follows: in, Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the active power transmitted at time t between the flexible interconnection switch and node j. Let be the active power loss value of the port connected to node i by the flexible interconnection switch at time t. Let t be the active power loss value of the port connected to node j by the flexible interconnection switch; Let be the converter loss factor of the flexible interconnection switch connected at node i. Let be the converter loss factor of the flexible interconnection switch connected at node j. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. σ is the reactive power transmitted at time t by the port connected to node j by the flexible interconnection switch; i σ represents the operating status of the flexible interconnection switch connected at node i. j A represents the operating status of the flexible interconnection switch connected at node j. N N is the set of AC nodes in an AC / DC distribution network. SOP This refers to the number of flexible interconnection switches connected in the distribution network.

[0016] The operating constraints of the voltage source converter station are expressed as follows: Among them, S i,VSC This represents the rated apparent power of the voltage source converter station at node i; and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. R represents the active power flowing out of the DC side of the voltage source converter station at time t; i,VSC and X i,VSC V represents the equivalent resistance and reactance of the voltage source converter station at node i, respectively; k,t and V i,t Let represent the square of the effective voltage value at port k of the voltage source converter station at time t and the square of the effective voltage value at node i, respectively.

[0017] The line power flow constraints of the DC power flow model based on the AC component are expressed as follows: The nodal voltage constraints of the DC power flow model based on the AC component are expressed as follows: Among them, P ji,t and Q ji,t B represents the active power and reactive power flowing through branch ij at time t, respectively; i A is the set of child nodes of node i. N It is the set of AC nodes in an AC / DC distribution network; and These represent the injected active power and reactive power at node i, respectively. and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. Let be the reactive power of the load at node i at time t; ΔS is the node injected power correction vector; and ΔV is the correction vector for the node voltage amplitude reference value vector. V b Y is the reference vector for the node voltage magnitude. + Here is the admittance matrix; ΔS i,t Inject a power correction amount into node i. and These are the reference values ​​for the voltage amplitudes at nodes i and j, respectively. V is an element of the admittance matrix. ui_A and V li_A These are the upper and lower voltage limits for node i, ΔV. i,t This is the correction amount for the voltage amplitude reference value at node i.

[0018] The line power flow constraints of the DC power flow model based on the DC component are expressed as follows: The node voltage constraint based on the DC-side DC power flow model is expressed as follows: Among them, P ji,t B represents the power flowing through branch ij at time t; i D is the set of child nodes of node i. N It is the set of DC nodes in an AC / DC distribution network. Inject active power into node i; and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. P represents the active power flowing out of the DC side of the voltage source converter station at time t. LB is the active power vector of the DC line. s V is the inverse of a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages. ui_D and V li_D These are the upper and lower voltage limits for node i, respectively.

[0019] The technical solution adopted by this invention to solve its technical problem is: to provide a flexible interconnected distribution network optimized operation device, comprising:

[0020] The AC component construction module is used to approximate the linearization of the nonlinear power flow calculation equations of the AC component of the AC / DC distribution network and construct the DC power flow model of the AC component.

[0021] The DC component construction module is used to approximate the linearization of the nonlinear power flow calculation equations of the DC component of the AC / DC distribution network and construct the DC power flow model of the DC component.

[0022] The operation model construction module is used to construct an optimized operation model for the flexible interconnected distribution network with the goal of minimizing network losses and with the DC power flow models of the AC and DC components as constraints.

[0023] The solution module is used to solve the optimized operation model of the flexible interconnected distribution network to obtain the optimized operation scheme of the flexible interconnected distribution network.

[0024] The control module is used to control the operation of the flexible interconnected distribution network according to the optimized operation scheme of the flexible interconnected distribution network.

[0025] The DC power flow model of the AC section constructed by the AC section construction module is expressed as: ΔS=A s ·ΔV, where ΔS is the node injected power correction vector, ΔV is the correction vector for the node voltage magnitude reference value vector, and A s =diag[Y + V b ]+diag[V b ]Y + V b Y is the reference vector for the node voltage magnitude. + Let be the admittance matrix.

[0026] The DC power flow model of the DC section constructed by the DC section construction module is represented as: P L =B s ·V, where P L B is the active power vector of the DC line. s V is a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages.

[0027] The objective function of the optimized operation model for the flexible interconnected distribution network constructed by the operation model construction module is: Where f is the objective function of the flexible interconnected distribution network optimization operation model, T is the number of daily sampling points within the optimization period, and N is the objective function of the flexible interconnected distribution network optimization operation model. L R is the sum of AC and DC distribution network lines. ij Let I be the resistance value of branch ij. ij,t Let N be the effective value of the current in branch ij at time t. SOP This refers to the number of flexible interconnection switches connected in the distribution network. Let be the active power loss value of the i′-th flexible interconnection switch at time t.

[0028] The constraints of the optimized operation model of the flexible interconnected distribution network constructed by the operation model construction module include: operation constraints of flexible interconnected switches, operation constraints of voltage source converter stations, line power flow constraints based on the DC power flow model of the AC part, node voltage constraints based on the DC power flow model of the AC part, line power flow constraints based on the DC power flow model of the DC part, and node voltage constraints based on the DC power flow model of the DC side.

[0029] The operational constraints of the flexible interconnection switch are expressed as follows: in, Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the active power transmitted at time t between the flexible interconnection switch and node j. Let be the active power loss value of the port connected to node i by the flexible interconnection switch at time t. Let t be the active power loss value of the port connected to node j by the flexible interconnection switch; Let be the converter loss factor of the flexible interconnection switch connected at node i. Let be the converter loss factor of the flexible interconnection switch connected at node j. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. σ is the reactive power transmitted at time t by the port connected to node j by the flexible interconnection switch; i σ represents the operating status of the flexible interconnection switch connected at node i. j A represents the operating status of the flexible interconnection switch connected at node j. N N is the set of AC nodes in an AC / DC distribution network. SOP This refers to the number of flexible interconnection switches connected in the distribution network.

[0030] The operating constraints of the voltage source converter station are expressed as follows: Among them, S i,VSC This represents the rated apparent power of the voltage source converter station at node i; and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. R represents the active power flowing out of the DC side of the voltage source converter station at time t; i,VSC and X i,VSC V represents the equivalent resistance and reactance of the voltage source converter station at node i, respectively; k,t and V i,t Let represent the square of the effective voltage value at port k of the voltage source converter station at time t and the square of the effective voltage value at node i, respectively.

[0031] The line power flow constraints of the DC power flow model based on the AC component are expressed as follows: The nodal voltage constraints of the DC power flow model based on the AC component are expressed as follows: Among them, P ji,t and Q ji,t B represents the active power and reactive power flowing through branch ij at time t, respectively; i A is the set of child nodes of node i. N It is the set of AC nodes in an AC / DC distribution network; and These represent the injected active power and reactive power at node i, respectively. and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. Let be the reactive power of the load at node i at time t; ΔS is the node injected power correction vector; and ΔV is the correction vector of the node voltage magnitude reference value vector. V b Y is the reference vector for the node voltage magnitude. + Here is the admittance matrix; ΔS i,t Inject a power correction amount into node i. and These are the reference values ​​for the voltage amplitudes at nodes i and j, respectively. V is an element of the admittance matrix. ui_A and V li_A These are the upper and lower voltage limits for node i, ΔV. i,t This is the correction amount for the voltage amplitude reference value at node i.

[0032] The line power flow constraints of the DC power flow model based on the DC component are expressed as follows: The node voltage constraint based on the DC-side DC power flow model is expressed as follows: Among them, P ji,t B represents the power flowing through branch ij at time t; i D is the set of child nodes of node i. N It is the set of DC nodes in an AC / DC distribution network. Inject active power into node i; and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. P represents the active power flowing out of the DC side of the voltage source converter station at time t. L B is the active power vector of the DC line. s V is the inverse of a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages. ui_D and V li_D These are the upper and lower voltage limits for node i, respectively.

[0033] The technical solution adopted by the present invention to solve its technical problem is: to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-mentioned flexible interconnected distribution network optimization operation method.

[0034] The technical solution adopted by the present invention to solve its technical problem is: to provide a computer-readable storage medium on which a computer program is stored, wherein the computer program, when executed by a processor, implements the steps of the above-mentioned flexible interconnected distribution network optimized operation method.

[0035] Beneficial effects

[0036] By adopting the above-mentioned technical solution, this invention has the following advantages and positive effects compared with the prior art: This invention establishes approximate linear power flow equations for both the AC and DC components of the AC / DC distribution network, forming a unified DC model. This unified DC model serves as a constraint for the optimized operation of the flexible interconnected distribution network, thereby transforming the original nonlinear, non-convex optimization model into an approximate mixed-integer linear programming model. This avoids cone relaxation of large-scale nonlinear constraints, eliminates convergence issues, and improves the computational efficiency of the optimization algorithm. This invention compensates for the shortcomings of other current methods for optimizing the operation of flexible interconnected equipment, facilitating a more comprehensive and in-depth exploration of the role of flexible interconnected equipment in the distribution network, enhancing the flexibility of the distribution system, improving power quality, and providing a reliable reference for subsequent distribution network upgrades and transformations. Attached Figure Description

[0037] Figure 1 This is a flowchart of the first embodiment of the flexible interconnected distribution network optimization operation method of the present invention;

[0038] Figure 2 This is a topology diagram of the AC / DC flexible interconnected distribution network in the first embodiment of the present invention. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0040] The first embodiment of the present invention relates to a method for optimizing the operation of a flexible interconnected distribution network, which can be applied to, for example... Figure 2 The AC / DC flexible interconnected distribution network shown firstly has DC power flow models for the AC part and DC power flow models for the DC part. Secondly, these DC power flow models are used as constraints for the optimized operation model of the flexible interconnected distribution network. This transforms the original nonlinear nonconvex optimization configuration model into an approximate mixed integer linear programming model, thereby avoiding cone relaxation of large-scale nonlinear constraints and improving solution efficiency and accuracy.

[0041] like Figure 1 As shown, the optimized operation method for flexible interconnected distribution networks in this embodiment specifically includes the following steps:

[0042] Step 1: Approximate the linearization of the nonlinear power flow calculation equations of the AC part of the AC / DC distribution network to construct the DC power flow model of the AC part.

[0043] In this step, for a radial low-voltage AC distribution network, the voltage phase of each node can be calculated by substituting the active and reactive power of each branch of the distribution network back into the following linear equation:

[0044]

[0045] Among them, P ij and Q ij These represent the active power and reactive power flowing through the branch, respectively; θ i and θ j Let θi and θj be the voltage phase angles at nodes i and j, respectively, and θ0 be the phase angle of the source node; r ij and x ij These are the resistance and reactance of branch ij, respectively.

[0046] Furthermore, the voltage at node i and the system admittance matrix are expressed in the following form:

[0047]

[0048] Among them, V i b Let ΔV be the reference value for the voltage amplitude at node i. i θ represents the correction amount for the voltage amplitude reference value at node i; θ is an N-order phase angle difference matrix, in which elements... N-order square matrix Y + Inner element y ij The coefficients are the system admittance matrix coefficients.

[0049] Substituting the above equation into the conventional power flow equations of a distribution network and neglecting second-order minor quantities, we obtain the following equation:

[0050]

[0051] Among them, V b Let be the reference vector for node voltage amplitude, and ΔV be the correction vector for the reference vector; S be the node injected power vector, and ΔS be the correction vector for the node injected power. Also, because diag[Y] + ·V b ]·ΔV=diag[ΔV]·Y + ·V b Substituting into the above equation, we can obtain the DC power flow model for the AC component:

[0052] ΔS=A s ·ΔV;

[0053] In the formula, A s =diag[Y + V b ]+diag[V b ]Y + The real part of the above-mentioned node voltage correction is taken as the correction amount of the actual voltage, thereby obtaining the amplitude and phase of the voltage at each node of the distribution network.

[0054] Step 2: Approximate the linearization of the nonlinear power flow calculation equations of the DC part of the AC / DC distribution network to construct the DC power flow model of the DC part.

[0055] Based on the injected power at each node of the DC distribution network and the network topology, and ignoring active and reactive power losses, the active power of each DC branch can be calculated using the following formula:

[0056]

[0057] Where: P ij P represents the active power flowing through the branch. jjLet k ∈ j represent the injected active power; k ∈ j indicates that node k is one of the child nodes of node j. Then, the active power of each branch can be recursively calculated using the above formula. Based on the active power distribution of the branches, the voltage amplitude of each node can be calculated by substituting the following equation back into the equation:

[0058]

[0059] Where: U i and U j I represents the voltage magnitudes at node i and node j, respectively; ij R represents the current flowing through branch ij; ij Uij represents the resistance value of branch ij. U0 represents the voltage amplitude of the DC grid source node, and its value is related to the reference value Uij of the DC port voltage of the converter station at that location. ref Consistent.

[0060] To establish a DC power flow model, we first introduce two intermediate variables to replace the squared terms in the above equation, and ignore second-order minor quantities, transforming it into first-order terms, as shown in the following equation:

[0061]

[0062] In the formula, the intermediate variable V i and V j Let represent the squares of the voltage magnitudes at nodes i and j, respectively. Finally, the power flow model of the DC branch in the DC distribution network is as follows:

[0063] P L =B s ·V;

[0064] In the formula: B s P is a constant matrix related to network topology and line resistance. L V is the vector of active power of the DC line, and V is the vector of the square of the DC node voltage magnitude.

[0065] Step 3: With the goal of minimizing network losses in the flexible interconnected distribution network, and with the DC power flow models of the AC and DC components as constraints, construct an optimized operation model for the flexible interconnected distribution network.

[0066] Optimizing the power flow of AC / DC distribution networks using flexible interconnection switches helps improve the economic efficiency of distribution network operation and the capacity for renewable energy absorption. However, the traditional AC / DC distribution network power flow optimization model is a non-convex nonlinear model. In order to improve the solution speed and convergence of the model, based on the above AC distribution network DC branch power flow model and DC distribution network DC branch power flow model, the nonlinear constraints of the traditional optimization model are transformed into approximately linear constraints.

[0067] The objective function of the flexible interconnected distribution network optimization operation model constructed in this step is:

[0068]

[0069] Where f is the objective function of the flexible interconnected distribution network optimization operation model, T is the number of daily sampling points within the optimization period, and N is the objective function of the flexible interconnected distribution network optimization operation model. L R is the sum of AC and DC distribution network lines. ij Let I be the resistance value of branch ij. ij,t Let N be the effective value of the current in branch ij at time t. SOP This refers to the number of flexible interconnection switches connected in the distribution network. Let be the active power loss value of the i′-th flexible interconnection switch at time t.

[0070] The constraints of the flexible interconnected distribution network optimization operation model constructed in this step include: flexible interconnection switch operation constraints, voltage source converter station operation constraints, line power flow constraints based on the AC part of the DC power flow model, node voltage constraints based on the AC part of the DC power flow model, line power flow constraints based on the DC part of the DC power flow model, and node voltage constraints based on the DC side DC power flow model.

[0071] The Flexible Interconnect Switch (SOP) aims to replace traditional feeder tie switches with controllable power electronic converters, thereby achieving a normalized flexible soft connection between feeders. It provides flexible, fast, and precise power exchange control and power flow optimization capabilities. This implementation uses a back-to-back voltage source type SOP as the modeling object, and the SOP operating constraints are expressed as follows:

[0072]

[0073] in, Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the active power transmitted at time t between the flexible interconnection switch and node j. Let be the active power loss value of the port connected to node i by the flexible interconnection switch at time t. Let t be the active power loss value of the port connected to node j by the flexible interconnection switch; Let be the converter loss factor of the flexible interconnection switch connected at node i. Let be the converter loss factor of the flexible interconnection switch connected at node j. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. σ is the reactive power transmitted at time t by the port connected to node j by the flexible interconnection switch; i σ represents the operating status of the flexible interconnection switch connected at node i. j This represents the operating status of the flexible interconnection switch connected at node j, and is a 0-1 variable. A value of 0 indicates that the SOP is not operating, and a value of 1 indicates that it is operating.N N is the set of AC nodes in an AC / DC distribution network. SOP This refers to the number of flexible interconnection switches connected in the distribution network.

[0074] A voltage source converter station (VSC) is the connection point of AC / DC lines. Ignoring the VSC's own losses, its simplified constraints include capacity constraints and line power constraints. Therefore, the VSC operating constraints are expressed as:

[0075]

[0076] Among them, S i,VSC This represents the rated apparent power of the voltage source converter station at node i; and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. R represents the active power flowing out of the DC side of the voltage source converter station at time t; i,VSC and X i,VSC V represents the equivalent resistance and reactance of the voltage source converter station at node i, respectively; k,t and V i,t Let represent the squares of the effective voltage at port k of the voltage source converter station at time t and the squares of the effective voltage at node i, respectively; i is an AC node, i∈A. N j is a DC node, j∈D N k is the VSC AC port node.

[0077] The line power flow constraints based on the AC portion of the DC power flow model are expressed as follows:

[0078]

[0079] In the formula, P ji,t and Q ji,t B represents the active power and reactive power flowing through branch ij at time t, respectively; i It is the set of child nodes of node i, where i is a communication node, i∈A N ; and These represent the injected active power and reactive power at node i, respectively. and These represent the active power of distributed renewable energy sources and loads at node i at time t, respectively. Let be the reactive power of the load at node i at time t. The other parameters are the same as above.

[0080] The nodal voltage constraints of the DC power flow model based on the AC component are expressed as follows:

[0081]

[0082] Among them, Vui_A and V li_A These are the upper and lower voltage limits for node i, respectively; and Here, ΔV represents the reference values ​​for the voltage amplitudes at nodes i and j, respectively. i,t ΔS is the correction amount for the voltage amplitude reference value at node i. i,t ΔS is the correction amount for the injected power at node i; ΔS is the correction vector for the injected power at node i, and ΔV is the correction vector for the reference value vector of the node voltage magnitude. Matrix A s Determined by the system admittance matrix, The parameters and voltage values ​​in the voltage constraints mentioned above are calculated using the approximate DC power flow equations in the AC section.

[0083] The line power flow constraints based on the DC power flow model of the DC component are expressed as follows:

[0084]

[0085] Among them, P ji,t B represents the power flowing through branch ij at time t; i It is the set of child nodes of node i, where i is a DC node, i∈D N ; Inject active power into node i. and These represent the active power of distributed renewable energy sources and loads at node i at time t, respectively; the other parameters are the same as above.

[0086] The nodal voltage constraint based on the DC power flow model on the DC side is expressed as:

[0087]

[0088] In the formula, V ui_D and V li_D These are the upper and lower voltage limits for node i, respectively; V i P represents the voltage magnitude at node i; V is the vector of the squared DC node voltage magnitudes; P represents the voltage magnitude at node i. L This represents the active power vector of a DC line. Matrix B s The inverse of the constant matrix related to network topology and line resistance is determined by the system admittance matrix. The parameters and voltage values ​​in the voltage constraints above are calculated using the approximate DC power flow equations in the DC section.

[0089] Step 4: Solve the optimized operation model of the flexible interconnected distribution network to obtain the optimized operation scheme of the flexible interconnected distribution network;

[0090] Step 5: Control the operation of the flexible interconnected distribution network using the optimized operation scheme of the flexible interconnected distribution network.

[0091] It is easy to see that this invention establishes approximate linear power flow equations for both the AC and DC components of an AC / DC distribution network, forming a unified DC model. This unified DC model serves as a constraint for the optimized operation of the flexible interconnected distribution network, thereby transforming the original nonlinear, nonconvex optimization model into an approximate mixed-integer linear programming model. This avoids cone relaxation of large-scale nonlinear constraints, eliminates convergence issues, and improves the computational efficiency of the optimization algorithm. This invention addresses the shortcomings of other current methods for optimizing the operation of flexible interconnected equipment, facilitating a more comprehensive and in-depth exploration of the role of flexible interconnected equipment in the distribution network, enhancing the flexibility of the distribution system, improving power quality, and providing a reliable reference for subsequent distribution network upgrades and transformations.

[0092] The second embodiment of the present invention relates to a flexible interconnected distribution network optimized operation device, comprising:

[0093] The AC component construction module is used to approximate the linearization of the nonlinear power flow calculation equations of the AC component of the AC / DC distribution network and construct the DC power flow model of the AC component.

[0094] The DC component construction module is used to approximate the linearization of the nonlinear power flow calculation equations of the DC component of the AC / DC distribution network and construct the DC power flow model of the DC component.

[0095] The operation model construction module is used to construct an optimized operation model for the flexible interconnected distribution network with the goal of minimizing network losses and with the DC power flow models of the AC and DC components as constraints.

[0096] The solution module is used to solve the optimized operation model of the flexible interconnected distribution network to obtain the optimized operation scheme of the flexible interconnected distribution network.

[0097] The control module is used to control the operation of the flexible interconnected distribution network according to the optimized operation scheme of the flexible interconnected distribution network.

[0098] The DC power flow model of the AC section constructed by the AC section construction module is expressed as: ΔS=A s ·ΔV, where ΔS is the node injected power correction vector, ΔV is the correction vector for the node voltage magnitude reference value vector, and A s =diag[Y + V b ]+diag[V b ]Y + V b Y is the reference vector for the node voltage magnitude. + Let be the admittance matrix.

[0099] The DC power flow model of the DC section constructed by the DC section construction module is represented as: P L =B s·V, where P L B is the active power vector of the DC line. s V is a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages.

[0100] The objective function of the optimized operation model for the flexible interconnected distribution network constructed by the operation model construction module is: Where f is the objective function of the flexible interconnected distribution network optimization operation model, T is the number of daily sampling points within the optimization period, and N is the objective function of the flexible interconnected distribution network optimization operation model. L R is the sum of AC and DC distribution network lines. ij Let I be the resistance value of branch ij. ij,t Let N be the effective value of the current in branch ij at time t. SOP This refers to the number of flexible interconnection switches connected in the distribution network. Let be the active power loss value of the i′-th flexible interconnection switch at time t.

[0101] The constraints of the optimized operation model of the flexible interconnected distribution network constructed by the operation model construction module include: operation constraints of flexible interconnected switches, operation constraints of voltage source converter stations, line power flow constraints based on the DC power flow model of the AC part, node voltage constraints based on the DC power flow model of the AC part, line power flow constraints based on the DC power flow model of the DC part, and node voltage constraints based on the DC power flow model of the DC side.

[0102] The operational constraints of the flexible interconnection switch are expressed as follows: in, Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the active power transmitted at time t between the flexible interconnection switch and node j. Let be the active power loss value of the port connected to node i by the flexible interconnection switch at time t. Let t be the active power loss value of the port connected to node j by the flexible interconnection switch; Let be the converter loss factor of the flexible interconnection switch connected at node i. Let be the converter loss factor of the flexible interconnection switch connected at node j. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. σ is the reactive power transmitted at time t by the port connected to node j by the flexible interconnection switch; i σ represents the operating status of the flexible interconnection switch connected at node i. j A represents the operating status of the flexible interconnection switch connected at node j. N N is the set of AC nodes in an AC / DC distribution network. SOP This refers to the number of flexible interconnection switches connected in the distribution network.

[0103] The operating constraints of the voltage source converter station are expressed as follows: Among them, S i,VSC This represents the rated apparent power of the voltage source converter station at node i; and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. R represents the active power flowing out of the DC side of the voltage source converter station at time t; i,VSC and X i,VSC V represents the equivalent resistance and reactance of the voltage source converter station at node i, respectively; k,t and V i,t Let represent the square of the effective voltage value at port k of the voltage source converter station at time t and the square of the effective voltage value at node i, respectively.

[0104] The line power flow constraints of the DC power flow model based on the AC component are expressed as follows: The nodal voltage constraints of the DC power flow model based on the AC component are expressed as follows: Among them, P ji,t and Q ji,t B represents the active power and reactive power flowing through branch ij at time t, respectively; i A is the set of child nodes of node i. N It is the set of AC nodes in an AC / DC distribution network; and These represent the injected active power and reactive power at node i, respectively. and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. Let be the reactive power of the load at node i at time t; ΔS is the node injected power correction vector; and ΔV is the correction vector for the node voltage amplitude reference value vector. V b Y is the reference vector for the node voltage magnitude. + Here is the admittance matrix; ΔS i,t Inject a power correction amount into node i. and These are the reference values ​​for the voltage amplitudes at nodes i and j, respectively. V is an element of the admittance matrix. ui_A and Vli_A These are the upper and lower voltage limits for node i, ΔV. i,t This is the correction amount for the voltage amplitude reference value at node i.

[0105] The line power flow constraints of the DC power flow model based on the DC component are expressed as follows: The node voltage constraint based on the DC-side DC power flow model is expressed as follows: Among them, P ji,t B represents the power flowing through branch ij at time t; i D is the set of child nodes of node i. N It is the set of DC nodes in an AC / DC distribution network. Inject active power into node i; and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. P represents the active power flowing out of the DC side of the voltage source converter station at time t. L B is the active power vector of the DC line. s V is the inverse of a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages. ui_D and V li_D These are the upper and lower voltage limits for node i, respectively.

[0106] The third embodiment of the present invention relates to an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the flexible interconnected distribution network optimization operation method of the first embodiment.

[0107] The fourth embodiment of the present invention relates to a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the flexible interconnected distribution network optimization operation method of the first embodiment.

[0108] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0109] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0110] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction methods implemented in a process. Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0111] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0112] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for optimizing the operation of a flexible interconnected distribution network, characterized in that, Includes the following steps: The nonlinear power flow calculation equations of the AC portion of the AC / DC distribution network are approximated and linearized to construct a DC power flow model for the AC portion; the DC power flow model for the AC portion is expressed as: ΔS=A s ·ΔV, where ΔS is the node injected power correction vector, and ΔV is the correction vector for the node voltage magnitude reference value vector. A s =diag[Y + V b ]+diag[V b ]Y + V b Y is the reference vector for the node voltage magnitude. + Here is the admittance matrix; The nonlinear power flow calculation equations of the DC portion of the AC / DC distribution network are approximated and linearized to construct a DC power flow model for the DC portion; the DC power flow model for the DC portion is expressed as: P L =B s ·V, where P L B is the active power vector of the DC line. s V is a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages. With the goal of minimizing network losses in the flexible interconnected distribution network, and constrained by the DC power flow models of the AC and DC components, an optimized operation model for the flexible interconnected distribution network is constructed. The objective function of this optimized operation model is: Where f is the objective function of the flexible interconnected distribution network optimization operation model, T is the number of daily sampling points within the optimization period, and N is the objective function of the flexible interconnected distribution network optimization operation model. L R is the sum of AC and DC distribution network lines. ij Let I be the resistance value of branch ij. ij,t Let N be the effective value of the current in branch ij at time t. SOP This refers to the number of flexible interconnection switches connected in the distribution network. Let be the active power loss value of the i′-th flexible interconnection switch at time t; the constraints of the flexible interconnection distribution network optimization operation model include: flexible interconnection switch operation constraints, voltage source converter station operation constraints, line power flow constraints based on the AC part of the DC power flow model, node voltage constraints based on the AC part of the DC power flow model, line power flow constraints based on the DC part of the DC power flow model, and node voltage constraints based on the DC side DC power flow model; the voltage source converter station operation constraints are expressed as: Among them, S i,VSC This represents the rated apparent power of the voltage source converter station at node i; and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. R represents the active power flowing out of the DC side of the voltage source converter station at time t; i,VSC and X i,VSC V represents the equivalent resistance and reactance of the voltage source converter station at node i, respectively; k,t and V i,t Let represent the square of the effective voltage value at port k of the voltage source converter station at time t and the square of the effective voltage value at node i, respectively. The optimized operation model of the flexible interconnected distribution network is solved to obtain the optimized operation scheme of the flexible interconnected distribution network; The flexible interconnected distribution network is controlled to operate using the optimized operation scheme of the flexible interconnected distribution network.

2. The method for optimizing the operation of a flexible interconnected distribution network according to claim 1, characterized in that, The operational constraints of the flexible interconnection switch are expressed as follows: in, Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the active power transmitted at time t between the flexible interconnection switch and node j. Let be the active power loss value of the port connected to node i by the flexible interconnection switch at time t. Let t be the active power loss value of the port connected to node j by the flexible interconnection switch; Let be the converter loss factor of the flexible interconnection switch connected at node i. Let be the converter loss factor of the flexible interconnection switch connected at node j. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. σ is the reactive power transmitted at time t by the port connected to node j by the flexible interconnection switch; i σ represents the operating status of the flexible interconnection switch connected at node i. j A represents the operating status of the flexible interconnection switch connected at node j. N N is the set of AC nodes in an AC / DC distribution network. SOP This refers to the number of flexible interconnection switches connected in the distribution network.

3. The method for optimizing the operation of a flexible interconnected distribution network according to claim 1, characterized in that, The line power flow constraints of the DC power flow model based on the AC component are expressed as follows: The nodal voltage constraints of the DC power flow model based on the AC component are expressed as follows: Among them, P ji,t and Q ji,t B represents the active power and reactive power flowing through branch ij at time t, respectively; i A is the set of child nodes of node i. N It is the set of AC nodes in an AC / DC distribution network; and These represent the injected active power and reactive power at node i, respectively. and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. Let be the reactive power of the load at node i at time t; ΔS is the node injected power correction vector; and ΔV is the correction vector for the node voltage amplitude reference value vector. V b Y is the reference vector for the node voltage magnitude. + Here is the admittance matrix; ΔS i,t Inject a power correction amount, V, into node i. i b and These are the reference values ​​for the voltage amplitudes at nodes i and j, respectively. V is an element of the admittance matrix. ui_A and V li_A These are the upper and lower voltage limits for node i, ΔV. i,t This is the correction amount for the voltage amplitude reference value at node i.

4. The method for optimizing the operation of a flexible interconnected distribution network according to claim 1, characterized in that, The line power flow constraints of the DC power flow model based on the DC component are expressed as follows: The node voltage constraint based on the DC-side DC power flow model is expressed as follows: Among them, P ji,t B represents the power flowing through branch ij at time t; i D is the set of child nodes of node i. N It is the set of DC nodes in an AC / DC distribution network. Inject active power into node i; and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. P represents the active power flowing out of the DC side of the voltage source converter station at time t. L B is the active power vector of the DC line. s V is the inverse of a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages. ui_D and V li_D These are the upper and lower voltage limits for node i, respectively.

5. A flexible interconnected distribution network optimized operation device, characterized in that, include: The AC component construction module is used to approximately linearize the nonlinear power flow calculation equations of the AC component of the AC / DC distribution network, and construct the DC power flow model of the AC component; the DC power flow model of the AC component constructed by the AC component construction module is expressed as: ΔS=A s ·ΔV, where ΔS is the node injected power correction vector, ΔV is the correction vector for the node voltage magnitude reference value vector, and A s =diag[Y+V b ]+diag[V b ]Y + V b Y is the reference vector for the node voltage magnitude. + Here is the admittance matrix; The DC power flow construction module is used to approximate the linearization of the nonlinear power flow calculation equations of the DC portion of the AC / DC distribution network, and construct the DC power flow model of the DC portion; the DC power flow model of the DC portion constructed by the DC portion construction module is expressed as: P L =B s ·V, where P L B is the active power vector of the DC line. s V is a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages. The operation model construction module is used to construct an optimized operation model for the flexible interconnected distribution network, with the goal of minimizing network losses and constrained by the DC power flow models of the AC and DC components. The objective function of the optimized operation model for the flexible interconnected distribution network constructed by the operation model construction module is: Where f is the objective function of the flexible interconnected distribution network optimization operation model, T is the number of daily sampling points within the optimization period, and N is the objective function of the flexible interconnected distribution network optimization operation model. L R is the sum of AC and DC distribution network lines. ij Let I be the resistance value of branch ij. ij,t Let N be the effective value of the current in branch ij at time t. SOP This refers to the number of flexible interconnection switches connected in the distribution network. Let be the active power loss value of the i′-th flexible interconnection switch at time t; the constraints of the flexible interconnection distribution network optimization operation model constructed by the operation model construction module include: flexible interconnection switch operation constraints, voltage source converter station operation constraints, line power flow constraints based on the AC part of the DC power flow model, node voltage constraints based on the AC part of the DC power flow model, line power flow constraints based on the DC part of the DC power flow model, and node voltage constraints based on the DC side DC power flow model; the voltage source converter station operation constraints are expressed as: Among them, S i,VSC This represents the rated apparent power of the voltage source converter station at node i; and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. R represents the active power flowing out of the DC side of the voltage source converter station at time t; i,VSC and X i,VSC V represents the equivalent resistance and reactance of the voltage source converter station at node i, respectively; k,t and V i,t Let represent the square of the effective voltage value at port k of the voltage source converter station at time t and the square of the effective voltage value at node i, respectively. The solution module is used to solve the optimized operation model of the flexible interconnected distribution network to obtain the optimized operation scheme of the flexible interconnected distribution network. The control module is used to control the operation of the flexible interconnected distribution network according to the optimized operation scheme of the flexible interconnected distribution network.

6. The flexible interconnected distribution network optimized operation device according to claim 5, characterized in that, The operational constraints of the flexible interconnection switch are expressed as follows: in, Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the active power transmitted at time t between the flexible interconnection switch and node j. Let be the active power loss value of the port connected to node i by the flexible interconnection switch at time t. Let t be the active power loss value of the port connected to node j by the flexible interconnection switch; Let be the converter loss factor of the flexible interconnection switch connected at node i. Let be the converter loss factor of the flexible interconnection switch connected at node j. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. σ is the reactive power transmitted at time t by the port connected to node j by the flexible interconnection switch; i σ represents the operating status of the flexible interconnection switch connected at node i. j A represents the operating status of the flexible interconnection switch connected at node j. N N is the set of AC nodes in an AC / DC distribution network. SOP This refers to the number of flexible interconnection switches connected in the distribution network.

7. The flexible interconnected distribution network optimized operation device according to claim 5, characterized in that, The line power flow constraints of the DC power flow model based on the AC component are expressed as follows: The nodal voltage constraints of the DC power flow model based on the AC component are expressed as follows: Among them, P ji,t and Q ji,t B represents the active power and reactive power flowing through branch ij at time t, respectively; i A is the set of child nodes of node i. N It is the set of AC nodes in an AC / DC distribution network; and These represent the injected active power and reactive power at node i, respectively. and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. Let be the active power transmitted at time t by the port connected to node i via the flexible interconnection switch. Let be the reactive power transmitted at time t by the port connected to node i via the flexible interconnection switch. and These represent the active power and reactive power injected into the AC side of the voltage source converter station at time t, respectively. Let be the reactive power of the load at node i at time t; ΔS is the node injected power correction vector; and ΔV is the correction vector for the node voltage amplitude reference value vector. V b Y is the reference vector for the node voltage magnitude. + Here is the admittance matrix; ΔS i,t Inject a power correction amount, V, into node i. i b and These are the reference values ​​for the voltage amplitudes at nodes i and j, respectively. V is an element of the admittance matrix. ui_A and V li_A These are the upper and lower voltage limits for node i, ΔV. i,t This is the correction amount for the voltage amplitude reference value at node i.

8. The flexible interconnected distribution network optimized operation device according to claim 5, characterized in that, The line power flow constraints of the DC power flow model based on the DC component are expressed as follows: The node voltage constraint based on the DC-side DC power flow model is expressed as follows: Among them, P ji,t B represents the power flowing through branch ij at time t; i D is the set of child nodes of node i. N It is the set of DC nodes in an AC / DC distribution network. Inject active power into node i; and Let be the active power of the distributed renewable energy source and the load at node i at time t, respectively. P represents the active power flowing out of the DC side of the voltage source converter station at time t. L B is the active power vector of the DC line. s V is the inverse of a constant matrix related to network topology and line resistance, and V is a vector of the squared magnitudes of DC node voltages. ui_D and V li_D These are the upper and lower voltage limits for node i, respectively.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the flexible interconnected distribution network optimization operation method as described in any one of claims 1-4.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the flexible interconnected distribution network optimization operation method as described in any one of claims 1-4.

Images