Sequential quadratic programming-based global optimization regulation and control method for flexible interconnection photovoltaic courts

Abstract

The invention discloses a flexible interconnection photovoltaic transformer area global optimization regulation and control method based on sequential quadratic programming, and the method comprises the steps: selecting a DC port of a current converter, employing a constant voltage control strategy for maintaining the voltage stability of a DC bus, and employing a constant power control strategy for the DC ports of the remaining transformer area current converters; reading data information of the transformer area, generating real-time data, and performing derivation and back substitution processes on nodes of the multi-distribution transformer area flexible interconnection system to obtain final power flow information; calculating power loss on the direct current bus by using the power transmission loss coefficient, and obtaining constraint conditions between power; and S3, optimizing the power loss in the step S3 by using an SQP optimization algorithm to obtain a power control instruction of the multi-distribution transformer area flexible interconnection system, and completing regulation and control optimization. According to the invention, the maximum consumption of photovoltaic resources is realized, and the voltage of each node is regulated and controlled to a certain extent through active-reactive coordinated voltage regulation.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network optimization control, and in particular to a global optimization control method for flexible interconnected photovoltaic stations based on sequential quadratic programming. Background Art

[0002] Distributed photovoltaic power generation is affected by many factors such as weather, season, and temperature, which makes photovoltaic power generation have obvious volatility and intermittency. This fluctuation can easily affect the voltage of the distribution network, especially when the photovoltaic output is greater than the load, which may cause the voltage to exceed the limit. The rural distribution network has a weak network structure and limited pressure resistance, so the voltage problem will be more prominent. Secondly, when the photovoltaic output is greater than the load, photovoltaic power cannot be consumed nearby and may be sent back to the surrounding loads or even the substation. When the photovoltaic capacity is too large and the substation has a phased reverse power supply, it will not only cause certain damage to the substation transformer, but also greatly increase the transmission power loss.

[0003] The current grid voltage regulation strategies can be divided into two categories: one is the conventional voltage regulation strategy without the participation of distributed power sources, which mainly achieves voltage regulation by adding reactive compensation equipment such as on-load tap-changing transformers, shunt capacitors and static reactive compensators; the other is the voltage regulation strategy with the participation of distributed power sources, the core of which is to effectively utilize the remaining capacity of the inverter and implement "active-reactive" coordinated voltage regulation. However, the reactive regulation potential of the inverter is limited by its active output, and the solution of adding reactive compensation equipment is often not suitable for rural areas due to the large initial investment and high maintenance costs. It is worth noting that the above strategies mainly focus on voltage regulation, while ignoring the in-depth development and utilization of optical resources within the substation area. Summary of the invention

[0004] The purpose of the present invention is to provide a global optimization and control method for flexible interconnected photovoltaic areas based on sequential quadratic programming, which can realize the interconnection and mutual supply of energy in the areas, improve the power supply level of the areas, reduce the risk of voltage exceeding the limit in the areas and improve the photovoltaic absorption level.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The global optimization control method of flexible interconnected photovoltaic area based on sequential quadratic programming includes the following steps:

[0007] S1. The DC port of a selected converter adopts a constant voltage control strategy to maintain the voltage stability of the DC bus, and the DC ports of the remaining converters adopt a constant power control strategy.

[0008] S2. Read the data information of the substation area, generate real-time data, and obtain the final power flow information by deducing and back-substituting the nodes of the flexible interconnection system of multiple distribution substations.

[0009] S3. Calculate the power loss on the DC bus using the power transmission loss coefficient and obtain the constraints between the powers.

[0010] S4. Use the SQP optimization algorithm to optimize the power loss in step S3, obtain the power control instructions of the flexible interconnection system of multiple distribution areas, and complete the control optimization.

[0011] Furthermore, in step S1, the converter is a voltage source converter.

[0012] Furthermore, in step S2, the data information includes transmission line impedance information, real-time load conditions and photovoltaic output conditions.

[0013] Furthermore, in step S2, the final flow information obtained includes the following contents:

[0014] According to the load power and initial voltage of the branch, the current of the node is calculated. The specific formula is:

[0015]

[0016] Among them, I i represents the current flowing into the i-th node; S i represents the complex power of the ith node; V i represents the voltage of the i-th node.

[0017] The voltage is derived from the source node to the end node, and the node voltage drop of the branch (i, j) from the i-th node to the j-th node is calculated according to Ohm's law. The specific formula is:

[0018] V j =V i -Z ij I j

[0019] Among them, Z ij represents the line impedance from the i-th node to the j-th node, I j represents the current flowing into the jth node, V j represents the voltage of the jth node.

[0020] Starting from the end node of the flexible interconnection system in the multi-distribution area, back-substitution is performed, and the current of the branch is calculated step by step to the source node. The specific formula is:

[0021]

[0022] Among them, I k represents the current flowing into the kth child node, and children of i represents the set of child nodes belonging to the i-th node.

[0023] After derivation and back substitution, check the convergence of voltage. When |V i t+1 -V i t |≤ε, the voltage change meets the convergence condition, and then the final power flow information is obtained, which includes the distribution of voltage, active power and reactive power at each node of the multi-distribution area flexible interconnection system; if the voltage change does not meet the convergence condition, the derivation and back substitution process is repeated.

[0024] Among them, V i t represents the voltage of the ith node at the tth iteration, V i t+1 represents the voltage of the i-th node at the t+1-th iteration, and ε represents the tolerance.

[0025] Furthermore, in step S3, calculating the power loss includes the following:

[0026] Assuming that there is no power loss in the AC-DC conversion of the flexible interconnection device, the power transmission loss on the DC side is calculated. The specific formula is:

[0027]

[0028] Among them, P loss1 represents the power transmission loss on the DC side, It represents the active power flowing into the AC measurement from the DC side of the u-th substation, It represents the active power flowing from the AC side to the DC side of the u-th substation, k1 represents the DC power transmission loss coefficient, and n represents the total number of substations.

[0029] The power balance equation that needs to be satisfied is:

[0030]

[0031] Based on the impedance and load data of the substation area, the transmission loss on the AC side is calculated using the forward-backward method. The specific formula is:

[0032]

[0033] Among them, P loss2 represents the AC side power transmission loss, k2 represents the AC power transmission loss coefficient, Represents the active power on the low-voltage side of the AC transformer in the u-th substation.

[0034] The active power transmitted and reactive power emitted by the flexible interconnection device have corresponding constraints, and the specific expressions are:

[0035]

[0036] Among them, Q u represents the reactive power generated by the flexible interconnection device in the u-th substation, S u Represents the capacity of the flexible interconnection device of the u-th station.

[0037] Further, in step S4, the power control instruction is obtained, including the following contents:

[0038] The objective function to be optimized is:

[0039] f(x)=P loss1 +P loss2

[0040] Where f(x) represents the total power loss of the flexible interconnection system in multiple distribution areas, that is, the objective function; P loss1 Represents the power transmission loss on the DC side; P loss2 Indicates the power transmission loss on the AC side.

[0041] In the flexible interconnection system with multiple distribution areas, the voltage of each node meets the allowable deviation of the power supply voltage. The specific expression is:

[0042] -7%V N ≤ΔV i ≤7%V N

[0043] Among them, V N Indicates the standard voltage rating, ΔV i Indicates the deviation of each node voltage from the standard voltage rating.

[0044] The objective function is optimized using the SQP algorithm. The initial point x0 is selected, the initial Hessian matrix H0 is set to the unit matrix, and the tolerance value is set. In each iteration, the kth iteration point x k Linearize the constraints and construct the quadratic programming subproblem based on the second-order Taylor expansion of the objective function. The specific formula is:

[0045]

[0046] st▽c i (x k ) T d+c i (x k )≤0

[0047] ▽h j (x k ) T d+h j (x k )=0

[0048] Where d represents the search direction, H k represents the approximate value of the Hessian matrix of the objective function f(x), ▽f(x k ) represents the gradient of the objective function at the kth iteration point, ▽c i (x k ) and ▽h j (x k ) represent the gradient of the constraint function.

[0049] The standard quadratic programming algorithm is used to solve the power command of the flexible interconnection system in multiple distribution areas, obtain the search direction, perform line search along the search direction to determine the step size, and update the iteration point. The specific formula is:

[0050] x k+1 =x k +α k d k

[0051] Among them, x k+1 represents the k+1th iteration point, α k represents the step size of the kth iteration point, d k Indicates the search direction of the kth iteration point.

[0052] Use the quasi-Newton method to update the approximate value H of the Hessian matrix at the k+1th iteration point k+1 , determine whether the step size tolerance, optimality tolerance, maximum number of function evaluations, and maximum number of iterations meet the termination conditions.

[0053] When any one of the step size tolerance, optimality tolerance, maximum number of function evaluations, and maximum number of iterations meets the conditions, the termination condition is met.

[0054] When the termination condition is met, the optimization is stopped, the current optimal solution is output, and the power control instructions of each flexible interconnection device, that is, the optimal scheduling solution, are obtained.

[0055] Furthermore, for step size tolerance, when the norm of the power instruction update step size of the flexible interconnection device is less than 1×10 -6 , then the condition is met.

[0056] For optimality tolerance, when the gradient norm of the objective function is less than 1×10 -6 When , the condition is met, and the specific expression is:

[0057] ‖▽f(x)‖<1×10 -6

[0058] Among them, ▽f(x) represents the gradient of the objective function.

[0059] For the maximum number of function evaluations, the condition is met when the number of evaluations of the objective function reaches the set number of evaluations.

[0060] For the maximum number of iterations, the condition is met when the number of iterations reaches the set number of iterations.

[0061] Furthermore, the present invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the global optimization control method of flexible interconnected photovoltaic areas based on sequential quadratic programming are implemented.

[0062] Furthermore, the present invention also proposes a computer-readable storage medium, which stores a computer program. When the computer program is run by a processor, it executes the global optimization and control method of flexible interconnected photovoltaic stations based on sequential quadratic programming.

[0063] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0064] 1. The method proposed in the present invention can achieve the maximum consumption of photovoltaic resources, while giving full play to the voltage regulation capability of the flexible interconnection device, and through the "active-reactive" coordinated voltage regulation, it plays a certain role in regulating the voltage of each node.

[0065] 2. The present invention constructs a low-voltage multi-station interconnection system model based on the line structure characteristics of the low-voltage power distribution system. At the same time, the power loss of AC and DC transmission is considered, and the power instruction setting of the flexible interconnection device is determined by the SQP optimization algorithm with the minimum loss as the optimization goal. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is an overall implementation flow chart of the present invention.

[0067] Figure 2 It is the flow chart of the SQP optimization algorithm of the present invention.

[0068] Figure 3 It is a schematic diagram of the structure of a low-voltage multi-zone system according to an embodiment of the present invention.

[0069] Figure 4 3 is a voltage distribution diagram before and after optimization of an embodiment of the present invention. DETAILED DESCRIPTION

[0070] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0071] To achieve the above objectives, the present invention proposes a global optimization control method for flexible interconnected photovoltaic areas based on sequential quadratic programming, such as Figure 1 As shown, the specific steps are as follows:

[0072] S1. The topology of the flexible interconnection system of multiple distribution areas is that the distribution area takes power from the upper power grid through a transformer, and the low-voltage side is connected to the AC port of the flexible interconnection device through an AC cable, and then connected to the DC bus through the DC port. Flexible interconnection is achieved between distribution areas through the DC bus, thereby achieving power mutual assistance between distribution areas. The DC port of a voltage source converter is selected to adopt a constant voltage (V dc The constant power (PQ) control strategy is used to maintain the voltage stability of the DC bus. The DC ports of the voltage source converters in the remaining substations adopt the constant power (PQ) control strategy to control the power interaction between the AC and DC areas within the substation and between the interconnected substations.

[0073] The voltage source converter has the advantages of low system cost and bidirectional power flow. It can realize four-quadrant instantaneous and flexible control of the power flow, meeting the needs of flexible interconnection of substations.

[0074] S2. Read the data information of the substation, including the impedance information of the transmission line, the real-time load situation and the photovoltaic output situation, generate real-time data, and obtain the final power flow information by deducing and back-substituting the nodes of the flexible interconnection system of multiple distribution substations; the specific contents are as follows:

[0075] According to the load power and initial voltage of the branch, the current of the node is calculated. The specific formula is:

[0076]

[0077] Among them, I i represents the current flowing into the i-th node; S i represents the complex power of the ith node; V i represents the voltage of the i-th node.

[0078] The voltage is derived from the source node to the end node, and the node voltage drop of the branch (i, j) from the i-th node to the j-th node is calculated according to Ohm's law. The specific formula is:

[0079] V j =V i -Z ij I j

[0080] Among them, Z ij represents the line impedance from the i-th node to the j-th node, I j represents the current flowing into the jth node, V j represents the voltage of the jth node.

[0081] Starting from the end node of the flexible interconnection system in the multi-distribution area, back-substitution is performed, and the current of the branch is calculated step by step to the source node. The specific formula is:

[0082]

[0083] Among them, I k represents the current flowing into the kth child node, and children of i represents the set of child nodes belonging to the i-th node.

[0084] After derivation and back substitution, check the convergence of voltage. When |V i t+1 -V i t |≤ε, the voltage change meets the convergence condition, and then the final power flow information is obtained, which includes the voltage (including amplitude and phase angle) at each node of the multi-distribution area flexible interconnection system, the distribution of active power and reactive power; if the voltage change does not meet the convergence condition, the derivation and back substitution process is repeated.

[0085] Among them, V i t represents the voltage of the ith node at the tth iteration, V i t+1 represents the voltage of the i-th node at the t+1-th iteration, and ε represents the tolerance.

[0086] S3. The power exchange between stations will generate certain power loss on the DC bus. The power loss on the DC bus is related to multiple factors such as the DC bus voltage, transmission power, and distance. Therefore, it is difficult to express the power loss with an accurate formula. Therefore, the present invention uses the power transmission loss coefficient to calculate the power loss on the DC bus and obtain the constraints between the powers. The specific contents are:

[0087] Assuming that there is no power loss in the AC-DC conversion of the flexible interconnection device, the power transmission loss on the DC side is calculated. The specific formula is:

[0088]

[0089] Among them, P loss1 represents the power transmission loss on the DC side, It represents the active power flowing into the AC measurement from the DC side of the u-th substation, It represents the active power flowing from the AC side to the DC side of the u-th substation, k1 represents the DC power transmission loss coefficient, and n represents the total number of substations.

[0090] The power balance equation that needs to be satisfied is:

[0091]

[0092] In the flexible interconnection mode, in addition to exchanging energy with other substations through interconnection devices, the substation also exchanges energy with the 10kV distribution network through AC transformers. Therefore, based on the substation impedance and load data, the forward-backward method is used to calculate the AC side transmission loss. The specific formula is:

[0093]

[0094] Among them, P loss2 represents the AC side power transmission loss, k2 represents the AC power transmission loss coefficient, Represents the active power on the low-voltage side of the AC transformer in the u-th substation.

[0095] Since the capacity of the flexible interconnection device is limited, the active power transmitted and reactive power generated by the flexible interconnection device have corresponding constraints, and the specific expression is:

[0096]

[0097] Among them, Q u represents the reactive power generated by the flexible interconnection device in the u-th substation, S u Represents the capacity of the flexible interconnection device of the u-th station.

[0098] S4, using the SQP optimization algorithm to optimize the power loss in step S3, obtain the power control instructions of the flexible interconnection system of multiple distribution areas, and complete the control optimization; the specific content is:

[0099] The present invention takes minimizing power loss as the optimization goal, and coordinates and controls the power output by the flexible interconnection devices in each substation, and realizes the minimization of power loss in the flexible interconnection system of multiple distribution substations under the premise of satisfying a series of constraints such as system power balance constraints and equipment operation constraints. The objective function to be optimized is:

[0100] f(x)=P loss1 +P loss2

[0101] Where f(x) represents the total power loss of the flexible interconnection system in multiple distribution areas, that is, the objective function; P loss1 Represents the power transmission loss on the DC side; P loss2 Indicates the power transmission loss on the AC side.

[0102] In addition to the power balance constraints and equipment operation constraints, in the multi-distribution area flexible interconnection system, the voltage of each node meets the allowable deviation of the power supply voltage. The specific expression is:

[0103] -7%V N ≤ΔV i ≤7%V N

[0104] Among them, V N Indicates the standard voltage rating, ΔV i Indicates the deviation of each node voltage from the standard voltage rating.

[0105] SQP (Sequential Quadratic Programming) is an efficient algorithm for nonlinear optimization problems. It decomposes the original nonlinear optimization problem into a series of quadratic programming sub-problems, each of which can be solved more easily and gradually approach the optimal solution of the original problem.

[0106] like Figure 2 As shown, the SQP algorithm is used to optimize the objective function, select the initial point x0, set the initial Hessian matrix H0 to the unit matrix, and set the tolerance value; in each iteration, at the kth iteration point x k Linearize the constraints and construct the quadratic programming subproblem based on the second-order Taylor expansion of the objective function. The specific formula is:

[0107]

[0108] st▽c i (x k ) T d+c i (x k )≤0

[0109] ▽h j (x k ) T d+h j (x k )=0

[0110] Where d represents the search direction, H k represents the approximate value of the Hessian matrix of the objective function f(x), ▽f(x k ) represents the gradient of the objective function at the kth iteration point, ▽c i (x k ) and ▽h j (x k ) represent the gradient of the constraint function.

[0111] The standard quadratic programming algorithm is used to solve the power command of the flexible interconnection system in multiple distribution areas, obtain the search direction, perform line search along the search direction to determine the step size, and update the iteration point. The specific formula is:

[0112] x k+1 =x k +α k dk

[0113] Among them, x k+1 represents the k+1th iteration point, α k represents the step size of the kth iteration point, d k Indicates the search direction of the kth iteration point.

[0114] Use the quasi-Newton method to update the approximate value H of the Hessian matrix at the k+1th iteration point k+1 , determine whether the step tolerance (StepTolerance), optimality tolerance (OptimalityTolerance), maximum number of function evaluations (MaxFunctionEvaluations) and maximum number of iterations (MaxIterations) meet the termination conditions.

[0115] For step size tolerance, when the norm of the power instruction update step size of the flexible interconnection device is less than 1×10 -6 , then the condition is met.

[0116] For optimality tolerance, when the gradient norm of the objective function is less than 1×10 -6 When , the condition is met, and the specific expression is:

[0117] ||▽f(x)‖<1×10 -6

[0118] Among them, ▽f(x) represents the gradient of the objective function.

[0119] For the maximum number of function evaluations, the condition is met when the number of evaluations of the objective function reaches 10,000.

[0120] For the maximum number of iterations, the condition is met when the number of iterations reaches 2000.

[0121] When any one of the step size tolerance, optimality tolerance, maximum number of function evaluations, and maximum number of iterations meets the conditions, the termination condition is met.

[0122] When the termination condition is met, the optimization is stopped, the current optimal solution is output, and the power control instructions of each flexible interconnection device, that is, the optimal scheduling solution, are obtained.

[0123] In this embodiment, the low-voltage power distribution system is an important part of the power system, and its wiring form determines the reliability and efficiency of power supply. The following are three common wiring forms: radial, trunk and chain. The present invention uses the trunk type to perform low-voltage area interconnection calculation example analysis. Figure 3The diagram shows the structure of three 9-node substations connected by a flexible interconnection device using a trunk wiring. Flexible interconnection devices are installed on the low-voltage side of the transformers in the three substations to adjust the substation voltage. Figure 3 The multi-distribution area flexible interconnection system is analyzed, and the example data are shown in Table 1.

[0124] Table 1 Parameters and values ​​of the flexible interconnection system in multiple distribution areas

[0125]

[0126]

[0127] The voltage distribution diagram before and after optimization is as follows Figure 4 As shown in the figure, after optimization, the voltage deviation returns to the allowable deviation of the power supply voltage, and the quality of the power supply voltage is improved. Before optimization, the total power loss is 2.528kW, and after optimization, the total power loss is 0.761kW, which is greatly reduced.

[0128] The embodiment of the present invention further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. It should be noted that when the processor executes the computer program, the specific steps of the method provided in the embodiment of the present invention are corresponding to the specific steps of the method provided in the embodiment of the present invention, and the processor has the functional modules and beneficial effects corresponding to the execution method. For technical details not described in detail in this embodiment, please refer to the method provided in the embodiment of the present invention.

[0129] The embodiment of the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. It should be noted that when the computer program is executed by the processor, it corresponds to the specific steps of the method provided in the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not described in detail in this embodiment, please refer to the method provided in the embodiment of the present invention.

[0130] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A global optimization control method for flexible interconnected photovoltaic areas based on sequential quadratic programming, characterized in that: include: S1. The DC port of a selected converter adopts a constant voltage control strategy to maintain the voltage stability of the DC bus, and the DC ports of the remaining converters adopt a constant power control strategy; S2, read the data information of the substation area, generate real-time data, and obtain the final power flow information by deducing and back-substituting the nodes of the flexible interconnection system of multiple distribution substations; S3, using the power transmission loss coefficient to calculate the power loss on the DC bus and obtain the constraints between the powers; S4. Use the SQP optimization algorithm to optimize the power loss in step S3, obtain the power control instructions of the flexible interconnection system of multiple distribution areas, and complete the control optimization.

2. The method for global optimization and control of flexible interconnected photovoltaic areas based on sequential quadratic programming according to claim 1 is characterized in that: In step S1, a voltage source converter is selected as the converter.

3. The method for global optimization and control of flexible interconnected photovoltaic areas based on sequential quadratic programming according to claim 1 is characterized in that: In step S2, the data information includes transmission line impedance information, real-time load conditions and photovoltaic output conditions.

4. The method for global optimization and control of flexible interconnected photovoltaic areas based on sequential quadratic programming according to claim 3 is characterized in that: In step S2, the final flow information obtained includes the following contents: According to the load power and initial voltage of the branch, the current of the node is calculated. The specific formula is: Among them, I i represents the current flowing into the i-th node; S i represents the complex power of the ith node; V i represents the voltage of the i-th node; The voltage is derived from the source node to the end node, and the node voltage drop of the branch (i, j) from the i-th node to the j-th node is calculated according to Ohm's law. The specific formula is: V j =V i -Z ij I j Among them, Z ij represents the line impedance from the i-th node to the j-th node, I j represents the current flowing into the jth node, V j represents the voltage of the jth node; Starting from the end node of the flexible interconnection system in the multi-distribution area, back-substitution is performed, and the current of the branch is calculated step by step to the source node. The specific formula is: Among them, I k represents the current flowing into the kth child node, and children of i represents the set of child nodes belonging to the i-th node; After derivation and back substitution, check the convergence of voltage. When |V i t+1 -V i t |≤ε, the voltage change meets the convergence condition, and then the final power flow information is obtained, which includes the distribution of voltage, active power and reactive power at each node of the multi-distribution area flexible interconnection system; if the voltage change does not meet the convergence condition, the derivation and back substitution process is repeated; Among them, V i t represents the voltage of the ith node at the tth iteration, V i t+1 represents the voltage of the i-th node at the t+1-th iteration, and ε represents the tolerance.

5. The method for global optimization and control of flexible interconnected photovoltaic areas based on sequential quadratic programming according to claim 1 is characterized in that: In step S3, calculating the power loss includes the following: Assuming that there is no power loss in the AC-DC conversion of the flexible interconnection device, the power transmission loss on the DC side is calculated. The specific formula is: Among them, P loss1 represents the power transmission loss on the DC side, It represents the active power flowing into the AC measurement from the DC side of the u-th substation, represents the active power from the AC measurement of the u-th substation to the DC side, k1 represents the DC power transmission loss coefficient, and n represents the total number of substations; The power balance equation that needs to be satisfied is: Based on the impedance and load data of the substation area, the transmission loss on the AC side is calculated using the forward-backward method. The specific formula is: Among them, P loss2 represents the AC side power transmission loss, k2 represents the AC power transmission loss coefficient, represents the active power on the low-voltage side of the AC transformer in the u-th substation; The active power transmitted and reactive power emitted by the flexible interconnection device have corresponding constraints, and the specific expressions are: Among them, Q u represents the reactive power generated by the flexible interconnection device in the u-th substation, S u Represents the capacity of the flexible interconnection device of the u-th station.

6. The method for global optimization and control of flexible interconnected photovoltaic areas based on sequential quadratic programming according to claim 1 is characterized in that: Step S4, obtaining a power control instruction includes the following contents: The objective function to be optimized is: f(x)=P loss1 +P loss2 Where f(x) represents the total power loss of the flexible interconnection system in multiple distribution areas, that is, the objective function; P loss1 Represents the power transmission loss on the DC side; P loss2 Indicates the power transmission loss on the AC side; In the flexible interconnection system with multiple distribution areas, the voltage of each node meets the allowable deviation of the power supply voltage. The specific expression is: -7%V N ≤ΔV i ≤7%V N Among them, V N Indicates the standard voltage rating, ΔV i Indicates the deviation of each node voltage from the standard voltage rating; The objective function is optimized using the SQP algorithm. The initial point x0 is selected, the initial Hessian matrix H0 is set to the unit matrix, and the tolerance value is set. In each iteration, the kth iteration point x k Linearize the constraints and construct the quadratic programming subproblem based on the second-order Taylor expansion of the objective function. The specific formula is: s.t.▽c i (x k ) T d+c i (x k )≤0 ▽h j (x k ) T d+h j (x k )=0 Where d represents the search direction, H k represents the approximation of the Hessian matrix of the objective function f(x), ▽f(x k ) represents the gradient of the objective function at the kth iteration point, ▽c i (x k ) and ▽h j (x k ) represent the gradient of the constraint function; The standard quadratic programming algorithm is used to solve the power command of the flexible interconnection system in multiple distribution areas, obtain the search direction, perform line search along the search direction to determine the step size, and update the iteration point. The specific formula is: x k+1 =x k +a k d k Among them, x k+1 represents the k+1th iteration point, α k represents the step size of the kth iteration point, d k Indicates the search direction of the kth iteration point; Use the quasi-Newton method to update the approximate value H of the Hessian matrix at the k+1th iteration point k+1 , determine whether the step size tolerance, optimality tolerance, maximum number of function evaluations and maximum number of iterations meet the termination conditions; When any one of the step size tolerance, optimality tolerance, maximum number of function evaluations, and maximum number of iterations meets the conditions, the termination condition is met; When the termination condition is met, the optimization is stopped, the current optimal solution is output, and the power control instructions of each flexible interconnection device, that is, the optimal scheduling solution, are obtained.

7. The method for global optimization and control of flexible interconnected photovoltaic areas based on sequential quadratic programming according to claim 6 is characterized in that: For step size tolerance, when the norm of the power instruction update step size of the flexible interconnection device is less than 1×10 -6 , then the condition is met; For optimality tolerance, when the gradient norm of the objective function is less than 1×10 -6 When , the condition is met, and the specific expression is: ||▽f(x)||<1×10 -6 Among them, ▽f(x) represents the gradient of the objective function; For the maximum number of function evaluations, the condition is met when the number of evaluations of the objective function reaches the set number of evaluations; For the maximum number of iterations, the condition is met when the number of iterations reaches the set number of iterations.

8. 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, the steps of the global optimization control method of flexible interconnected photovoltaic stations based on sequential quadratic programming as described in any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the global optimization control method of flexible interconnected photovoltaic stations based on sequential quadratic programming described in any one of claims 1 to 7 is executed.

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